GOOD MORNING

TRIANGLE OF NECK

Presented by:Dr.Brijesh M. Patel

M.D.S PART IOral & Maxillofacial Surgery

KMSDCH

Underguidence of:Dr.Rakeshsir(PG Guide)

Dr.Navinsir(HOD)Dr.Deepankarsir

INTRODUCTION:

• Anatomists use the term triangles of the neck to describe the divisions created

by the major muscles in the region.

• The side of the neck presents a somewhat quadrilateral outline, limited, above,

by the lower border of the body of the mandible, and an imaginary line

extending from the angle of the mandible to the mastiod process; below, by

the upper border of the clavicle; in front, by the middle line of the neck;

behind, by the anterior margin of the trapezius.

• This space is subdivided into two large triangles by sternocleidomastoid, which

passes obliquely across the neck, from the sternum and clavicle below, to the

mastiod process and occipital bone above.

• The triangular space in front of this muscle is called the Anterior Triangle Of

The Neck; and that behind it, the Posterior Triangle Of The Neck.

Triangle of neck

Anterior

Submentle

Carotid

Muscular

Submandibular (digastric)

Posterior

Occipital

Subclavian

Anterior Triangle of Neck

BOUNDRIES Anterior:anterior meian line of neck

extending from symphysis menti to the suprasternal notch

Posterior:anterior border of sternocleiomastoid muscle

Base:lower border of mandible and imaginary line joining the angle of mandible to the mastoid process

Apex: suprasternal notch at the meeting point betwwen ant. Border of SCM and ant. Median line

Roof: investing layer of deep cevical fascia

STERNOCLEIDOMASTOID MUSCLE• Origin

– medial third of the clavicle (clavicular head)

– manubrium (sternal head)• Insertion

– mastoid process• Nerve supply

– spinal accessory nerve (CNXI)• Blood supply

– occipital a. or direct from ECA– superior thyroid a.– transverse cervical a.

• Actions Acting alone, tilt the head towards the

ipsilateral shoulder, simultaneously rotating the head so as to turn the face towards the opposite side.

• The clavicular fibres are directed mainly to the mastoid process

• the sternal fibres are more oblique and superficial, and extend to the occiput.

• The direction of pull of the two heads is therefore different, and the muscle may be classed as ‘cruciate’ and slightly ‘spiralized'.

• The two heads are separated near their attachments by a triangular interval which corresponds to a surface depression, the lesser supraclavicular fossa.

Applied Anatomy to SCM• Branchial cysts in the upper neck in early adulthood as fluctuant

swellings at the junction of the upper and middle thirds of the anterior border of sternocleidomastoid. The cyst typically passes backwards and upwards through the carotid bifurcation and ends at the pharyngeal constrictor muscles, a course which brings it into intimate association with the hypoglossal, glossopharyngeal and spinal accessory nerves. Great care must be taken to avoid damage to these nerves during surgical removal of a branchial cyst.

• Branchial fistulae -connection between the second branchial pouch

and the cervical sinus. -The fistula typically presents as a small pit adjacent

to the anterior border of the lower third of sternocleidomastoid, which may weep saliva and become intermittently infected.

• Branchial cysts, sinuses and fistulae are thought to arise from inclusions of salivary gland tissue in lymph nodes: they may also occur around the parotid gland.

TRAPEZIUS MUSCLE• Origin: Superior nuchal line,

ext. occipital protuberance, lig. nuchae, spines of C7 – T12

• Insertion: Lateral 1/3 of clavicle, acromion, spine of scapula

• Functions: elevation of scapula (sup. fibers), depression of scapula (inf. fibers), retraction of scapula (middle fibers), superior rotation of glenoid fossa of scapula (sup. + inferior fibers).

• Nerve innervation: spinal accessory and ventral rami of C3 and C4• Vascular supply:The upper third -by a transverse muscular branch which

arises from the occipital artery at the level of the mastoid process

The middle portion -by the superficial cervical artery or by a superficial branch of the transverse cervical artery

The lower third -by a muscular branch from the dorsal scapular artery

• Anterior triangle of neck subdivide into four triangle by digastric muscle and superior belly of omohyoid muscle

1.Submental Triangle2.Digastric(submandibular Triangle)3.Carotid Triangle4.Muscular Triangle(visceral triangle)

Submental TriangleBoundries:On each side anterior belly

of digastric muscleBase:body of hyoid boneApex:chin or symphysis

mentiFloor:formed by the meeting

of mylohoid muscle at the median raphe extending from symphysis menti to th hyoid bone

Roof: investing layer of deep cevical fascia

CONTENTS OF SUBMENTAL TRIANGLE 1. Submental lymph nodes. • These receive lymph from the following areas:

• Tip of the tongue. • Floor of the mouth. • Mandibular incisor teeth and associated gingivae • Central part of the lower lip. • Skin of the chin.

• Lymph from here drains into submandibular and deep cervical lymph nodes.

2. Submental veins and arteries. • The submental veins unite to form the anterior jugular

vein

Applied Anatomy Of Submental Triangle

• In infections or cancer from any of the areas of drainage of the submental nodes, especially the tip of tongue and lip, the first nodes to be involved are submental nodes. Subsequently, the submandibular and deep cervical get involved.

• A discharging sinus on the point of the chin often results from an abscess of a mandibular incisor tooth. The pus from the infected tooth passes from the apex of the submental triangle located at the inferior end of the symphysis menti where it forms a sinus from which pus escapes.

Mylohyoid • forms a muscular floor for the

oral cavity.• Origin: It is a flat, triangular

sheet attached to the whole length of the mylohyoid line of the mandible .The mylohyoid line is of variable ength, sometimes ending before the lower third molar (wisdom) tooth.

• Insertion:The posterior fibres of mylohyoid pass medially and slightly downwards to the front of the body of the hyoid bone near its lower border.

• The middle and anterior fibres from each side decussate in a median fibrous raphe that stretches from the symphysis menti to the hyoid bone. The median raphe is sometimes absent, in which case the two muscles form a continuous sheet, or it may be fused with the anterior belly of digastric.

• In about one-third of subjects there is a hiatus in the muscle through which a process of the sublingual gland protrudes.

Relations • The inferior (external) surface platysma anterior belly of digastric the superficial part of the submandibular gland the facial and submental vessels the mylohyoid vessels and nerve• The superior (internal) surface geniohyoid part of hyoglossus and styloglossus the hypoglossal and lingual nerves the submandibular ganglion the sublingual gland the deep part of the submandibular gland and its duct the lingual and sublingual vessels posteriorly, the mucous membrane of the mouth

Vascular supply • Arterial supply from the sublingual branch of the

lingual artery, the maxillary artery, via the mylohyoid branch of the inferior alveolar artery, and the submental branch of the facial artery.

Nerve Innervation • Nerve to mylohyoid branch of the inferior alveolar

nerve, which can sometimes also supply accessory innervation to the posterior mandibular teeth.

Digastric(submandibular triangle)BOUNDRIES

Anteroinferiorly: ant. Belly of digastric

Posteroinferiorly: post. Belly og digastric

Base: base of mandible and imaginary line joining angle of mandible and mastoid process

Apex: intermediate tendon of digastric muscle which is bound down to hyoid bone by fascial sling

Floor: anteriorly-mylohyoid muscle posteriorly-hyoglossus and

small part of superior constrictor

ROOF OF SUBMANDIBULAR TRIANGLE:

The skin. Superficial fasciaPlatysmaDeep fascia containing

branches of the facial and transverse cutaneous cervical nerves e.g. cervical branch of facial nerve

Content• Its divide into two part by stylomandibular ligament 1.Anterior part Submandibular gland Submandibular lymph node Hypoglossal nerve Facial vein(suprficial to gland) Facial artery (deep to land) Submental artery Mylohyoid nerve and vessels2.Posterior part external carotid artery carotid sheath and its content structure passing between external and internal carotid artery

Digastric muscle• Origin

– digastric fossa of the mandible (at the symphyseal border)

• Insertion – hyoid bone via the

intermediate tendon– mastoid process

• Function – elevate the hyoid bone– depress the mandible

(assists lateral pterygoid)

Digastric

• Surgical considerationsPosterior belly is superficial toECAHypoglossal nerveICAIJV

• Anterior bellyLandmark for identification of mylohyoid fordissection of the submandibular triangle

Submandibular gland

• superficial part of the gland is situated in the digastric triangle where it reaches forward to the anterior belly of digastric and back to the stylomandibular ligament

• Vascular supply:branches of the facial and lingual arteries

• Lymphatic drainage:deep cervical group of lymph nodes (particularly the jugulo-omohyoid node), interrupted by the submandibular nodes.

• Nerve supply:secretomotor supply to the submandibular gland is derived from the submandibular ganglion by chorda tympani branch of facial nerve

Submandibular lymphnode

• Internal to the deep cervical fascia in the submandibular triangle

• Direct dtrain from external nose, cheek, upper lip and lateral parts of the lower lip

• Submental,buccal and lingual group of node drain into submandibular node.

Hypoglossal nerve

• The hypoglossal nerve is motor to all the muscles of the tongue, except palatoglossus.

• Branches: 1.descending branch 2.meningeal branch 3. Nerves to thyrohyoid and geniohyoid

Applied anatomy

• Complete hypoglossal division causes unilateral lingual paralysis and eventual hemiatrophy

• the protruded tongue deviates to the paralysed side and on retraction.

• The larynx may deviate towards the active side in swallowing, due to unilateral paralysis of the hyoid depressors associated with loss of the first cervical spinal nerve which runs with the hypoglossal nerve

Facial artery

• The facial artery arises anteriorly from the external carotid in the carotid triangle, above the lingual artery and immediately above the greater cornu of the hyoid bone.

• Branches: 1.ascending palatine artery 2.submental artery 3.tonsillarartery 4.glandular branches

Submental Artery

• largest cervical branch of the facial artery.• Supply:skin and muscle over submental region• Anastomoses: sublingual branch of the lingual

and mylohyoid branch of the inferior alveolar artery

over chin: anastomose with the inferior labial and mental arteries to supply the chin and lower lip

THE CAROTID SHEATH: Location: Longitudinal interval between cervical viscera (pharynx, esophagus, larynx, trachea and thyroid gland) medially, and prevertebral muscles posteriorly

Formation: Prevertebral fascia behindPretracheal fascia medially

Mnemonics Of Carotid Sheath Contents

"I SEE(I.C)10 CC's IN THE IV"

I SEE (I.C) = Internal carotid artery 10 = 10 cranial nerve (vagus nerve)CC = Common carotid artery IV = Internal juglar vein

CONTENTS OF CAROTID SHEATH 1. Common and Internal Carotid arteries medially. 2. Internal jugular vein laterally. 3. Vagus nerve posteriorly and between the above two.4. Ansa cervicalis embedded in the carotid sheath(anteriorly). 5. Deep cervical lymph nodes.

Note:1) Common carotid artery divides at superior border of thyroid gland (C3,4).

2) The carotid sinus (the baroreceptor) is a slight dilatation at the proximal part of the internal carotid artery. It is innervated by: •Carotid sinus nerve, a branch of glossopharyngeal.

•A branch of vagus nerve. •Sympathetic division of ANS.

3) The carotid body, is a small reddish brown, ovoid mass of tissue located at the carotid bifurcation. The same nerves that go to the carotid sinus innervate it.

A-Vagus nerveB-Comon carotid artery

Applied anatomy of submandibular triangle

• Infection in submandibular region is limited to a triangular region.

• Posteriorly; hyoid bone and anterolaterally on each side by halves of mandibular base

• Because the layer of deep fascia is attached to these bones.

• Triangular swelling= Ludwig’s Angina• The swelling may push tongue upwards

Carotid Triangle• BOUNDRIESSuperiorly:posterior belly of

digastric supplemented by stylohyoid

Anteroinferiorly: superior belly of omohyoid

Posterior: anterior border of SCM

Floor:four muscle.I. ThyrohyoidII. Hyoglossus III. Middle constrictorIV. Inferior constrictor

Floor of the carotid triangle • The floor is the the deepest aspect

of the carotid triangle. • The muscles, at this level, are the

middle and lower pharyngeal constrictors (mpc and ipc).

• The structures seen passing through this level are: – superior laryngeal nerve, a branch

of the vagus its 2 terminal branches – internal laryngeal (ilb--sensory to

upper part of the larynx) – external laryngeal (elb--motor to

the cricoid muscle)

Roof of the Carotid Triangle

• Skin and superficial fascia

• Platysma

• Deep fascia; ramifying in which are branches of the facial and cutaneous cervical nerves.

Omohyoid muscle

• Origin– upper border of the scapula

• Insertion – via the intermediate tendon

onto the clavicle and first rib– hyoid bone lateral to the

sternohyoid muscle• Blood supply

– Inferior thyroid a.• Function

– depress the hyoid– tense the deep cervical fascia

Omohyoid

• Surgical considerations• Absent in 10% of individuals• Landmark demarcating level III from IV • Inferior belly lies superficial to the brachial

plexus• Phrenic nerve transverse cervical vessels• Superior belly lies superficial to IJV

Contents carotid triangle

1. Carotid artery:common carotid artery,internal carotid artery,external carotid artery and its first five branch

2. Carotid sinus and carotid body3. Last three cranial nerve:vagus nerve,spinal

accessory nerve,hypoglossal nerve4. Ansa cervicalis5. Cervical part of the sympathetic chain6. Deep cervical lyph nodes

ORIGINRight: Brachio cephalic trunk- behind right sternoclavicular jointLeft: Aortic arch – behind manubrium sterniCourseExtends from sternoclavicular joint to upper border of thyroid gland c3/ c4Anterolateral neck in the carotid sheath lateral to trachea/ esophagus and larynx/ pharynxPalpable between sternocleidomastoid and angle of the mandibleDivides in the carotid triangle into internal and external carotid arteriesInnervation

Parasympathetic: Submandibular ganglion

Sympathetic: superior cervical ganglion

COMMON CAROTID ARTERY

From the ventral side:

From the dorsal side:

Terminates by dividing into:

•Superior thyroid artery. [5]

•Lingual artery. [4]

•Facial artery. [3]

•Ascending pharyngeal (may form from medial side).

•Occipital artery. [7]

•Posterior auricular. [6]

•Superficial temporal artery [1]

•Maxillary artery. [2]

BRANCHES OF EXTERNAL CAROTID ARTERY

OriginUnion of sigmoid and inferior petrosal sinusesExtentBase of skull to sternoclavicular jointLandmarkBetween sternal and clavicular heads of sterno cleido mastoid musclesTributariesPharyngeal veinsLingualCommon facialSuperior thyroidMiddle thyroidTermination:Joins subclavian vein to form brachio-cephalic vein

INTERNAL JUGULAR VEIN

COURSE1. Emerges through jugular foramen

2. Two ganglia- superior and inferior cervical ganglia

3. Runs straight down in the carotid sheath

4. Between and behind carotid artery and internal jugular veins

5. At the root of the neck, it passes infront of the subclavian artery to enter mediastinum

VAGUS NERVE

BRANCHES AND DISTRIBUTIONBranch Distribution

Meningeal •Dura of posterior cranial fossaAuricular •Postero inferior quadrant of external surface of tympanic

membrane•Floor of external auditory meatus•Skin on the cranial auricular canal

Carotid body branch •Carotid body•Carotid sinus

Pharyngeal branch •Muscles of pharynx except stylopharyngeus•Muscles of soft palate except tensor palate

Superior laryngeal • External Laryngeal •Cricothyroid muscle

•Inferior pharyngeal constrictors

Internal Laryngeal •Pharyngeal mucosa•Laryngeal mucosa above vocal folds

Recurrent Laryngeal •Trachea and Esophagus•Cricopharyngeus•Laryngeal muscles except cricothyroid•Laryngeal mucosa below vocal folds•

Cardiac branches •Heart

Carotid body and sinus•The common carotid artery shows two specialized organs near its bifurcation, the carotid sinus and the carotid body. •They relay information concerning the pressure and chemical composition of the arterial blood respectively.•innervated principally by carotid branch(es) of the glossopharyngeal nerve, with small contributions from the cervical sympathetic trunk and the vagus nerve.

Veins of the Carotid Triangle• common facial vein (cf) (within

carotid triangle)

• Other structures near by: – retromandibular vein (rm) – posterior auricular vein (pav) – facial vein (fv) – external jugular vein (ej) – anterior jugular vein (aj)

Nerves within the Carotid Triangle

• The nerves that enter the carotid triangle and that lie superficial to the internal jugular vein, internal and external carotid arteries are: – hypoglossal (XII) – C1 root of ansa cervicalis (C1) – C1 fibers running with

hypoglossal nerve (nerve to thyrohyoid muscle (nth)

– C2-C3 root of ansa cervicalis – ansa cervicalis (ac)

Nerves within the Carotid Triangle

Reflection of sternomastoid and removal of common facial vein

• cca-common carotid artery eca-external carotid artery

• sta-supterior thyroid artery

• oa-occipital artery • la-lingual artery • fa-facial artery • ica-internal carotid

artery

Muscular Triangle(visceral)• BoundriesAnteriorly:anterior median line

extending from hyoid bone to suprasternal notch

Anterosuperiorly:supe. Belly of omohyoid

Posteroinferiorly:anterior border of SCM

Floor: sternohyoid and sternothyroid muscle

Roof: investing layer of deep cervical fascia.superficial fascia contain-anterior jugular vein and associated lymph node

Apex-jugular notch

CONTENTS OF MUSCULAR TRIANGLE

1) Infrahyoid muscles (strap muscles).• Sternohyoid 1• Sternothyroid • Thyrohyoid • Omohyoid* 2forming part of the

boundary. NOTE: These muscles are innervated by

ansa cervicalis (c1-c3) except thyrohyoid that is innervated by C1 via Hypoglossal nerve. They depress the hyoid bone and larynx during swallowing and speaking, anchoring it in position

2) The anterior jugular veins, run in both sides of the midline. They are joined by the jugular arch at the suprasternal notch.

1-Sternohyoid2-Omohyoid3-Sternal head of sternocleidomastoid

Table of Muscles

Muscle Origin Insertion Action Nerve Supply

Sternohyoid sternum hyoid ansa

OmohyoidSuprascapular notch

hyoid ansa

SternothyroidBelow sternohyoid on manubrium

Thyroid cartilage oblique line

ansa

ThyrohyoidThyroid cartilage oblique line

hyoid C1-C2 (ansa)

Anterior Belly Digastric

-----intermediate tendon------

Inner surface of mandile

Trigeminal nerve

Posterior BellyDigastric

Medial aspect of the mastoid process

-intermediate tendon-

Facial nerve

MylohyoidMylohyoid line of mandible

Hyoid boneTrigeminal nerve

Hyoglossus Hyoid boneLateral side of tongue

hypoglossal

Stylohyoid Styloid process hyoid Facial nerve

SUPRAHYOID MUSCLESMUSCLE ORIGIN INSERTION ACTION INNERVATION

Digastric •Digastric notch,•medial surface of base of mastoid process

•Digastric fossa •Depress the mandible •Posterior belly: facial nerve •Anterior belly:nerve to mylohyoid

Stylohyoid •Back of styloid process near the base of skull

•By two slips into the junction between the greater horn and body of hyoid bone

•ELevate hyoid bone •Facial nerve

Mylohyoid •Whole length of mylohyoid line of its own side on the inner aspect of the mandible from medial to the third molar tooth to below the mental spines

•Anterior ¾: into each other (interdigitation) •Posterior ¼: anterior surface of the body of hyoid bone

•Forms a mobile but stable floor of the mouth

•Mylohyoid nerve

Geniohyoid •Inferior mental spine •Upper border of the body of hyoid bone.

•Protracts and elevates the hyoid bone in swallowing or if the hyoid is fixed to depresses the mandible.

•C1(superior root of ansa cervicalis)

Posterior Triangle• BOUNDRIESAnterior:postrior border of SCMPosterior:anterior border of

trapeziusInferior(base):superior aspect of

middle third of clavicleApex:meeting point of SCM and

trapezius muscle at superior nuchal line of occipital bone.its often truncated.

Roof:investing layer of deep cervical fascia stretching btween SCM and trapezius.superficial fascia contain-platysma,external and posterior jugularr vein,cutaneous nerv and vessels

Floor

• Mainly form by 2nd layer of muscle of neck (above

downward)

1. Splenius capitis.

2. Levator scapulae.

3. Occasionally by semispinalis capitis at apex.

4. Scaleneus medius.

5. Scaleneus posterior.

6. Muscular floor is carpeted by preverterbral facia.

splenius capitis (sc) levator scapulae (ls) scalenus posterior (sp) scalenus medius (sm) scalenus anterior (sa) inferior belly of omohyoid (io)

• Structure piercing Roof:as follow lesser occipital nerve,great aurical nerve,transverse

cervical nerve,supraclavicular nerveFloor:formed from above downward by the following

muscle.Semispinalis capitisSplenius capitisLevator scapulaeScalenus mediusFirst digitation of serrtus anterior(sometimes)

Roof a. Skin

b. Superficial facia

c. Investing layer of deep cervical facia

d. Roof is pierced by :

1. Nerves :

i. Lesser occipital

ii. Great auricle

iii. Transverse cutaneous nerves of neck

iv. Supraclavicular nerves

2. Veins : external jugular veins and its tributaries.

3. Lypmh vessels

1. external jugular vein (blue)

2. superficial cervical lymph nodes (green)

3. lesser occipital nerve (lc)

4. great auricular nerve (ga)

5. transverse cervical nerve (tc)

6. supraclavicular nerves (sc)

7. spinal accessory nerve (sa)

SubdivisionsBy inferior belly of

omohyoid muscle• Larger upper part called

occipital triangle(omoclvicular)

• Small lower part called subclavian triangle(supraclavicular triangle)

{named by:occipital and subclavian arteries respectively contain}

Occipital triangle(omoclavicular triangle)

• shares the same borders, except that inferiorly it is limited by the inferior belly of omohyoid.

• Floor: from above down, is formed by splenius capitis, levator scapulae, and scaleni medius and posterior; semispinalis capitis occasionally appears at the apex.

• Roof:The triangle is covered by skin, superficial and deep fasciae and inferiorly by platysma

Content • Spinal accessory nerve• 3rd and 4th cervical

nerves providin branches to levator scapulae and trapezius muscles

• Dorsal scapular nerve(C5)

• Four cutaneous branchs of cervical plexus(initial parts)

• Upper trunk of brachial plexus

• Superficial transverse cervical artery

• Occipital artery

•spinal accessory nerveIt pierces sternocleidomastoid and crosses levator scapulae obliquely downwards and backwards to reach the deep surface of trapezius. The surface marking of its course is in a line from the junction of the superior one-third and inferior two-thirds of sternocleidomastoid, to the junction of the inferior one-third and superior two-thirds of trapezius.•Cutaneous and muscular branches of the cervical plexus emerge at the posterior border of sternocleidomastoid.•Inferiorly, supraclavicular nerves, transverse cervical vessels and the uppermost part of the brachial plexus cross the triangle.• Lymph nodes lie along the posterior border of sternocleidomastoid from the mastoid process to the root of the neck.

Subclavian Triangle •The supraclavicular triangle is the lower and smaller division of the posterior triangle, with which it shares the same boundaries, except that superiorly it is limited by omohyoid. •It corresponds greater supraclavicular fossa. •floor :first rib, scalenus medius and the first slip of serratus anterior. •Roof:The triangle is covered by skin, superficial and deep fasciae and platysma and crossed by the supraclavicular nerves.

Content

Subclavian/supraclavicular triangle

• 3rd part of subclavian artery• Subclavian vein• Terminal part of external

jugular vein• Trunks of brachial plexus• Superficial (transverse )

cervical,suprascapular and dorsal scapular arteries

• lymphnodes

• Just above the clavicle, the third part of the subclavian artery curves inferolaterally from the lateral margin of scalenus anterior across the first rib to the axilla. The subclavian vein is behind the clavicle and is not usually in the triangle; but it may rise as high as the artery and even accompany it behind scalenus anterior.

• The brachial plexus is partly superior, and partly posterior to the artery and is always closely related to it. The trunks of the brachial plexus may easily be palpated here if the neck is contralaterally flexed and the examining finger is drawn across the trunks at right angles to their length. With the musculature relaxed, pulsation of the subclavian artery may be felt and the arterial flow can be controlled by retroclavicular compression against the first rib.

• The suprascapular vessels pass transversely behind the clavicle, below the transverse cervical artery and vein.

• The external jugular vein descends behind the posterior border of sternocleidomastoid to end in the subclavian vein. It receives the transverse cervical and suprascapular veins, which form a plexus in front of the third part of the subclavian artery; occasionally it is joined by a small vein that crosses the clavicle anteriorly from the cephalic vein. Other structures within the triangle include the nerve to subclavius, which crosses the triangle, and lymph nodes

Applied Anatomy of Posterior Triangle• Nerve point of the neck: is the region around the midpoint of the posterior border of the

sternocleidomastoid muscle. Several nerves lie superficially here, deep to the platysma. This point is important because:- – Slash wounds of the neck may severe these relatively superficial nerves , resulting in

loss of cutaneous sensation in the neck, and posterior part of the scalp.– Anaesthetic agent can be injected here.

• Brachial plexus block . Local anaesthetic solution is injected around the brachial plexus, superior to the midpoint of the clavicle. Be careful to locate the subclavian artery by palpation so it is not damaged.

• Subclavian artery, can be pressed in the suprascapular fossa, to control bleeding in the upper limb.

• Block dessection, is sometimes done in this region for the removal of lymph nodes. The accessory and Phrenic nerves, together with the other structures should be saved.

• Safe/ danger sides. The accessory nerve may be used to divide the posterior triangle into a carefree area superiorly and a danger area inferiorly, which has major nerves and blood vessels

Carefree and carefull zoneSpinal accessory XI runs posteroinferiorly across the post. triangle and divides it into an upper "CAREFREE ZONE" and a lower "CAREFUL ZONE". This is because superior to XI one can dissect without care (there are not many structures in this area) but inferior to XI great caution must be exercised

Accessory N. (XI)

Horner's syndrome

• Results from damage to the cervical sympathetic chain.

• Therefore it presents with• Ptosis• Myosis• Facial flushing on the affected site

• “The earliest evidence of ancient dentistry -an amazingly detailed dental work on a mummy from ancient Egypt that archaeologists have dated to 2000 BCE. The work shows intricate gold work around the teeth. This mummy was found with two donor teeth that had holes drilled into them. Wires were strung through the holes and then around the neighboring teeth.” Source: metalonmetal blog.

Thank you