FACE - University Examination Answers

Q1. FACE (Overview / Introduction)

1. Skin
2. Superficial fascia (contains muscles of facial expression, vessels, nerves, fat)
3. Deep fascia (absent over most of the face)
4. Muscles of facial expression
5. Deep structures (bones of skull)

• Muscles of facial expression are derived from the 2nd branchial arch
• All muscles of facial expression are supplied by the facial nerve (CN VII)
• Skin of face is supplied by the trigeminal nerve (CN V)
• Rich blood supply from the facial artery (branch of external carotid artery)

Q2. FACIAL NERVE - COURSE

A. Intracranial Course (Within the Skull)

1. Origin: Arises from the facial nucleus in the pons (at the junction of pons and medulla)
2. The nerve fibers loop around the abducens nucleus (forming the facial colliculus in the floor of the 4th ventricle)
3. Exits the brainstem at the cerebellopontine angle (junction of pons and medulla)
4. Passes through the internal acoustic meatus (IAM) with CN VIII
5. Enters the petrous part of the temporal bone - traverses the facial canal
6. Passes through the geniculate ganglion (sensory ganglion) - gives off the greater petrosal nerve
7. Travels horizontally above the oval window, then turns downward (posterior to the middle ear)
8. Exits the skull through the stylomastoid foramen

B. Extracranial Course (Outside the Skull)

1. Exits from stylomastoid foramen
2. Gives off posterior auricular nerve, nerve to stylohyoid, nerve to posterior belly of digastric
3. Enters the parotid gland - runs between the superficial and deep lobes
4. Divides into upper (temporofacial) and lower (cervicofacial) divisions within the parotid gland
5. Gives off 5 terminal branches from the parotid gland

"Two Zebras Bit My Cat" T - Temporal Z - Zygomatic B - Buccal M - Marginal mandibular C - Cervical

Q3. FACIAL NERVE - BRANCHES AND DISTRIBUTION

A. Branches Within the Petrous Bone:

B. Branches After Stylomastoid Foramen (Before Parotid):

1. Posterior auricular nerve - muscles of auricle, occipitalis muscle
2. Nerve to posterior belly of digastric
3. Nerve to stylohyoid

C. Five Terminal Branches (From Parotid Gland):

Q4. BELL'S PALSY (Applied Anatomy)

• Most commonly caused by reactivation of Herpes Simplex Virus (HSV-1)
• The nerve becomes swollen and compressed within the rigid bony canal
• Leading to ischemia and demyelination

1. Sudden onset unilateral facial weakness
2. Inability to close the eye on the affected side (lagophthalmos)
3. Drooping of the corner of the mouth
4. Flattening of the nasolabial fold
5. Loss of forehead wrinkles
6. Bell's phenomenon - on attempting to close the eye, the eyeball rolls upward and outward (protective reflex)
7. Difficulty chewing food
8. Drooling of saliva
9. If lesion is proximal to chorda tympani: loss of taste in anterior 2/3 of tongue
10. If lesion is proximal to greater petrosal nerve: decreased lacrimation

• Oral Corticosteroids (Prednisolone) - started within 72 hours, 1 mg/kg/day for 10 days
• Antiviral drugs (Acyclovir) if viral etiology suspected
• Eye protection - artificial tears, eye patch (to prevent corneal damage from lagophthalmos)
• Physiotherapy and facial exercises

Q5. SENSORY NERVE SUPPLY OF FACE

Division 1 - Ophthalmic (V1):

• Supraorbital nerve - forehead, upper eyelid
• Supratrochlear nerve - medial forehead, root of nose
• Infratrochlear nerve - medial angle of eye, root of nose
• Lacrimal nerve - lateral upper eyelid, lacrimal gland area
• External nasal nerve - skin of nose

Division 2 - Maxillary (V2):

• Infraorbital nerve - lower eyelid, cheek, side of nose, upper lip
• Zygomaticofacial nerve - prominence of cheek
• Zygomaticotemporal nerve - temporal region

Division 3 - Mandibular (V3):

• Mental nerve (branch of inferior alveolar) - chin, lower lip
• Buccal nerve - cheek skin
• Auriculotemporal nerve - temporal region, auricle, parotid region, scalp in front of ear

• The angle of the mandible is NOT supplied by CN V - it is supplied by the great auricular nerve (C2, C3 - from cervical plexus)
• This is a clinically important fact (tested frequently!)

V1 = Forehead and eye region V2 = Cheek and midface V3 = Lower face and jaw Angle of jaw = Great auricular nerve (C2, C3)

Q6. DANGEROUS AREA OF FACE

1. Infection starts (e.g., furuncle/boil/pimple in this region)
2. Spreads to the facial vein
3. The facial vein communicates with the superior ophthalmic vein
4. Superior ophthalmic vein drains into the cavernous sinus
5. Infection spreads to the cavernous sinus → Cavernous Sinus Thrombosis

• The facial vein has no valves (unlike most veins in the body)
• Therefore blood (and infection) can flow in either direction (retrograde spread is possible)

• Severe headache, high fever
• Proptosis (bulging eye)
• Periorbital edema and chemosis
• Palsies of CN III, IV, V1, V2, VI (nerves passing through cavernous sinus)
• Most common nerve affected first: CN VI palsy (lateral gaze palsy)

"Never squeeze a pimple in the dangerous area of the face" - this is the classic teaching because squeezing increases the risk of retrograde spread of infection to the cavernous sinus.

Q7. BLACK EYE (Applied Anatomy)

1. Direct trauma to the eye or orbit (most common) - blunt injury
2. Fracture of the orbital plate - blood tracks forward to the eyelid
3. Fracture of base of skull (anterior cranial fossa fracture) - produces bilateral black eyes ("panda eyes" or "raccoon eyes")

• Blunt force causes rupture of small vessels around the orbit
• Blood collects in the loose connective tissue of the eyelids (which is very lax, hence even small amounts of blood cause visible bruising)
• Skin around the orbit is thin and transparent, making bruising very visible

1. Initially: Dark red/purple (fresh blood - due to haemoglobin)
2. Day 2-3: Blue-black
3. Day 4-5: Greenish (haemoglobin → biliverdin)
4. Day 6-7: Yellow (biliverdin → bilirubin)
5. Eventually fades completely

1. Bilateral black eye ("panda eyes") without direct orbital trauma = Fracture of the anterior cranial fossa (basal skull fracture) - a neurosurgical emergency
2. Subconjunctival hemorrhage without a visible posterior limit = may indicate an orbital roof fracture
3. Associated with severe pain, loss of vision, or diplopia = serious intraocular injury
4. Associated with hyphaema (blood in anterior chamber) = needs urgent ophthalmology referral

Bilateral black eyes after a head injury (without direct trauma to the eyes) = Basal skull fracture until proven otherwise. This is because blood from the fractured base of skull tracks forward through the tissue planes to collect around both eyes.

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