Head & Neck Flashcards
Describe 3 structural differences between cervical vertebrae and others
Triangular vertebral foramen
Bifid spinous process
Transverse foramina within the transverse processes
What passes through the transverse foramina?
The vertebral artery, vein and sympathetic nerves
How does C7 differ to other cervical vertebrae?
The vertebral artery runs around the vertebral body rather than through the transverse foramina.
The spinal nerves appear above AND below C7 - which is why C8 is present when there are only 7 cervical vertebrae.
At which level do the vertebral arteries enter the transverse foramina?
C6
Describe the relationship of the vertebral arteries to C1 (atlas)
The vertebral artery runs around along the groove for the vertebral artery rather than through transverse foramen.
State the joints at which rotation and flexion of the head occur
Rotation - atlanto-axis joint
Flexion - atlanto-occipital joint
Name the muscle which causes rotation of the head & it’s innervation
The sternocleidomastoid. Innervated by the spinal accessory nerve (CNXI)
Explain why vertebral subluxation at C2/3 is more dangerous than at C6/7
Vertebral subluxation at C2 involves the anterior displacement of C2 with respect to C3. This is likely to have spinal cord involvement with a risk of quadraplegia or death
Describe the pattern of trauma associated with hangman’s fracture.
How is this different to a Jefferson #?
Hangman’s fracture is due to the hyperextension of the head on the neck which leads to fracture of the pars interarticularis of the axis - the result of which is shearing or compression of the spinal cord.
Jefferson fracture, or burst fracture is also known as the “burst #” and could be due to a head first fall from height. The axis breaks into several segments although this is less dangerous due to the wide vertebral foramen.
Explain why CNXI (Spinal Accessory Nerve) can be tested by asking the patient to shrug their shoulders
The descending fibres of the trapezius muscle are supplied by CNXI. The action of these fibres is to elevate the spine of the scapula and clavicle leading to shrugging of the shoulders.
Describe the actions of the sternocleidomastoid
Rotation and lateral flexion of the head
Name the 4 suprahyoid muscles and state their action
digastric, mylohyoid, stylohyoid, geniohyoid
These elevate the hyoid and larynx during swallowing
Name the 4 infrahyoid muscles and state their action
Omohyoid, thyrohyoid, sternohyoid and sternothyroid.
How does the nerve supply to the anterior and posterior bellies of the digastric muscle differ?
Anterior belly = inferior alveolar nerve from the mandibular branch of trigeminal.
Posterior belly = digastric branch of the facial nerve
Name the muscle responsible for, and the branch of the facial nerve responsible for their innervation:
a) Elevating eyebrows
b) Smiling
c) Keeping cheeks taut
d) Closing the eyelids
a) Frontalis- temporal branch
b) Levator anguli oris
c) Buccinator muscle - buccal
d) Orbicularis oculi - zygomatic
Explain why damage to the facial nerve causes ptosis
Ptosis is the drooping of the eyelid. This is because of loss of innervation to the muscles that elevate the brow which gives an overall drooped appearance to the eyelid
Explain why yawning can lead to dislocation of the TMJ
Can over-open the jaw causing the mandible to displace anteriorly from the mandibular fossa
Name the 4 muscles of mastication and what is their innervation?
Masseter, temporalis, medial and lateral pterygoids.
These are innervated by the mandibular branch of the trigeminal nerve (V3)
Describe the structure of the bones of the cranium
The bones are flat bones which form fibrocartilaginous joints, or sutures with one another.
Name the bones which articular at each of the following lines:
a) Lamboid
b) Coronal
c) Sagittal
a) Occipital and parietal
b) Frontal and parietal
c) Parietal bones
Explain why damage to the pterion can lead to an extradural haematoma and why is this dangerous?
The middle meningeal artery runs underneath the pterion which can be ruptured if this structure is damaged. This is dangerous because of increased intracranial pressure.
Explain why damage to the ethmoid bone can lead to anosmia?
The ethmoid bone allows passage for the olfactory nerve fibres through the cribriform plate. If this is damaged then the olfactory cells can be damaged resulting in a loss of smell.
Describe the structure of the mandible
The mandible is a symmetrical horseshoe shaped, irregular bone that forms the jaw. It also articulates with the temporal bone at the TMJ joint.
Describe how the structure of the skull differs in the neonate. Why is this important? Therefore why is premature birth a risk?
- Cranial sutures are wide, bones are held together by thick connective tissue
- Lambda and bregma do not exist (more a membranous islands)
The open sutures allow for the bones to be pushed together during birth, with the serrated bone edges temporarily interlocking to protect the brain.
If birth is premature then the bones do not interlock which means a high probability of brain damage.
State 4 roles of the fascia in the head and neck
- Compartmental
- Aid in movement of structures
- Form natural planes
- Determine the spread of infection
Explain why infection in the retropharyngeal space can lead to a unilateral abscess?
How far can an infection spread?
This is a potential space, posterior to the oesophageal wall and anterior to the pre-vertebal fascia. Infection can come from the nasopharynx, paranasal sinuses and middle ear.
This could spread to the diaphragm
State how far an infection can spread along the parapharyngeal space.
Describe a complication of infection within this space.
Up to the level of the mediastinum (T2/3).
Could affect the carotid sheath structures causing internal jugular vein thrombosis or
Describe the borders and contents of the carotid triangle
Superior: posterior belly of digastric
Lateral: medial border of SCM
Inferior: Superior belly of omohyoid
Contents = common carotid artery, internal jugular vein, hypoglossal and vagus nerve
Describe the borders and contents of the posterior triangle
Anterior: posterior border of SCM
Posterior: anterior border of trapezius
Inferior: middle 1/3 of clavicle
Contents: muscles, vasculature: EXTERNAL JUGULAR VEIN, CNXI
Name the triangle formed by the anterior and posterior bellies of digastric and the mandible.
Submandibular triangle
What is the clinical significance of the carotid triangle?
Area of the carotid sinus - presence of baroreceptors (in. CNIX)
Explain why subdural haematomas have the potential to be life-threatening
Subdural haematomas increase the intracranial pressure which could cause compression on the brain. The brainstem may prolapse through the foramen magnum due to the increased pressure, compressing the breathing centres leading to death.
Describe the location at which the facial artery can be palpated
Can be palpated on the mandible just anterior to the masseter muscle.
What condition causes paralysis of SCM and how can childbirth be can cause?
Spinal accessory nerve palsy or torticollis. Childbirth may cause trauma to this nerve or the muscle directly due to hyperextension or tightening of the muscle during delivery.
Why is a runny nose is a symptom of a fracture of the ethmoid bone?
Damage to the cribriform plate of the ethmoid bone which leads to a route for cerbrospinal fluid to leak.
Why can a fracture of the mandible lead to numbness in the lower teeth and the central part of the lower lip?
The inferior alveolar nerve which supplies the lower teeth and the later mental nerve which supplies the lower lip may both be affected by injury to the mandible because they lie along the mandible and could be compressed.
At the start of week 4, what proportion of the embryo does the H+N occupy?
Folding has completed - H&N = about half of the length
Describe how the neural tube is formed
The notochord signals ectoderm thickening which causes the edges to elevate out of the plane of the disk, curling towards each-other to create the neural tube.
Describe the basic components of the pharyngeal arches
Each pharyngeal arch is a system of mesenchymal proliferations in the neck region of the embryo which develops into muscles, cartilages, nerves and arteries.
Describe the structures which are contributed to by the first arch
Nerve: trigeminal nerve (CNV)
Muscles: muscles of mastication, digastric & mylohyoid
Arteries: internal carotid artery
Cartilages: meckel’s cartilage (becomes the mandible, malleus & incus)
How can the neural tube be segmented?
Anterior end can be split into 3 vesicles:
Prosencephalon - forebrain
Mesencephalon - midbrain
Rhombencephalon - hindbrain
Why are the muscles of facial expression innervated by CNVII?
Both are derivatives of pharyngeal arch 2.
Suggest why the nerve to stapedius originates from the second arch
Nerve to stapedius is a branch of the facial nerve (branches within the facial canal) which is the 2nd arch derivative
Describe the innervation of the tongue
Motor - hypoglossal (CNXII)
Sensory (general) - Glossopharyngeal (CNIX)
(special) Anterior 2/3 = chorda tympani (CNVII)
Posterior 1/3 = glossopharyngeal (CNIX)
Describe the remnants of the cartilage of the 3rd arch
Greater cornu (horn) of hyoid, Inferior body of hyoid bone
How does the mandible form?
Derived from Meckel’s cartilage of the 1st arch. Undergoes membranous ossification.
Describe how the nerves given off by the 4th and 6th arches differ
Both arches nerves are from the Vagus nerve (CNX) however the 4th arch associates with the Superior laryngeal nerve
6th arch associates with the recurrent laryngeal nerve.
State the pharyngeal arch from which the thyroid cartilage arises
4th & 6th Pharyngeal arches
What is the primative aortic arch associated with:
a) Internal carotid
b) Aortic arch
c) Brachiocephalic trunk
d) pulmonary arch
a) 3rd
b) Left 4th
c) Right 4th
d) 6th
What is the clinical importance of the recurrent laryngeal nerve, with relation to the aortic arch?
The RLN loops under the 4th arch artery during development passing under the ductus arteriosus.
This is a site of possible compression and damage to the RLN.
On the whole, what do the pharyngeal pouches become?
The pharyngeal gut tube and it’s glandular derivatives
Describe the development of the palatine tonsils
2nd Pharyngeal Pouch
Epithelial proliferation followed by colonisation of lymphoid precursors
Describe the development of the parathyroid glands and the thymus
The thymus is derived from the ventral component of the 3rd Ph. Pouch, developing as two seperate lobes that migrate inferiorly, merging to form a bilobular gland.
Parathyroid is derived from the dorsal component of the 3rd and 4th Ph. Pouches - superior and inferior respectively.
Describe the embryological origin of the external auditory meatus and middle ear.
1st Pharyngeal Pouch
Space between the cartilaginous bars of the 1st and 2nd arch which later become the ossicles.
What is a fisulae and why may babies be born with fistula or cysts along the anterior border of the SCM?
Fistula = abnormal opening between 2 epithelial lined tracts
Failure of the pharyngeal clefts to obliterate following 2nd arch growth.
List 3 functions of the lymphatic system
- Returning lymph back to the blood circulation
- Immune function - contains macrophages
- Transport of FA via chylomicrons
Why do patients who are immobile suffer from lymphoedema?
Lymph vessels are valveless with no pump present - drainage relies on external muscle contraction to move the lymph against gravity. (Passive constriction)
Describe the composition of lymph
- Porous
- Tissue fluid
- Protein
- Microbes
- Chylomicrons
Describe the route of lymph from capillaries to the vasculature
Tissue fluid Lymphatic capillaries Lymphatic afferent vessels Lymph nodes Lymphatic efferent vessels Lymphatic trunks Lymphatic ducts
Why is the course of lymph vessels different between the body and the H&N region?
H&N lymphatic drainage is bilateral with an equal amount draining into the left lymphatic duct and the right lymphatic duct.
However the body does not have an equal distribution of drainage and the majority drains into the left lymphatic duct.
How can the lymphatics of the H&N be classified?
Superficial (regional) or deep (terminal)
What structures comprise waldeyer’s ring?
Adenoids
Lingual Tonsils
Palatine tonsils
Why may infection of the tonsils cause small, firm swellings at the angle of the jaw?
Drainage of the tonsils is into the jugulo-digastric terminal lymph node which is positioned inferior to the angle of the mandible.
Name the lymph node which becomes inflammed in tonsilitis
Pharyngeal tonsil/adenoids
Describe the arrangement of the deep nodes of the neck
Deep to the sternocleidomastoid and in close relation to the internal jugular vein and carotid sheath are the jugulodigastric and jugulo-omohyoid
*note the supraclavicular lymph nodes should also be palpated on examination
Why does GI cancer lead to swelling of the left supraclavicular lymph node?
If cancer cells enter the lymphatic system from the GI system then they would drain into the supraclavicular lymph node as their primary mode of metastases.
Suggest a diagnosis for an enlarged right supraclavicular lymph node
- Lung infection
- Oesophageal cancer
(Drains the lungs, oesophagus & mid section of chest)
State the vertebral level at which the carotid artery bifurcates
C4
Explain why massaging this area can help manage a tachycardia
Stimulation of baroreceptors which increases vagal parasympathetic stimulation to the SAN to slow the rate of depolarisation and therefore slowing the heart rate (brachycardia)
Name 3 main branches of the subclavian artery
- Thyrocervical trunk
- Internal thoracic artery
- Vertebral artery
Describe the structure of the thyrocervical trunk
Branches to give ascending and transverse cervical; subscapular and the inferior thyroid artery
Describe the course of the vertebral artery
Ascends through the transverse foramen of cervical vertebrae (C6-C1)
*C1 the course is along the vertebral artery groove not through the transverse foramina
Explain why carotid artery bifurcation is a common site of atherosclerosis
It is an area of increased turbulance which increases the risk of endothelial cell injury. Endothelial cell injury allows for LDL uptake and deposition. This leads to inflammation and lumen narrowing.
Describe how atherosclerosis can lead to a stroke
More likely to lead to an ischaemic stroke.
Occlusion of a cerebral artery due to severe atherosclerosis or rupture of an atherosclerotic plaque which leads to thrombus formation and acute lumen narrowing. This results in reduced oxygen supply to an area of the brain leading to a stroke.
Name the branches of the external carotid artery
Superior thyroid artery Ascending pharyngeal Lingual Facial Occipital Posterior auricular artery Superficial Temporal artery Maxillary
*latter 2 are terminal arteries
Name the branch of the maxillary artery that runs under the pterion
Middle meningeal artery
Name the two arteries of the scalp which come from the internal carotid
Supra-orbital & supratrochear
Explain why lacerations of the scalp lead to profuse bleeding
The blood supply to the scalp lies within the dense connective tissue layer just underneath the skin.
The blood supply is a vast anastamosis network which means bleeding can be severe.
Why may bursting a spot by the nose cause cavernous sinus thrombosis?
Danger triangle of the face is formed from the medial angle of the eyes to the corners of the mouth.
The drainage from this area is via the supratrocheal and supraorbital veins which form the angular (and then the facial) vein. The facial vein drains into the cavernous sinus.
As the veins of the face are valveless there is a risk of infection tracking back into the cavernous sinus. This would cause an immune response and blockage due to thrombosis.
Why may cavernous sinus thrombosis cause abnormalities in the motor functions of the eye?
The cavernous sinus has close relations to several nerves which supply the muscles of the eye*:
- CNIII (occulomotor)
- CNIV (trochlear)
- CNVI (abducens)
Thrombosis could damage these nerves which would result in loss of stimulation to the rectus and oblique muscles of the eye.
- V1/V2
How may infection spread from the scalp to the meninges?
Drainage of the scalp is via the emissary and diploid veins which drain into the dural venous sinuses.
As these veins are valveless, infection could spread into these sinuses which lie between the periosteal and meningeal dura within the cranial cavity. This poses a risk to the meninges.
Describe the course of the thoracic plane (plane of ludwig) and name 3 events/structures which lie here.
Divides the mediastinum into superior and inferior sections. Horizontally runs from angle of louis to T4
- Pulmonary trunk
- Arch of the aorta
- The carina
- Ligamentum arteriosum
What is the origin of neural crest cells?
Specialised population of cells from the lateral neuroectoderm.
Known as a “fourth germ lineage”.
What are the structures that arise from the maxillary prominences?
Cheeks, lateral upper lip, jaw, secondary palate.
What is the stomadodeum?
Depression within the FNP which is the position of the buccopharyngeal membrane.
What external features are derived from the frontonasal prominence?
Forehead, nose (+bridge of the nose), philtrum, front 4 teeth, primary palate.
Describe the formation of the nose
Nasal placodes form within the FNP.
Medial and lateral nasal prominences form around the nasal placode.
As the maxillary prominences of the 1st ph. arch begins to grow medially they push the nasal prominences along with them.
Medial nasal prominences fuse in the midline and with the maxillary prominences.
Explain how abnormalities in the development of the nose can lead to a cleft lip
Results from failure of either the primary or secondary palatal shelves to reach the midline or fuse in the midline.
Describe how the nasal and oral cavities become seperated
Maxillary prominences form palatal shelves.
Due to the slow development of the mandible these originally grow downwards
Once the mandible has formed the palatal shelves can grow towards each other where they fuse in the midline.
Explain the origin of a dual cleft lip and palate
This is where the maxillary prominence has failed to fuse with the medial nasal prominence and failed to fuse with the other maxillary prominence
How to the eyes develop?
Optic vesicle arises in the forebrain
Grows out towards the lens placode which invaginates and pinches off.
The optic vesicle gives rise to the lens and the retina is formed from diencephalon (forebrain)
How does the position of the eye change during development?
Originates from the sides of the head but moves anterio-medially as the facial prominences migrate.
Name the structures of the ear that arise from the 1st pharyngeal pouch
Eustachian tube, tympanic membrane.
Name the auricles which come from the 1st and 2nd pharngeal arches respectively
1st - Malleus & incus
2nd - Stapes
What is the fate of the otic placode
These invaginate to form auditory vesciles which form the membranous labyrinth of the inner ear (cochlea and semi-lunar canals)
Explain why exophthalmos occurs in hyperthyroidism
Exopthalmos = abnormal protrusion of the eyeball or eyeballs.
In hyperthyroidism this is due to inflammation of the fatty tissues and muscles behind the eyeball.
Explain why nasal secretions increase when people cry
Tears arise from the lacrimal gland which drains into the medial corner of the eye by lacrimal ducts.
Tears then drain into the nasolacrimal duct which drains into the inferior nasal meatus
State the part of the nose into which the nasolacrimal duct drains
Inferior meatus
Name two structures which pass through the optic canal
Opthalmic artery Optic nerve (CNII)
Explain why raised ICP can cause papilloedema
Venous drainage from the eye is compromised leading to distension of the retinal veins which causes papilloedema
State the contents of the superior orbital fissure
CNIII (Superior and inferior branches) CNIV CNVI Branches of CNV1 Superior opthalmic vein
Why does damage to the optic chiasm only affect lateral vision
The retina is essentally split into two halves with a slightly different nervous supply on the “temporal” half to the “nasal” half.
The nerves running through the optic chiasm supply the nasal retina, but the temporal retina innervation runs lateral to the chiasm so wouldn’t be affected if it was damaged..
State a cause of damage to the optic chiasm
Pituitary adenoma
Which part of the orbit is most likely to be fractured in a blow to the skull and why?
Medial wall. This is because it is made of several small, thin bones.
Why may a blow out fracture of the orbit lead to infection of the cavernous sinus?
FIND THIS OUT
Describe two complications of blowout fractures of the orbit?
Trapped inferior rectus muscle
Double vision
Why does damage to CNV1 increase the risk of infection to the eye?
CNV1 supplies the sensory innervation to the cornea. Damage to this nerve means loss of the corneal reflex. This means that dust, bacteria etc may get trapped leading to increased risk of infection
Describe the arterial supply to the eye
Opthalmic artery travels through the optic canal alongside CNII. This is a branch of the internal carotid artery and gives rise to the central retinal artery.
Why may a nasal furuncle cause cavernous sinus thrombosis?
Venous drainage of the nose is via the facial vein which drains into the cavernous sinus. The valveless nature of these veins increases the risk of spread of infection from the nose.
Describe the complications of cavernous sinus thrombosis
CNIII, CNIV, V1 & V2 and CNVI all travel lateral to the cavernous sinus. Thrombosis may damage these nerves leading to:
- Loss of motor movement of the eye
- Loss of sensation to the cornea
- Loss of sensation to the opthalmic and maxillary areas of the face
The internal carotid artery may also be affected. This could lead to loss of blood supply to neural structures and the eye
A patient suffers damage to CNVII. Give 2 reasons why they are more likely to suffer from eye infections
Parasympathetic supply to the lacrimal gland is prevented which leads to reduced lacrimal gland secretions so eye dries out.
Reduced motor innervation to the orbicularis oculi therefore the eye doesn’t close fully - loss of protective blink reflex.
State 3 infectious causes of conjunctivitis
Staphylococcus aureus
Streptococcus pneumoniae
Haemophillus influenzae
A patient presents with an inability to blink. Give 3 potential causes of this
Facial nerve paralysis
Occulomotor nerve palsy - levator palpebrae superioris paralysed
Skin disorders such as Ichythyosis
Outline 3 causes of CNIII dysfunction.
Cavernous sinus thrombosis
Head injury
Brainstem injury
How may CNIII palsy present?
Double vision (loss of occulomotor function)
Ptosis (unopposed orbicularis oculi)
Mydriasis (unopposed dilator papillae)