Face, Scalp, and Parotid Gland Flashcards
Layers of SCALP
Skin CT, dense = contains vessels and nerves Aponeurosis epicranius Loose CT, which allows movement of the scalp Pericranium (periosteum)
Cutaneous innervation of scalp (spinal and cranial nn.)
Spinal nerves = greater occipital (dorsal ramus C2), dorsal ramus C3, lesser occipital, and great auricular nn.
Cranial nerves = Auriculotemporal (V3), zygomaticotemporal (V2), supraorbital (V1), and suprtrochlear (V1) nn.
Arterial supply of scalp (external and internal carotid aa.)
External Carotid Artery = occipital, posterior auricular, and superficial temporal aa.
Internal Carotid Artery = supraorbital and supratrochlear aa.
Why do scalp wounds bleed profusely?
Scalp is highly vascularized in dense CT limiting vasoconstriciton
Due to high number of anastomoses there is no single place to compress to stop bleeding
Venous drainage of scalp
Emissary vv. and venae comitantes
Note: Emissary veins are valveless allowing infection to easily spread from the scalp the the intracranial fossa
How do ecchymosis occur?
Extravasation of blood under skin
Infections and bleeding can easily spread through the 4th layer (loose CT) of the scalp to the eyelid and dorsum of the nose
Which pharyngeal arch is face musculature derived from and which cranial nerve innervates it?
Second arch; CN VII (SVE)
Actions of Orbicularis Oculi (3 parts)
Orbital part - forcefully closes eye
Palpebral part - gently closes eye
Lacrimal part - assists with emptying lacrimal gland
Actions of Corrugator Supercilli
Draws eyebrowns down and in
Actions of Occipitofrontalis (2 parts)
Frontal - draws eyebrows upward
Occipital part - retracts scalp; and assist frontal belly with surprised look
Note: These muscle bellies are attached to one another by the epicranial aponeurosis
Acitons of orbicularis oris
Closes lips and mouth
Actions of buccinator
Maintains contact between cheek and gums so food doesn’t accumulate in the vestibule
Actions of levator labii superioris
elevates upper lip
Actions of levator anguli oris
elevates upper lip and widens mouth
Actions of zygomaticus major
Elevates upper lip; major smile muscle
Actions of zygomaticus minor muscle
Elevates upper lip
Actions of Risorius
Stretches lip laterally and widens smile
Actions of levator labii superioris alaque nasi
Elevates the upper lip and flares the nostrils
Actions of depressor anguli oris
Depresses lower lip; frowns
Actions of depressor labii inferioris
Depresses lower lip; frowns and pouts
Actions of mentalis
protrudes lower lip
Actions of procerus
wrinkles skin over dorsum of nose
Actions of nasalis
flares nostrils
What is the course of SVE fibers of CN VII
After entering the internal acoustic meatus SVE fibers travel laterally between the cochlea and semicircular canals and bends posteriorly and inferiorly to course along the posterior wall of the middle ear to the stylomastoid foramen
Branches of SVE portion of CN VII
Posterior auricular n. (occipital belly of occipitofrontalis m.)
Digastric n.
Stylohyoid n.
Temporofacial trunk = temporal, zygomatic, and buccal branches
Cervicofacial trunk = buccal, marginal mandibular, and cervical branches
NOTE: Ten Zebras Beat My Camel
Bells’ Paralysis (Cause, Manifestation)
Typically idiopathic, but associated with herpes, trauma, and otitis media
Asymmetry of face and drooping.
Drooping of lower eyelid causes drainage of tears and ulceration of eye.
Dribbling of saliva and accumulation of food within the vestibule.
Imparied speech.
Cutaneous innervation of Ophthalmic nerve (CN V1; Embryologic structure, area, and branches)
Associated with the frontonasal eminence
Supplies forehead, upper eye lid, and nose
Supraorbital, supratrochlear, lacrimal, infratrochlear, and external nasal nn.
Cutaneous innervation of Maxillary nerve (CN V2; Embryologic structure, area, and branches)
Associated with the maxillary prominence
Supplies temples, upper cheeks, lower eyelids, upper lip, and nasal alae
infraorbital, zygomaticfacial, and zygomaticotemporal nn.
Cutaneous innervation of Mandibular nerve (CN V3; embryologic structure, area, and branches)
Associated with mandibular prominence
Supplies lower cheek, lower lip, and chin
Auricultemporal, buccal, and mental nn.
Trigeminal Neuralgia (Cause, Manifestation)
Believed to be caused by demyelination of the sensory roots of CN V.
Also possibly compression by the superior cerebellar artery.
Sudden, excruciating facial pain. Some people kill themselves
Note: V2>V3.V1 affected in this order
Where are common nerve blocks? (3 cutaneous nerves)
Infraorbital nerve via superior oral vestibule
mental via the mental foramen
Buccal via vestibule just posterior to the 3rd mandibular molar
Facial Artery (course and superficial branches)
Course = Travels through the substance of the submandibular gland after branching from the external carotid artery. Turns around mandible anterior to the masseter ascends in a tortuous path along the angle of the mouth and lateral to the nose to reach the medial angle of the eye
Branches = Inferior labial, superior labial, angular, and lateral nasal aa.
Superficial temporal artery (superficial branches)
Transverse facial, frontal, and parietal aa.
Maxillary Artery (superficial branches)
Infraorbital, buccal, and mental aa.
Ophtalmic Artery (superficial branches)
Supraorbital, supratrochlear, lacrimal (lateral palpebral), medial palpebral, and dorsal nasal aa.
Retromandibular Vein (formation and course)
Created by the merging of superficial temporal and maxillary vv. Courses through the parotid gland and splits into anterior and posterior divisions. Anterior division will merge with facial vein to form common facial v. Posterior division will merge with posterior auricular v. to form the external jugular v.
Facial Vein (formation, course, and communications)
Begins at the medial corner of the eye as the angular vein and receives venae comitantes. Descends face to join the anterior division of the retromandibular v. forming the common facial v. Common facial drains to internal jugular v.
Communicates with the pterygoid plexus via deep facial vv. and cavernous sinus via ophtalmic vv.
Note: Communications turn the face into a danger zone for infections
Lymphatic Drainage
Lymphatics of the face drain to the parotid, submandibular, and submental nodes. Eventually the deep cervical nodes.
Parotid duct course
Crosses masseter to enter the buccinator. Empties into the oral cavity opposite the 2nd maxillary molar.
Note: infections may spread to the parotid gland via the duct
Which structures must be isolated in parotidectomy?
SVE of CN VII
Retromadibular vein
External carotid artery
Parasympathetic innervation of parotid gland (course of pre- and post-ganglionic fibers; action on gland)
Pre-ganglionic cell bodies lie in the salivatory nucles. After CN IX exits the jugular foramen the tympanic branch traverses the tympanic canaliculus to enter the middle ear where it becomes the lesser petrosal n. This exits the hiatous for lesser petrosal to enter the middle cranial fossa and exit via the foramen ovale to synapse of post-ganglionic cell bodies at the otic ganglion.
Post-ganglionic fibers distribute via the auriculotemporal nerve (CN V3)
Stimulates secretion
Sympathetic innervation of parotid gland (course of pre- and poste-ganglionic fibers; actions on gland)
Pre-ganglionic cell bodies lie in segments T1-4 and travel through the sympathetic chain to synapse on post-ganglionic cell bodies in the superior cervical sympathetic ganglion.
Post-ganglionic fibers travel with the external carotid nerve to the parotid gland
Vasomotor
Parotiditis (Pain refers where and why?)
Inflammation of the parotid gland causes stretching of the parotid fascia. This information is carried by the auriculotemporal nerve and may be referred to the auricle, TMJ, and external acoustic meatus.
Consequences of sialolith?
Can sometimes enter parotid duct causing obstruction and pain
