1. Face (Skin & Fascia)

• Skin of the face is thick, elastic, and highly vascular (explains blushing). It's rich in sweat and sebaceous glands - the sebaceous glands can cause oily skin and acne.
• Superficial fascia contains the muscles of facial expression, blood vessels, nerves, and variable fat. The fat is absent in eyelids but prominent in the cheek (buccal fat pad), which aids suckling in newborns.
• Deep fascia is absent on most of the face except over the parotid gland and buccinator muscle (called buccopharyngeal fascia). Over the masseter muscle it forms the parotidomasseteric fascia.

2. Muscles of Facial Expression

3. Nerve Supply (Facial Nerve - CN VII)

1. Temporal branch - Frontalis, orbicularis oculi, auricularis
2. Zygomatic branch - Orbicularis oculi (lower eyelid)
3. Buccal branch - Cheek & upper lip muscles (Buccinator, Risorius, Zygomaticus major & minor, LLSAN, LLS)
4. Marginal mandibular branch - Lower lip & chin muscles (Depressor anguli oris, Depressor labii inferioris, Mentalis)
5. Cervical branch - Platysma (neck)

4. Clinical Anatomy - Bell's Palsy

• Common site of injury: compression/damage at the stylomastoid foramen
• Results in:
  • Loss of movement of affected side
  • Mouth deviation toward the healthy side
  • Loss of forehead wrinkling
  • Inability to close eye (overflow of tears, drooling)
  • Food accumulation in the vestibule of the mouth (between teeth and cheek)

5. Blood Supply of the Face

• Main supply: Facial artery (branch of external carotid artery)
• The facial artery is highly tortuous (winding) because it runs through facial muscles and needs extra length to avoid rupture during expression.
• It has two parts:
  • Cervical part (mnemonic: STAG): Submental a., Tonsilar a., Ascending palatine a., Glandular a.
  • Facial part: Inferior labial a., Superior labial a., Lateral nasal a., Angular a.
• Additional supply from the Dorsal Nasal artery (branch of ophthalmic a., which is a branch of the Internal Carotid Artery)

6. Venous Drainage

• Mainly by the facial vein
• Origin: Near the medial canthus of the orbit where the supra-trochlear and supra-orbital veins form the angular vein
• The angular vein continues downward as the facial vein, combines with the retromandibular vein to form the common facial vein, which drains into the internal jugular vein

7. Dangerous Area of the Face

• The triangular area from the corners of the mouth to the bridge of the nose - veins here are valveless emissary veins
• Infection (pimple, boil, squeezing acne) in this area can spread backward to the cavernous sinus inside the skull, potentially causing cavernous sinus thrombosis - a life-threatening condition
• Never squeeze pimples in this area!