Facial Innervation, Lymphatics, Muscles, Fascia, and Scalp
2.
Facial Innervation The cranial nerves provides sensory and motor innervation for the head and neck including:
Cranial Nerve V: Trigeminal Nerve Emerges on the midlateral surface of the pons: Big sensory root and a small motor root The Sensory Ganglion: Gasserian sits in a depression called the Meckel’s cave in the floor of the middle cranial fossa. Sensory Axons: V1, V2 y V3. Motor axons: V3 V1
Superior Orbital Fissure
Ophthalmic
V2
Foramen Rotundum
Maxillary
Foramen Ovale
Mandibular
V3
(Sensory)
(Sensory)
(Motor and Sensory)
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Almost wholly sensory: eyeball, lacrimal gland, conjunctiva, part of nasal mucosa, from brow ridge superiorly.
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Carries a bit of sympathetic fibers for dilator pupillae. From upper thoracic levels, synapsing in in upper cervical ganglion. Reaches via branches of internal carotid artery.
Cranial Nerve V2 (Maxillary) § §
Sensory nerve. Leaves the skull through the foramen rotundum and enters the orbit through the inferior orbital fissure; it traverses the infraorbital groove and canal in the floor of the orbit, and appears upon the face at the infraorbital foramen.
Sphenopalatine ganglion
Alveolar branches of superior maxillary nerve
Cranial Nerve V3 (Mandibular) §
Sensory to lower jaw region, including teeth.
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Motor nerve to muscles of the mandibular arch: masseter, temporalis, anterior and posterior pterygoids, mylohyoid, tensor tympani, anterior digastric, and tensor veli palatini.
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The auriculotemporal branch contains secretomotor fibers to the parotid gland via the parotid branches.
Clinical Testing CN V § § § §
Discriminative touch Pain Temperature Simple touch
Motor component § § §
Clamp the jaws together Open the mouth (deviation toward weak side) Move the jaw to sides
Cranial Nerve VII: Facial Nerve Motor and sensory: Enters skull via internal auditory meatus
Geniculate Ganglion: Nerve cell bodies: Petrous part Temporal bone Taste from the tongue Somatic sensory § §
External ear Auditory meatus
Parasympathetic greater petrosal nerve: pterygopalatine ganglion
Facial Canal Chorda tympani nerve: Taste and parasympathetic motor General sensory and motor fibers exit skull via stylomastoid foramen.
Clinical Testing CN V §
Motor facial Muscles § T – Raise eyebrows § Z – Raise Upper Lip § B - Smile § M – Depress lower lip § C - Contract platysma
Corneal Reflex §
V1 and VII
Nerves of the Face and Neck
Lymphatics The lymph glands of the head are arranged in the following groups: Occipital Posterior Auricular Facial Deep Facial Anterior Auricular Lingual Parotid Retropharyngeal
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Vessels carrying lymph from the face pass through nodes arranged like a “collar” around the base of the head. Occipital § § § §
Retro-auricular (Mastoid) Parotid Submandibular Submental
Lymphatic drainage in 3 territories§
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Upper territories- greater part of forehead, lateral ½ of eye lid, conjunctiva, lateral part of cheek and parotid area– preauricular lymph node (parotid) Middle territories- median part of forehead, external nose, upper lip, lateral part of lower lip, medial ½ of eye lid, medial part of cheek, greater part of lower jaw– submandibular lymph node Lower territories- central part of lower lip, chin– sub mental lymph node
Musculofascial Collars: Platysma § § § §
Directly beneath the skin and subcutaneous tissue Muscle of facial expression: 7 CN Superficial to the outer muscle collar Sternomastoid muscle and the trapezius muscle with the dense fascia
Origin–upper part pectoral & deltoid fascia Insertion– base of mandible, skin of lower face and lip Action– releases pressure of skin on the subjacent veins, depress mandible, pulls angle of mouth downwards Sternomastoid muscle §
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Sternal head: Origin from superior portion of the front of the manubrium Clavicular head: Origin from medial third of the clavicle
Insertion – mastoid process and the lateral part of the superior nuchal line
Muscles of Facial Expression §
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Primary action is to act as either a sphincter or dilator of the orifices of the face Facial expression is a by-product Insertion into the skin Bony Origen , except orbicularis oris
Mouth Muscles § § § § § § § § § §
Depressor anguli oris Depressor labii inferior Mentalis Risorius Orbicularis oris Buccinator Zygomaticus major Zygomaticus minor Levator labii superioris Platysma
Scalp §
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Soft tissue covering the cranial vault, It is hair bearing area of the skull Extend from supra orbital margin anteriorly to external occipital protuberance & superior nuchal line posteriorly Subcutaneous layer with many nerves and vessels running through here, binds skin to inner layer Galea Aponeuroticaepicranial aponeurosis Anteriorly frontal belly and posteriorly occipital belly of occipitofrontalis muscle Frontal belly originate from skin of forehead and mingled with orbicularis oculi muscle Occipital belly originate from lateral 2/3 of superior nuchal line
Scalp Blood supply Arteries § § § § §
Supratrochlear Supraorbital Superficial temporal Posterior auricular Occipital
Veins - follow the arteries
Suggested Reading: Wexler A. (2008) Craniofacial Anatomy. In Thaller S, Bradley J, Garri J: Craniofacial Surgery (pp. 7-40). New York: Informa Healthcare USA. Netter F. Atlas of Human Anatomy. Grey H and Lewis W: Grey’s Anatomy 12th Edition. Philadelphia: Lea & Febiger, 1918. New York, Bartleby.com, 2000. Available at: http://www.bartleby.com/107/