Regional Anatomy I: Thorax, Abdomen, and Pelvis

Recall the location and identify the major organs, vessels and nerves of the thorax, abdomen, and pelvis.
Recall the function of the major organs, vessels and nerves of the thorax, abdomen, and pelvis.

I covered a lot of this stuff in a lot of detail in my posts for ANHB2212. However, rest assured that we do not need to go into that level of detail for now.

Thorax

Things we have in the thorax:

• The Heart and Major Blood Vessels
• Lungs and bronchi (The Respiratory System)
• Oesophagus. Has skeletal muscle at the top (acts as a sphincter to stop us from swallowing anything we don't want), a mix of skeletal and smooth muscle for the middle third, and smooth muscle at the bottom. The inner muscular layer is circular and the outer layer is longitudinal.
• Thoracic duct: the main duct that carries lymph back to the circulatory system.
• Phrenic nerve: arises from C3, C4, and C5 and keeps the diaphragm alive. It also innervates the fibrous pericardium.
• Vagus nerve (Cranial Nerve X): travels behind the lungs and wraps around the oesophagus. Also travels down through the diaphragm to the abdomen. Innervates damn near everything.

All of the organs in the thorax are surrounded by the rib cage, made up of 12 ribs, most of which are attached to the sternum (breastbone).

Abdomen

Things we have in the abdomen:

• The stomach (Digestion and Absorption of Food- Part 1)
• The spleen: found in the upper left part of the abdomen, it filters the blood and protects against blood-borne pathogens. In fetal life, and in certain disease states, it is involved in haematopoiesis.
• The pancreas: has exocrine and endocrine functions. Exocrine functions: secretes digestive enzymes. Endocrine functions: secrete insulin and glucagon. Its head is encircled by the duodenum and its tail points to the spleen.
• Liver: receives some oxygenated blood from the hepatic artery, as well as a ton of deoxygenated blood from the GI tract. Filters blood and produces bile.
• Gallbladder: stores and concentrates bile received from the liver (does not produce bile). Bile helps to break down fats. Note that while the gallbladder looks green in cadavers, it is only green because formalin makes it green.
• Small intestine: made up of the duodenum, jejunum, and ileum. The main site of absorption. Has folds (plicae circularis), villi, and microvilli, all of which increase the absorptive area. The ileum also has lymphoid tissue known as Peyer's patches.
• Large intestine: made up of caecum, ascending colon, transverse colon, descending colon, and sigmoid colon. Absorbs water and makes poo.
• Kidneys: filters blood to make urine. Has ureters that deliver said urine to bladder.
• Suprarenal (adrenal) glands: sit on top of the kidneys and secrete a bunch of important hormones.

Pelvis

The pelvis is made up of three main bones: ilium, ischium, and pelvis. Here are the things that we have in the pelvis:

• Pelvic diaphragm muscles (a.k.a. levator ani): puborectalis, pubococcygeus, iliococcygeus. Act as sphincters and stop the contents of the abdomen from falling out the bottom.
• Rectum and anus: has two sphincters- internal smooth, external skeletal.
• Urinary bladder: stores the urine produced by the kidneys. The urethra connects the bladder to the outside world.
• Male and female reproductive organs.