Download TSM19 - Anatomy of the Face

TSM19: ANATOMY OF THE FACE
07/10/08
LEARNING OUTCOMES
Describe the motor and sensory innervation of the face
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The sensory supply to the face is from the trigeminal nerve (CN V) which has three divisions:
o Ophthalmic nerve (V1) – passing through the supraorbital foramen
o Maxillary nerve (V2) – passing through the infraorbital foramen
o Mandibular nerve (V3) – passing through the mental foramen
The motor supply to the face is from the facial nerve (CN VII) which has two roots:
o Intermediate nerve – sensory elements of the ear; taste from anterior two-thirds of the
tongue; parasympathetic secreto-motor fibres to salivary glands (not parotid – see below)
o Motor root – motor innervation to the muscles of facial expression (see below)
Describe the anatomy and innervation of the parotid gland
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The parotid gland is situated anterior to the ear below the level of the external auditory meatus
o It extends from the inferior border of the mandible up to the zygomatic arch
o It extends medially between the mandible and mastoid process
The parotid duct arises just above the level of the mouth and passes anteriorly through the buccinator
muscle terminating in the mouth at the second upper molar tooth
The facial nerve (CN VII) pass through the parotid gland and emerges as five terminal branches:
o Temporal – Two
o Zygomatic – Zebras
o Buccal – Brought
o Mandibular – Me
o Cervical – Cake
The external carotid artery ascends deep to the parotid gland and divides into its terminal branches:
o It first gives off the posterior auricular artery just below the level of the ear
o It then splits into the maxillary and superficial temporal arteries
The retromandibular vein is formed within the parotid by the anastomoses of the superficial
temporal and maxillary veins
o Inferior to the gland it typically divides into anterior and posterior branches
Branches of the mandibular nerve (V3) provide sensory innervation to the parotid gland
The glossopharyngeal nerve (CN IX) gives off parasympathetic fibres to the otic ganglion from which
post-ganglionic fibres give secreto-motor innervation to the parotid gland
Outline the organisation of the important muscles of facial expression
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Orbicularis oculi is a large circular muscle around the eyes that allows you to close the eyelids
o The smaller corrugator supercilii enables you to frown and raise eyebrows
Nasalis is the largest muscle of the nose and allows you to flare the nostrils
Orbicularis oris is a large circular muscle around the mouth that allows you to purse and close the lips
Buccinator is the main muscle of the cheek and is used in mastication and expulsion of air
o Originates as the pterygomandibular raphe
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o Inserts at the alveolar margins and blends into orbicularis oris
The scalp is made up of five layers:
o Skin
o Connective tissue (dense)
o Aponeurosis
o Loose connective tissue
o Pericranium
The uppermost three layers are tightly bound together and act as a single unit
o The aponeurosis is held under tension such that scalp trauma results in gaping wounds