Face

Face and Parotid

Background Information:

The dissection now moves into the head. As in the transition from the upper limb to the neck, the structures in the head become smaller and more delicate. In addition, each individual dissection now focuses on a more detailed area. There will be sections in the lectures that are not covered by this project and there will be some sections where the material will go beyond the dissection possible in class to give a unique perspective to the material.
Both sides of the face will be dissected. One side of the face will be devoted to superficial structures. The other side will be used to isolate deeper structures and be continued as the infratemporal fossa dissection. It is best when the side of the deep dissection of the external carotid artery in the neck is used for the infratemporal dissection.
Bell's Palsy is a paralysis of CN VII which usually affects the muscles of facial expression on one side of the face. The patient may complain of a pain in the head befind his or her ear followed by a paralysis of the muscles. The exact cause can vary and the condition is usually treated with steriods and clears within a few weeks to months.

Dissection:
    1. Make three shallow incisions. The first extends from the hairline at the center of the forehead down to the eyebrows and then circles each orbit ending at the medial corner of the eye. Continue the incision inferiorly around the edge of the nose around the border of the lips and ending at the center of the chin. The second incision extends laterally from the upper border of the ear to the lateral corner of the orbit. The third incision extends laterally from the lower border of the ear to the corner of the mouth.
    2. Reflect the skin posteriorly and begin to delicately remove the fat and fascia from the face.
    3. On one side, locate the parotid duct. The duct will be found running horizontally from the tragus of the ear towards the corner of the mouth within the fat of the face running across the masseter muscle. The duct hooks around the anterior edge of the masseter and disapears into the buccal fat pad, piercing the buccinator muscle and emptying into the oral cavity adjacent to the second maxillary molar.
    4. Locate the parotid salivary gland which can range in size depending on the individual. At the anterior border of the gland, begin to dissect out the branches of the facial nerve (CN VII) from the fat of the face:
    A. Temporal Branch - found traveling from the superior edge of the parotid duct towards the lateral corner of the eye.
    B. Zygomatic Branch - found above the parotid duct traveling from the anterior edge of the parotid gland towards the nose.
        There will be a small communicating branch crossing the parotid duct which connects the zygomatic and buccal branches. The
        transverse facial artery will be found traveling parallel to the zygomatic branch.
    C. Buccal Branch - found below the parotid duct traveling from the anterior edge of the parotid gland towards the corner of
        the mouth.
    D. Mandibular Branch - can be found at the lower edge of the mandible traveling forward towards the chin. It is usually quite
        small and found with in the fascia below the skin.
    E. Cervical Branch - the branch to the platysma muscle.
    5. Follow each of the nerves posteriorly through the parotid gland to their common root which is anterior to the ear. The posterior auricular nerve, nerve to stylohyoid, posterior digastric, and platysma, and the cervical branch of the facial nerve may be found originating from this trunk
    6. Locate the superficial temporal artery and vein and the auriculotemporal nerve travelling above the superior edge of the parotid gland and just anterior to the ear
    7. Locate the facial artery and its branches the superior and inferior labial arteries and its terminal branch the angular artery.
     8. Locate the cutaneous nerves of the face which are terminal sensory branches of the trigeminal nerve (CN V). These are the supraorbital, infraorbital and mental branches and all three exit from foramina in the skull and mandible.
    9. Remove the fat and fascia from the muscles of facial expression.

Pictorial Atlas:
Skin Incisions
Nerves
Muscles of Facial Expression
Parotid Gland and Duct
Cutaneous Face
Vessels
Face and Parotid Structures List