I. FACE

A. Facial Skin and Fascia - Skin on face is thin and moveable; has many sebaceous glands and sweat glands. Superficial fascia of face is loose, except at nose; facial muscles are embedded in superficial fascia; there is NO deep fascia over face.

B. Arterial supply to Face - extensive; vessels have many anastomoses. (Atlas Fig. 7.7, 7.8, 8.6; Snell Fig. 11-32)

1. branches of External Carotid artery (major blood supply to head)

a. Facial artery - course: extremely winding and tortuous; artery arises from anterior side of External Carotid, first courses medial to mandible, then appears on face anterior to the mandible (site of pulse of Facial artery); artery ascends lateral to lips and ends medial and inferior to orbit. Branches on face:

i) Superior and Inferior Labial arteries - upper and lower lips. ii) Angular artery = main part of facial artery adjacent to nose and to angle (corner) of eye.

b. Superficial Temporal artery - one of two terminal branches of External Carotid; course - arises anterior to external auditory meatus (opening to ear), deep to parotid salivary gland; has many branches to scalp; named branch on face:

i) Transverse Facial artery - arises within the parotid gland; courses anteriorly and medially just above parotid duct.

2. branches of Internal Carotid artery (major blood supply to brain, orbit)

a. Ophthalmic artery - many branches to orbit but also has a number of named branches to face, forehead and nose:

i) Supraorbital artery (above orbit)

ii) Supratrochlear artery (on medial and superior side of orbit)

Note: Orbit (= eye socket) contains the eye and muscles that move the eye, but it is also a major route for nerves and blood vessels to get to other places, (ex. to face and nasal cavity).

C. Venous drainage - veins of face generally follow arteries (Atlas Fig. 8.4; Snell Fig. 11-32); have no valves; veins drain both into the skull and down face to the neck; have extensive anastomoses.

Note: Prolonged infections on face (pimples or acne) can be dangerous because veins of face anastomose, have no valves and drain both to the brain and down to the neck; infections can spread via anastomoses from face into venous sinuses inside of skull (through orbit, for example); can involve cranial nerves to muscles of eye (clinical sign is blurred vision); infections on face lateral to nose are particularly dangerous.

D. Sensory supply - via branches of Trigeminal nerve (cranial nerve V); Trigeminal nerve has three divisions: Ophthalmic division (V1), Maxillary division (V2) and Mandibular division (V3). (Atlas Fig. page 605)

1. branches of Ophthalmic division - to skin above orbit; Supraorbital, Supratrochlear, Infratrochlear, Lacrimal and External Nasal nerves.

2. branches of Maxillary division - to skin of cheek below orbit; Infraorbital, Zygomaticofacial and Zygomaticotemporal nerves.

3. branches of Mandibular division - to skin of jaw and face below angle of mouth; Mental nerve, Auriculotemporal nerve and Buccal branch of Trigeminal nerve.

E. Muscles of Facial Expression - move skin of face, close eyes and close and open mouth; allow you to convey emotions by facial gestures (ex. sneering and contempt); most are attached to bones and insert upon skin; many named for their actions or Latin or Greek words; movements elicited in test for Facial Nerve function (Atlas Figs. pages 603, 605, 663.; Snell Fig. 11-34)

1. Orbicularis oculi - has palpebral (eyelid) and orbital part (edge of orbit); action - close eyelids (note: orbital part 'buries' eyelids, as closing eyes in a sandstorm).

2. Orbicularis oris - surrounds and closes mouth.

3. Muscles of nose - a. Compressor naris - acts to compress nasal cartilages; b. Dilator naris - dilates nostrils; c. Procerus - wrinkles skin of nose.

4. Muscles of upper lip - a. Levator labii superioris - lifts upper lip; b. Zygomaticus major and minor - raise and pull upper lip laterally.

5. Muscles at angle of mouth - a. Levator anguli oris - raises corner of mouth; b. Risorius - smiling muscle; b. Depressor anguli oris - tragedy muscle.

6. Muscle of lower lip and chin - a. Depressor labii inferioris - depresses lower lip; b. Mentalis - wrinkles skin of chin.

7. Buccinator - muscle in cheek; compresses mouth and keeps food between teeth when chewing; buccinator is latin for trumpeter.

8. Frontalis and Occipitalis – muscles in scalp attached to Epicranial Aponeurosis, skin; frontalis raises eyebrows.

8. Platysma - extends in neck from mandible to fascia over Pectoralis Major muscle; moves skin of neck.

F. Motor innervation to muscles of facial expression - via Facial nerve (cranial nerve VII); nerve leaves skull via stylomastoid foramen; enters parotid gland; divides into 5 terminal branches: superior to inferior (Atlas Fig. page 603)

1. Temporal

2. Zygomatic

3. Buccal - (not to be confused with Buccal branch of V)

4. Mandibular

5. Cervical

II. DEVELOPMENT OF FACE (Sadler Figs. 15.5, 15.21 - 15.23; Snell Fig. 11-27)

A. Five facial primordia - form in fourth week in development and surround developing stomodeum (= primitive mouth) (Note: the term process is the same thing as prominence) (Sadler Figs. 15.5, 15.21)

1. Frontonasal process - formed by mesenchyme below brain; unpaired

2. Maxillary processes - from first branchial arch; paired.

3. Mandibular processes - from first branchial arch, inferior to maxillary processes.

B. Sequence of Development (Sadler Figs. 15.21-15.23)

1. Thickenings (Nasal placodes) form on each side of Frontonasal process.

2. Medial and Lateral Nasal processes form at margins of Nasal placodes.

3. Upper parts of Medial and Lateral Nasal processes fuse to form upper part of nostril.

4. Inferior part of Medial Nasal processes fuse with Maxillary process on each side to form upper lip.

Note: Cleft Lip (Sadler Fig. 15.29, Snell Fig. 11-28) - results from failure of fusion of Medial Nasal processes with Maxillary process on that side; can be unilateral or bilateral; occurs in 1 in 1000 births.

5. Nasolacrimal duct (Snell Figure 11-59, Atlas Fig. 7.37; Sadler Fig. 15.23) - connects anterior eye to nasal cavity; drains tears; forms in development as a solid epithelial cord that extends from medial angle of eye to nasal cavity; cord becomes canalized to form duct.

Note: Obstructed Nasolacrimal duct - results from failure of duct to canalize; must be opened for tears to drain to nasal cavity.