Face & Scalp Lecture Notes PDF

Face & Scalp MGA II: Lecture 6 January 21, 2025 Liam Zachary, PhD 2 Learning Objectives: 1. Describe the superficial structures of the face & scalp. 2. Identify the cutaneous nerves of the face & describe their sensory territories. 3. Identify the major branches of facial ne...

Face & Scalp MGA II: Lecture 6 January 21, 2025 Liam Zachary, PhD 2 Learning Objectives: 1. Describe the superficial structures of the face & scalp. 2. Identify the cutaneous nerves of the face & describe their sensory territories. 3. Identify the major branches of facial nerve & the muscles of facial expression they innervate. Describe the main actions of the muscles of facial expression. 4. Distinguish between upper & lower motor neuron lesions of facial nerve. Describe the symptoms of a LMNL of facial n. (Bell’s Palsy). Determine facial n. lesion location based on patient symptoms. 5. Describe the blood supply & venous drainage of the face. 3 Scalp & Superficial Tissues of the Face LO#1 4  Superficial Tissues of the Face Up to 7 tissues line the viscerocranium: 1. Skin 2. Fibro-adipose, subcutaneous tissue 3. Superficial musculo-aponeruotic system (SMAS) including mm. of facial expression and temporoparietal fascia (superior to zygomatic arch) 4. Deep fascia and parotid-masseteric fascia (inferior to zygomatic arch, superficial to buccal fat pad) 5. Facial n. divisions (in parotid gland) 6. Buccopharyngeal fascia (deep to buccal fat pad); muscles of mastication 7. Periosteum Skin Fibro-adipose tissue (subcutaneous layer) Superficial musculo-aponeurotic system (SMAS) including muscles of facial expression AND Temporoparietal fascia (superior to zygomatic arch) Parotid-masseteric fascia (inferior to zygomatic arch, superficial to buccal fat pad) Facial n. divisions (in parotid gland) Buccopharyngeal fascia (deep to buccal fat pad); Muscles of mastication 5 Scalp: Layers 5 layers: S – Skin C – Connective tissue (dense) A – Epicranial aponeurosis L – Loose connective tissue (areolar fascia) P – Pericranium 6 Scalp: Relationships S – Skin C – Connective tissue (dense) contains veins, arteries, & nerves supplying the scalp A – Epicranial aponeurosis L – Loose connective tissue (areolar fascia) P – Pericranium 7  Clinical Correlates: Subgaleal Hemorrhage Subgaleal (subaponeurotic) space: Potential space between periosteum and epicranial aponeurosis Subgaleal hemorrhage: Rupture of emissary vein(s) during scalping injury Associated with instrumentation birth in neonates E.g. Ventouse-assisted delivery Coronal section Subgaleal hematoma Potential space between periosteum and galea aponeurosis Tearing of emissary veins between Associated with instrumentation birth in neonates 8 Sensory Innervation of Face LO#2 9  Proprioception/ Mechanoreception Sensory Innervation SVE of Face: Overview GSA General sensation from the skin of the face is carried via Trigeminal n. (CN V) Pain/temp. via its 3 divisions: 1. Ophthalmic n. (V1) 2. Maxillary n. (V2) 3. Mandibular n. (V3) Anterior View 8. Describe the dermatomes of the face & head. Which divisions of the trigeminal n. (CN V) serve these dermatomes, and what are the major terminal cutaneous nerves of the face? The trigeminal n. (CN V) is responsible for innervating muscles of mastication (efferent) and sensation of the skin of the face (afferent). The trigeminal n. has three divisions: Ophthalmic n. (V1), Maxillary n. (V2), and Mandibular n. (V3). The complete courses and functions of these 10 divisions will be discussed elsewhere, but there are five nerves of these divisions afferently serving the skin of the face: the supra-orbital n. & supratrochlear [supratrochlear will be discussed in more detail in Session 6] (V1), the infra-orbital n. (V2), the mental n. (V3), and the cutaneous portion of the auriculotemporal n. (V3). Converge on the trigeminal ganglion located in “Meckel’s Cave” formed of cranial dura and containing the cell bodies of incoming sensory nerve fibers (GSA) & synapse there. From the trigeminal ganglion, a sensory root enters the pons; 10  Sensory Innervation of Face: V1 General sensation (GSA) from skin of upper face, scalp, superior orbit & external nose via 5 branches of V1: 1. Lacrimal n. 2. Supraorbital n. Supraorbital foramen 3. Supratrochlear n. 4. Infratrochlear n. 5. External nasal n. Anterior View The supra-orbital n. is the terminal continuation of the frontal n. through the supra-orbital notch or foramen, which afferently serves the conjunctiva, mucosa of the frontal sinus, and skin of the superior palpebra, forehead, and epicranial scalp. The supra-orbital n. is a branch of the ophthalmic n. (V1). Variations of crania include those with supra-orbital notches and those with supra- orbital foramen. Either of these structures, when present, are found along the superior rim of the orbit, nearly halfway between the 11 midpoint of the superior rim and the medial rim of the orbit. 11  Sensory Innervation of Face: V2 General sensation (GSA) from skin of anterior temple, midface, inferolateral orbit, & some internal nose via 3 branches of V2: 1. Zygomaticofacial n. Zygomaticofacial foramen 2. Zygomaticotemporal n. 3. Infraorbital n. Infraorbital foramen Anterior View The infra-orbital n. is the branch of the maxillary n. (V2) which exits the infra- orbital foramen of the maxilla. The infra- orbital foramen is below the orbit, approximately in-line with (or just lateral) to the supra-orbital foramen (or notch) above. The infra-orbital n. afferently supplies the mucosa of the maxillary sinus and gingiva, and skin of the: inferior palpebra, the lateral nose, upper lip, and cheek. 12  Sensory Innervation of Face: V3 General sensation (GSA) from skin of lower face, jaw, lower lip, upper ear, & posterior temple via 3 branches of V3: 1. Auriculotemporal n. 2. Buccal n. 3. Mental n. Mental foramen Anterior View The mental n. is the terminal continuation of the inferior alveolar n., a branch of the mandibular n. (V3), which passes through the mental foramen of the mandible to afferently serve the mandibular gingiva, and skin of the: lower lip and chin. The buccal n. Is also a branch of the mandibular n. (V3). The auriculotemporal n. is also a branch of the mandibular n. (V3). The auriculotemporal n. serves many functions, but germane to this session, it afferently serves the skin of the: 13 tragus of the ear, the external auditory meatus, and the area anterosuperior to the ear. The cutaneous portion of the auriculotemporal n. may be found accompanying the superficial temporal a. and v. superiorly from the parotid gland. 13 Clinical Correlates: Trigeminal Neuralgia Jabs of severe pain in the sensory region of one of the branches of CN V Causes a “tic” Most common in CN V2 May be caused by small artery in the sensory root Can be treated by removing aberrant artery, blocking sensation, or avulsion/ablation of the effected nerve or sensory root 14 Muscles of Facial Expression LO#3 15 Muscles of Facial Expression: Innervation Innervation from Facial n. (CN VII) Exits stylomastoid foramen 6 main motor branches: 1. Posterior auricular 2. Temporal 3. Zygomatic 4. Buccal Lateral View 5. Marginal mandibular 6. Cervical Pneumonic: To Zanzibar By Motor Car Stylomastoid foramen 16 Muscles of Facial Expression: Craniofacial & Epicranial mm. Frontalis Orbicularis Oculi Levator Labii Superioris Occipitalis Levator Labii Superioris Alaeque Nasi Muscle Nasalis Zygomaticus Minor Zygomaticus Major Auricularis Orbicularis Oris (Anterior, Posterior, Superior) Mentalis Depressor Labii Inferioris Depressor Anguli Oris Risorius Platysma 17 Muscles of Facial Expression: Temporal Branch Lateral View 18 Muscles of Facial Expression: Zygomatic Branch Lateral View 19 Muscles of Facial Expression: Buccal Branch Lateral View 20 Muscles of Facial Expression: Mandibular Branch Lateral View 21 Muscles of Facial Expression: Cervical Branch Lateral View 22 Facial Nerve Palsy LO#4 23  Facial Nerve Palsy: UMNL vs. LMNL Bell’s palsy: ipsilateral paralysis of facial mm. due to LMNL of facial n. Supranuclear lesion: weakness or paralysis of the lower face on the contralateral side of the UMNL lesion, while largely sparing the upper face muscles (forehead sparing) due to bilateral innervation Facial n. (Bell’s) palsy is the ipsilateral paralysis of facial mm. due to a neuropathy of the facial n. Facial nerve palsy symptoms include: Ipsilateral paralysis/paresis of facial mm. Ipsilateral hypo-lacrimation Greater petrosal n. to pterygopalatine ganglion Ipsilateral hypo-salivation Chorda tympani to submandibular ganglion Ipsilateral ageusia from anterior tongue Chorda tympani Ipsilateral hyperacusis N. to stapedius m. 24  Rare Many of the upper motor neurons of the temporofacial division originate bilaterally in the cerebral cortex, whereas the upper motor neurons for the cervicofacial division are sourced in the contralateral cerebral cortex. A cerebrovascular accident (CVA, or a stroke) may typically present with contralateral facial muscle paralysis of the lower face, whereas facial n. (Bell’s) palsy typically presents with total ipsilateral facial muscle paralysis. 24 Bell’s Palsy: Presentation of Hemifacial Paralysis Smooth forehead (frontalis) Wide palpebral fissure with visible cornea below iris (orbicularis oculi) Asymmetrical philtrum Asymmetrical labial line (zygomaticus major et al) (depressor labii inferioris) 25  Internal Acoustic Facial Nerve Subway Map-Style Meatus Superior Orbital Fissure Lacrimal Gland Facial Nerve: Fa Lacrimal N. c ia N.l To: Nasal Mucosa Overview Nasociliary Hiatus of the Greater Petrosal N. Zygomatic N. ne Greater Petrosal N. Bo Facial Genu l ra Internal Carotid Foramen Lacerum Inferior Orbital Fissure po Pterygoid Canal m Te Carotid Canal Pterygopalatine in ith Ganglion. lN W Middle Ear Deep Petrosal N. ia to: External Cartilaginous Plug Nerve of the Sphenopalatine Foramen c Fa Acoustic Meatus Nasopalatine and Pterygoid Canal Lin Lateral Nasal Nerves to: Stapedius gu al N. Greater and Lesser Chorda Tympani Chorda Tympani Palatine Nerves To: Nasal Mucosa Petrotympanic Fissure Hard Palate Poster e at Stylomastoid to: Stylohyoid & l Pa Posterior Belly of Digastric ft Foramen ior So Temporal Branches Au ul Zyg ric ar oma N. tic Br anche s Tongue Buccal Branches Mandibular Branches Submandibular Ganglion Cervical Branches Sublingual Gland ry rte lA cia Facial N. and Fibers Submandibular Gland Fa Post Synaptic Parasympathetic Fibers of Facial Branches of Mandibular Division of Trigeminal Branches of Maxillary Division of Trigeminal Branches of Ophthalmic Division of Trigeminal Post Synaptic Sympathetic Fibers Facial’s Combined General Sensory and Taste Sensory Ganglion Parasympathetic Ganglia from Trigeminal 26  1. 2. & 3. Bell’s Palsy: Symptoms Bell’s palsy symptoms vary by lesion location & facial n. branches involved: 1. Ipsilateral hypo-lacrimation Greater petrosal n. to pterygopalatine ganglion 2. Ipsilateral hypo-salivation Chorda tympani to submandibular ganglion 3. Ipsilateral ageusia from anterior tongue 5. Chorda tympani 4. 4. Ipsilateral hyperacusis N. to stapedius m. 5. Ipsilateral paralysis/paresis of facial mm. 27  Bell’s Phenomenon Bell’s Palsy: a unilateral idiopathic paralysis of facial mm. due to a lesion of CN VII Bell’s Phenomenon: a normal defense mechanism – upward & outward movement of the eye which occurs when an individual closes their eyes forcibly It can be appreciated clinically in a patient with paralysis of orbicularis oculi (e.g., Bell’s palsy), as the eyelid remains elevated when the patient tries to close the eye Bell's palsy: a unilateral idiopathic paralysis of facial muscles due to a lesion of the facial nerve. Bell's phenomenon: A normal defense mechanism—upward and outward movement of the eye which occurs when an individual closes their eyes forcibly. It can be appreciated clinically in a patient with paralysis of the orbicularis oculi (e.g. Guillain–Barré syndrome or Bell's palsy), as the eyelid remains elevated when the patient tries to close the eye. 28 Facial Vasculature LO#5 29 Facial Vasculature: Blood Supply 5 major branches of external carotid a. supply face & scalp: 1. FACIAL 2. MAXILLARY 3. SUPERFICIAL TEMPORAL 4. POSTERIOR AURICULAR 5. OCCIPITAL 1 major branch of internal carotid a. also supplies portions of face near orbit: 1. OPTHALMIC Lateral View 30  Lateral View Facial Vasculature: Blood Supply * Skin of face & craniofacial muscles of facial expression supplied by 4 branches: * 1. FACIAL Angular * Superior/Inferior Labial 2. MAXILLARY Mental * Infraorbital 3. SUPERFICIAL TEMPORAL Transverse facial 4. OPTHALMIC Supraorbital Supratrochlear Zygomaticofacial Zygomaticotemporal * Arise from or are branches of OPHTHALMIC ARTERY 31  Lateral View Facial Vasculature: Blood Supply * Scalp & epicranial muscles of facial expression supplied by 4 branches: * 1. SUPERFICIAL TEMPORAL Transverse facial * 2. OPTHALMIC Supraorbital Supratrochlear * 3. POSTERIOR AURICULAR 4. OCCIPITAL * Arise from or are branches of OPHTHALMIC ARTERY 32  Facial Vasculature: Lateral View Venous Drainage Superficial Temporal Supraorbital Skin of face, scalp & muscles of facial expression drained by 3 tributaries of IJV: Supratrochlear 1. Facial v. Angular v. Zygomaticotemporal 2. Retromandibular v. Angular Superficial temporal v. Occipital 3. Occipital v. And 1 tributary of EJV: Zygomaticofacial Posterior Auricular 4. Posterior auricular v. Deep Facial External Jugular Facial Retromandibular Submental Internal Jugular Lingual 33  Supraorbital and Supratrochlear vv Facial Vasculature: Lateral View Venous Drainage Superior Ophthalmic Vorticose vv Face drained via 3 routes: Danger Triangle 1. Cavernous Sinus Supraorbital v. Cavernous Sinus Superior ophthalmic v. Angular v. Facial Angular Inferior ophthalmic v. 2. Facial Vein Supratrochlear v. Inferior Ophthalmic Supraorbital v. Angular v. 3. Pterygoid Plexus Inferior ophthalmic v. Retromandibular Facial Facial v. Maxillary Pterygoid Plexus Deep Facial Deep facial v. The superior ophthalmic v. drains blood from the eye, superior orbit, ethmoidal cells, forehead, and the angular v. of the face. The superior ophthalmic v. traverses the superior optic fissure en route to the cavernous sinus. The inferior ophthalmic v. collects blood from the face and inferior orbit. The inferior ophthalmic v. may join the superior ophthalmic v. in traversing the superior orbital fissure, and it also may have parts that traverse the inferior orbital fissure to communicate with the deep face. Both the superior and 34