Anatomy of the Head: Face and Scalp
FACE
I. Cutaneous Innervation: Trigeminal Nerve (C V) – Main sensory nerve of face
A. Ophthalmic N. (CN V1)- Superior Subdivision / Sensory
1. Frontal n.
a. Supratrochlear n.
b. Supraorbital n.
B. Maxillary N. ( CN V2)- Intermediate Subdivision / Sensory
1. Infraorbital n
a. External nasal n.
b. Superior labial n.
c. Superior alveolar n..
2. Zygomatic n.
a. Zygomaticofacial n.
b. Zygomaticotemporal n.
C. Mandibular N. (CN V3)- Inferior Subdivision / Sensory and contain fibers of motor root of CN V
1. Auriculotemporal n.
2. Interior Alvelolar n.
a. Mental nerve
| Nerve | Origin | Course | Distribution |
| Frontal | Ophthalmic n. (CN V1) | Crosses orbit of superior aspect of levator palpebrae superioris m.; divies into supraorbitla and supratrochlear branches | Skin of forehead, scalp, upper eyelid, and nose |
| Zygomatic | Maxillary n. (CN V2) | Arises in floor of orbit, divides into zygomaticofacial and zygomatico temporal nn. | Skin over zygomatic arch and anteiro temporal region |
| Infraorbital | Terminal branch of maxillary n. (CN V2) | Runs in floor of orbit and emerges at infraorbital foramen | Skin of cheek, lateral side of nose, and uuper lip |
| Buccal | Mandibualr n. (CN V3) | Skin of cheek | |
| Auriculotemporal | Mandiular n. | From posterior division of CN V3 passes between neck of mandible and external acousti meatus to accompany superficial temporal artery | Skin anterior to ear and temporal region |
| Mental | Terminal branch of inferior alveolar n. (CN V3) | Emerges from mandibular canal at mental foramen | Skin of chin and lower lip |
II. Face Myology
§ Muscles of facial expression are contained within the subcutaneious tissue
§ And are attached to SKIN of face
III. Innervation: Facial Nerve (CN VII) – Motor nerve of face / Exits skull via the stylomastoid foramen
A. Divisions of facial nerve
1. Temporofacial
2. Cervicofacial
B. Branches of facial nerve
1. Temporal
To frontralbellyof occipitofonalis orbicularis oculi, corrugator supercilii, and anterior and supeiro auricular muscles
2. Zygomatic
To zygomatic, orbital, and infraorbital muscles
3. Buccal
To buccinator, upper lip and nostril muscles
4. Mandivular
To lower lip and chin muscles
5. Cervical
To platysma and superficial back muscle
6. Occipital
To occipital belly of occipitofrontalis, and posterior auricular muscle
7. Motor branches of stylohyoid and digastric muscles
IV. Angiography
A. Arterial Subdivisions of the External Carotid Artery- most arteries of face branch off here
1. Facial Artery- major arterial supply to face / terminates in angular a.
a. Submental a.
b. Inferior Labial a.
c. Superior Labial a.
d. Lateral Nasal a.
2. Maxillary Artery- smaller terminal branch of external carotid
3. Superficial Temporal Artery- smaller terminal branch of external carotid
4. Transverse Facial Artery
B. Arterial Subdivisions of the Internal Carotid Artery
1. Ophthalmic Artery
a. Supraorbital a.
b. Supratrochlear a.
| Artery | Origin | Course | Distribution |
| Facial | External carotid a. | Ascendsddep to submandibular gland, winds around inferior border of mandible and enters face | Macules of facial expression and face |
| Superior labial | Facial a. | Runs medially in upper lip | Upper lip and ala and septum of nose |
| Inferior labial | Facial a. | Runs medially in lower lip | Lower lip and chin |
| Lateral nasal | Facial a. | Passes to ala of nose | Skin on ala and dorsum of nose |
| Angular | Terminal branch of facial a | Passes to medial canthus of eye | Superior part of cheek and lower eyelid |
| Superficial temporal | Smaller terminal branch of external carotid | Ascends anterior to ear to temporal region and ends in scalp | Facial mm and skin of frontal and temporal regions |
| Transverse facial | Superficial temporal a. within parotid gland | Crosses face superficial to masseter and inferior to zygomatic arch | Parotid gland and duct, mm of skin of face |
| Mental | Terminal branch of inferior alveolar a. | Emerges from mental foramen and passes to chin | Facial muscles and skin of chin |
| Supraorbital | Terminal branch of ophthalmic a, a branch of internal carotid a. | Passes superiorly from supraorbital foramen | Mm of skin of forehead and scalp |
| Supratrochlear | Terminal branch of ophthalmic a., a branch of internal carotid a. | Passes superiorly from supratrochlear notch | Muscles and skin of scalp |
V. Parotid Gland
§ Largest of three paired salivary glands enclosed within fasical parotid sheath
§ Parotid duct passes horizontally from the anterior edge of gland
§ Structures within gland: facial nerve, retromandibular v., external carotid a., parotid lymph nodes that drain into cervical lymph nodes
§ Auriculotemporal n. of CN V3 closely related to parotid gland
VI. Clinical
§ Superficial fascia is loose between attachments of mm., injury or infection causes marked swelling
§ Facial lacerations tend to gape
§ Looseness of superficial fasica enables tissue fluid and blood to accumulate after bruising of face (black eye)
§ Trigeminal neuralgia is a sensory disorder of the sensory division of CN V that is characterized by sudden attacks of excruciating facial pain
§ A lesion of the entire trigeminal nerve causes widespread anesthesia
§ Sometimes the sensory root of CN V is cut to alleviate trigeminal pain
§ Injury to the facial nerve CN VII produces paralysis of some or all facial muscles on affected side. The most common cause of facial paralysis is inflammation of the facial nerve near the stylomastoid foramen (Bell’s Palsy), produces selling and compression of the nerve in the facial canal. Patients cannot close their lips and eyelids on affected side, cornea is not lubricated, cannot whistle or chew (paralyzes buccinator), displacement of mouth results in food and saliva dribbling out of the side of mouth.
§ Carcinomas of lip usually involve the lower lip. Cancer cells from the central part of the lip spead to the submental lymph nodes, caner cells from the lateral part of the lip drain to the submandibular lymph nodes.
§ Parotid gland may become infected through the bloodstrea, as occurs in mumps. Infection of the parotid gland cuass inflammation and swelling of the land. Severe pain occurs because the parotid capsule limits swelling. Mumps may also cuase inflammation of the parotid duct, producing redness of the parotid papilla (opening of the duct into the oral cavity); because apin produced by mumps may be confused with a tooth ache, redness of the papilla is often an early sign tha the disease involves the gland and not a tooth.
SCALP
I. Layers
§ Skin
Contains numerous arteries and veins
Good lymphatic drainage
Many sweat and sebaceous glands and hair follicles
§ Connective tissue
Collagenous and elastic fibers
Tough and tight
Thick
Richly vascularized
Well supplied with nerves
§ Aponeurosis epicranious
Occipitofrontalis m. has 4 bellies, 2 occipital and 2 frontal, all innervated by CN VII
§ Loose areolar tissue
Potential space that may distend with fluid that results from injury or infection
Allows free movement of scalp proper
Dangerous area of scalp- communicates with cranial cavity via emissary veins
§ Pericaranium
Periosteium at outer surface of skull bones
At sutures, it becomes continuous with periostium of inner surface of skull
II. Sensory Innervation
A. Anterior to ear
§ Supertrochlear n. (V1)
§ Supraorbital n. (V1)
§ Zygomaticotemporal n. (V2)
§ Auriculotemporal n. (V3)
B. Posterior to ear
§ Lesser occipital n. (cervical plexus: C2)
§ Greater occipital n. (C2 posterior ramus)
III. Angiography
A. Arteries
§ Anastomoses within the subcutaneous connective tissue layer
Internal carotid
§ Supratrochlear a.
§ Supraorbital a.
External carotid
§ Superficial temporal a.
§ Occipital a.
§ Posterior auricular a.
B. Veins
§ Supraorbital v.
§ Supratorchlear v.
§ Superficial temporal v.
§ Retromandibular v.
§ Posterior auricular v.
§ Occipital v.
IV. Clinical Correlation
§ The loose connective tissue layer is the dangerous area of the scalp becausepus or blood spreads easily in it. Infection in this layer can also pass into the cranial cavity through emissary veins.
§ Scalp lacerations- wounds bleed profusely because the arteries enter around the periphery of the scalp and do not retract when lacerated because they are held open by the dense fibrous tissue in the second layer of the scalp, thus patients may die if bleeding is not controlled
§ Arteries of the scalp supply very little blood to the bones of the calvaria, these bones are supplied by the middle meningeal a., thus loss of the scalp does not produce death of the cranial bones
Tags: acoustic meatus, Auriculotemporal, buccinator, calvaria, Cervicofacial, corrugator supercilii, Cutaneous Innervation, face, Face Myology, levator palpebrae superioris, Mandibular, Maxillary, occipitofonalis orbicularis oculi, Periosteium, supeiro auricular muscles, Temporofacial, Trigeminal Nerve, Trigeminal neuralgia, Zygomaticofacial, Zygomaticotemporal
