S1B4 - Anatomy - Face and Scalp

Opthalmic nerve/trigeminal nerve

- 1st part of trigeminal nerve (V1) - 5 branches a. Supraorbital -> anterior scalp b. Supratrochlear -> medial region of forehead c. Infratrochlear -> medial eyelids, side/bridge of nose d. Lacrimal -> lateral eyelids e. External nasal (from anterior ethmoidal nerve) -> anterior nose

Nasal group (facial expression muscles)

- 3 muscles -> Nasalis, Procerus, & Depressor septi nasi - Nasalis a. Transverse part -> compresses nares b. Alar part -> opens the nares - Procerus a. Function - draws medial portion of the eyebrows downwards - Depressor septi nasi a. Assists in widening the nares

Mandibular nerve/trigeminal nerve

- 3rd part of trigeminal nerve - 3 branches: a. Auriculotemporal -> most of scalp in temple area b. Buccal -> cheek c. Mental -> continuation of inferior alveolar nerve

Muscles of facial expression

- All muscles in this group innervated by FACIAL NERVE branches (CN VII) a. Derived from 2nd pharyngeal arch - In superficial fascia - Origins from fascia or bone -> insert into skin - Can be either constrictors or dilators

Auricular muscles

- Anterior, superior & posterior - Anterior -> elevates and moves the ear forward - Superior -> elevates the ear - Posterior -> retracts and elevates the ear - Innervation: facial nerve

Occipitofrontalis

- Associated w/ the scalp - Frontal belly (frontalis) - Occipital belly (occipitalis) - Moves the scalp and wrinkles the forehead - Innervation: facial nerve

Lower group of oral muscles (facial expression muscles)

- Depressor anguli oris a. Active in frowning - Depressor labii inferioris a. Deep to the depressor anguli oris - Mentalis a. Helps position the lips during drinking or pouting b. DEEPEST of the lower group of oral muscles. Arises from the mandible just inferior to the incisor teeth.

Scalp innervations (sensory/anterior)

- Either from Cranial nerve (CN V) (trigeminal N.) or cervical nerves - Anterior to the ears and the vertex a. Supratrochlear N. (V1) (frontal N. branch) b. Supraorbital N. (V1) -> ant. scalp (frontal N. branch) c. Zygomaticotemporal N. (V2) -> ant. scalp d. Auriculotemporal N. (V3) -> scalp/temple area

Vessels of the face (facial & superior temporal arteries)

- Facial artery (ECA) -> (most arterial supply is via ECA branches) a. Angular A. -> (terminal branch, corner of eye) b. Superior/inferior labial branches c. Lateral nasal branch - Superior temporal artery (ECA) -> branches to scalp a. Transverse facial (arises from w/i parotid gland, travels 1" inferior to zygo. arch)

Arteries to the scalp

- From Opthalmic A. (branch of ICA) a. Supratrochlear A. -> muscles/skin forehead/scalp b. Supraorbital A. - From ECA a. Posterior auricular A. -> scalp post. to ear b. Occipital A. -> post. scalp c. Superficial temporal A.

Platysma

- Large, thin sheet in SUPERFICIAL FASCIA of the neck - Arises just below clavicle -> ascends to mandible - Tenses the skin of the neck, depresses the lower lip and corner of the mouth

Upper group of oral muscles (levators; facial expression muscles)

- Levator labii superioris: a. Arises from MAXILLA -> deepens furrow between nose and corner of mouth - Levator labii superioris alaeque nasi a. May assist in flaring the nostrils - Levator anguli oris a. DEEP -> covered by other levators b. Raises corner of mouth

Vessels of the face (maxillary & opthalmic)

- Maxillary A. (ECA) -> a. Infraorbital: lower eyelid, upper lip b. Buccal: superficial buccinator c. Mental: chin - Opthalmic (ICA) -> a. Zygomaticofacial + zygomaticotemporal -> lacrimal artery (over zygomatic bone) b. Dorsal nasal: terminal branch of opthalmic A. to nose dorsum c. Supraorbital A. d. Supratrochlear A. -> muscles/skin forehead & scalp

Facial motor innervation

- Motor innervation -> FACIAL NERVE (CN VII) - Course: a. Exits the posterior cranial fossa -> interior auditory meatus -> stylomastoid foramen (-> parotid gland to form plexus) - Branches: a. TZBMC (Temporal, Zygomatic, Buccal, Mandibular, Cervical branches) b. Posterior auricular nerve c. Nerve to stylohyoid and posterior belly of digastric d. Nerve to stapedius m. e. SENSORY: Chorda tympani nerve f. Parasympathetic - CLINICAL CORRELATION: Bell's palsy -> damage to facial nerve on 1 side will result in paralysis of muscles on that side

Buccinator (oral group/facial expression muscles)

- Muscular component of cheek, deep to other muscles of the face - Arises from posterior portion of maxilla and mandible -> also PTERYGOMANDIBULAR RAPHE - Action: Presses the cheek against the teeth (closing the oral cavity)

Oral group muscles (facial expression muscles)

- Orbicularis oris - Buccinator - Lower group -> a. Depressor anguli oris b. Depressor labii inferioris c. Mentalis - Upper group -> a. Risorius b. Zygomaticus major c. Zygomaticus minor d. Levator labii superioris e. Levator labii superioris alaeque nasi f. Levator anguli oris

Orbicularis oris (oral group/facial expression muscles)

- Purses the lips (during whistling), narrows the mouth, closes the lips

Scalp

- Remember: "SCALP" a. Skin b. Connective tissue c. Aponeurotic layer (epicranial) d. Loose connective tissue e. Pericranium - CLINICAL: a. Cuts of the scalp bleed profusely (b/c CT is very thick -> keeps veins open) b. Diploic veins unite scalp veins w/ veins of brain -> infections, air emboli can easily travel

Upper group of oral muscles (risorius & zygomaticus major/minor; facial expression muscles)

- Risorius a. helps produce a grin, extends laterally from corner of mouth (a SCOFF) - Zygomaticus major and minor a. Origin - posterior/anterior portion of lateral surface of zygomatic bone b. Helps produce a smile

Maxillary nerve/trigeminal nerve

- Second part of trigeminal nerve - 3 branches: a. Zygomaticotemporal -> anterior scalp -> temple b. Zygomaticofacial -> lateral eyelids c. Infraorbital -> (3 branches = inferior palpebral, superior labial, int. & ext. nasal) -> medial, lower eyelid; cheek/upper lip; side of nose (respectively)

Scalp innervations (sensory/posterior)

- Sensory -> cranial/cervical nerves - Posterior to the ears and vertex: a. Great auricular (ventral rami C2/C3) -> skin, front of ear b. Lesser occipital (ventral rami C2) -> skin, behind ear c. Greater occipital nerve (posterior ramus C2) -> post. scalp to interauricular line d. 3rd Occipital nerve (from posterior ramus of C3) -> small area of scalp, medial to greater occipital nerve

Facial sensory innervation

- Sensory: Trigeminal (V3) nerve -> IN FRONT OF EAR, from top of head to middle of mandible - Derived from 1st pharyngeal arch - 3 sections: a. Opthalmic -> level of eyes and above b. Maxillary -> level of eyes to (including) upper lip c. Mandibular -> lower lip to middle of mandible

Scalp venous drainage

- Supratrochlear & supraorbital veins -> sup. opthalmic & angular V. - POSTERIOR AURICULAR V. -> retromandibular v. (helps form EJV) - OCCIPITAL V. -> Occipital plexus (w/i suboccipital triangle) -> deep cervical V. and vertebral venous plexus - SUPERFICIAL TEMPORAL V. -> retromandibular v.

Venous drainage of the face

- Supratrochlear + supraorbital (branches of) -> ANGULAR VEIN -> FACIAL VEIN (ant. scalp) a. Both angular V. & facial V. communicate w/ opthalmic veins - Transverse facial vein -> SUPERFICIAL TEMPORAL VEIN + MAXILLARY VEIN -> RETROMANDIBULAR V. a. Post. branch of retromandibular -> post. auricular V. = EJV - Intracranial venous connections w/ a. Opthalmic veins b. Veins passing through the infraorbital foramen c. Pterygoid plexus - CLINICAL: Triangle of Danger a. Facial veins have no valves, can flow in either direction -> b/c facial vein anastomoses w/ veins inside cranial cavity, area between root of nose/corners of mouth = TRIANGLE

Orbital group (facial expression muscles)

- Two groups -> orbiculari oculi & corrugator supercilii - Orbicularis oculi -> closes eyelids (gently, forcefully) a. Palpebral portion b. Orbital portion - Corrugator supercilii -> deep to eyebrows, draws eyebrows towards midline