The Face

Sensory supply of face (116)

Trigeminal nerve

3 zones by 3 branches of V; meet at margins of eyelids & angles of mouth ® junction lines curve out from there. Angle of mandible = only part of facial skin not supplied by V (gr auricular nerve).

- pattern of facial haemangioma and distribution of herpes zoster vesicles often go with these.

- Brainstem representation of these inputs ® onion skin model with central areas highest.

(A) Ophthalmic division ® 5 cutaneous branches (31)

(1) Lacrimal

® lateral upper eyelid

(2) Supraorbital

Emerges from supraorbital notch ® up to upper eyelid, forehead, scalp up to vertex (31)

(3) Supratrochlear

Medial to (2), ® central forehead up to hairline

(4) Infratrochlear

® skin on medial upper lid, descends ® side of external nose and bridge

4 above branches also ®conjunctiva of upper lid

(5) External nasal

® midline skin of nose down to tip

Supraorbital and supratrochlear are branches of the frontal nerve

Infratrochlear and external nasal are from nasociliary (latter via anterior ethmoidal branch)

- when these are involved in herpes zoster, cornea may also become infected ® ulceration

(B) Maxillary division ® 3 cutaneous branches (40)

Exits foramen rotundum ® pterygopalatine fossa ® exits infraorbital fissure

(1) infraorbital nerve

Emerges from infraorbital foramen to lie b/n levator labii superioris and levator anguli oris

Tuft of branches radiate ® palpebral, nasal & labial (from midline to 2^nd premolar tooth) branches.

(2) zygomaticofacial

From foramen on outer surface of zygomatic bone ® overlying skin

(3) zygomaticotemporal

Emerges in temporal fossa by foramen ® small area of temporal skin.

(C) Mandibular division ® 3 cutaneous branches

Nerve of 1^st pharyngeal arch, exiting foramen ovale with motor root of trigeminal nerve ® infratemporal fossa.

(1) auriculotemporal

Passes back around neck of mandible ® ascends over posterior zygomatic arch behind sup temp a.

- Auricular branch ® EAM & external surface of auricle,

- Temporal branch ® scalp, skin of temple.

(2) buccal

Gives cutaneous twigs then pierces buccinator ® cheek below zygomatic bone

(3) mental

From inferior alveolar nerve; Breaks up into tuft of branches then ®

enters mandibular foramen ® sensation to posterior 5 teeth; incisive branch ® remaining 3.

Blood supply to face

Facial artery (63)

Highest of anterior branches of ECA.

Hooks over inferior border of mandible at anterior border of masseter muscle

® tortuous course toward medial eye on buccinator deep to lip dilators.

® sizeable inferior and superior labial arteries, anastomose across midline (superior ® nasal septum)

Branches of ophthalmic artery ® forehead (supraorbital and supratrochlear) & ® dorsal nasal to nose root

Branches of superficial temporal artery ® temple (transverse facial)

- supraorbital anastomoses with superficial temporal = ICA ® ECA communication

Venous return (64)

Blood from temple collected by superficial temporal vein, joined by maxillary vein from pterygoid plexus to form retromandibular vein.

- its posterior branch and post-auricular vein form EJV.

Supraorbital and supratrochlear veins unite at medial canthus ® angular vein, becomes facial vein

® straight course behind artery to angle of mandible

® pierces investing fascia and joined by anterior branch of retromandibular vein (and sometimes superior thyroid); empty together into IJV

Note that facial vein connects with cavernous sinus via ophthalmic vein and deep facial vein; obstruction of facial vein between these ® flow via cavernous sinus.

- danger are of infection of upper lip, nearby cheek and up to between angular veins

Lymphatics

Three superficial groups (66)

Chin & tip of tongue ® submental nodes

Central face ® submandibular nodes

Lateral face ® preauricular nodes

Eventually all of this reaches deep cervical nodes.