Coursing between these structures is the small intestine. The third quadrant generally contains the stomach, gallbladder, spleen, pancreas, (or splenopancreas depending on the species), adrenal glands, gonads, and the lung(s)/air sacs. The liver and stomach are located approximately midway between the snout and the vent.The left lung is never greater than 85% of right lung size. The left lung is vestigial or absent, except in boids (boas and pythons), where two lungs in boids are almost equal in length.This dark red to brown, cigar-shaped structure is pointed at both ends. The liver is the largest organ within the coelomic cavity.The stomach is spindle shaped or filiform and clearly demarcated from the esophagus.The second quadrant contains a continuation of the esophagus as well as the anterior, vascularized portion of the lung(s), and the liver. The thymus gland is bilateral and consists of two lobes, which are usually asymmetrical.Ĭlinical Tip: The heart is typically located in the upper third of the body however its exact position varies greatly among species.If paired caudally, the PTG are between and often medial to the cranial or caudal lobes of the thymus. Parathyroid glands (PTG) are single or paired.The thyroid gland is ventral to the trachea and cranial to the heart.The trachea, which consists of incomplete cartilaginous rings, begins in the first quadrant and extends down into the second quadrant.When the snake consumes large food items, the glottis is pushed to one side and the jaw is lowered to allow respiration to continue. The glottis is a small opening caudal to the tongue.The distensible esophagus is dorsal to the trachea.The proximal quadrant of the snake generally contains the trachea, esophagus, parathyroid glands, thymus, thyroid, and the heart. Also see Mader’s Reptile and Amphibian Medicine and Surgery: Figure 55.2 of Radiography-Snakes illustrates the relative position of organs in four major serpent families. Visit LafeberVet’s A Necropsy Guide to Serpentes for gross images of normal anatomy. Using the quadrant system, the location of this lump within the snake’s coelom could provide valuable diagnostic clues to the anatomic structure(s) involved. Although the sequence of organs is the same for all species, the relative position and size of the viscera can vary significantly between and within families.įigure 2. It is possible to divide this tube into four quadrants (Fig 1). Snakes have a long narrow body adapted for crawling and their internal anatomy has evolved to fit into a long narrow tube. There are over 3,500 species of snakes in the world, however, for the most part, the anatomy of the snake is consistent across species. Snakes are members of the class Reptilia, order Squamata, and suborder Serpentes. The fourth quadrant contains the junction between the small and large intestine, the cecum (in boas and pythons), kidneys, cloaca, and hemipenes.Coursing between these structures is the small intestine and adjacent to them is the right lung. The third quadrant contains the gallbladder, spleen, pancreas (or splenopancreas), and gonads.The anterior, vascularized portion of the lung(s), as well as the liver and stomach are found within the second quadrant.Major structures of the first quadrant consist of the head, esophagus, heart, and trachea.Snakes have a long narrow body that can be divided into four quadrants.