Page:Laboratory Manual of the Anatomy of the Rat (Hunt 1924).djvu/62



The glands of the neck should be studied first, because they or their ducts are likely to be injured during the dissection of the blood vessels of this region. Cautiously remove the skin from the head and neck, taking care to avoid injuring the underlying muscles, blood vessels, and glands. Removal of the subcutaneous connective tissue on the ventral and lateral surfaces of the neck will now reveal the glands. These are of three types, salivary, lymph, and lacrimal.

The salivary glands secrete the saliva, which is mixed with the food in the mouth during mastication. Look for two of them in the rat, the parotid and the submaxillary glands. The parotid is the rather loosely organized, elongated, mass extending from the base of the external ear along the side of the neck to the ventral surface of it. Find and trace the parotid duct (Stenson's duct) which transports the salivary secretion from the gland to the mouth cavity. The duct is formed by the union of several tributaries from different parts of the gland, traverses the lateral surface of the jaw muscle (masseter), then turns inward to the mouth cavity. The duct should not be confused with the nerves which cross the surface of the muscle in this region. Immediately anterior to the dorsal portion of the parotid is the extra-orbital portion of the lacrimal, or tear, gland. Locate its duct and trace it to the eye. The submaxillary glands are the large elongated pair on the ventral surface of the neck. The median faces of these glands are in contact with one another, in the sagittal plane