clinical anatomy of head & neck - wordpress.com

Clinical Anatomy of Head & NeckKhaleel Alyahya, PhD, MEdwww.khaleelalyahya.net

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Resources

Clinical Neuroanatomy

Richard Snell

Essential of Human Anatomy & Physiology

Elaine Marieb

Gray’s Anatomy

Richard Drake, Wayne Vogl & Adam Mitchell

Atlas of Human Anatomy

Frank Netter

KENHUB

www.kenhub.com

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INTRODUCTION

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▪ The head and neck are two examples of the perfect anatomical relation

between form and function.

▪ It is mixed with a dash of complexity.

▪ It is a complex anatomical structure weighing up to five kilograms that

rests on the bony skull and in turn, the neck.

▪ In addition to the evident ears, eyes, nose, and mouth, the head

supports a variety of other important structures.

▪ The neck supports the position of the head and enables us to turn our

head towards stimuli.

Khaleel Alyahya, PhD, MEd

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THE HEAD

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▪ The human skull consists of 22 bones which are mostly

connected together by ossified joints called sutures.

• Single: frontal, occipital, sphenoid, ethmoid, vomer and mandible

bones.

• Paired: parietal, temporal, maxillary, lacrimal, nasal, palatine,

zygomatic bones.

▪ The skull is divided into the braincase (neurocranium) and the

facial skeleton (viscerocranium).

▪ The main task is the protection of the most important organ in

the human body, which is the brain.

▪ The brain is almost entirely enclosed by the neurocranium

with the exception of the foramen magnum and

other foramina at the skull base which serve as entry and exit

point for blood vessels and cranial nerves.

▪ Also, the skull provides support for all of the facial structures. THE SKULL

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▪ Organs:

• Eyes

• Ears

• Nasal cavity

• Oral cavity

• Glands (parotid, submandibular, sublingual and lacrimal)

▪ Muscles

• Muscles of facial expression

• Muscles of mastication

• Muscles of extraocular

• Tongue

▪ Joint

• Tempomandibular joint

▪ Blood vessels

• Common carotid arteries

• Jugular veins

▪ Innervation

• Sympathetic and parasympathetic

STRUCTURES


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▪ Fractures of the cranium typically arise from blunt force or

penetrating trauma.

▪ When considering cranial fractures, one area of clinical

importance is the pterion – a H-shaped junction between the

temporal, parietal, frontal, and sphenoid bones.

▪ The pterion overlies the middle meningeal artery, and

fractures in this area may injury the vessel.

▪ Blood can accumulate between the skull and the dura mater,

forming an extradural haematoma.

▪ Fractures of the facial skeleton are also relatively common

and most frequently result from road traffic collisions, fist

fights, and falls.

▪ A mandibular fracture rarely occurs in isolation. Much like

fractures of the pelvic brim, a fracture on one side is

frequently associated with a fracture on the contralateral side. Fractures


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▪ The tympanic membrane is a relatively thin connective tissue

structure and is susceptible to perforation (usually by trauma

or infection).

▪ An infection of the middle ear (otitis media) causes pus and

fluid to build up behind the tympanic membrane.

▪ This causes an increase in pressure within the middle ear,

and eventually the eardrum can rupture.

▪ In some cases, the tympanic membrane heals itself, but in

larger perforations surgical grafting may be required.

Tympanic Membrane Perforation


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▪ Meniere’s disease is a disorder of the inner ear, characterised

by episodes of vertigo, low-pitched tinnitus, and hearing loss.

▪ The symptoms are thought to be caused by an excess

accumulation of endolymph within the membranous labyrinth,

causing progressive distension of the ducts.

▪ The resulting pressure level changes damage the thin

membranes of the ear that detect balance and sound.

Meniere’s Disease


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▪ Glaucoma is an eye disease in which the optic nerve at the

back of the eye atrophies.

▪ In most people this damage is due to raised intraocular

pressure due to problems with the drainage of the aqueous

humor.

▪ Chronic (primary open-angle) glaucoma is the most common

type.

▪ Damage progresses very slowly and destroys vision

gradually, starting with peripheral vision.

▪ It has no real symptoms until eyesight is lost at a late stage.

▪ It can lead to blindness if not treated.

Glaucoma


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▪ As the paranasal sinuses are continuous with the nasal

cavity, an upper respiratory tract infection can spread to the

sinuses.

▪ Infection of the sinuses causes inflammation (particularly pain

and swelling) of the mucosa and is known as sinusitis.

▪ If more than one sinus is affected, it is called pansinusitis.

▪ The maxillary nerve supplies both the maxillary sinus and

maxillary teeth, and so inflammation of that sinus can present

with toothache.

Sinusitis


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▪ The gag reflex is protective against foreign bodies touching

the posterior aspects of the oral cavity, which are most

innervated by the glossopharyngeal nerve (CN IX).

▪ When stimulated, a reflex arc leads to contraction of the

pharyngeal musculature and the elevation of the soft palate.

The efferent nerve in this case is the vagus nerve (CN X).

Gag Reflex


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▪ A dislocation of the temporomandibular joint can occur via a

blow to the side of the face, yawning, or taking a large bite.

▪ The head of the mandible ‘slips’ out of the mandibular fossa

and is pulled anteriorly.

▪ The patient becomes unable to close their mouth.

▪ The facial and auriculotemporal nerves run close to the joint

and can be damaged if the injury is high-energy.

▪ Posterior dislocations of the TMJ are possible, but very rare,

requiring a large amount of force to overcome the postglenoid

tubercle and strong intrinsic lateral ligament.

TMJ Dislocation


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THE NECK THE NECK

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▪ Areas

• Anterior triangle

• Posterior triangle

▪ Bones

• Cervical spine

• Hyoid bone

▪ Viscera

• Pharynx

• Larynx

• Esophagus

• Trachea

• Thyroid gland

• Parathyroid gland

▪ Muscles

• Suprahyoid muscles

• Infrahyoid muscles

• Scalene muscles

• Suboccipital muscles

▪ Cartilages

• Thyroid cartilage

• Cricoid cartilage

▪ Blood supply

• External carotid arteries

• Jugular veins

▪ Innervation

• Cervical plexus

• Phrenic nerve

Structures


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▪ The external jugular vein has a relatively superficial course

down the neck, leaving it vulnerable to damage.

▪ If it is severed, in an injury such as a knife slash, its lumen is

held open – this is due to the thick layer of investing fascia.

▪ Air will be drawn into the vein, producing cyanosis, and can

stop blood flow through the right atrium.

▪ This is a medical emergency, managed by the application

of pressure to the wound – stopping the bleeding, and the

entry of air.

External Jugular Vein


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▪ The hyoid is well protected by the mandible and cervical

spine, so fractures are relatively rare.

▪ Hyoid bones fractures are characteristically associated

with strangulation (found in approximately 1/3 of all homicides

by strangulation).

▪ It is therefore a significant post-mortem finding.

▪ They can also occur as a result of trauma, with clinical

features of pain on speaking, odynophagia and dyspnoea.

Fracture of Hyoid Bone


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▪ The inferior pharyngeal constrictor is split into two parts; the

thyropharyngeus and the cricopharyngeus.

▪ This area between the two is a weak area in the mucosa.

▪ Normally during swallowing, the thyropharyngeus contracts as

the cricopharyngeus relaxes, allowing the bolus of food to be

propelled into the oesophagus and preventing the

intrapharyngeal pressure from rising.

▪ If this coordinated relaxation of the cricopharyngeus does not

occur, the intrapharyngeal pressure tends to rise and

pharyngeal mucosa forms a midline diverticulum in the area

between the thyropharyngeus and cricopharyngeus.

▪ It is possible for food to accumulate here, leading to

dysphagia.

Pharyngeal Diverticulum


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▪ The vocal cords are responsible for the production of speech.

▪ Their movement is controlled by the intrinsic muscles of the larynx – the

majority of which are innervated by the recurrent laryngeal nerve.

• exception is the cricothyroid muscle; innervated by the external

laryngeal nerve.

▪ Due to its long course, the recurrent laryngeal nerve is suspected to

damage.

▪ Unilateral RLN palsy:

• One vocal cord is paralyzed.

• The other vocal cord tends to recompense, and speech is not

affected to a great degree, although the patient may experience

hoarseness of voice.

▪ Bilateral palsy:

• Both vocal cords are paralyzed in a position between adduction and

abduction.

• Breathing is impaired, and phonation cannot occur.

• In situations where the nerves are only partially damaged, the vocal

folds become paralyzed in a fully adducted position.

• If this occurs bilaterally, the rima glottidis (space between the vocal

cords) is completely closed, and emergency surgical intervention is

required to restore the airway.

Vocal Cord Paralysis


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▪ Goiter is a generic term for the enlargement of the thyroid

gland caused by a tumor, lack of a dietary iodine or more

commonly by thyroid dysfunction.

▪ It presents as a swelling in the anterior neck.

▪ It could lead to a swelling of the larynx (voice box).

▪ Worldwide, over 90% cases of goiter are caused by iodine

deficiency.

GOITER


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▪ Hyperthyroidism generally results from a tumor of the thyroid

gland.

▪ Extreme overproduction of thyroxine results in a high basal

metabolic rate, intolerance of heat, rapid heartbeat, weight

loss, nervous and agitated behavior, and a general inability to

relax.

▪ In addition to the symptoms of hyperthyroidism described

earlier, the thyroid gland enlarges, and the eyes may bulge, or

protrude anteriorly.

▪ Hyperthyroidism may be treated surgically by removal of part

of the thyroid (and/or a tumor if present) or chemically with

thyroid-blocking drugs or radioactive iodine, which destroys

some of the thyroid cells.

Hyperthyroidism


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▪ A cricothyroidotomy is an emergency procedure to provide a

temporary airway.

▪ It is typically used in situations where there is an obstruction at

or above the larynx (e.g foreign body, angioedema or facial

trauma), and intubation has been unsuccessful.

▪ To perform the technique, the thyroid cartilage is palpated in

the neck – below which there is a depression representing

the cricothyroid ligament.

▪ A small incision is made in the midline of this ligament, and an

endotracheal tube is inserted to secure the airway.

Cricothyroidotomy


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▪ Barrett’s oesophagus is a pre-malignant condition in which the

tissue lining the oesophagus is replaced by tissue that is similar

to the lining of the intestine.

▪ The Barrett’s lining always begins at the bottom of the

oesophagus and extends upward towards the mouth for

varying distances.

▪ It is commonly found in people with gastro esophageal reflux

disease (GORD).

▪ It can progress to adenocarcinoma of the oesophagus.

Barrett’s Oesophagus


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▪ Esophageal varices are dilated (varicosed) veins in the lower

part of the oesophagus or in the upper part of the stomach.

▪ They are associated with the increased venous pressure that

occurs in liver diseases such as cirrhosis.

▪ Esophageal varices can rupture and cause extreme bleeding

which may be life threatening.

Oesophageal Varices


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▪ Gastro-Esophageal Reflux Disease (GORD) is a form of

chronic heartburn caused by the backflow (reflux) of acidic

stomach contents into the oesophagus.

▪ This is often due to incompetence of the cardiac sphincter

between the stomach and oesophagus.

▪ It results in a severe burning pain in the oesophagus and

can lead to esophagitis or ulceration.

GORD


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▪ Hypocalcemia is low calcium levels in the blood serum.

▪ The main function of the parathyroid glands is the production of

parathyroid hormone, which acts to regulate levels of calcium

(Ca+2),

▪ Due to their location on the posterior aspect of thyroid gland,

the parathyroid glands are at a high risk of being damaged or

removed inadvertently during thyroid surgery.

▪ This can result in an acute drop in serum calcium –

hypocalcaemia.

▪ Clinical features include tetany, muscle cramps and

paraesthesia of the fingers, toes, and mouth.

▪ Because of this risk, it is usually standard post-operative

practice to check the parathyroid hormone and serum calcium

in all patients following thyroid surgery.

Hypocalcaemia


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