Parotid

1. RADIO-ANATOMY PAROTID GLAND AND SUBMANDIBULAR GLAND

2. OVERVIEW OF ANATOMY 1)- DEVELOPMENTAL AND GROSS ANATOMY 2)- ULTRASOUND FEATURES 3)- X RAY 4)- CT AND MRI ANATOMICAL LOCATION

3. PAROTID GLAND Development Appear early - sixth week of prenatal age. The epithelial buds of these glands are located on the inner part of the cheek, near the labial commissures of the primitive mouth Grow posteriorly toward the otic placodes of the ears and branch to form solid cords with rounded terminal ends near the developing facial nerve. 10 weeks of prenatal development, these cords are canalized and form ducts, with the largest becoming the parotid duct for the parotid gland. Secretion by the parotid glands via the parotid duct begins at approximately 18 weeks of gestation.

4. Location Inferior and anterior to the external acoustic meatus and posterior to the mandibular ramus and anterior to the mastoid process of temporal bone. Draining The vestibule of oral cavity through Stensen duct or parotid duct that emerges from the anterior border of the gland, superficial to the masseter muscle pierces the buccinator muscle, then opening up into the oral cavity on the inner surface of the cheek, usually opposite the maxillary second molar. The parotid papilla is a small elevation of tissue that marks the opening of the parotid duct.

5. Surfaces and borders The gland has four surfaces superficial or lateral,superior , anteromedial and posteromedial. The gland has three borders anterior, medial and posterior. The Parotid gland has two ends: superior end in the form of small surface and an inferior end (apex).

6. Structures that pass through the gland These are from lateral to medial: Facial nerve (2) Retromandibular vein (3) External Carotid artery (4) Superficial temporal artery (5) branches of the great auricular nerve

7. Blood Supply The gland is mainly irrigated by External Carotid artery via the posterior auricular artery and the transverse facial. Venous Drainage Venous return is to the Retromandibular vein. Lymphatic drainage The gland is mainly drained into the preauricular or parotid lymph nodes which ultimately drain to the deep cervical chain.

8. SUBMENDIBULAR GLAND Develop later than the parotid glands and appear late in the sixth week of prenatal development. They develop bilaterally from epithelial buds in the sulcus surrounding the sublingual folds on the floor of the primitive mouth. Arise of solid cords branch from the buds and grow posteriorly, lateral to the developing tongue. The cords of the submandibular gland later branch and then become canalized to form the ductal part. The submandibular gland acini develop from the cords’ rounded terminal ends at 12 weeks, and secretory activity via the submandibular duct begins at 16 weeks. Growth of the submandibular gland continues after birth.

9. LOCTION Lying superior to the digastric muscles, divided into superficial and deep lobes, which are separated by the mylohyoid muscle. The superficial lobe comprises most of the gland, with the mylohyoid muscle runs under it. The deep lobe is the smaller part.

10. Indications Indications include: In the evaluation of the functional integrity of the salivary glands In case of obstructions To evaluate the ductal pattern In case of facial swellings, to rule out salivary gland pathology In case of intra-glandular neoplasms . Containdications Persons who are allergic to iodine and/or contrast medium. Cases where there is acute infection, patients with thyroid function tests When calculi are located in anterior part of the salivary gland duct Sialography

11. It is a fatty glandular tissue that is encased in a dense capsule. Because of this, the parotid gland on CT is consistently more lucent (-25 to 10 Hounsfield units [H ]) than surrounding muscles (35-60 H) and likewise is distinctly more radiodense than adjacent fat in the subcutaneous tissues , infratemponal fossa, and lateral pharyngeal space (-125 to -50 H)(figs. 1A, 1B, and 2B). CT OF SLIVERY GLAND