Head and Neck 2: Face and Skull Flashcards
What is CN V? What is its purpose?
Trigeminal nerve - conveys cutaneous sensation from the face and forehead
How many divisions of CN V are there?
3 divisions - each of which carries sensation from a particular area of the face/anterior scalp
What are the 3 divisions of the trigeminal nerve?
- CN V1 : opthalmic nerve
- CN V2 : maxillary nerve
- CN V3 : mandibular nerve

Which division of the trigeminal nerve innervates which area of skin?

Red - Ophthalmic Nerve
Blue - Maxillary Nerve
Green - Mandibular Nerve
What should clinical examination of the sensory innervation of the face involve?
involve testing pinprick and light touch sensations over each of these regions
What may lesions of these branches of the trigeminal nerve lead to?
lesions of any of these branches may lead to loss of sensation over the corresponding anatomical division.
What are the 3 important groups of muscles in the head?
- The muscles of facial expression
- The muscles of mastication
- The extraocular muscles
Info about muscles of facial expression:
Some of these, act as sphincters and dilators controlling the various openings, they support the angles of the eyes and mouth, and they prevent secretions dribbling on to the face. They all insert into the skin of the face and are thus very superficial.
What are the 6 most important muscles of facial expression?
- Occipitofrontalis
- Orbicularis oculi
- Orbicularis oris + Buccinator
- Orbicularis oris
- Dilators of the mouth
- Platysma

Label this diagram showing the most important muscles of facial expression

The right 6: (top to bottom)
- Occipitofrontalis (frontal belly)
- Obicularis oculi
- Dilators of the mouth
- Orbicularis oris + buccinator
- Orbicularis oris
- Buccinator
Left 2 (top to bottom):
- Occipitofrontalis (occipital belly)
- Platysma

Orbicularis Oculi:
- Location?
- Action?
- Innervation?
- Location: The orbicularis oculi muscle surrounds the eye socket and extends into the eyelid.
- Action:
- Closes the eyelids
- Acts to draw the eyebrows together, creating vertical wrinkles on the bridge of the nose.
- Innervation: facial nerve CN VII

Occipitofrontalis:
- Location?
- Action?
- Innervation?
- Location: Covers parts of the skull. It consists of two bellies: The occipital belly, near the occipital bone, and the frontal belly, near the frontal bone
- Action:
- Frontal part: This part of the muscle pulls the scalp anteriorly; wrinkles the forehead and elevates eyebrows
- Occipital part: This part pulls the scalp posteriorly (retracts)
- Innervation: Facial nerve CN VII

Orbicularis oris:
- Location?
- Action?
- Innervation?
- Location: The fibres of the orbicularis oris enclose the opening to the oral cavity.
- Action: Sphincter of the mouth. Purses the lips.
- Innervation: Facial nerve CN VII

Buccinator:
- Location?
- Action?
- Innervation?
- Location: This muscle is located between the mandible and maxilla, deep to the other muscles of the face.
- Action: The buccinator pulls the cheek inwards against the teeth, preventing accumulation of food in that area. Keeps cheeks taut when whistling etc
- Innervation: Facial nerve CN VII

Platysma:
- Location?
- Action?
- Innervation?
- Location: Lies superficially within the anterior aspect of the neck.
- Action: Tenses the skin of the inferior face and neck
- Innervation: Facial nerve CN VII

Which nerve innervates the muscles of facial expression?
Facial nerve CN VII
The facial nerve has motor, sensory and autonomic functions. What are the sensory and autonomic functions?
- Sensory:
- A small area around the concha of the external ear.
- Special Sensory – provides special taste sensation to the anterior 2/3 of the tongue via the chorda tympani
- Autonomic: supplies many of the glands of the head and neck including:
- Submandibular and sublingual salivary glands.
- Nasal, palatine and pharyngeal mucous glands.
- Lacrimal glands.
The orbicularis oculi, is the circular muscle that acts as a sphincter around the eye. Which two muscles act as dilators of the eyelids?
Levator palpebrae superioris and superior tarsal muscles both act to open the eyelid. They are only present in the upper eyelid.

Paralysis of orbicularis oculi can lead to a serious complication – what is it?
- Exposure keratitis: The eye cannot shut – this can cause the cornea to dry out.
- Ectropion: The lower eyelid droops. Lacrimal fluid pools in the lower eyelid and cannot be spread across the surface of the eye. This can result in a failure to remove debris, and ulceration of the corneal surface.
Which muscle acts as the sphincter of the mouth?
Orbicularis oris
What is the action of orbicularis oris opposed by?
A number of dilator muscles (You do not need to know the names of individual dilator muscles)
What is the function of the buccinator muscle?
a) in neonates?
b) in adults?
- Neonates: It is used to suckle (is one of the first muscles in infants to be activated)
- Adults: The buccinator compresses the cheeks against the teeth and is used in acts such as blowing. It is an assistant muscle of mastication (chewing).
What is the parotid gland?
the largest of the paired salivary glands
Location of the parotid gland?
It occupies the interval between the mastoid process posteriorly, and the ramus of the mandible (covered by the masseter muscle) which it overlaps, anteriorly.

What does the parotid gland lie within?
The parotid gland lies within the fascial parotid sheath, which is continuous with the investing fascia of the neck.
In some conditions the parotid gland may become swollen. Such swelling is extremely painful. Name one such condition and suggest why it is so painful.
Parotitis:
- Inflammation of the parotid gland, usually as a result of an infection. The parotid gland is enclosed in a tough fibrous capsule. This limits swelling of the gland, producing pain.
- The pain produced can be referred to the external ear. This is because the auriculotemporal nerve provides sensory innervation to the parotid gland and the external ear.
How do secretions from the parotid gland get to the mouth?
The parotid duct carries secretions from the parotid gland into the mouth

Describe course of parotid duct
During its course it travels anteriorly over the masseter muscle to pierce the buccinator muscle and open (drain) into the mouth.
Where does the parotid duct open in the mouth?
It opens out into the oral cavity near the second upper molar.

An important cranial nerve divides into its five terminal branches within the substance of the parotid gland. Which nerve is this? What are these 5 branches called?
The facial nerve (cranial nerve VII), gives rise to five terminal branches within the parotid gland. These terminal branches emerge from the anterior border of the gland and innervate the muscles of facial expression.
5 branches:
- Temporal branch
- Zygomatic branch
- Buccal branch
- Marginal mandibular branch
- Cervical branch

Why is the facial nerve vulnerable to damage in the parotid gland?
Lies superifically in the gland
Think of at least two situations in which the facial nerve nerve is at risk?
- The most common cause of an intracranial lesion of the facial nerve is infection related to the external or middle ear.
- Parotid gland pathology – e.g a tumour, parotitis, surgery.
What other structures lie within the substance of the parotid gland?
- the retromandibular vein
- the external carotid artery - which divides into its two terminal branches

How is the retromandibular vein formed?
formed by the union of the superficial temporal vein and the maxillary vein
Label the anterior branches of the external carotid artery

Left top to bottom:
- Superficial temporal
- Maxillary
- Facial
- Lingual
- Superior thyroid
What is the middle meningeal artery a branch of?
The maxillary artery
What does the middle meningeal artery supply?
the dura mater and the calvaria
What is the pterion? What artery runs under here? Why is this area clinically important?
The pterion is the weakest area of the skull because it is where several bones of the skull converge. The middle meningeal artery runs under here.
Meningeal branches diagram

Which bones converge at the pterion?
frontal, parietal, temporal, and sphenoid bones
What type of intracranial bleeding may result from a fracture at the pterion?
Blood can accumulate between the skull and the dura mater, forming an extradural haematoma.
Apart from the carotid pulse, in which other areas of the face can you feel pulses?
- Temporal pulse x2
- Facial pulse

Carotid pulse:
- Artery being palpated?
- Area being palpated?
- carotid artery
- on either side of the front of the neck just below the angle of the jaw.

Temporal pulse:
- Artery being palpated?
- Area being palpated?
- superficial temporal artery
- palpated on the temple directly in front of the ear with the index finger
- anterior branch of superficial temporal artery
- above the zygomatic arch, above and in front of the tragus of the ear.

Facial pulse:
- Artery being palpated?
- Area being palpated?
- Facial artery
- located on the mandible (lower jawbone) on a line with the corners of the mouth

Which cranial nerve is the hypoglossal nerve?
CN XII
Which nerve is intimately related to the carotid arteries?
The hypoglossal nerve - it loops around the internal and external carotid arteries to run towards the tongue

Label the diagram

Right 5 (top to bottom):
- Internal carotid artery
- External carotid artery
- Posterior belly of digastric
- Hypoglssal nerve
- Common carotid artery
Left 1:
- Internal jugular vein
What is the function of the Hypoglossal nerve?
Purely somatic motor function, innervating all the extrinsic and intrinsic muscles of the tongue (except the palatoglossus, innervated by vagus nerve).
What are the orbits?
The orbits (eye sockets) are bilateral bony cavities in the facial skeleton, formed by 7 bones of the skull.
On this diagram of the right orbit, label:
- The bones of the skull
- The main formaina
Bones:
F - Frontal bone
E - Ethmoid bone
N - Nasal
L - Lacrimal bone
M - Maxilla
Z - Zygomatic
S - Sphenoid bone
Foramina:
Far left: Superior orbital fissure
Middle left: Optic canal
Bottom left: Inferior orbital fissure
Bottom middle: Infra-orbital foramen
What passes through the optic canal?
- optic nerve (CN II)
- ophthalmic artery
Which cranial nerves pass through the superior orbital fissure?
- CN III
- CN IV
- CN V1
- Lacrimal nerve
- Frontal nerve
- Nasociliary nerve (these are all branches of the opthalmic)
- CN VI
Which cranial nerves pass through the inferior orbital fissure?
zygomatic branch of the maxillary nerve
Which cranial nerves pass through the infraorbital foramen?
- infraorbital branch of the maxillary nerve
- the second division of the fifth cranial nerve.
How many extraocular muscles are there? What are they?
- The extraocular muscles are located within the orbit, but are extrinsic and separate from the eyeball itself. They act to control the movements of the eyeball and the superior eyelid.
Which 6 of the 7 extraoccular muscles are involved in eye movement?
- Superior rectus muscle
- Inferior rectus muscle
- Medial rectus muscle
- Lateral rectus muscle
- Superior oblique muscle
- Inferior oblique muscle
What are the actions of the 6 extraocular muscles involved in eye movement? What are they innervated by?
-
Superior rectus muscle:
- Elevates the eyeball.
- Supplied by CN III, the oculomotor nerve.
-
Inferior rectus muscle:
- Depresses the eyeball.
- Supplied by CN III, the oculomotor nerve.
-
Medial rectus muscle:
- Adducts the eyeball.
- Supplied by CN III, the oculomotor nerve.
-
Lateral rectus muscle:
- Abducts the eyeball.
- Supplied by CN VI, the abducens nerve.
-
Superior oblique muscle:
- Inverts (medially rotates) the eyeball.
- Supplied by CNIV, the trochlear nerve.
-
Inferior oblique muscle:
- Everts (laterally rotates) the eyeball.
- Supplied by CN III, the oculomotor nerve.
Describe the innervation of the 6 extraocular muscles involved in eye movement
Most muscles are innervated by CN III except for the lateral rectus and superior oblique muscles, which are innervated by the 6th and 4th cranial nerves, respectively; the ‘chemical formula’ LR6SO4 may help you to remember this.
What is the 7th extraocular muscle? Function? Innervation?
Levator palpebrae superioris
- lifts the eyelids
- supplied by CN III, the oculomotor nerve.
Label the 7 extraocular muscles

Left picture (from top to bottom)
- ?
- medial rectus
- superior rectus
- lateral rectus
Right picture (from top clockwise)
- levator palpebrae superioris
- superior oblique
- medial rectus
- inferior rectus
- lateral rectus
- inferior oblique
Cranial nerves III, IV and VI; the oculomotor, trochlear and abducens supply all the extraocular muscles. Which is the only one of these nerves to emerge from the dorsal aspect of the brainstem.
The trochlear nerve
Label these nerves

Orange: occulomotor
Purple: trochlear nerve
Green: aducens
What is diplopia?
Double vision (seen in disorders of cranial nerves III, IV and VI)
How would you examine a patient’s eye movements? (i.e. how would you test whether the extraocular muscles were functioning properly?)
- Hold your finger (or a pin) approximately 30cm in front of the patient’s eyes and ask them to focus on it. Look at the eyes in the primary position for any deviation or abnormal movements.
- Ask the patient to keep their head still whilst following your finger with their eyes. Ask them to let you know if they experience any double vision or pain.
- Move your finger through the various axes of eye movement in a ‘H’ pattern.
- Observe for any restriction of eye movement and note any nystagmus (which may suggest vestibular nerve pathology or stroke).
There are many non-neurological causes of eye movement abnormalities e.g. defects of the extraocular muscles or the neuromuscular junction. How can the functioning of:
- Oculomotor
- Abducens
- Trochlear
be examined individually?
Which muscles are being tested in each of the above assessments?
- Occulomotor: ask the patient to look medially. Check that the upper lid is fully retracted on upward gaze.
- Medial rectus
- Abducens: ask the patient to look laterally.
- Lateral rectus
- Trochlear: ask the patient to look medially and then look downwards
- inferior rectus
What is the function of levator palpabrae superioris?
Elevates the upper eyelid.
What is ptosis? It results from malfunction of which muscles?
Drooping of the upper eyelid - superior tarsal muscle.
What is Horner’s syndrome?
Horner’s syndrome refers to a triad of symptoms produced by damage to the sympathetic trunk in the neck:
- Partial ptosis (drooping of the upper eyelid) – Due to denervation of the superior tarsal muscle.
- Miosis (pupillary constriction) – Due to denervation of the dilator pupillae muscle.
- Anhidrosis (absence of sweating) on the ipsilateral side of the face – Due to denervation of the sweat glands.
What are the intraocular muscles?
Muscles within the eye. The intraocular muscles include the ciliary muscle, the sphincter pupillae and the dilator pupillae.
What innervates the ciliary and the sphincter pupillae muscles?
CNIII, the oculomotor nerve
hat are the functions of each of the intraocular muscles?
Ciliary: changes the shape of the lens when your eyes focus on a near object
Dilator pupillae: acts to increase the size of the pupil to allow more light to enter the eye
Sphincter pupillae: functions to constrict the pupil in bright light
Are the intraocular muscles under voluntary or involuntary control? Find out which autonomic ganglion is involved in controlling these muscles?
Involuntary - ??
What is the temporomandibular joint (TMJ)?
A modified hinge synovial joint - connects your jaw to the temporal bones of your skull

What movements does the temporomandibular joint (TMJ) allow?
It permits gliding, rotation, flexion (elevation) and extension (depression) of the mandible
What is the temporomandibular joint (TMJ) formed by?
The joint is formed by the articulation between the mandibular fossa of the temporal bone and the condylar process of the mandible.
Label these structures

Left top to bottom:
- Mandibular fossa
- Condylar process of the mandible
- Mandibular ramus
- Mandibular angle
Right top to bottom:
- Zygotmatic process of temporal bone
- Articular tubercle of temporal bone
- Mandibular coronoid process
What are the two articulating surfaces of the TMJ separated by? What does this create?
the articular disc of the TMJ creating superior and inferior articular cavities

What is dislocation of the TMJ usually prevented by?
The articular tubercle - a bony structure which acts together with the ligaments to prevent dislocation.
Describe movements of TMJ when mouth opens
For the mouth to open the condylar process must glide anteriorly to lie directly beneath the articular tubercle – this is called protrusion
What contributes to depression of the mandible?
- only possible once the mandibular condyle is fully protracted.
- Depression of the mandible usually relies on gravity.
- However, the lateral pterygoid and the hyoid muscles can also contribute to actively opening the jaw
How many muscles of mastication are there? How are they organised?
4 - 2 superficial and 2 deep
Name of the muscles of mastication?
- Masseter
- Temporalis
- Medial pterygoid
- Lateral pterygoid
Origin and insertion of masseter?
Origin: Zygomatic process of temporal bone
Inserts: Lateral aspect of the ramus and angle of the mandible

Origin and insertion of temporalis?
Origin: temporal fossa
Inserts: the coronoid process of the mandible.

Origin and insertion of medial pterygoid?
Origin: the medial aspect of the lateral pterygoid plate of the sphenoid bone.
Inserts: medial aspect of the angle of the mandible.

Origin and insertion of lateral pterygoid?
Origin: lateral (external) aspect of the lateral pterygoid plate of the sphenoid bone
Insertion: condyloid process of the mandible
Label the:
- medial pterygoid plate
- lateral pterygoid plate


Label the:
- mastoid process
- mandibular fossa
- zygomatic process

?
Label the:
- ramus
- angle
- condyloid process
- coronoid process
- mandibular notch

?
Movements of the mandible and the muscles

What are all of the muscles of mastication innervated by?
A branch of cranial nerve V, the trigeminal nerve. This nerve sends a branch, the mandibular branch (V3) which travels from the brainstem to the face through the foramen ovale in the base of the skull
Unilateral damage to the mandibular branch of the trigeminal nerve will lead to the jaw deviating to one side when opened against resistance.
If the lesion is on the left side, which side will the jaw deviate to?
Mandible deviates towards paralysed side (i.e. will move left)