MUSCLES OF THE FACE

MUSCLES OF THE FACE

frontalis orbicularis oculi orbital portion palpebral portion zygomaticus major levator labii superioris alequae nasii levator anguli oris orbicularis oris risorius depressor anguli oris depressor labii inferioris mentalis platysma Image 2 displays the buccinator and the masseter muscles. The masseter is a muscle of mastication, not facial expression but it is superficial in the face. You might notice that the muscles of facial expression are arranged around the orifices of the face: orbit, nasal cavity, mouth and ear (although you wont examine these). Muscles around the mouth include: zygomaticus major (3) levator labii superior alequae nasii (4) levator anguli oris (5) orbicularis oris (6) risorius (7) depressor anguli oris (8) depressor labii inferioris (9) buccinator Muscles around the orbit are: frontalis (1) orbicularis oculi (2)

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MOTOR INNERVATION
TO THE FACE

The motor innervation to the muscles of facial expression is Cranial Nerve VII (Facial) (yellow in the diagram) It leaves the skull through the stylomastoid foramen on the base of the skull and immediately turns forward to enter the substance of the parotid gland (pink in the image). While within the gland, it divides into 5 major divisions: T -- temporal Z -- zygomatic B -- buccal M -- mandibular C -- cervical Another nerve enters deep in the buccal area where the buccal branches of the facial nerve are found but it is a purely sensory branch of the mandibular branch of Cranial Nerve V (Trigeminal). It supplies the mucous membrane inside the cheek and to the skin in this area. The parotid duct (white) can be seen crossing the masseter muscle on it way to penetrate the buccinator muscle. It opens into the mouth opposite the upper 2nd molar tooth. It forms a small swelling (papilla) inside the oral cavity that can be easily seen. The partotid gland is one of three salivary glands in the head and neck. The transverse facial artery (red) runs just above the parotid duct and is a branch of the superficial temporal artery.

The arterial and venous supply to the face is seen in the diagram. They are the: Facial artery inferior labial superior labial angular Facial vein Superficial temporal artery Superficial temporal vein The facial vein is important clinically because it has a direct connection to the ophthalmic vein and then to a deep venous sinus within the cranial cavity, the cavernous sinus. Bacteria can enter the facial vein and gain access to internal cranial structures resulting in infection there. This is probably the reason our mothers always said not to squeeze our pimples.