2. Facial Innervation, Lymphatics, Muscules and Fascia, Scalp

Facial Innervation

The cranial nerves provides sensory and motor innervation for the head and neck including:

   2.  Facial Innervation,

Lymphatics, Muscles, Fascia, and Scalp

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

(Sensory)

V2

 Foramen Rotundum

Maxillary  

(Sensory)  

V3

 Foramen Ovale  

Mandibular  

(Motor and Sensory)  

§ 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.

§ Almost wholly sensory: eyeball, lacrimal gland, conjunctiva, part of nasal mucosa, from brow ridge superiorly.  

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.

§ Motor nerve to muscles of the mandibular arch: masseter, temporalis, anterior and posterior pterygoids, mylohyoid, tensor tympani, anterior digastric, and tensor veli palatini.

§ 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

Taste from the tongue

Somatic sensory

§ External ear § Auditory meatus

Geniculate Ganglion: Nerve cell bodies: Petrous part Temporal bone  

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.  

Corneal Reflex

§ V1 and VII

Clinical Testing CN V

§ Motor facial Muscles § T – Raise eyebrows § Z – Raise Upper Lip § B - Smile § M – Depress lower lip § C - Contract platysma

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

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-

§ 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:

Sternomastoid muscle

§ 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

§ 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

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

Mouth Muscles

§ Depressor anguli oris § Depressor labii inferior § Mentalis § Risorius § Orbicularis oris § Buccinator § Zygomaticus major § Zygomaticus minor § Levator labii superioris § Platysma

Scalp

§ 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 Aponeurotica- epicranial 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/