Parotid

The parotid gland is the largest of the three major salivary glands. It is located in the preauricular region, extending from the zygomatic arch to the angle of the mandible and lying superficial to the masseter muscle. The gland produces saliva that is delivered to the mouth via Stensen’s duct, which opens in the oral cavity opposite the upper second molar. The saliva is rich in the enzyme salivary amylase.

Anatomy and relations: The gland is divided into superficial and deep lobes by the facial nerve (cranial nerve VII), which traverses the gland and gives its major terminal branches within it. This intimate relationship with the facial nerve is central to parotid surgery. Blood supply comes from branches of the external carotid artery, including the posterior auricular, maxillary, and superficial temporal arteries. Lymphatics drain to the parotid nodes and then to deep cervical nodes.

Innervation and physiology: Parasympathetic secretomotor fibers originate from the glossopharyngeal nerve (cranial nerve IX) via the tympanic nerve, the lesser petrosal nerve, and the otic ganglion, hitchhiking on the auriculotemporal nerve to the gland. Sympathetic fibers from the superior cervical ganglion modulate tone and secretion. These pathways regulate saliva production and glandular blood flow.

Clinical aspects: Common conditions include sialolithiasis affecting Stensen’s duct, acute bacterial parotitis, and viral parotitis such as mumps. Benign tumors are most frequent in the parotid, notably pleomorphic adenoma and Warthin tumor; malignant tumors are less common. Diagnostic workup typically starts with ultrasound, followed by MRI or CT for detailed assessment; fine-needle aspiration may aid histological evaluation.

Management: Infections are managed with hydration, analgesia, and antibiotics as indicated. Tumors often require surgical removal with preservation of the facial nerve, typically via parotidectomy; radiotherapy may be used for malignant disease or when surgery is not feasible.