Organs - Anatomy

The azygos vein runs along the esophagus and spine in the thoracic cavity. It get oxygen-poor blood from the intercostal muscles and drains into the superior vena cava.

The three branches off of the human aortic arch are the brachiocephalic trunk, the left common carotid artery, and the left subclavian artery. The brachiocephalic trunk bifurcates into the right subclavian artery and the right common carotid artery.

The axillary nerve, along with the posterior circumflex humeral artery and vein, pass through the quadrangular space. The quadrangular space boundaries consist of the teres minor muscle, the surgical neck of the humerus, the superior margin of the teres major, and the long head of the triceps brachii.

The Vagus nerve has both sensory and motor function. The sympathetic and parasympathetic nervous systems are responsible for the "fight or flight" and "rest and digest" actions of the autonomic nervous system respectively. The Vagus nerve is responsible for the parasympathetic motor nerves.

The question is asking for a sensory nerve, meaning we can eliminate the trochlear and hypoglossal nerves. The olfactory nerve is responsible for smell whereas the optic nerve for vision, making the correct answer the optic nerve.

The musculocutaneous nerve arises from the lateral cord of the brachial plexus. It innervates the biceps brachii, the coracobrachialis, and the brachialis muscle. All of these are muscles of the anterior arm.

The crista terminalis is a specialized region in the upper part of the right atrium. It houses the sinoatrial (SA) node, which is responsible for initiating the electrical impulses that cause the heart to contract.

The tricuspid valve separates the right atrium and the right ventricle. The bicuspid, or mitral, valve is located between the left atrium and left ventricle. The pulmonary valve is a semilunar valve that prevents backflow of blood from the pulmonary veins into the right ventricle.

The order of the strata of the epidermal cells from superficial to deep is corneum, lucidum, granulosum, spinosum, germinativum (basale). Note that in thin skin the stratum lucidum is absent.

Skin is the largest organ of the body. It consists of the superficial epidermis, a deeper dermis, and an even deeper fatty layer called the hypodermis. The skin has protective and sensory functions and is important in body temperature regulation, absorption, and production of vitamin D.

The fundus is the protruding upper left portion of the stomach. In the event that a great deal of food enters the stomach, the fundus will allow excess food to be stored until it is ready to be digested in the small intestine.

The body of the stomach is where most physical digestion occurs and some chemical digestion takes place. The cardia is the region joining the esophagus to the stomach and is characterized by the cardiac sphincter. The pylorus joins the stomach to the small intestine and contains the pyloric sphincter.

The left renal vein and third part of the duodenum lie between the superior mesenteric artery and abdominal aorta.

Compression of the left renal vein will cause pooling of blood in the left gonadal vein and subsequent varicocele formation, known as nutcracker syndrome. Compression of the third part of the duodenum is known as superior mesenteric artery syndrome and will result in malnutrition and symptoms of small bowel obstruction.

The inferior vena cava lies to the right of the abdominal aorta, while the pancreas lies superior and anterior to the superior mesenteric artery. The left gonadal vein drains into the left renal vein and is to the left and inferior to the superior mesenteric artery. The splenic vein lies superior to the superior mesenteric artery and joins with the superior mesenteric vein to form the hepatic portal vein. The transverse colon lies anterior to the superior mesenteric artery.

Only the stomach is intraperitoneal from the listed structures. The peritoneum is a membrane within the abdominal cavity; organs contained within the membrane are considered intraperitoneal and are almost completely covered with visceral peritoneum.

The kidneys are retroperitoneal (posterior to the intraperitoneal space), while the bladder and descending colon are subperitoneal (below the intraperitoneal space). The pancreas is superior to the peritoneum.

The stomach is involved in mechanical degradation of food, as well as a small amount of chemical degradation. Its function is to break food down so that the nutrients and electrolytes from the food can be absorbed in the small intestine and large intestine. The duodenum, ileum, and jejunum are all parts of the small intestine, where the majority of chemical digestion and nutrient absorption takes place. Absorption of water and certain nutrients occurs in the large intestine.

The liver synthesizes bile, however it is stored in the gall bladder. Bile is released into the duodenum of the small intestine in order to emulsify fats and aid in their digestion.

The spleen functions in to filter blood and identify potential pathogens. The stomach is involved in mechanical digestion and secretes pepsinogen to initiate protein digestion.

The pancreas functions to secrete the digestive enzymes amylase, lipase, and trypsin, which break down carbohyrdates, lipids, and proteins, respectively. The endocrine role of the pancreas is to secrete the hormones insulin and glucagon, which regulate blood glucose levels.

The function of the appendix is not well classified; it is considered a vestigial structure, which may have once aided in the breakdown of cellulose. The cecum is referred to as the "blind pouch" and is the first part of the ascending colon. The liver functions to manufacture and excrete bile, and removes toxins from the blood. The esophagus transports food that enters the mouth to the stomach.

The tongue is the organ for taste. The papillae contain the taste buds. The tongue is attached to the hyoid bone, mandible, styloid process, palate, floor of the mouth, pharynx, and epiglottis.

The tonsils are masses of lymphoid tissue at the base of the tongue. The epiglottis is cartilagenous tissue that separates the esophagus from the larynx and trachea. The roof of the mouth is the palate. The uvula closes off the nasopharynx during swallowing.

The stomach has two openings. The upper is surrounded by the esophageal (cardiac) sphincter, and the lower by the pyloric schincter. These sphincters open and close, allowing food to enter and exit the stomach. The rugae are the folds of mucous membrane on the surface of the stomach.

The esophagus is a tube that transports food from the mouth to the stomach. At the distal end of the esophagus is the esophgeal (cardiac) sphincter. The duodedum is the first part of the small intestine and works to absorb nutrients. The pyloric sphincter opens to empty food into the duodenum. The ileum ends at the ileocecal valve, a sphincter that controls entry into the colon. The colon stores waste products until the anal sphincter opens to allow defecation.

The liver is the largest organ in the body. It is roughly triangular, with a smooth brown surface. The liver receives arterial blood through the hepatic artery, venous blood leaves through the hepatic vein, and a third circulatory system, the portal, receives nutrient-rich blood from the gastro-intestinal tract. The liver works to detoxify substances in this blood.

The gallbladder stores bile, which is formed in the liver. Bile is used to digest fatty foods. The pancreas is wedge-shaped and secretes digestive enzymes and hormones. The parotid gland is located inferior and anterior to the ear. This gland secretes saliva. The adenoids are prominences of lymphoid tissue located in the nasopharynx.