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.
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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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