Head And Neck Week 1 Flashcards
Where does the neck begin and end?
The neck extends from the lower margin of the mandible superiorly
To the suprasternal notch of the manubrium and superior border of the clavicle inferiorly
What are the major functions of the neck?
Support the head
Conduit for structures passing between head and thorax/limbs
Location of the larynx, thyroid and parathyroid glands etc.
Provides flexibility to position the head - maximising efficiency of sensory organs
Why is the neck a well-known region of vulnerability?
Slender to allow flexibility of head Many important structures crowded together: -muscles -glands -arteries -veins -nerves -lymphatics -trachea -oesophagus -bones (hyoid and vertebrae) Several vital structures lack bony protection: -thyroid gland -trachea -oesophagus
Which arteries are the major supply of blood to the head and neck
Carotid arteries
What are the principal venous drainage of blood from the head and neck?
Jugular veins
Where do the carotid arteries and jugular veins lie in the neck
Anterolaterally
Which structures are commonly injured in penetrating wounds of the neck?
Carotid arteries and jugular veins
Which plexuses originate in the neck and pass inferolaterally through the axillae to supply the upper limbs?
Brachial plexuses
Where does the thyroid cartilage lie?
The middle of the anterior aspect of the neck
Where does lymph from structures int he head and neck drain into?
Cervical lymph nodes
Describe the bones that make up the skeleton of the neck
Axial skeleton: -cervical vertebrae -hyoid bone -manubrium of the sternum Appendicular skeleton: -clavicles
How many cervical vertebrae are there?
7
Which cervical vertebrae can be described as typical?
3-6th
Describe the features of the typical cervical vertebrae
- Vertebral body:
- small
- longer laterally than anteroposteriorly
- superiorly concave, inferiorly convex - Vertebral foramen:
- large
- triangular - Transverse foramen (transmits the vertebral artery, vein and nerve)
- Superior facets of articular processes directed superoposteriorly
- Inferior facets directed inferoanteriorly
- Spinous processes:
- short
- bifid
Which cervical vertebrae are described as being atypical?
C1, C2, C7
What is the alternative name for C1?
The atlas
What is the alternative name for C2?
The axis
Describe the atlas bone
- Lacks a spinous process or body
- Two lateral masses connected by an anterior and posterior arch
- Concave superior articular facets receive occipital condyles
- Facet for dens on the anterior arch
- Tubercle for transverse ligament on each lateral mass
- Flexion/extension of neck occurs between occiput and C1
Describe the axis bone
- Large vertebral body
- Strongest cervical vertebra
- Odontoid process (dens)
- Joint between C1 and C2 responsible for rotation of head
Describe C7
- Small transverse foramen (only transmits the accessory vertebral veins)
- Prominent spinous process which is not bifid
Describe the position of the hyoid bone
Lies in the anterior part of the neck
At the level of the C3 vertebra
In the angle between the mandible and the thyroid cartilage
What is unique about the hyoid bone compared to other bones of the body?
It is isolated from the remainder of the skeleton and therefore mobile
How is the hyoid bone supported?
Suspended by muscles that connect it to:
- the mandible
- styloid processes of the temporal bones
- thyroid cartilage
- manubrium
- scapulae
How is the hyoid bone attached to the styloid processes
Suspended by the stylohyoid ligaments
Describe the functions of the hyoid bone
- Attachment for anterior neck muscles
- Prop to keep the airway open
Describe the hyoid bone
- Body :
- middle portion
- faces anteriorly
- 2.5cm wide
- 1cm thick
- anterior convex surface projects anterosuperiorly
- posterior concave surface projects posteroinferiorly
- each end unites to a greater horn (by fibrocartilage in young people and by bone in older people) - Greater horn:
- projects posterosuperiorly and laterally from the body - Lesser horn:
- small
- projects superoposteriorly from each side of the superior surface of the body the body near its union with the greater horns (fibrous tissue joins to body and sometimes synovial joint between greater horn and lesser)
- may be partly or completely cartilaginous in some adults
Describe common causes of cervical pain
Inflamed lymph nodes (indicator of malignant tumour in head - primary or metastases from trunk)
Protruding IV disks
Muscle strain
Bony abnormalities (cervical osteoarthritis)
Trauma
Affected by movement of head and exaggerated by coughing/sneezing
Describe the common cause and result of a hyoid bone fracture
Commonly caused by manual strangulation (compression of throat)
Results in depression of body of hyoid bone onto thyroid cartilage –> cant elevate and move anteriorly beneath tongue during swallowing –> may lead to aspiration pneumonia due to inability to maintain separate alimentary and respiratory tracts and difficult or painful swallowing
Why are cervical vertebrae prone to dislocation
Because of the more horizontally oriented articular facets –> less tightly interlocked than other vertebrae “stacked like coins”
Why can a slight dislocation occur in the cervical region without damaging the spinal cord ?
Due to the large vertebral foramen
In what situation would n MRI be required with a suspected cervical dislocation?
If the dislocation does not result in “facet jumping” where the articular facets are locked in their displaced position
Cervical vertebrae may self-reduce (slip back into position)
Therefore X-ray may not indicate spinal cord damage
MRI will show soft tissue damage if the spinal cord has been affected
What is the alternative name for an atlas fracture?
Jefferson or burst fracture
When is an atlas fracture likely to occur?
Vertical forces e.g. Diving accidents
Compress lateral masses between occipital bones and C2
Drives them apart
Fractures one or both of the anterior and posterior arches
Is the spinal cord likely to be damaged in an atlas fracture?
No because the vertebral foramen gets larger
More likely to be damaged if the transverse ligament is also ruptured (indicated on X-ray by widespread lateral masses)
What is the alternative name for a fracture of the vertebral arch of the axis?
Hangman’s fracture
Where does a Hangman’s fracture typically occur?
Bony column formed by the superior and inferior articular processes (pars interarticularis)
What causes a fracture of the vertebral arch of the axis?
Hyperextension of the head on the neck (as opposed to hyperextension of the head and neck which causes whiplash)
What are the consequences of a Hangman’s fracture?
Injury of spinal cord or brainstem is likely
Sometimes results in:
- Death
- Quadriplegia
What is the other common fracture of the axis and how does this commonly occur?
Fracture of the dens
Blow to the side of the head or osteopenia (pathological loss of bone mass)
What is the superficial cervical fascia?
Layer of fatty connective tissue that lies between the dermis and the investing layer of deep cervical fascia
Usually thinner than in other regions - especially anteriorly
What is contained within the superficial cervical fascia?
Cutaneous nerves, blood and lymphatic vessels, superficial lymph nodes and variable amounts of fat
Anterolaterally - platysma
What is the platysma?
A broad, thin sheet of muscle in the subcutaneous tissue of the neck
Which nerve supplies the platysma?
Facial nerve (CNVII)
Which structures lie deep to the platysma?
External jugular veins and main cutaneous nerves of the neck
What is the origin and insertion of the platysma and where does it lie?
Lies of the anterolateral aspect of the neck
Fibres originate in the deep fascia covering the superior parts of the deltoid and pectoralis major muscles
Travels superomedially over the clavicles to the inferior border of the mandible
Anterior border decussates over chin and blends with facial muscles
Inferiorly the fibres diverge leaving a gap anterior to larynx and trachea
Much variation in completeness - often occurs as isolated strips
What is the function of the platysma?
Acting from its superior attachment at the mandible:
- Tenses the skin, releasing pressure on the superficial veins
Acting from its inferior attachment:
- Helps depress the mandible
- Draw the corners of the mouth inferiorly - grimace
As a muscle of facial expression - serves to convey tension or stress
What are the fascia layers of the deep cervical fascia (from superficial to deep)?
Investing
Pre-tracheal
Pre-vertebral
What are the functions of the deep cervical fascial layers?
Support the cervical viscera (thyroid gland), muscles, vessels and deep lymph nodes
Support the common carotid arteries, internal jugular veins and vagus nerves by condensing to form the carotid sheath
Provide the slipperiness for structures in the neck to slide over one another (e.g. Swallowing, turning head)
Limit the spread of infection
What is contained in the carotid sheath?
Common carotid artery (internal carotid artery from C4 upwards), internal jugular vein, vagus nerve (CN X), deep cervical lymph nodes, carotid sinus nerve, sympathetic nerve fibres (carotid peri-arterial plexuses)
What is the carotid sheath?
A condensation of the layers of the deep cervical fascia (investing and pretracheal anteriorly and prevertebral posteriorly) extending from the base of the cranium to the arch of the aorta, which encloses the common carotid arteries, internal jugular veins and the vagus nerves etc. It communicates freely with the mediastinum inferiorly and the cranial cavity superiorly
What is the consequence of the deep cervical fascial layers for surgery?
Form natural cleavage planes through which tissues may be separated
What muscles does the investing layer enclose and where?
At the four corners of the neck the investing layer splits into deep and superficial layers to enclose the trapezius and sternocleidomastoid muscles
What are the superior attachments of the investing layer?
- Superior nuchal lines of the occipital bone
- Mastoid processes of the temporal bones
- Zygomatic arches
- Inferior border of the mandible
- Hyoid bone
- Spinous processes of the cervical vertebrae
Which glands are enclosed by the investing layer and where?
Just inferior to its attachment to the mandible it splits to enclose the submandibular gland
Posterior to the mandible splits to form the fibrous capsule of the parotid gland
What is the stylomandibular ligament ?
A thickening of the investing layer of deep cervical fascia
What are the inferior attachments of the investing layer?
- Manubrium
- Clavicles
- Acromions
- Spines of the scapulae
What happens to the investing layer posteriorly?
Continuous with the periosteum of C7 and the nuchal ligament
What is the suprasternal space and what does it enclose?
The portion of the investing layer that remains divided into deep and superficial parts between the SCMs and superior to the manubrium
Superficial part attaches to the anterior surface of the manubrium and the deep part to the posterior surface
Encloses inferior ends of the anterior jugular veins, the jugular venous arch, fat, a few deep lymph nodes
Where does the pre-tracheal layer lie?
Limited to the anterior surface of the neck. Communicates freely with the mediastinum inferiorly and cranial cavity superiorly
What are the origins and insertions of the pre-tracheal layer?
Extends inferiorly from the hyoid bone into the thorax
Blends with the fibrous pericardium covering the heart
What is enclosed in the thin muscular part of the pre-tracheal layer?
The infrahyoid muscles
What is enclosed in the visceral part of the pre-tracheal layer?
Thyroid gland, trachea and oesophagus
What is the name of the tendon that passes through the thickening of the pre-tracheal layer superior to the hyoid and what is its function?
The intermediate tendon of the digastric muscle
Suspends the hyoid bone
What happens to the pre-tracheal layer posteriorly and superiorly?
Continuous with the buccopharyngeal fascia
What function does the pre-tracheal layer perform for the omohyoid muscle?
Wraps around the lateral border of the intermediate tendon, tethering the muscle and redirecting its course between its two bellies
What is the function of the pre-vertebral layer?
Forms a tubular sheath for the vertebral column and the muscles associated with it:
- Longus colli and longus capitis anteriorly
- Scalenes laterally
- Deep cervical muscles posteriorly
What are the origins and insertions of the pre-vertebral layer?
Fixed to the cranial base superiorly
Inferiorly blends with the endothoracic fascia peripherally and fuses with the anterior longitudinal ligament at T3
Anteriorly attaches to the transverse processes and vertebral bodies
Posteriorly attaches along ligamentum nuchae
Extends laterally as the axillary sheath (contains axillary vessels and brachial plexus)
What is embedded in the pre-vertebral layer
The cervical parts of the sympathetic trunks
What is the retropharyngeal space?
The largest and most important interfascial space in the neck
Potential space that consists of loose connective tissue between visceral part of pre-vertebral layer and the buccopharyngeal fascia surrounding the pharynx superficially
What is the alar fascia?
Thin layer attached along the midline of the buccopharyngeal fascia from the cranium to the level of C7 vertabra
Extends laterally and terminates in the carotid sheath
Divides the retropharyngeal space into the anterior “true” retropharyngeal space and the posterior “danger zone”
What is the function of the retropharyngeal space?
Permits movement of the pharynx, oesophagus, larynx and trachea relative to the vertebrae during swallowing
How is the retropharyngeal space enclosed?
Superiorly by the cranial base
Laterally by the carotid sheath
Opens inferiorly into the superior mediastinum
What is the clinical significance of the retropharyngeal space and, in particular, the “danger zone”
Because the retropharyngeal space communicates freely with the mediastinum, infection can spread from the neck down into the chest as far as the posterior mediastinum and potentially cause mediastinitis (a rare but life-threatening infection)
The danger zone communicates freely with the thorax as far down as the diaphragm whereas the true retropharyngeal space does not communicate this far down, therefore infection can travel further in the danger zone
Where does the investing layer attach anteriorly?
Hyoid bone
Where does infection in the area posterior to the prevertebral fascia spread?
Can erode through the prevertebral fascia into the retropharyngeal space and spread down into the mediastinum
Where is the pretracheal space and why is it important?
The pretracheal space is between the investing fascia and the visceral portion of the pretracheal fascia. It communicates with the anterior mediastinum and therefore acts as a conduit for infection to spread through
When might you be likely to introduce infection into the pretracheal space?
Inserting surgical airways e.g. Tracheostomy
Describe the common clinical appearance of retropharyngeal infection
Rare
Secondary to throat infection
Commonly seen in children under the age of 5
May develop into an abscess
What are the signs and symptoms of a retropharyngeal abscess?
Visible bulge on inspection of oropharynx Sore throat Difficulty swallowing Stridor Difficulty speaking Neck stiffness High temperature
Why is it important to recognise and treat a retropharyngeal abscess quickly?
Associated with significant morbidity and mortality
What are the two major muscle groups of the head?
Muscles of facial expression
Muscles of mastication
Which nerve supplies the muscles of facial expression?
Facial nerve (CN VII)
Which nerve supplies the muscles of mastication?
Trigeminal nerve (CN V)
Which muscles are described as muscles of facial expression?
Occipitofrontalis : frontalis and occipitalis Platysma Orbicularis oculi Levator palpebrae superioris Orbicularis oris Buccinator Zygomaticus major and minor Pterygoids lateral and medial
Which muscles are described as muscles of mastication?
Masseter
Temporalis
What is the function and innervation of sternocleidomastoid?
Acting unilaterally: Lateral flexion Rotates head towards opposite side Acting bilaterally: Flexes neck Draws head ventrally and elevates chin Draws the sternum superiorly in deep inspiration Innervation: Accessory nerve (CN XI)
What is the function and innervation of Trapezius?
Function: Superior portion - elevates the scapulae and rotates shoulder joint superiorly in abduction
Middle portion - retracts scapulae
Inferior portion - depresses scapulae
Innervation: Accessory nerve (CN XI)
What is the action of temporalis?
Elevation and retraction of mandible
What is the action of Masseter?
Elevation of mandible
What is the action of the Pterygoids (lateral and medial)?
Lateral:
Bilaterally - Protract the mandible, depress mandible
Unilaterally - Side to side movement of the jaw
Medial:
Elevates the mandible
What is the action of the zygomaticus muscles?
Action: Draw the angle of the mouth superiorly and posteriorly (SMILE :D)
What is the action of the Buccinator muscles?
Pulls the cheeks inwards against the teeth
What is the action of orbicularis oris?
Purses the lips
What is the action of Occipitofrontalis?
Frontalis raises the eyebrows, wrinkles the forehead
Occipitalis draws the scalp backwards
What is the action and innervation of Levator palpebrae superioris?
Action: Retracts/elevates upper eyelid
Innervation: Oculomotor nerve (CN III)
What are the actions of the Orbicularis oculi muscles?
Orbital part - closes eyelid forcefully
Palpebral part - closes eyelid gently
What is the action of Platysma?
Depresses the mandible and angles of the mouth
Draws skin up towards the mandible (tenses it)
What are the branches of the facial nerve?
- Temporal branch
- Zygomatic branch
- Buccal branch
- Marginal mandibular branch
- Cervical branch
What structure does the facial nerve pass through upon exiting the cranium?
Parotid gland
What is the clinical significance of the facial nerve passing through the parotid gland?
Vulnerable to damage in pathology or surgery of the parotid glands
(Also very superficial so vulnerable to damage in trauma)
What is the most common non-traumatic cause of facial paralysis?
Bell’s palsy (inflammation of the facial nerve at the stylomastoid foramen - oedema compresses the nerve)
What are the branches of the trigeminal nerve?
- Ophthalmic
- Maxillary
- Mandibular
What is the mnemonic for which cranial nerves are motor, sensory or both?
I. Some II. Say III. Money IV. Matters V. But VI. My VII. Brother VIII. Says IX. Big X. Boobs XI. Matter XII. More
How do you test the facial nerve?
It is purely a motor nerve so get the patient to perform actions:
Frontalis - raise eyebrows
Orbicularis oculi - close eyes against resistance
Buccinator - puff out cheeks against resistance
Orbicularis oris - pout
Zygomaticus - smile
Platysma - grimace
How do you test the trigeminal nerve?
Sensory and motor nerve.
Motor : ask them to clench teeth and manually feel for temporalis and masseter, ask to move jaw side to side (pterygoids)
Sensory: ask them to close their eyes and touch forehead, cheek and chin and check they can feel it
What are the borders of the anterior triangle of the neck?
Superior - Inferior border of mandible
Lateral - Medial border of sternocleidomastoid
Medial - Imaginary sagittal line down the neck
What are the borders of the posterior triangle?
Inferior - Superior surface of medial 1/3 of clavicle
Posterior - Anterior border of trapezius
Anterior - Posterior border of the sternocleidomastoid
What is the significance of the triangles of the neck (what are the contents)?
Different contents
Anterior contains structures passing from thorax to head:
Hyoid muscles, common carotid arteries, internal jugular vein, Cranial nerves VII, IX, X, XI, XII
Posterior contains structures passing from neck to limb:
Omohyoid muscle
Splenius capitis, levator scapulae, scalenes (form floor)
External jugular vein
Subclavian vein, transverse cervical and suprascapular veins and associated arteries
Accessory nerve, cervical plexus, phrenic nerve, brachial plexus
What is the scalp?
The layers of skin and subcutaneous tissue that cover the bones of the cranial vault
What are the layers of the scalp?
Skin - numerous hair follicles and sebaceous glands (common site for sebaceous cysts) Connective tissue (dense) - connects skin to aponeurosis, highly vascularised and innervated Aponeurosis (epicranial) - thin, tendon-like structure connecting frontalis and occipitalis muscles Loose areolar connective tissue - thin connective tissue separating eponeurosis from periosteum, contains numerous blood vessels including emissary veins which connect veins of scalp to diploic veins and intracranial venous sinuses Periosteum - outer layer of the skull bones - continuous with endosteum at the sutures
Which layer is a common site for sebaceous cysts?
Skin
Why can the scalp be a site of profuse bleeding?
Blood vessels within dense connective tissue layer are highly adherent to the tissue which restricts their ability to fully constrict when lacerated
The pull of the occipitofrontalis muscle prevents the closure of the bleeding vessel and surrounding skin
Blood supply to the scalp is made up of many anastomoses which contribute to the bleeding
Why is the loose connective tissue a danger area of the scalp?
Pus and blood spread easily within it
Infection can pass into the cranial cavity along the emissary veins and to the meninges, causing meningitis
Describe the blood supply of the scalp
Rich arterial supply via the external carotid artery :
- superficial temporal branch (frontal and temporal regions)
- posterior auricular branch (area superior and posterior to auricle)
- occipital branch (back of scalp)
Anteriorly and superiorly receives additional supply from two branches of the ophthalmic artery (branch of internal carotid): the supraorbital and supratrochlear arteries
Describe the venous drainage of the scalp
Superficial drainage follows the arteries of the same name: superficial temporal, occipital, posterior auricular, supraorbital and supratrochlear
Supraorbital and supratrochlear veins unit at medial angle of eye to form the angular vein which drains into the facial vein
Deep (temporal region) drainage - pterygoid venous plexus (situated between temporal and lateral pterygoid muscles) - drains into maxillary vein
Connect to the diploic veins of the skull via valveless emissary veins - connection between scalp and dural venous sinuses
Describe the innervation of the scalp
Cutaneous innervation from six main nerves
Trigeminal Nerve:
- Supratrochlear nerve: Branch of the opthalmic nerve which supplies the anteromedial forehead
- Supraorbital nerve: Branch of the opthalmic nerve which supplies a large portion of the scalp between the anterolateral forehead and the vertex.
- Zygomaticotemporal nerve: Branch of the maxillary nerve, supplies the temple
- Auriculotemporal nerve: Branch of the mandibular nerve which supplies skin anterosuperior to the auricle.
Cervical Nerves
- Lesser occipital nerve: Branch of the anterior rami of C2 and 3 supplies behind the ear.
- Greater occipital nerve: Branch of the anterior rami of C2 and 3 supplies the posterior scalp up to the vertex.
Does loss of blood supply to the scalp lead to bone necrosis?
No because most of the blood supply for the skull comes from the middle meningeal artery
What would be the clinical presentation of a patient with Bell’s palsy?
Sudden onset (hours to days)
Mild weakness to total paralysis on affected side of face
Facial droop/ difficulty making facial expressions
Drooling
Pain around jaw, in or behind ear of affected side
Increased sensitivity to sound
Headache
Decrease in ability to taste
Change in amount of tears and saliva produced
What would be the clinical presentation of a patient with a parotid gland tumour/disease?
Lump or swelling near jaw or in neck/mouth Muscle weakness on same side of face Persistent pain in area of parotid gland Difficulty swallowing Trouble opening mouth widely
What is the clinical significance of the connection between the veins of the scalp and the dural venous sinuses?
Infection of scalp can spread to the cranial cavity and affect the meninges - meningitis
What do the emissary veins and the facial veins have in common?
They are valveless
What is the significance of the emissary veins and the facial veins being valveless?
Blood and therefore infection can travel in either direction
