chapter 1 neck

8/10/2019 Chapter 1 Neck

1/125

5/24/2014 Print: Chapter 1. Neck

http://web.uni-plovdiv.bg/stu1104541018/docs/res/skandalakis'%20surgical%20anatomy%20-%202004/Chapter%2001_%20Neck.htm 1/

Print | Close Windo

Note:Large images and tables on this page may necessitate printing in landscape mode.

Skandalakis' Surgical Anatomy > Chapter 1. Neck >

NECK: GENERAL

HISTORY

The anatomic and surgical history of the general neck, thyroid, parathyroids, trachea, and salivary glands is shown in Table 1-1.

Table 1-1. Anatomic and Surgical History of the Neck, Thyroid, Parathyroids, Trachea, and Salivary Glands

Egypt 2780-2280B.C.

Statues show signs of Graves' disease

India 2000-1000B.C.

The Hindu Rig Vedamentions tracheal cannulation

China 1600B.C.

Used burnt sponge and seaweed to treat goiters

Sushruta 600B.C.

Introduced the nasolabial flap

India 400B.C.

TheAyur Vedadiscusses the treatment and diagnosis of goiters

Egypt 69-30B.C.

A temple wall engraving shows Cleopatra with goiter

Celsus 50-30B.C.

Described the appea rance and surgery of cystic goiters

Galen (ca. 130-200 A.D.)

Considered the thyroid a buffer betwe en the heart and the brain. Called the thyroid cartilage thyreos,meaning "oblong shield."

Paul of Aegina(625-690)

Surgically treated a bronchocele. Attributed parotitis to humoral imbalance in the head (collecting in the parotid gland during fevers, forexample).

Ali-ibn-Abbas ca.990

Reported on the surgical treatment of goiters

Abul CasenEbn Abbas(Albucasis)

1050 Treated "elephantiasis" of the throat (goiter) surgically and stopped hemorrhage using Khalaf cautery and ligatures

Wang Hei 1475 Described the thyroid gland while recommending that dried thyroid be used to treat goiterda Vinci (1452-1519)

Provided illustrations of the thyroid glands

Par (1510-

1590)

Described the parotid glands as "emunctories of the brain"

Vesalius 1543 Wrote of and il lustrated the "Glandes laryngis radici adnatae" (thyroid glands) in Fabrica

Eustachius 1563 Described the connection point of the two thyroid lobes as an "isthmus"

Severino(1580-1656)

Performed a tracheotomy to open an obstructed airway. Constructed a trocar to maintain air passage after the procedure.

Casserio 1601 Described the thyroid glands, calling them "the glands of the larynx"

Fabricius 1620 Thought of a goiter as an enlargement of the thyroid glands

Feyens 1649 Performed a tracheotomy, ca lling it a "bronchotomy"

Wharton 1656 Used the term "thyro id" correct ly in hisAdenographia.He be lieved that it se rved to lubricate, drain, and warm the larynx.

Hesiter (1683-1758)

Established the term "tracheotomy," and provided the first description of surgical excision of goiter

Von Haller 1743 First to describe a carotid body tumor

Duphenix 1757 Wrote of gus ta to ry swea ting in the Memoirs de L'Academie Royale de Chirurgie

Gooch 1773 Reported two thyroidectomies

Von Haller 1776 Classified the thyroid, thymus, and spleen as glands without ducts that release their fluids into the bloodstream

Parry 1786 Offe red an o rig ina l a ccount of exophthalmic goite r

Desault 1791 Reported a successfu l excis ion of part of the thyro id

Blizzard 1811 Successfully ligated the superior thyroid arteries, offering another form of thyroidectomy

Coindet 1820 Recommended iodine as a treatment for goiter

Parry 1825 In a posthumously published paper (d. 1822), he first described the effects of "thyrotoxicosis" now known as Graves' disease (in England)and Basedow's disease (in Europe)

Graves 1835 Observed and described effects of an overact ive thyro id


2/125



Owen 1852 Described the para thyro id gland o f a rh inoce ros

Buck 1853 Performed a partial laryngectomy

Lushka 1862 Described ca ro tid body tumors in great de ta il

Cze rny 1870 Perfo rmed la ryngectomies on 5 dogs (4 died)

Gull 1873 Described primary myxedema

Billroth 1873 As reported by Gussenbauer in 1874, he performed a laryngectomy

P. Von Bruns 1878 Argued, "The attempt at radical extirpation of cancer of the larynx by means of thyrotomy has proved itself completely unsatisfactory andworthless."

Re igner 1880 Attempted excis ion o f a ca ro tid body tumor

Sandstrm 1880 Described the parathyroid glands, suggesting they were embryonic portions of the thyroid

Rehn 1880 Perfo rmed a thyro idectomy to treat exophtha lmic go ite r

Steida 1881 Described thyroid development

Billroth 1881 Reported 48 thyroidectomies performed since 1877, in which only four patients died. First to use artery forceps to prevent and stophemorrhage. Noted the presence o f post-surgical tetany in many of his patients.

Kocher 1883 Reported his first 100 thyroidectomies (30 of which were total thyroidectomies). Method involved ligating the thyroid arteries outside thecapsule and the gland with an aneurysm needle, and ligating as close to the carotid artery as poss ible. Used a transverse collar incision nowbearing his name. Noted the presence o f "cachexia stermipriva" or po stoperative myxedema in his total thyroidectomy patients.

Born 1885 First used term "lateral thyroid"

Von Mikulicz-Radecki

1886 Described and pe rformed subto tal thyroidectomy to avoid complications arising from removal of the gland

Maydl 1886 Successfully removed a carotid body tumor. The patient suffered a postoperative stroke, causing hemiplegia and aphasia, and later died.

Horsley 1886 Observed nervous system depression after thyroidectomy in monkeys. Concluded that the thyroid secreted a vital substance.

M. Mackenzie 1887 Opposed total laryngectomy in the case of Emperor Frederick II of Prussia

Von Mikulicz-Radecki

1888 Reported a case in which the patient experienced sweating involving submandibular (submaxillary) and parotid gland swe lling (later namedMikulicz' disease)

Albert 1889 Successfully removed a carotid body tumor without postoperative stroke

VonRecklinhausen

1891 Observed and described os teitis fibrosa cystica in hyperparathyroidism

Gley 1891 Described tetany following removal of the parathyroid glands during thyroidectomy

Kocher 1895 Reported 900 cases of thyroidectomy with a mortality rate slightly higher than 1%. Avoided total thyroidectomies whenever possible.

1898 Reported an additional 600 thyroidectomies with only 1 operative death (caused by anesthesia).

Vassale andGenerali

1896 Introduced the term "parathyroid"

Butlin 1900 Advocated clearing out the anterior triangle of the neck (especially its lymphatic component) to combat the spread of metastatic disease fromthe tongue

Loeb 1901 Observed occurrence of tetany in frog muscle deprived of ca lcium

M. Askanazy 1903 Hypothesized on the relation between parathyroid tumors and osteitis fibrosa cystica

C. Mayo 1904 Presented a paper on thyroid surgery to the American Surgical Association. Reported 40 cases of Graves' disease that were treated bythyroidectomy.

Erdheim 1906 Studied the relationship between parathyroid glands and calcium metabolism, noting compensatory hypertrophy and osteomalacia

Halsted 1906 Provided dietary supplements of parathyroid glands from cattle to confront clinical tetany. Experimented with transplantation of theparathyroids.

Crile 1906 Reported on 132 cases in which he performed a radical neck excision. Procedure included en-bloc resection of the regional lymph nodes,sternocleidomastoid muscle, internal jugular vein, and submandibular (submaxillary) salivary gland.

C . Mayo 1907 Firs t to use the te rm "hyperthyro idism"

MacCallum andVoegtlin

1908 Studied hypoparathyroidism and its relation to low se rum calcium. Found that injecting calcium relieved tetany.

C. Jackson 1909 Performed the first modern tracheostomy

C. Mayo 1912 Operated on 278 patients with exophthalmic goiter without a death. Recommended the division of the strap muscles for adequate exposure(visualization of the recurrent laryngeal nerve) and for the prese rvation of the parathyroids to decrease the risk of tetany.

Kendall 1914 Isolated thyroxineSchlagenhaufer 1915 Found that a tumor, not compensa tory hypertrophy, is present in osteitis fibrosa cystica. Recommended the excision of parathyroid tumors.

Lipsztat 1922 Observed gustatory sweating near the parotid gland

L. Frey 1923 Published article on auriculotemporal nerve syndrome involving the parotid gland. The disease was later named Frey's syndrome.

Hanson 1924 Extracte d para thyro id ho rmone

Mandl 1925 Removed a parathyroid adenoma

Harington 1926 Determined the chemical structure of thyroxine

Collip 1926 Linked hyperparathyroidism to elevated serum calcium (also isolated parathyroid hormone in 1925)

DuBois 1926 Removed a parathyroid adenoma finally found in the mediastinum after seven previous explorations in a patient with osteitis fibrosa

cystica due to hyperparathyroidism

Harington andBarger

1927 Synthesized thyroxine

Weller 1933 Believed that 3 primordia are responsible for thyroid genesis ("lateral thyroid primordium")


3/125



Gilmour 1938 Published his studies on the gross and histological anatomy of the parathyroid glands

Hyde 1944 Reported on the to ta l remova l o f a ce rvica l thymic cys t

Ramsay 1950 Transplanted and cultured the 4th pharyngeal apparatus; was not able to produce thyroid tissue, but produced parathyroid and thymic tissu

Wendlet 1950 Synthesized cortisol

Martin 1951 Published Neck Dissection,which outlined his experiences w ith prophylactic neck dissection as a treatment for cervical cancer

Gross and Pitt-Rivers

1953 Extracted triiodothyronine from the thyroid gland. Later synthesized it as liothyronine.

Redon 1955 Published his class ic report on the surgery of the sa livary glands

Martin 1957 Published his classic work, Surgery of Head and Neck Tumors

Patey,

Thackray, andKeeling

1965 Published an extensive report describing the behavior of salivary gland tumors and their treatment

Pearse 1966 Renamed the interfollicular cells the "C" cells because of their calcitonin-producing properties

Toye andWeinstein

1969 Established the concept of minimally invasive airway access for surgery

Beahrs 1977 Detailed technique and surgical anatomy of radical neck dissection

Conley andClairmont

1977 Described the use of the scapula flap for reconstruction

Futrell et al. 1978 Described platysma myocutaneous flap use in neck reconstruction

Ariyan 1979 Described the use of the pectoralis major myocutaneous flap in neck reconstruction

Panje et al. 1987 Described gastroomental flap use in neck reconstruction

Gaz 1987 Noted the unusual location of parathyro id g lands in surg ica l pat ients

History table compiled by David A. McClusky III and John E. Skandalakis.

References:

Albright F. A page out o f the history of hyperparathyroidism. J Clin Endocrinol 1948;8:637-657.

Ariyan S. The pectoralis major myocutaneous flap: a versatile flap for reconstruction in the he ad and neck. Plast Reconst r Surg 1979;63:73-81.

Beahrs OH. The surgical anatomy and technique of parotidectomy. Surg Clin North Am 1977;57:477.

Beahrs OH. Presidential Address: Lest we forget. Surgery 1987;102:893-897.

Becker WF. Presidential Address: Pioneers in thyroid surgery. Ann Surg 1977;185:493-504.

Burton MJ, Brochwicz-Lewinski M. Lucja Frey and the auriculotemporal nerve syndrome. J Roy Soc Med 1991;84:619-620.

Cady B. History of thyroid and parathyroid surgery. In: Cady B, Rossi RL (eds). Surgery of the Thyroid and Parathyroid Glands (3rd ed). Philadelphia: W.B. Saunders,1991. pp. 1-4.

Colcock BP. Lest we forget: A story of five surgeons . Surgery 1968;64:1162-1171.

Conley JJ, Clairmont AA Jr. Regional flaps in ab lative surgery in the head and neck. Am Fam Physician 1977;15:100-105.

Futrell JW, Johns ME, Edgerton MT, Cantrell RW, Fitz-Hugh GS. Platysma myocutaneous flap for intraoral reconstruction. Am J Surg 1978;136:504-507.

Givel JC. Historical review. In: Givel JC (ed). Surgery of the Thymus: Pathology, Associated Disorders and Surgical Technique. Berlin: Springer-Verlag, 1990, pp. 1-8.

Gray SW, Skandalakis JE, Akin JT Jr, Droulias C, Vohman MD. Parathyroid glands. Am Surg 42(9):653-656, 1976.

Ioannides C, Fossion E. Nasolabial flap for the recons truction o f defects of the floor of the mouth. Int J Oral Maxillofac Surg 1991;20:40-43.

Liapis C, Gougoulakis A, Karydakis V, Verikokos C, Doussaitou B, Skandalakis P, Gogas J, Sechas M. Changing trends in management of carotid body tumors. Am Surg1995;61:989-993.

McIntosh D. Surgical interests in some a nomalies of the cervical viscera. J R Coll Surg Edinburgh 1979;24(4):191-204.

Martin H. Surgery of Head and Neck Tumors. New York: Hoeber-Harper, 1957, pp. 3-13.

Martin H, Valle BD, Ehrlich H, Cahan WG. Neck dissection. Cancer 1951;4:441-499.

Nelson WR. In sea rch of the first head and neck surgeon. Am J Surg 1978;154:342-346.

Pahor AL. Historical article: Ear, nose and throat in ancient Egypt. J Laryngol Otol 106:863-873, 1992.

Panje WR, Little AG, Moran WJ, Ferguson MK, Scher N. Immediate free gastro-omental flap reconstruction of the mouth and throat. Ann Otol Rhinol Laryngol

1987;96:15-21.

Ramsay AJ. Experimental stud ies on the developmental potentialities of the third pharyngeal pouch in the mammalian embryo (mouse). Anat Rec 1950;106-234.

Schwartz SI. Little glands, big names (editorial). Contemp Surg 1993;42:402.

Wilkins EW Jr. Thymoma. In: Pearson FG, Deslauriers J, Hiebert CA, McKneally MF, Ginsberg RJ, Urschel HC (eds). Thoracic Surgery. New York: Churchill Livingstone,1995, p. 1419.

Wilkins EW Jr. Thymectomy. In: Pearson FG, Deslauriers J, Hiebert CA, McKneally MF, Ginsberg RJ, Urschel HC (eds). Thoracic Surgery. New York: Churchill Livingstone,1995, p. 1483.

EMBRYOGENESIS OF THE NECK

Normal Development

The neck, as seen in the adult human, does not exist in the embryo. The embryogenesis of the region is that of the organs contained within it: chiefly thepharynx and its derivatives, the thyroid, parathyroid, and thymus gland (the last is also considered part of the superior mediastinum). In addition, vesselspassing through the neck from the head to the thorax are elongated and modified during the course of development.


4/125



The pharynx elongates at 5 weeks and the esophagus elongates later. After the diaphragm has descended, these three structures separate the head of thedeveloping embryo from the relatively large heart. By 7 weeks, a neck is visible (Fig. 1-1). Further details of differentiation and migration will be discussed inthe chapters on the specific organs.

Fig. 1-1.

The development of the neck. A,Fifth week. Prominent branchial arches mark the s ite of the neck. B,Seventh week. Branchial arches are reduced, a constrictionappears between head and thorax. C,Twelfth week. From this s tage on, the true neck is present. (Modified from Skandalakis JE, Gray SW, Rowe JS Jr. AnatomicalComplications in General Surgery. New York: McGraw-Hill, 1983; with permission.)

We present a very brief description of the pharyngeal apparatus to help the student understand clinically applicable accounts of the autogenic origin of themany anatomic entities of the neck, as well as their phylogenetic significance. The embryonic pharynx consists of a lateral branchial apparatus on each side,and the unpaired ventral floor between them. Each lateral branchial apparatus is formed by endodermal pouches, ectodermal branchial clefts, mesodermalbranchial arches, and branchial membranes (c losing plates).

The unpaired floor is of endodermal origin and produces the tongue, thyroid gland, larynx, and trachea. The embryogenesis of the four arches starts in the

fourth and fifth weeks. They are marked externally by the four ectodermal branchial or pharyngeal clefts on each side. At the same time, the pharyngealpouches develop internally. Characteristically, they do not communicate with the clefts.

The bridges between the arches are the branchial membranes, or closing plates, which are formed by the ectoderm and endoderm (Figs. 1-2, 1-3).

Fig. 1-2.


5/125



Drawings illustrating the human branchial apparatus. A,Dorsal view o f the cranial part of an early embryo. B to D,Lateral views, show ing later development of thebranchial arches. E to G,Facial views, illustrating the relationship of the first a rch to the stomodeum or primitive mouth. H,Transverse section through the cranialregion of an embryo, illustrating the branchial arch components a nd the floor of the primitive pha rynx. I,Horizontal section through the cranial region of an embryo,illustrating the branchial arch components and the floor of the p rimitive pha rynx. Each arch contains a cartilaginous component, a nerve, an a rtery, and a muscularcomponent. J,Sagittal section of the upper region of an e mbryo, illustrating the open ings of the pharyngeal pouches in the lateral wall of the primitive pharynx.

(Based on Moore KL. The Developing Human: Clinically Oriented Embryology. Philadelphia: WB Saunders, 1973.)

Fig. 1-3.


6/125



Branchial grooves, branchial arches, pharyngeal pouches, and closing plates. (Modified from Brantigan OC. Clinical Anatomy. New York: McGraw-Hill, 1963; withpermission.)

Remember

All pharyngeal grooves (clefts) disappear except the first one, which remains as the external auditory canal (external auditory meatus).

All the pharyngeal membranes (closing plates) disappea r except the first one, which remains as the tympanic membrane (eardrum).

The pharyngeal arches:

The first (mandibular) pharyngeal arch is responsible for the embryogenesis of the muscles of mastication, the upper and lower jaws , and the chee k and lowe reyelids. Innervation is by the mandibular branch of the trigeminal nerve (V), and its b lood supply is from the facial artery.

The second (hyoid) pharyngeal arch is respons ible for the embryogenesis of the muscle of facial expression and for the styloid process, stylohyoid muscle,stylohyoid ligament, part of the hyoid bone, the sta pes and stapedius muscle, and the pos terior belly of the digastric muscle. Its nerve is the facial (VII), and itsartery is the external carotid.

The only muscle thought to be derived from the third (thyrohyoid or glossopharyngeal) pharyngeal arch is the s tylopharyngeus. It is innervated by the


7/125



glossopha ryngeal nerve. The artery is the common carotid.

The fourth pharyngeal arch is unnamed. It is responsible for the embryogenesis o f the cricothyroid muscle of the larynx. Its nerve is the superior laryngeal branchof the vagus nerve.

For all practical purposes, the fifth arch does not exist.

The sixth a rch fuses w ith the fourth for the formation of the laryngeal cartilages, thyroid cartilage, and perhaps the aortic arch, right subclavian a rtery, pulmonaryarteries, and ductus a rteriosus. Mesoderm of the sixth arch is responsible for the embryogenesis of the pharyngeal constrictors, pharyngeal muscles, and thelaryngeal muscles. Its nerve is the recurrent branch of the vagus ne rve.

The pharyngeal pouches:

The first pharyngeal pouch is responsible for the embryogenesis o f the eus tachian tube, tympanic cavity, mastoid antrum (about 9 th month of ges tation), and

mastoid air cells (about 2 years of age). Small benign growths called cholesteatoma2in the form of thickenings of the endodermal lining of the middle ea r developand a re said to commonly cause hearing losses. While their origin is not fully understood, it is believed that they form normally in all embryos, but occasionally somepersist and proliferate to form these growths.

The second pharyngeal pouch produces the palatine tonsils and the tonsillar fossa.Note:A persisting second plate opening can appear as a branchial cleft sinus,notoriously open into the tonsillar fossa.

The third pharyngeal pouch: the dorsa l part is responsible for the genes is of the lower parathyroids (parathyroids III); the ventral part for the thymus. In the adupharynx, the piriform recess is the site o f the third pouch.

The fourth pharyngeal pouch: the dorsal part is responsible for the genesis of the upper parathyroids (parathyroids IV); the ventral part may be involved with asmall amount o f thymic tissue and w ith the ultimobranchial body.

For all practical purposes, the fifth pharyngea l pouch, like the fifth pharyngea l arch, does no t exist.

Congenital Anomalies

Fistulas, external and internal sinuses, and cysts are the result of obliteration of pharyngeal clefts and pouches. Thymic and parathyroid deficiencies (e.g.,DiGeorge syndrome) are secondary to partial or total agenesis of the parathyroid and thymus glands.

Neck hygromas are congenital malformations of the lymphatic system of the neck. Gidvani and Bhowmick3indicated that cystic hygromas are commoncongenital neck masses, tend to develop in the left posterior triangle, and appear early in life. The authors reported the case of a posterior cervical midlinecystic hygroma.

Remember

Most pharyngeal fistulas and cysts originate from the second pharyngeal pouch and cleft.

Fistulas of the s econd pouch open a t the lower one-third of the medial border of the s ternocleidomastoid (SCM) muscle.

Anomalies o f the first cleft are related to the facial nerve.

A pharyngeal sinus o r fistula typically travels from the pharyngeal wall, between the internal and external carotid arteries, to reach the skin. In 1993, Miller and

Cohn4presented the 31st report of a fourth branchial pouch sinus.

SURGICAL ANATOMY

Surface Anatomy

Landmarks

The most prominent landmarks of the surface anatomy of the neck, especially in males, are as follows:

The sternocleidomastoid muscle separates the ante rior part of the neck (anterior triangle) from the pos terior part of the neck (posterior triangle).

In males with well-developed musculature, the lateral portion of the trapezius muscle produces much of the fullness o f the gentle curve that joins the lateral

posterior part of the neck with the s houlder region. The anterior tuberosity of the transverse process of the s ixth cervical vertebra (carotid tubercle of Cha ssaignac) located at the medial border of the sternocleidomastoid and a t the level of the cricoid cartilage. Pressure a t this point w ill compress the common carotid artery.

In the midline, from above downw ard, the following landmarks are noted:

The most prominent midline feature and the most readily palpated is the thyroid cartilage, the "Adam's apple," which is especially prominent in post-pubertal maleIt is located between the third and fifth cervical vertebrae. The bifurcation of the common carotid artery is located on the horizontal plane at this level. Variations inthe site of division of the carotid artery will always be located above this point.

The body of the hyoid bone can be palpated at about 1.5 cm above the thyroid cartilage at the level of the third cervical vertebra. (Note:At the midpoint of a linebetween the mastoid process and the thyroid prominence, the greate r horn of the hyoid bone can be palpated laterally.)

The arch of the cricoid cartilage is palpable jus t inferior to the thyroid cartilage. The cricoid cartilage forms the only complete cartilaginous ring around the a irway,something that is not observed with the o ther cartilages of the respiratory system.

The cricoid cartila e is located at the level of the s ixth cervical vertebra.


8/125



A horizontal plane approximately at the junction of the s ixth and seventh cervical vertebrae can be associated w ith the following anatomic entities (Figs. 1-4, 1-5, 16, and 1-7):

pharyngoesophageal junction

laryngotracheal junction

inferior thyroid artery (which is ventral to the middle cervical ganglion), and then (in order), the carotid sheath, and the omohyoid muscle

entrance of the inferior laryngeal nerve (recurrent ne rve) into the larynx

entrance of the vertebral artery into the transverse foramen o f the s ixth cervical vertebra and, slightly more inferiorly, the s tellate ganglion

thyroid isthmus and the g reatest height of the thoracic duct, which are located at the level of the s eventh cervical vertebra

Fig. 1-4.

The third cervical vertebra is at the level of the hyoid bone; the fourth and fifth cervical vertebrae a re at the level of the thyroid cartilage. (Modified from BrantiganOC. Clinical Anatomy. New York: McGraw-Hill, 1963; with permission.)

Fig. 1-5.


9/125



Sixth cervical vertebra. (Modified from Brantigan OC. Clinical Anatomy. New York: McGraw-Hill, 1963; with permission.)

Fig. 1-6.

Seventh cervical vertebra. (Modified from Brantigan OC. Clinical Anatomy. New York: McGraw-Hill, 1963; with permission.)

Fig. 1-7.


10/125



Diagrammatic cross section through the neck below the hyoid bone show ing the layers of the deep cervical fascia and the structures that they envelop. (Modified

from Skandalakis JE, Gray SW, Skandalakis LJ. Surgical anatomy of the o esopha gus. In: Jamieson GG (ed). Surgery of the Oesophagus. Edinburgh: ChurchillLivingstone , 1988; with permission.)

Surgical Applications

The consistency of cervical skin changes with age. Hyperextension of the neck will give a better appreciation of the topography of the underlying structures inrelation to the skin.

The surgeon selects the proper incision and its placement in relation to the underlying pathology. The orientation of the connective tissues of the dermiscreates lines of tension in the skin, known as the lines of Langer, which are associated with skin creases of the body. Generally speaking, the transverse

incision is cosmetically superior to the vertical, since crossing the normal skin lines will produce a more prominent scar.

However, the vertical lines produce excellent exposure for surgery of the arteries. Most of the commonly used incisions in the neck are presented in Figures1-8 and 1-9. Combinations of vertical and transverse incisions can be used, if necessary. Remember, a superiorly-based apron flap should be used for neckdissection. Close the edges of the divided platysma muscle carefully, and reapproximate the margins of the skin incision meticulously to lessen the likelihoodof unsightly scarring from tension upon the skin.

Fig. 1-8.

Proper placement of incisions in the neck paralleling the normal lines and creases o f the skin. A,Excision of conge nital sinus: partial mobilization here and lowersegment at B1. B,Excision of carotid tumor or branchial cleft cyst. C,Diverticulum of esophagus. D,Scalenotomy or phrenic nerve interruption. E,Drainage ofsubmental abscess. F, Excision of thyroglossal cyst or sinus. G,Cricothyreotomy. H,Tracheotomy. I,Thyroidectomy. J,Drainage of cervical abscess at a ngle of jaw.K,Exposure o f internal or external carotid arteries. L,Exposure of common carotid artery. M,Exposure of brachial plexus or s ubclavian a rtery. (Modified from AnsonBJ, McVay CB. Surgical Anatomy (5th ed). Philadelphia, Saunders, 1971; with permission.)

Fig. 1-9.


11/125



Selected incisions used for classic radical neck dissection. A,Attie. B,Eckers and Byer. C,MacFee. D,Morestin. E,Conley. F,Latyshevsky and Freund. G,Martin. H,Z.I,Barbosa. (Modified from Strong EW. Radical neck dissection. In Nyhus LM, Baker RJ (eds). Mastery of Surgery, 2nd Ed. Boston: Little, Brown, 1992; withpermission.)

Roon and Christensen5subdivided the areas of the neck into three regions w ith respect to injuries:

High (above the angle of the mandible)

Middle (between the angle and the bo ttom of the cricoid cartilage)

Low (below the cricoid cartilage)

Surgeons continue to use Roon and Christensen's classification, but they now refer to zones (Fig. 1-10): Zone I is the area Roon and Christensen called"low"; Zone II, middle; Zone III, high.

Fig. 1-10.

Zones o f the neck. The junction of zones I and II is variously described as being at the cricoid cartilage or at the top of the clavicles. The important implication of azone I injury is the greater potential for intrathoracic great vessel injury. (Modified from Jurkovich GJ. Definitive care phase: neck injuries. In Greenfield LJ (ed).Surgery: Scientific Principles and Practice (2nd ed). Philadelphia: Lippincott-Raven, 1997, pp. 309-317; with permission.)

In the same study cited above, Roon and Christensen stated correctly, from an anatomic standpoint, that either high or low injuries can involve vesselswhere proximal and distal c ontrol is difficult. T hey advised immediate exploration.

Roden and Pomerantz6also advised early operation (neck exploration) for penetrating wounds of the neck. However, Atteberry et al.7found physical examinationalone to be safe and accurate for evaluation of vascular penetrating injuries in zone II of the neck.

However, Biffl et al.8stated that selective management of penetrating neck injuries is safe and does not require routine diagnostic testing for asymptomaticpatients with injuries in zones II and III.

We quote from Bumpous et al.9on penetrating injuries of the visceral compartment of the neck:

Zone II of the anterior neck was the most commonly injured area, with the trachea (69%), esophagus (38%), and larynx (31%) the most commonlyinjured structures. Although 31% underwent angiograms, only 13% showed vascular injuries. Eighty-one percent of the patients had injuries involving


12/125



more than 1 major structure of the neck. Neck exploration was performed in 81% of the patients and tracheostomies in 75% as well as repair of thetrachea (50%), larynx (31%), and esophagus (38%). There is significant mortality associated with these injuries...and many of the patients have long-term sequelae such as dysphagia, hoarseness, and prolonged tracheostomy.

For the evaluation of penetrating neck injuries, Demetriades et al.10concluded that physical examination and color-flow Doppler imaging are the diagnostictools of choice for the physician. They presented an algorithm for the evaluation of these injuries (Fig. 1-11).

Fig. 1-11.

Algorithm for evaluation of penetrating neck injuries. (From Demetriades D, Theodorou D, Cornwell E, Berne TV, Asensio J, Belzberg H, Velmahos G, Weaver F, YellinA. Evaluation of penetrating injuries of the neck: prospective study of 223 patients. Wo rld J Surg 1997;21:41-48; with permission.)

Britt and Cole11recommend a paradigm for penetrating neck injuries (Fig. 1-12).

Fig. 1-12.

- *


13/125



. , , , , . , ."Alternative" surgery in trauma management. Arch Surg 1998, 133:1177-1181; w ith permission.)

Topographic Anatomy of the Neck

The topography of the neck lends itself to description by using a series of natural triangular areas, beginning with the division of the neck into anterior andposterior cervical triangles, and then by division of these into smaller triangular regions.

The Anterior Cervical Triangle

BOUNDARIES

The boundaries are:

Lateral: sternocleidomastoid muscle

Superior: inferior border of the mandible

Medial: anterior midline of the neck

This large t riangle may be subdivided into four more triangles: the submandibular, carotid, muscular, and submental (Fig. 1-13).

Fig. 1-13.

The ante rior triangle o f the neck is divided into four smaller triangles by the digastric and omohyoid muscles. SCM, sternocleidomastoid muscle. (Modified fromSkandalakis JE, Gray SW, Rowe JS Jr. Surgical anatomy of the submandibular triangle. Am Surg 1979;45:590-596; with permission.)

SUBMANDIBULAR TRIANGLE

The submandibular triangle is demarcated by the inferior border of the mandible above and the anterior and posterior bellies of the digastric muscle below.

Sarikcioglu et al.12reported an anomalous digastric muscle with three accessory bellies and one fibrous band (Fig. 1-14).

Fig. 1-14.


14/125



Schematic drawing of an anatomic anomaly. 1, anterior belly of digastric muscle; 2, posterior belly of digastric muscle; 3, accessory belly; 4, fibrous band. (Modifiedfrom Sarikcioglu L, Demir S, Oguz N, Sindel M. Anomalous digastric muscle with three accessory bellies and one fibrous band. Surg Radiol Anat 1998;20:453-454; withpermission.)

The largest structure in the triangle, and the most frequent object of the surgeon's attention, is the submandibular salivary gland. Near the end of the sixthweek (slightly later than the parotid gland), it develops from the oral ectoderm. It forms as a solid primordium, becoming canalized later.

Several vessels, nerves, and muscles also are found in the triangle. For the surgeon, the contents of the triangle are best described in four layers, or surgicaplanes, starting from the skin. It must be noted that severe inflammation of the submandibular gland can destroy all traces of normal anatomy. In suchinstances, identifying and sparing the essential nerves becomes a great challenge.

First Surgical Plane: The Roof of the Submandibular Triangle

The roof of the submandibular triangle is composed of skin, superficial fascia enclosing the platysma muscle and fat, and the underlying mandibular andcervical branches of the facial nerve (VII) (Fig. 1-15). The mandibular and cervical branches of the facial nerve arise from the cervicofacial division of thefacial nerve. This, the lower division of the facial nerve, passes lateral to the retromandibular (posterior facial) vein within the substance of the parotid gland

in more than 90% of cases;13in others, it passes medial to the vein. A line drawn from the intertragic notch of the ear, intersecting the midpoint of a linebetween the angle of the mandible and the lowest part of the ear, will lie close to the position of the cervicofacial division of the facial nerve.

Fig. 1-15.

The first surgical plane of the s ubmandibular triangle. The platysma lies over the mandibular and cervical branches of the facial nerve. (Modified from Skandalakis JE,Gray SW, Rowe JS Jr. Surgical anatomy of the submandibular triangle. Am Surg 1979;45:590-596; with permission.)

Remember

The skin should be incised 4 to 5 cm below the mandibular angle.

The platysma and fat compose the superficial fascia.


15/125



e man ua r or margna man ua r ra nc o t e ac a nerve es us t e ow t e a nge , s uper c a to t e ac a arte ry. avary e t a . a ter s tu yngfresh cadavers a nd 1 embalmed cadaver, found several marginal branches, particularly the intermediate ramus, which can form a neural plexus a round the facial

artery. Basar e t al.15reported tha t the marginal mandibular branch of the facial nerve was single in 14 facial halves, consisted of two major branches in 24 facialhalves, and had multiple major branches in 2 ha lves.

Cervicofacial Division of the Facial Nerve.The nomenclature and topography of the branches of the facial nerve are confusing and variable. The mandibular(marginal mandibular) nerve is usually the first branch of the cervicofacial division of the facial nerve. In all individuals, this branch crosses superficial to thefacial vein within 2 cm beneath the angular notch of the mandible, wherein the facial vessels can be palpated. From this position it ascends toward the angleof the lips so that anterior to the position of the facial artery it crosses the lower border of the mandible to supply the muscles of the corner of the mouthand lower lip.

The curved course of this nerve and the similarly shaped courses of other nerves in this region have led to the term "neural hammocks." The mandibular nerveforms the first of such hammocks of the submandibular triangle. Skandalakis et al. saw this hammock hanging so far below the mandible that a high

transverse incision would have severed it.16

The mandibular branch of the facial nerve always passes posterior to the angle of the mandible. It lies between the platysma and the deep cervical fascia(general investing layer), and proceeds to supply the quadratus labii inferioris muscle.

The cervical branch of the facial nerve divides to form descending and anterior branches. The descending branch innervates the platysma and communicateswith the transverse cervical (C2, C3) and great auricular (C2, C3) cutaneous nerves of the neck. The anterior branch, the ramus coli mandibularis, crossesthe mandible superficial to the facial artery and vein, and joins the mandibular branch to contribute to the innervation of the muscles of the lower lip. Thisanterior branch forms the second neural hammock of the triangle. It is frequently confused with the mandibular hammock.

Injury to the mandibular branch of the facial nerve results in a very slight drooping of the corner of the mouth. The drooping is not noticeable when themouth is in repose only when it is in motion (smiling). Depending on the nature of the injury, the drooping may be neuropraxia or permanent. Remember thatthe orbicularis oris and the muscles innervated by buccal branches actually raise the commissure on the affected side. Injury to the anterior cervical branchproduces minimal drooling that will disappear in 4 to 6 months.

Skandalakis et al.16measured the distance between these two neural hammocks and the lower border of the mandible in 40 cadavers (80 cervicofacialdissections). These measurements are shown in Fig. 1-16. In 50 percent of the specimens, the mandibular branch was above the mandibular border and thus

outside the boundaries of the submandibular triangle. In a similar study, Dingman and Grabb17found the branch to be above the border in 81 percent of theispecimens. If the skin incision is placed at least 4 cm below the border of the mandible, even an exceptionally low cervical branch will not be accidentallycut.

Fig. 1-16.

The neural "hammocks" formed by the mandibular branch (upper) and the anterior ramus o f the cervical branch (lowe r) of the facial nerve. The distance below themandible is g iven in centimeters. Pe rcentages indicate the frequency of the configuration in 80 dissections o f these nerves. (From Skandalakis JE, Gray SW, Rowe JSJr. Surgical anatomy of the submandibular triangle. Am Surg 1979;45:590-596; with permission.)

A study of Chinese adults demonstrated that in 67% the marginal mandibular branch ran above the lower border of the mandible, suggesting the existence of

ethnic variations in the topography of the nerve branches.18

Second Surgical Plane: The Contents of the Submandibular Triangle

The structures of the second surgical plane, from superficial to deep, are the facial (anterior facial) vein, the retromandibular (posterior facial) vein, part ofthe facial (external maxillary) artery, the submental branch of the facial artery, the superficial layer of submaxillary fascia (deep cervical fascia), the lymphnodes, the deep layer of submaxillary fascia (deep cervical fascia), and the hypoglossal nerve (XII) (Fig. 1-17).

Fig. 1-17.


16/125



The second surgical plane of the s ubmandibular triangle. The superficial portion of the gland is exposed. (Modified from Skandalakis JE, Gray SW, Rowe JS Jr. Surgicalanatomy of the submandibular triangle. Am Surg 1979;45:590-596; with permission.)

The retromandibular vein, formed by the union of t he superficial temporal and maxillary veins, divides near the angle of the mandible into anterior andposterior divisions. The posterior division joins the posterior auricular vein to form the external jugular vein. The anterior division passes forward to join the

facial vein, which is inferior to the mandibular notch, thereby forming the common facial vein.13

It is necessary to remember that the facial artery pierces the stylomandibular ligament. This ligament, which most often is thick but sometimes is thin,extends from the styloid process to the angle of the mandible, with occasional extensions to the stylohyoid muscle and the posterior belly of the digastricmuscle. The ligament is a particularly thickened portion of the deep layer of the fascial capsule of the parotid, which is derived from the superficial investing

lamina of the deep fascia of the neck; it separates the parotid and submandibular glands. Jovanovic 19desc ribed this ligament, emphasizing its importance inclinical and surgical anatomy. It must be ligated before it is cut to prevent bleeding after retraction. Also, it is important to remember that the lymph nodeslie within the envelope of the submandibular fascia, in close relationship with the gland, and that nodes occur along facial vessels (this is important in treatingmetastatic skin cancers). Differentiation between glands and lymph nodes may be difficult.

The facial vein and the anterior division of the retromandibular vein cross the triangle in front of the submandibular gland, and unite close to the angle of themandible to form the common facial vein. The common facial vein empties into the internal jugular vein near the greater cornu of the hyoid bone. It is wise toidentify, isolate, clamp, and ligate both the facial vein and the anterior division of the retromandibular vein.

The facial artery, a branch of the external carotid artery, enters the submandibular triangle under the posterior belly of the digastric muscle and under thestylohyoid muscle. At its entrance into the triangle, it is under the submandibular gland. After crossing the gland posteriorly, the artery passes over themandible, always lying under the platysma. It can be ligated easily.

Third Surgical Plane: The Floor of the Submandibular Triangle

The structures of the third surgical plane, from superficial to deep, include the mylohyoid muscle with its nerve, the hyoglossus muscle, the middle constrictomuscle covering the lower part of the superior constrictor muscle, and part of the styloglossus muscle (Fig. 1-18).

Fig. 1-18.

The third surgical plane of the submandibular triangle. The superficial portion of the gland has been removed and the deep portion is visible under the edge o f themylohyoid muscle. (Modified from Skandalakis JE, Gray SW, Rowe JS Jr. Surgical anatomy of the submandibular triangle. Am Surg 1979;45:590-596; with permission.)

Mylohyoid Musc le.According to DuPlessis,20the mylohyoid muscles are considered to form a true diaphragm for the floor of the mouth, with the geniohyoidmuscle and the muscles of the tongue above, and the anterior bellies of the digastric muscles and a major portion of the submandibular gland below. Themylohyoid arises from the mylohyoid line of the inner surface of the mandible; its more posterior part inserts on the body of the hyoid bone, and its more


17/125



anterior part inserts with the opposite mylohyoid into the midline raphe between the hyoid bone and the mandible. The superior surface of the mylohyoid is inrelationship with the lingual and hypoglossal nerves.

Sehirli and avdar21reported a case of a left accessory mylohyoid muscle, located between the anterior belly of the digastric and the normal mylohyoidmuscles. The left accessory mylohyoid muscle extended from the mylohyoid line of the mandible to the lower part of the mylohyoid raphe and hyoid bone.

Hyoglossus Musc le.The thin and quadrilateral hyoglossus muscle arises from the greater horn and body of the hyoid bone. It ascends almost vertically intothe side of the tongue between the styloglossus muscle laterally and the inferior longitudinal musculature of the tongue. The hypoglossal nerve and its venaecomitantes enter the floor of the mouth over the posterior edge of the mylohyoid, lateral to the hyoglossus. From its origin in the neck, the lingual arterypasses deep to the hyoglossus muscle. It enters the floor of the mouth between the hyoglossus muscle laterally and the genioglossus muscle medially.

The nerve to the mylohyoid, which also supplies the anterior belly of the digastric, arises from the inferior alveolar branch of the mandibular division of thetrigeminal nerve. The mylohyoid nerve lies on the inferior surface of the muscle, between it and the digastric. The submandibular space can be thought of as

the combination of the sublingual and submaxillary spaces.

Middle Constrictor Muscle.The middle constrictor originates from the angle between the lesser and greater horns of the hyoid bone and from the stylohyoidligament. Its insertion is the median raphe. The fibers travel backward, with the highest ascending and overlapping the superior constrictor, and the lowestfibers traveling down under the inferior constrictor.

Styloglossus Musc le.The styloglossus muscle has two origins and two insertions. The origins are from the front area of the styloid process and from thestylomandibular ligament. Insertions are into the side of the tongue and at its inferior area.

Submandibular Space and Ludwig's Angina.The sublingual and submaxillary spaces, above and below the mylohyoid muscle, respectively, are continuous atthe posterior border of the mylohyoid. These spaces can be involved in the diffuse inflammation (cellulitis) of Ludwig's angina, which often results from

infections of the lower molar teeth, most commonly with streptococcus hemolyticus as the infectious agent. As noted by Lindner,22the entire submandibulaspace is bounded tightly by the attachments of the cervical investing fascia to the mandible, the mucous membrane of the floor of the mouth, theattachment of cervical fascia to the hyoid bone, the hyoid bone itself, and the fascial investment of the posterior belly of the digastric. Edema here, and theswollen and displaced tongue can cause asphyxiation. Infection of the submandibular space can spread posteriorly along the styloglossus muscle into thepharyngomaxillary space. From this region, the process can pass into the retropharyngeal space and then inferiorly into the superior mediastinum.

Remember, in Ludwig's angina (as urged by Lindner22):

Cellulitic areas should not be incised. Incisions invite additional foreign organisms into an area that frequently (and early) becomes gangrenous .

Cellulitis should be met with systemic treatment w ith specific antibiotic therapy, and w ith local treatment w ith massive hot compresses a nd hourly hot sa linegavages to the oral cavity. Intravenous the rapy should be used to maintain fluid and electrolyte balances.

To avoid asphyxiation, maintenance o f an adequate a irway is of utmost importance. Tracheotomy is imperative if the breathing becomes shallow and rapid.

Surgical division o f the fascia and mylohyoid is performed only for complications s uch as drainage o f pus under tens ion, erosion of cervical vessels by the infectiousprocess, and internal jugular vein thrombosis.

Fourth Surgical Plane: The Basement of the Submandibular Triangle

The structures of the fourth surgical plane, or basement of the triangle, include the deep portion of the submandibular gland, the submandibular (Wharton's)

duct, the lingual nerve, the sublingual vein, the sublingual gland, the hypoglossal nerve (XII), and the submandibular ganglion (Fig. 1-19). The uncinate partof the submandibular gland rounds the posterior border of the mylohyoid to lie in the connective tissue above it. Here, the submandibular duct arises andpasses through the floor of the mouth to end at the sublingual caruncle beside the frenulum of the tongue anteriorly.

Fig. 1-19.


18/125



The fourth surgical plane of the submandibular triangle. The deep portion of the gland and duct are exposed. (Modified from Skandalakis JE, Gray SW, Rowe JS Jr.Surgical anatomy of the submandibular triangle. Am Surg 1979;45:590-596; with permission.)

The submandibular duct lies below the lingual nerve (except where the nerve passes under it) and above the hypoglossal nerve.

Lymphatic Drainage

The submandibular lymph nodes receive afferent channels from the submental nodes, the oral cavity, and the anterior parts of the face. Efferent channels

drain primarily into the jugulodigastric, jugulocarotid, and juguloomohyoid nodes of the chain accompanying the internal jugular vein (deep cervical chain). Afew channels pass by way of the subparotid nodes to the spinal accessory chain.

The contents of the submandibular triangle are cleared out during radical neck dissection by removing the submandibular (submaxillary) gland and its envelopand lymph nodes within, and by removing its capsule and all surrounding tissue without.

SUBMENTAL TRIANGLE

Boundaries

The boundaries of this triangle are:

Lateral: anterior belly of the digastric muscle

Inferior: hyoid bone

Media l: midline

Floor: mylohyoid muscle

Roof: skin and superficial fascia

Contents

The submental triangle contains lymph nodes. The contents of this triangle should be sacrificed in radical neck dissection. 23

Lymphatic Drainage

The lymph nodes of the submental triangle receive lymph from the skin of the chin, the lower lip, the floor of the mouth, and the tip of the tongue. They senlymph to the submandibular and jugular chains of nodes.

CAROTID TRIANGLE

Boundaries

The boundaries are:

Poste rior: sternocleidomastoid muscle

Anterior: anterior (superior) belly of the omohyoid muscle

Superior: posterior belly of the digastric muscle

Floor: hyoglossus muscle, inferior constrictor of the pharynx, thyrohyoid muscle, middle cons trictor of the pharynx, longus capitus muscle

Roof: investing layer of deep cervical fascia

Contents

The carotid triangle contains:

bifurcation of the carotid artery

internal carotid artery (no branches in the neck)

branches of the external carotid artery

superior thyroid artery (rare)

posterior auricular artery

superficial temporal artery

internal maxillary artery

occipital artery


19/125



ascending pharyngeal artery

sternocleidomastoid artery

lingual a rtery (occasional)

external maxillary artery (occasional)

facial artery (occasional)

tributaries of the internal jugular vein

superior thyroid vein

pharyngeal vein

vagus nerve

spinal accessory nerve

hypoglossal nerve

ansa hypoglossi

cervical sympathetic trunks (partial)

Protection of nerves and vessels, and removal of the lymphatic tissue is essential.

The posterior belly of the digastric muscle which is between the submandibular and carotid triangles is a reliable landmark in a dangerous area. Deep tothe posterior belly, the following anatomic entities will be found:

internal and external carotid arteries

internal jugular vein

glossopharyngeal nerve (9th cranial nerve)

spinal accessory nerve (11th cranial nerve)

hypoglossa l nerve (12th cranial nerve)

sympathetic trunk

Lymphatic Drainage

Lymph is received by jugulodigastric, jugulocarot id, and juguloomohyoid nodes, and by nodes along the internal jugular vein from the submandibular andsubmental nodes, the deep parotid nodes, and the posterior deep cervical nodes. Lymph passes to the supraclavicular nodes.

MUSCULAR TRIANGLE

Boundaries

The boundaries are:

Superior lateral: ante rior belly of the omohyoid muscle

Inferior lateral: s ternocleidomastoid muscle

Medial: midline of the neck

Floor: prevertebral fascia and prevertebral muscles; sternohyoid and sternothyroid muscles

Roof: investing layer of the deep fascia; strap, sternohyoid, and cricothyroid muscles

Contents

The muscular triangle contains the thyroid and parathyroid glands, trachea, esophagus, and sympathetic nerve trunk. According to Beahrs, 23this triangle isthe least important.

Remember that occasionally the strap muscles must be cut to facilitate thyroid surgery. They should be cut across the upper third of their length to avoidsacrificing their nerve supply.

Read an Editorial Comment
http://windowreference%28%27editorialcomment%27%2C%27editorialcomment.aspx/?aID=67001&comment_aID=67591%27);http://windowreference%28%27editorialcomment%27%2C%27editorialcomment.aspx/?aID=67001&comment_aID=67591%27);


20/125



Lymphatic Drainage

Lymphatic drainage of the muscular triangle will be discussed with the thyroid gland.

Posterior Cervical Triangle

The posterior cervical triangle is sometimes considered to be two triangles the occipital and the subclavian which are divided by the posterior (inferior)belly of the omohyoid muscle (Fig. 1-20). We will treat it as one entity.

Fig. 1-20.

The poste rior triangle of the neck. The triangle may be divided into two smaller triangles by the omohyoid muscle. (Modified from Skandalakis JE, Gray SW, Rowe JSJr. Anatomical Complications in General Surgery. New York: McGraw-Hill, 1983; with permission.)

BOUNDARIES

The boundaries are:

Anterior: sternocleidomastoid muscle

Pos terior: anterior border o f the trapezius muscle (Fig. 1-21)

Inferior: clavicle

Roof: supe rficial investing layer o f the deep cervical fascia

Floor: prevertebral fascia and muscles, splenius capitus muscle, levator scapulae muscle, and three scalene muscles

Fig. 1-21.


21/125



The floor of the pos terior triangle.

CONTENTS

Between the investing fascia and the prevertebral fascia are the accessory nerve (XI) and a portion of the external jugular vein. Variably deep within thetriangle are the subclavian artery, subclavian vein, cervical nerves, brachial plexus, phrenic nerve, accessory phrenic nerve, spinal accessory nerve, andlymph nodes.

LYMPHATIC DRAINAGE

Superficial occipital lymph nodes receive lymph from the occipital region of the scalp and the back of the neck. Efferent vessels pass to a deep occipitallymph node (or occasionally to more than one node) which drains into deep cervical nodes along the spinal accessory nerve.

SURGICAL NOTES

The following are surgical points to remember for the upper or occipital part of the posterior triangle:

Clear the lymph nodes around the spinal accessory nerve very carefully.

Sacrifice the nerve if it is abso lutely necessary.

Surgical points for the lower or subclavian part of the posterior triangle:

Be careful with the triangle's contents: the subclavian vein, portions of the transverse cervical vessels, and lymph nodes .

Surgical Applications of the Cervical Triangles

ANTERIOR TRIANGLE

In the pas t, inflammatory processes in the neck, such as Ludwig's angina, presented with se vere mortality and morbidity. Although these inflammatory processesstill occur, they are far less common, w ith lower mortality, because e ffective antibiotics arrest and cure the inflammation.

Do not confuse the carotid sinus and the carotid body. Anatomically, the carotid sinus is a dilated a rea that is usually located at the beginning of the internal carotidartery. There, the media is th in and poor in muscle. But the adventitia is thick; it is rich with elastic tissue, recepto rs, and se nsory nerve fibers from theglossopharyngeal nerve.

The carotid sinus (Fig. 1-22) acts as a baroreceptor, responding reflexively to changes in arterial pressure. Elevation of pressure or compression of thecarotid sinus can result in slowing of the heart rate, a sudden fall in arterial pressure, cerebral ischemia, and ipsilateral and secondary syncope.

Fig. 1-22.


22/125



Diagram of the carotid sinus, carotid body, and the ir innervation. What pa rt the carotid branch of the vagus plays in this innervation is not known. Note tha t thecarotid body lies not so much in, as medial to, the carotid bifurcation.

The carotid body (Fig. 1-22) is a tiny bilateral lobular anatomic entity 2 to 7 mm in size. It is located at the carotid bifurcation or on the posterior medial side

of the common carotid artery.24It may be partially embedded in the carotid adventitia from which it developed embryologically. It is composed of a fibrouscapsule with septae which divide it into lobules composed of epithelioid glomus cells, supporting cells, and sinusoids. Tumors of the carotid body may developand present serious surgical problems, part icularly with regard to hemorrhage during surgery.

The carotid body is a chemoreceptor which is sensitive to low levels of oxygen, high levels of carbon dioxide, or hydrogen ion concentrations. It responds tothese by reflexively increasing respiratory ventilation via its connections with the brainstem. Its nerve supply is derived principally from the glossopharyngealnerve, although it also seems to receive fibers from the vagus.

POSTERIOR TRIANGLE

The subclavian artery can be compressed against the first rib by pressure of the thumb placed in the supraclavicular fossa when the hand is grasping the neck.

One o f the most common fractures is that of the clavicle, perhaps due in part to the fact that the middle one -third of the clavicle is not protected by muscularattachments. The subclavius muscle does not ha ve the power to protect the clavicle.


23/125



The accessory nerve (XI) divides the posterior triangle into two nearly equal parts. Borrowing from the terminology of Grant and Basmajian,25we refer to the uppearea as "carefree," and the lowe r area as "careful." The position of the accessory nerve in the poste rior triangle can be ascertained as follows. First, place a point onthe anterior border of the trapez ius one third of the distance betw een the acromion process and the back of the skull. Second, place a po int on the pos terior borderof the sternocleidomastoid, two-thirds of the distance from the clavicle to the mastoid process. A line drawn be tween the two points w ill lie over the course of theaccessory nerve, deep to the investing fascia. Erb's point, where the external jugular crosses the pos terior border of the SCM, emphasizes the exit of the greaterauricular nerve along w ith cranial nerve XI.

We quote from Kierner et al.26on the anatomy of the s pinal accessory nerve (SAN) and the trapez ius branches of the cervical plexus:

(1) The SAN can be found medial as well as lateral to the internal jugular vein, depending how far cranial in the neck it is identified. The crossingbetween these 2 important structures can happen only dorsally (44%) or ventrally (56%) to the internal jugular vein...

(2) When the SAN passes through the sternocleidomastoid muscle, it takes an S-shaped, 3-dimensional course instead of running straight through themuscle...If the nerve were followed through the muscle...the communicating branch(es) with the cervical plexus would obviously be cut.

(3) The cervical plexus branches passing to the trapezius muscle are always subfascial because another relationship to the fasciae of the neck -whether superfic ial or deep - is anatomically impossible.

(4) The SAN can easily be mixed up with the minor occipital nerve because the latter sometimes takes a similar course, turning upward just slightlymedial to the anterior border of the trapezius muscle...Therefore, the supposed SAN must be followed right to the anterior border of the trapeziusmuscle to be sure that it keeps its craniocaudal direction. Furthermore, we found that measuring at the posterior border of the sternocleidomastoidmuscle from the clavicle provides the most reliable results and that the nerve can always be identified. The other landmarks cited in the literature,such as the great auricular nerve or the sternocleidomastoid muscle itself, show much more variability.

In a few preparations, cutaneous branches of the posterior spinal nerves passed through the tendon plane between the spinous processes of thevertebral column and the trapezius muscle to reach the skin. However, in contradiction to some former works, they were never found to branch withinthe muscle, which would have indicated additional innervation.

The following are descriptions of the anatomic entities (from above dow nward) within the "careful" areas, as well as some indications about their potential for injur

The spinal accessory nerve is closely related to the deep posterior cervical nodes. If an abscess is present in this area, make an incision just through the skin. Usea hemostat to penetrate and drain the abscess. This method avoids injury to the nerve with resultant wasting of the trapezius and drooping of the shoulder.

The brachial plexus can be injured in the lower part of the triangle by such diverse means as stab w ounds, bullets, excessive abnormal traction at childbirth, fallsupon the s houlder, or other sources of blunt trauma.

The subclavian artery and the brachial plexus can be compressed as they cross the first rib poste rior to the ante rior scalene muscle.

The phrenic nerve passes inferiorly on the ventral surface of the anterior scalene muscle bene ath the covering of the prevertebral fascia. Because this fascia isdrawn dista lly as the axillary sheath upon the brachial plexus and axillary artery, anesthetics injected into the sheath can affect the phrenic nerve, resulting in ahemiparalysis of the d iaphragm.

The topographic pathway and relations of the phrenic nerve with other anatomic entities in the neck:

1. Poste rior to the inferior belly of the omohyoid muscle, very close to its intermediate tendon

2. Poste rior to the internal jugular vein, transverse cervical, and suprascapular a rteries

3. Posterior to the thoracic duct on the left neck

4. Anterior to the subclavian a rtery

5. Posterior to the subclavian vein

We quote from Kline et al.27:

The surgeon can feel the characteristic rounded anterior border of the scalenus anticus as he or she palpates through the fat and lymphoid tissue.This is an important clue, as the novice tends to operate too far laterally and superiorly, thereby missing the brachial plexus altogether. The surgeon

can clear down to the anterior border of the scalenus anticus with dispatch, knowing that the phrenic nerve is deep to the prevertebral fascia at thispoint. Once the phrenic nerve has been dissected free and guarded, the scalenus anticus can be divided after the surgeon has seen that thesubclavian artery is free from its posterior surface.

NOTE: At that point, the phrenic nerve enters the thoracic cavity, anterior to the internal thoracic artery and to the pulmonary hilum, between themediastinal pleura and the pericardium. Here the pericardiophrenic vessels are fellow travelers of the phrenic nerve.

The cervical pleura and the apical parts of the lungs extend upward above the clavicle into the root of the neck. Scalene lymph node biopsy can produce iatrogenicpneumothorax or injury to the apex of the lung, as well as injury to the highest part o f the left thoracic duct.

The external jugular vein passes downward from the area of the angle of the mandible to the middle of the clavicle. Just above the clavicle, the vein pierces theinvesting fascia and drains into the subclavian vein. In this area, a pene trating neck wound w ith division of the vein can allow air to be sucked into the vein becausethe deep fascia is fixed firmly to the venous wall, thereby keeping the lumen o f the vein open. During inspiration a fatal air embolism may take place.

Remember, there are three topographic features in the vicinity of the supraclavicular triangle region of the "careful" part of the posterior triangle. The interscalenegroove and the supraclavicular fossa are present within the triangle; the infraclavicular fossa is located just unde r the middle one -third of the clavicle, outside of theposterior triangle (Figs. 1-23, 1-24).


24/125



Fig. 1-23.

The supraclavicular fossa, the infraclavicular fossa, and the jugular fossa.

Fig. 1-24.


25/125



Compression of the subclavian artery and brachial plexus. A,muscle is relaxed; B,contraction of the anterior scalene muscle in the p resence of a cervical rib canproduce compression of the subclavian artery and brachial plexus; C,scalenotomy alone may relieve this compression by allowing the vesse l and nerves to dropforward.

Inte rscalene Groove: If the head is turned strongly to the opposite s ide, a triangle is formed by the clavicle inferiorly, the sternocleidomastoid muscle medially, andthe ante rior border of the trapez ius muscle laterally. The anterior and middle scalenes lie in the floor of this triangle. In different individuals, the groove be tween thecan be palpated with varying ease.

The position of the cricoid cartilage can be used to approximate the level of the 6th cervical vertebra. Likewise, Chassaignac's tubercle of the transverse process ofC6 can be pa lpated just behind the posterior border of the ste rnocleidomastoid. A point located in such fashion in the middle of the triangle approximates the site ofthe pass age of the subclavian artery and the emerging of the brachial plexus from between the anterior and middle scalenes . The second part of the subclavianartery lies behind the anterior scalene muscle. A finger passed downward palpating in the interscalene groove will usually feel the pulse o f the subclavian artery

without difficulty.28

The Supraclavicular Fossa: The sup raclavicular fossa is formed by the late ral (posterior) border of the s ternocleidomastoid muscle, the ante rior border of thetrapezius, and the proximal one-half or one-third of the clavicle. This is the pressure point o f the subclavian artery, which may be pa lpated between the finger andthe first rib.

The Infraclavicular Fossa: The infraclavicular fossa is the soft, palpable ho llow located inferior to the middle of the clavicle. It is bounded by the pectoralis major,deltoid, and clavicle. The axillary vein appea rs deep to the skin, superficial fascia, and clavipectoral fascia. The axillary artery, bounded by elements of the brachialplexus, is located deep to the axillary vein. The apical and infraclavicular lymph node s also are found in this fossa.

The anterior scalene muscle arises from the ventral tubercles of the transverse processes of the 4th through the 6th cervical vertebrae. It descends almost verticalto insert on the scalene tubercle of the first rib, anterior to the g roove for the subclavian artery. The middle scalene muscle, the largest of the three scalenes , arisesfrom the posterior tubercles of the transverse processes of vertebrae C2-C7. It inserts on the first rib between its tube rcle and the subclavian artery groove. The

osterior scalene arises from the osterior tubercles of vertebrae C4-C6. It inserts u on the second rib.


26/125



Harry et al.29reported that the commonly described anatomic relationship of the brachial plexus located between the anterior scalene and middle scalenemuscles was found only in 60 percent of cases. The same authors observed the following variations:

The scalenus minimus muscle was p resent in 46 percent of instances (Fig. 1-25)

In 15 percent of cases the anterior scalene muscle was penetrated by fused C5-C6 roots

Fig. 1-25.

Variations se en in relations betwe en scalene muscles and the brachial plexus. A,subclavian a rtery piercing the anterior scalene muscle be lly; B,roots of C5 & C6

piercing the anterior scalene muscle be lly. (Modified from Harry WG, Bennett JDC, Guha SC. Scalene muscles and the brachial plexus: anatomical variations and the irclinical significance. Clin Anat 1997;10:250-252; with permission.)

The subclavian vein crosses the first rib ventral to the anterior scalene, where it is closely associated with, and often compressed by, the subclavius muscleFrequently, individuals thus affected have spontaneous or effort-related upper extremity axillary and subclavian venous thrombosis (Paget-von Schroettersyndrome), unrelated to intercurrent illness or iatrogenic manipulation. Patients with this problem can be treated with a combination of thrombolytic agents

and anticoagulation, resection of the first rib, and balloon angioplasty.30

Thoracic outlet syndrome: The subclavian artery, in company with the brachial plexus and w ith contributions from cervical nerves C5-C8 and the 1st tho racic nerve,passes between the anterior and middle scalene muscles. Here the artery and nerves cross the first rib, and can be subject to compression.

Thoracic outlet syndrome actually refers to compression at the upper opening (inlet, superior aperture). Perhaps the use of the word "outlet" is incorrect,since the lower opening of the thorax is the true "outlet."

The topographic relations of the thoracic inlet:

Posterior:First thoracic vertebral body

Anterior:Superior border of the manubrium of the sternum

Lateral:First rib

We quote from Obuchowski and Ortiz31on magnetic resonance (MR) imaging of the thoracic inlet:

The borders of the thoracic inlet define an oblique plane that angles downward from the spine anteriorly to the first ribs. It is therefore best toconsider the thoracic inlet as a region or "zone" which extends a short distance above and below this plane to include the lower portion of theinfrahyoid neck and the upper portion of the superior mediastinum. MR's multiplanar imaging capacity allows the thoracic inlet to be subdivided into fourdistinct zones: visceral, neurovascular, pulmonary, and spinal.

Post-stenotic dilatation of the subclavian artery can be associated with the development of thrombi. These thrombi, discharged distally into the artery, can

produce confusing symptoms similar to carpal tunnel entrapment of the median nerve. Sanders and Pearce32observed that 86% of patients suffering fromthoracic outlet syndrome had a history of some form of cervical trauma, especially whiplash injuries. In such individuals, scalenectomy is preferable toresection of the first rib.


27/125



, , , , , , .results in scalenus anticus (anterior scalene) syndrome, with pain, paresthesia or weakened pulses. During development, the 7th cervical rib forms, and thennormally regresses to its transverse process. Variations in its fate vary from a fully formed rib to rudimentary forms associated with a fibrocartilaginous band.

In a study of 390 transaxillary resections of the first rib for arterial, venous, or brachial plexus compression at the thoracic outlet, Makhoul and Machleder33

found that 66% of the 175 patients had single or multiple abnormalities representing developmental variations: 86 scalene and 39 subclavius muscles wereatypical in form or attachments; 20 scalene muscles were supernumerary; and 17 ribs exhibited abnormalities (7th cervical or atypical 1st thoracic).

In another study of patients suffering from thoracic outlet syndrome, Machleder et al.34showed that there were demonstrable morphologic transformations oanterior scalene muscle fibers that reflect metabolic and enzymatic changes characteristic of various adaptive and pathologic processes. In such changes,attributable to traumatic stress and stretch injury, muscle fibers change from a fast-twitch type 2 fiber to a hypertrophied slow-twitch type 1 fiber. Suchchanges occur predominantly in young individuals in response to exercise.

The presence of a cervical rib (found in about 1% of cases) often was shown to be indicative of a variation in the scalene musculature or in the brachialplexus where the first thoracic nerve had little input, replaced by a major contribution from C4. When the C7 rib was incomplete, the regressed part of the rib

was often replaced by a fibrous band. About 67% of cervical ribs are bilateral. In Makhoul and Machleder's 33study of patients suffering from Paget-vonSchroetter syndrome, 55% had hypertrophy of the tendon of the subclavius muscle as well as enlargement of the insertion tubercle.

Paget-von Schroetter syndrome is frequently associated with thrombosis of the axillary-subclavian vein from exertion, leading to the phrase "effort vein

thrombosis." The condition develops as an abrupt swelling of the upper extremity. According to Flye, 35even with early medical treatment complete resolutiooccurs in only 15% to 30% of patients.

Fasciae of the Neck

The following classification of the rather complicated fascial planes of the neck follows the work of several investigators:

Superficial fascia

Deep fascia

Investing layer (superficial layer)

Middle, or pretracheal, layer (surrounding the larynx, trachea, and pha rynx)

Prevertebral layer (posterior or deep layer)

Superficial Fascia

The superficial fascia of the neck lies beneath the skin. It is composed of loose connective tissue, fat, the platysma muscle, cutaneous branches of thecervical plexus, the cervicofacial division of the facial nerve and small cutaneous blood vessels (Fig. 1-26). The surgeon should remember that the cutaneousnerves of the neck and the anterior and external jugular veins are between the platysma and the deep cervical fascia. If the veins are to be cut, they mustfirst be ligated. Because of their attachment to the platysma above and the fascia below, they do not retract; bleeding from them can be serious, and thesurgeon must guard against the possibility of production of an air embolism. For all practical purposes, there is no space between this layer and the deepfascia.

Fig. 1-26.

The superficial fascia of the neck lies between the skin and the investing layer of the deep cervical fascia. CT, connective tissue. (Modified from Skandalakis JE, Gray

SW, Rowe JS Jr. Anatomical Complications in General Surgery. New York: McGraw-Hill, 1983; with permission.)

Deep Fascia

INVESTING LAYER

The superficial (investing) layer of the deep cervical fascia (Figs. 1-26 and 1-27) attaches above to the occipital and temporal bones and the mandible,posteriorly to the spines and supraspinous ligaments of the cervical vertebrae, and below to the clavicle, scapula, and manubrium of the sternum. It enveloptwo muscles the trapezius and sternocleidomastoid and two glands the parotid and submandibular. It forms two spaces the supraclavicular andsuprasternal; and forms the roof of the anterior and posterior cervical triangles.

Fig. 1-27.


28/125



Fascial layers and spaces above the hyoid bone, in a sagittal section. Note that the "danger space" and the retropharyngeal space show no interruption, but arecontinuous w ith the danger space and the retrovisceral space, respectively, below the level of the hyoid bone . Note also that unde r normal circumstances, these are"potential," rather than "actual" spaces . (Based on Hollinshead WH. Anatomy for Surgeons, Vol. 1, 2nd Ed. New York: Harper & Row, 1968.)

PRETRACHEAL LAYER

The middle (pretracheal) layer of the deep fascia (Fig. 1-28) is sometimes described as investing the strap muscles anteriorly, merging with the superficial

investing layer. Conversely, it is also said to be a lamina that passes deep to the strap muscles, uniting with the superficial investing layer lateral to them. 36

In keeping with the former view, it is said that a posterior layer of the pretracheal fascia envelops the thyroid gland, forming the false capsule of the gland(Fig. 1-29). This layer is fixed to the thyroid and cricoid cartilages above. The attachment to the cartilages may be thickened to form the suspensoryligament of the thyroid gland (ligament of Berry).

Fig. 1-28.


29/125



Fascial layers of the neck. A,Cross section. D, "danger space" w ithin the prevertebral fascia; RV, retrovisceral or retropharyngeal space between the prevertebralfascia and the pretrachea l (visceral) fascial layers. B,Chief fascial layers of the neck below the hyoid bone, in longitudinal section. (A,From Colborn GL, SkandalakisJE. Clinical Gross Anatomy: A Guide for Dissection, Study, and Review. Pearl River NY: Parthenon, 1993; B,modified from Hollinshead, Anatomy for Surgeons, Vol 1:The Head a nd Neck, New York: Harper & Row, 1968; w ith permission.)

Fig. 1-29.


30/125



The anchor of the thyroid gland: the ligament of Berry.

Posteriorly, the middle cervical fascia becomes ill-defined, permitting an enlarging thyroid gland to extend posteriorly. This posterior, or deep, portion of thepretracheal fascia can be thought of as the visceral portion of this fascial layer. It is continuous posteriorly with the buccopharyngeal and esophageal

fasciae, as noted some time ago by Grodinsky and Holyoke.37It is because of this continuity that some prefer the term "visceral layer" to "pretracheal layer,as the more appropriate name for the middle layer of deep cervical fascia.

Anteriorly, the middle layer attaches above to the hyoid bone and below to the fibrous pericardium. Laterally, it contributes to the carotid sheath. Posteriorlythis fascial layer continues as buccopharyngeal fascia to the base of the skull; it terminates inferiorly at about the level of the bifurcation of the trachea byblending with the alar part of the prevertebral fascia.

PREVERTEBRAL LAYER

The prevertebral (posterior) layer (Fig. 1-27) lies in front of the prevertebral muscles. It originates from the spinous processes and the ligamentum nuchaeposteriorly, and covers the cervical spine muscles, including the scalene muscles and vertebral column anteriorly. At its attachment to the transverseprocesses of the cervical vertebrae, the prevertebral fascia divides to form a space in front of the vertebral bodies, the anterior layer being the alar fascia,the posterior layer retaining the designation of prevertebral fascia.

CAROTID SHEATH

Three fasciae investing, pretracheal, and prevertebral compose a fascial tube, the carotid sheath (Fig. 1-28, Fig. 1-30), beneath the sternocleidomastoidmuscle. Within this tube lie the common carotid artery, internal jugular vein, vagus nerve, and deep cervical lymph nodes. In the upper part of the neck, theconnective tissue of the sheath blends with the fascial investments of the stylohyoid muscle and the posterior belly of the digastric. Above this, the sheathbecomes more adherent to the adventitial coverings of the carotid vessels and internal jugular vein.

Fig. 1-30.


31/125



Two views of the visceral compartment of the neck.

Inferiorly, the carotid sheath is adherent to the posterior aspect of the sternum and clavicle and is lateral to the origins of the sternocleidomastoid and strapmuscles. Posteriorly, it is fused with the first rib and Sibson's fascia. In the root of the neck, the visceral fascia passes on to the alar fascia of the carotidsheath, continuing into the thorax to the fibrous pericardium of the heart and great vessels. As the sheath passes into the thorax, the connective tissue of

the sheath separately encloses each structure within as they diverge from one another.

Behind the carotid sheath, the prevertebral fascia covers the scalene muscles and phrenic nerve, and provides origin for the axillary sheath. The potential

danger space of Grodinsky and Holyoke37(Figs. 1-27 and 1-28) lies between the alar component and the deeper, muscular part of the prevertebral fascia.This space provides a plane for the spread of fluids or pathologic processes from the base of the skull to the thoracic diaphragm.

BUCCOPHARYNGEAL FASCIA

The buccopharyngeal fascia (Fig. 1-27) is continuous below with the visceral fascial covering of the esophagus. Superiorly, it covers the posterior and laterasurfaces of the pharynx and continues forward over the external surface of the buccinator muscle of the cheek. It is joined rather loosely by delicate areolartissue to the alar layer of the prevertebral fascia. The interval between the two fascial layers is the retropharyngeal space (Fig. 1-27) which extendssuperiorly to the skull base and terminates inferiorly in the upper part of the thorax. This space can be infected by descending infections, by direct

perforations of the esophagus, or by infections of the deep cervical lymph nodes which lie adjacent to it.36

AXILLARY FASCIA

The axillary fascia takes its origin from the prevertebral fascia. It is considered in the chapter on the breast under the heading "Topographic Anatomy and

Relations: Deep Fascia."

Spaces of the Neck

There are many spaces in the neck that are defined by the fasciae (Figs. 1-27, 1-28). Because this book is for the general surgeon, only those spaces thatneed special emphasis will be described. Some others, such as the parotid and submaxillary spaces, will be discussed with the organs they are related to. The

authoritative works on the cervical spaces are those of Grodinsky and Holyoke37and Coller and Yglesias.38

Spaces above the Hyoid Bone

Intrafascial spaces are formed by splitting of the several fascial layers of the neck. The spaces a re those related to the body of the mandible, and the submaxillary,parotid, and masticator spaces .

Peripharyngeal spaces include the retropharyngeal, lateral pharyngeal, and submandibular spaces. Buser and Bart39studied the no rmal anatomy of theretropharyngeal space (Fig. 1-27): this involves the posterior neck in toto from the base of the skull to the level of T1, T2 in the upper mediastinum in front of theprevertebral fascia and behind the buccopharyngeal or visceral fascia. The lateral pharyngeal space (Fig. 1-31) is a lateral extension of the retropha ryngeal spacearound the pharynx. The submandibular space (Fig. 1-27) is related to the ante rior elements o f the several peripharyngeal spaces; it is highly complex.

Fig. 1-31.


32/125


http://web.uni-plovdiv.bg/stu1104541018/

chapter 1 neck

Documents