Parotid Region Anatomy Quiz

Parotid Region Anatomy

• The parotid region encompasses the area below and in front of the ear, beneath the zygomatic arch.
• Key structures in this region include the parotid gland and the masseter muscle (part of the mastication group).
• Other mastication muscles include the temporalis and two pterygoid muscles.

Masseter Muscle

• The masseter muscle has three heads that fuse on the zygomatic arch before diverging posteriorly.
• The superficial part, the largest, arises from the anterior two-thirds of the zygomatic arch and inserts along the mandible's lower border.
• The intermediate part arises from the middle third of the zygomatic arch, and the deep part from its deep surface. Both insert into the mandibular ramus.
• The masseteric nerve runs between the deep and intermediate parts, and an artery runs between the superficial and intermediate parts, dividing the muscle into three portions.
• This muscle is responsible for jaw closure by elevating and pulling forward the mandible's angle.
• Blood supply to the muscle comes primarily from the artery accompanying the masseteric nerve.

Parotid Gland

• The parotid gland, predominantly serous, fills the space between the mastoid process, mandibular ramus, and styloid process, extending onto adjacent muscles.

• It has upper and lower poles, and lateral, anterior, and deep surfaces.

• The parotid gland is encased in a tough capsule.

• Within the gland are the facial nerve, retromandibular vein, and external carotid artery (superficial to deep).

• The facial nerve passes forward through the gland's deep surface and becomes the most superficial structure as it enters the parotid.

• Branches emerge from the anterior border and not the lateral surface.

• The retromandibular vein aids in locating nerve positions.

• Large structures are the external carotid artery and its terminal branches internally.

• Variations in size influence facial nerve and artery/vein positions.

• Lymph nodes of the preauricular group, lymphatic filaments of the auriculotemporal nerve are present within the gland.

• The parotid duct, about 5 cm long, crosses the masseter and pierces the buccinator muscle.

• It opens opposite the second upper molar.

• An accessory parotid gland frequently exists on the masseter muscle containing several ducts opening into the main parotid duct.

Blood Supply, Nerve Supply and Lymph Drainage of Parotid gland

• The parotid gland receives blood supply from branches of the external carotid artery.
• Venous return is to the retromandibular vein.
• Lymph drains to nodes within the parotid sheath, then to upper deep cervical nodes along with the external carotid artery.
• Secretomotor fibers from the otic ganglion travel along the auriculotemporal nerve.
• Preganglionic parasympathetic fibers originate from the inferior salivary nucleus and travel via the glossopharyngeal nerve.
• Sympathetic (vasoconstrictor) fibers from the superior cervical ganglion arrive via the external and middle meningeal arteries' plexus..
• Sensory fibers are from the auriculotemporal nerve, and parotid fascia from the great auricular nerve.

Parotid Gland Development and Surgical Approach

• The parotid gland develops from an ectodermal groove in the cheek.
• Parotidectomy (parotid gland removal) involves an S-shaped incision.
• The facial nerve, accompanied by accompanying structures, is carefully dissected and protected.
• The parotid duct is divided at the masseter's anterior border during the procedure.
• For total parotidectomy, arteries (external carotid, superficial temporal, maxillary), adjacent veins, and the styloid process may need further dissection.