Lab 9 Abdomen MUSCLES External abdominal oblique continuous with the external intercostal muscle; its fibers point in a caudal direction as it moves anteriorly until it inserts on the linea alba via its aponeurosis; most superficial of the muscles of the abdominal wall; immediately superficial to the internal abdominal oblique. Aponeurosis shaped a little like a bell; milky in appearance and flares laterally as it approaches the inferior portion of the abdomen; it is a broad, flat tendon. Internal abdominal oblique continuous with the internal intercostal muscle; its fibers point in a cranial direction as it moves anteriorly until it inserts on the linea alba via its aponeurosis; deep to the external abdominal oblique; superficial to the transverse abdominis muscle; Dr. J has been known to tag this muscle! What an awful guy! Aponeurosis shaped a little like a "V" getting wider at the cranial end and more narrow at the caudal end; milky in appearance; it is a broad, flat tendon. Linea alba white line where the aponeuroses of the anterior abdominal muscles fuse with each other to form a single tendinous band; runs along the anterior midline from the xiphoid process to the pubic symphysis; contains the umbilicus. Psoas major merges with the iliacus to form the iliopsoas which is the prime flexor of the thigh. Psoas minor lateral to the Psoas Major; smaller of the 2 muscles Quadratus lumborum can be seen in two places in the cat: 1. in the thoracic cavity running along the vertebral border just cranial to the diaphragm and 2. dorsal to the psoas major in the abdomen. Rectus abdominis eight pack muscle of humans; it is enclosed within the aponeurosis of the internal abdominal oblique; looks like bacon. Transverse abdominis deepest of the three muscles making up the majority of the abdominal wall; immediately deep to the internal abdominal oblique; in the cat its fibers move caudally as they approach the midline, while in humans it is more transverse. Aponeurosis shaped a little like a narrow oval. 1
NERVES Femoral nerve emerges from the Psoas Major just before it passes deep to the inguinal ligament; enters the thigh lateral to the femoral artery; gives rise to the saphenous nerve. Genitofemoral nerve found adjacent to the external iliac artery. Lateral cutaneous nerve diameter of dental floss; found near the deep iliac circumflex artery and runs obliquely in a caudal direction as it moves laterally, passes through the internal and external abdominal oblique muscles. Lumbar nerve Medial and lateral lumbar nerves; found dorsal to the kidney and lateral to the psoas major muscle. Usually close to the adrenolumbar artery or one of its branches. ORGANS Cecum very beginning of the colon. Looks like the Pope s slippers. Colon looks like a huge question mark. Common bile duct begins at the union of the cystic duct and the hepatic duct. It carries bile to the duodenum. Cystic duct cystic duct is on the cat's right and the hepatic duct is on the cat's left side. These two ducts (quack) meet to form the common bile duct. Diaphragm anatomical barrier between the thoracic and abdominal cavities; dome shaped; insertion is at the central tendon; phrenic nerve serves the diaphragm Central tendon insertion of the diaphragm; it is an aponeurosis and connects the central portions of the diaphragm; phrenic nerve passes through the central tendon on both sides as well as the caudal vena cava on the right. Crura musculotendinous extensions of the diaphragm; one on each side. The singular for is crus. 2
Esophagus begins at the inferior end of the pharynx, passes through the diaphragm and then enters the stomach. Gall bladder looks like a green raisin in the cat; found between the quadrate and right medial lobes of the liver. Hepatic duct the hepatic duct comes from the liver on the cat s left side and joins the cystic duct (on the right) to form the common bile duct. Kidney kidney shaped organ; major excretory organ of the abdomen; has portal circulation; right kidney is cranial to the left kidney in the cat. In humans the left is superior to the right kidney. Calyx funnel or cup shaped space near middle of kidney. Cortex outer layer of the kidney; where the glomerulus, Bowman's capsule, and part of the tubular system of the nephron are found; usually a lighter color than the medulla. Medulla inner portion of the kidney; cat has a single piece medulla which is called a pyramid; medulla is usually darker than the cortex. This is where the loop of Henle is and where the collecting tubules drop the urine into the calyx. Pyramid of medulla cat has a single piece medulla which is called a pyramid; usually darker than the cortex. Humans have 8 to 10 pyramids in each kidney and pigs have 10 or more per kidney. Liver from left to right: Left lateral lobe caudal to the left medial lobe; it is the larger of the two lobes on the left side. Left medial lobe cranial and medial to the left lateral lobe; it is the smaller of the two lobes on the left side. Quadrate lobe found on the right side; it is between the gall bladder and the left medial lobe; it is often four sided in appearance. 3
Right medial lobe cranial to the right lateral lobe and lateral to the quadrate lobe; larger than the right lateral lobe. Right lateral lobe caudal to the right medial lobe and cranial to the caudate lobe; smaller than the right medial lobe. Caudate lobe found on the right side; largest portion is caudal to the right lateral lobe of the liver; caudate lobe can be seen in two places, one being the papillary process of the caudate lobe. The papillary process is to the left of the common bile duct and is covered on its ventral surface by the lesser omentum (gastrohepatic ligament). Papillary process of caudate lobe only found on the right side; relatively small portion of the caudate lobe and it is found dorsal to the lesser omentum and to the left of the common bile duct and the hepatic artery; it is one of the two portions of the caudate lobe of the liver that can be tagged. Pancreas right lobe runs in a cranial/caudal direction adjacent to the duodenum and the left lobe runs transversely from the cranial end of the duodenum to the spleen; looks like hamburger helper. Peritoneum forms two abdominal organs, the greater omentum and the lesser omentum; covers the abdominal wall as well as the organs; shiny material inside transverse abdominal flap. Greater omentum part of the peritoneum; attached to the greater curvature of the stomach and part of the duodenum; looks like mozzarella cheese in a hair net; flip it up to see intestines. Lesser omentum part of the peritoneum; primarily between the stomach, duodenum, liver and the diaphragm; much smaller than the greater omentum. Rectum portion of the large intestine that is between the sigmoid colon and the anal canal. 4
Small intestine: Duodendum first portion of the small intestine; the chyme enters the duodenum from the stomach and material leaves the duodenum to enter the jejunum; it is directed caudally from the pylorus of the stomach; travels adjacent to the pancreas. In a humans this reflects and is directed transversely to the left. Jejunum makes up most of the small intestine in the cat and is highly coiled; middle portion of the small intestine; receives material from the duodenum and the material that leaves enters the ileum. Ilem less coiled than the jejunum; joins the large intestine at the ileocecal junction; last portion of the small intestine. Mesentery also known as the mesenteric ligament; it is a double layer of peritoneum that comes out around the small intestine; arteries, veins, nerves, and lymphatics that come to and from the small intestine pass between these two layers; prevents the small intestine from tying itself in knots. Spleen produces red blood cells before birth; important part of the lymphatic system; can produce some white blood cells; it is the primary organ that removes old red blood cells, old platelets and debris from the blood. Stomach stomach shaped organ between the esophagus and the duodenum of the small intestine; has rugae in its walls. Rugae longitudinal folds in the walls in the stomach. Suprarenal (adrenal) gland endocrine glands; they are about 1 cm cranial and medial to the kidneys. Ureter transports urine from the kidney to the urinary bladder; there are two ureters, one on each side; can trace from kidneys. Urethra transports urine from the urinary bladder to the outside; trace from urinary bladder. Urinary bladder receives urine from the two ureters and stores it until it is discharged to the outside by means of the urethra; has rugae that allow it to expand without increasing pressure.. 5