Anatomy Part II

A graduate student observes the typical differences in right versus left lung size. What accounts for the smaller volume of the left?

A cardiac notch located in the left lung accommodates the heart and results in the left lung typically displaying an overall smaller size than the right (although the right is shorter). The shorter height of the right lung is related to the presence of the liver and the higher right dome of the diaphragm. The ribs and sternum lie along the costal surface of the lungs and limit the sizes of both similarly.

What region of the mediastinum is significant regarding potential descending thoracic aortic aneurysm?

A clinical consideration for the posterior region includes descending thoracic aortic aneurysm and other life-threatening situations.

Which region of the mediastinum can be obstructed by ingestion of foreign substances?

A clinical consideration for the superior region is that the esophagus and trachea are subject to obstruction or injury related to ingested or inhaled substances.

Bundles of fibers transmit information to and away from the spinal cord. Which part of these structures forms an intersecting convergence after exiting the vertebral column?

A plexus is a convergence of rami.

Which portion of the small intestine absorbs B12 and bile salts?

B12, bile salts, and remaining nutrients are absorbed in the ileum.

The intercostal arteries supply the muscles of the thoracic wall. They are located between the internal intercostal and what other structure?

Between the internal intercostal muscles and the innermost intercostal muscles lies a neurovascular bundle composed of veins, arteries, and nerves.

What structure does bile flow through directly before formation of the right and left hepatic ducts?

Bile flows through interlobular ducts before they merge to form the right and left hepatic ducts. After leaving the liver, these ducts merge to form the common hepatic duct. This duct then merges with the cystic duct to form the common bile duct. The hepatopancreatic ampulla is located at the entry point of the small intestine. Collection of bile by canaliculi and subsequent drainage into intralobular ducts occurs upstream of this process.

What is the main pigment of bile and where in the body is it derived?

Bilirubin is the main pigment present in bile. It is made by the breakdown of red blood cells in the liver

Where in the hepatic portal system does blood mix with hepatic arterial supply?

Blood from the hepatic portal system mixes with blood from the hepatic artery inside sinusoids.

Where in the hepatic portal system is blood shuttled to the inferior vena cava?

Blood travels from the hepatic vein to the inferior vena cava.

The conducting zone of the respiratory system ends when terminal bronchioles divide into respiratory bronchioles. Which structure of subsequent divisions is the main site of gas exchange?

Bronchi produce secondary lobar bronchi in the conducting zone. In the respiratory zone, bronchioles produce alveolar ducts, which produce alveolar sacs. Alveolar sacs are the main site of gas exchange.

Which vertebrae contains an odontoid process that assists in rotational movement?

C2 (the axis) has the odontoid process. The odontoid process is a bony projection that serves as a point of attachment for soft tissue that stabilizes the junction that enables rotational movement.

What structure's contraction is stimulated by the release of Cholecystokinin?

Cholecystokinin is a hormone that regulates smooth muscle contraction. It stimulates contraction of the gallbladder so that bile and pancreatic secretions may be emptied into the common bile duct.

What nerve provides primary innervation for peristaltic propulsion inside the esophagus?

For the esophagus, the cervical chain nerve and thoracic chain nerve provide innervation to constrict blood vessels, contract esophageal sphincters, relax the muscle wall, and increase peristaltic activity. These nerves increase peristaltic activity, but the vagus nerve is the primary innervation for the excitatory pathway of primary peristalsis in the esophagus. The phrenic nerve provides innervation for the crural diaphragm.

Which portion of the abdominal wall contains fibers from the external oblique?

In the abdominal wall, aponeuroses arise from the external oblique. This layer is part of the abdominal muscle layer.

What may be caused by inflammation of the pericardium?

Inflammation of the pericardium can cause pericardial effusion.

Which part of the hepatic portal system results from divisions of left and right branches of a major vein?

Inside the liver, the portal vein branches right and left and subsequently divides into smaller branches, leading to venules.

Cartilaginous structures between adjacent vertebrae enable motion of the spine and protection from heavy loads. Which component of these structures is composed of loose collagen fibers, water, and proteins?

Intervertebral discs are composed of annulus fibrosus (the outer portion) and nucleus pulposus (inner gel). Nucleus pulposus is composed of loose collagen fibers, water, and proteins.

Which spinal nerve supplies the lower extremities?

L3 is the spinal nerve that innervates the lower extremities.

An adult demonstrates a slight extension of the cervical and lumbar spine. What condition in these regions of the spine is likely?

Lordosis of the lumbar and cervical region is typical of a healthy spine.

What does bile secrete to protect from enteric infections?

Out of all the immunoglobulins (IgM, IgA, IgG, IgE, and IgD), IgA is recognized for its presence in bile for the prevention of enteric infections.

A muscle is attached to the sternal portion of the xiphoid process, the lumbar vertebrae, and the lower 6 ribs. How does this muscle aid in normal exhalation?

Passive relaxation of the diaphragm forces the air within the lungs to be expelled from the body during normal exhalation.

Ligaments attach the pericardium anteriorly to what?

Posteriorly, the pericardium approaches the descending aorta, esophagus, and vertebrae T5-T8.

The vessels of the lungs are classified into pulmonary and systemic groups with key differences of function, size, and origin. Which of these structures receives oxygenated blood from capillaries surrounding alveoli?

Pulmonary veins receive blood from two sources: oxygenated blood from alveolar capillaries and deoxygenated blood from bronchial arteries. Bronchial arteries supply oxygenated blood to lung tissue, and bronchial veins collect deoxygenated blood. Pulmonary arteries carry deoxygenated blood from the heart to the lungs.

What deep membranous layer of the abdominal wall is part of the subcutaneous tissue?

Scarper's fascia is the deep membranous layer of the subcutaneous tissue of the abdominal wall.

A female teenager demonstrates abnormal lateral deviation of the thoracic spine. What condition is likely?

Scoliosis is characterized by increased lateral curvature of the spine. Scoliosis is often congenital.

A portion of the alimentary canal absorbs water from indigestible contents. What else is absorbed by this structure?

Some vitamins are absorbed in the large intestine.

What condition involving the spleen may result from bacterial infection?

Splenomegaly (enlargement of the spleen) can occur as a result of bacterial infection.

What region of the mediastinum contains no major named nerves?

The anterior region does not contain any major named nerves.

What is the proximal segment of the ascending portion of the large intestine?

The cecum is the proximal segment of the ascending colon, which is the second portion of the large intestine.

Which major branch of the abdominal aorta divides into the arteries that supply the liver, pancreas, and spleen?

The celiac trunk is the major branch described.

Organs within a pleural cavity provide oxygen to the blood. Their costal surface is molded to what structure?

The costal surface is molded to the chest wall.

Where does the cervical segment of the esophagus begin?

The cricopharyngeus marks the beginning of the cervical segment of the esophagus.

Which of the spinal meninges is deepest?

The deepest of the spinal meninges is the pia mater.

The descending aorta courses slightly left of midline towards the diaphragm. This occurs in which region of the mediastinum?

The descending aorta courses left of midline towards the diaphragm in the posterior mediastinum.

What is anterior to the left kidney?

The descending colon is anterior to the left kidney.

A muscle is attached to the sternal portion of the xiphoid process, the lumbar vertebrae, and the lower 6 ribs. How does this muscle aid in inspiration?

The diaphragm contracts and pulls its central tendon inferiorly, increases the diameter of the thorax, increases the negative pressure, and draws air into the thoracic cavity.

What mediates relaxation of the lower esophageal sphincter (LES)?

The dorsal motor nucleus innervates the myenteric plexus—as opposed to the smooth muscle of the LES—to mediate relaxation.

Defined surfaces of the heart are organized into layers. Which layer, under typical physiological conditions, contains adipose tissue constituting 20% of heart mass?

The epicardium contains adipose tissue.

Nervous tissue is protected from vertebrae by membrane-like coatings that cover the spinal cord. Analgesics target the space between which of these structures?

The epidural space, between the dura mater and ligamentum flavum, is used analgesic purposes.

What directly covers the kidney?

The fibrous capsule directly covers the kidney.

Which segment of the duodenom contains the bulb?

The first segment of the duodenum contains the duodenal bulb.

What structure collects bile from the functional unit of the liver?

The functional unit of the liver is the lobule. Collection of bile at this level occurs by intralobular ducts. From here, bile drains into interlobular ducts. The ducts merge to form the right and left hepatic ducts. After leaving the liver, these ducts merge to form the common hepatic duct. This duct then merges with the cystic duct to form the common bile duct. The hepatopancreatic ampulla is located at the entry point of the small intestine. Bile collection by canaliculi occurs upstream of lobules.

What dome-shaped portion is the superior portion of the stomach?

The fundus of the stomach is dome-shaped. It follows the cardia and is the superior portion of the stomach

What marks the endpoint of the abdominal segment of the esophagus?

The fundus of the stomach marks the endpoint of the abdominal segment of the esophagus.

What attaches the spleen to the lateral border of the stomach?

The gastrosplenic ligament attaches the spleen to the stomach.

Which major branch of the abdominal aorta divides into the arteries that supply the sigmoid colon and superior rectum?

The inferior mesenteric artery is the major branch described.

The thoracic musculature works in unison to support respiration. In what direction does the innermost layer insert onto the rib below?

The innermost layer is composed of the innermost intercostal muscle. The fibers of the innermost intercostal are orientated superiorly and medially. The fibers of the external intercostal are oriented inferiorly and medially.

Which muscle of the abdominal wall originates from the lateral inguinal ligament and iliac crest?

The internal oblique of the abdominal wall originates from the lateral inguinal ligament and iliac crest.

Where in the small intestine are villi longest?

The jejunum is characterized by having the longest villi, but some are also present in the ileum.

What is anterior to the upper esophageal sphincter?

The larynx is anterior to the upper esophageal sphincter.

Endothelial cells arrange into a single layer to line the chambers of the heart. Beginning within the chamber of the heart, which layer located just deep to the endothelium?

The layer is the endocardium, which is located on the inner surface of the myocardium. The pericardium encloses the heart. The epicardium is immediately deep to the pericardium.

Two atria are superior to two ventricles. Which of these forms the most posterior surface of the heart?

The left atrium is the most posterior chamber.

Two atria are superior to two ventricles. Which of these contains the thickest wall?

The left ventricle is thicker than the right ventricle due to its need to withstand the force required to propel blood throughout the body. Atria are relatively thinner structures.

A structure forms the central axis of bearing weight. Which region of this structure is subjected to forces that may cause anterior spondylolisthesis?

The lumbosacral region may demonstrate impairments such as anterior spondylolisthesis or partial dislocation of the sacroiliac joints. This region is typically subject to larger forces than the cervicothoracic, craniocervical, and thoracolumbar regions due to weight transfer from the body through the pelvis to the lower extremities.

Bundles of fibers transmit information to and away from the spinal cord. Which of these structures provides innervation to the multifidus?

The medial branch of the dorsal ramus innervates the multifidus, an epaxial muscle.

Where does a branch re-enter the intervertebral foramen of a spinal nerve to supply the vertebrae?

The meningeal branch re-enters the vertebrae through the intervertebral foramen from the dorsal rami of spinal nerves, which provides supply to the posterior elements of the vertebral column.

Which region of the mediastinum is innervated by the cardiac plexus?

The middle region is innervated by the cardiac plexus and the phrenic nerves.

Which layer of the stomach is responsible for churning?

The muscularis of the stomach contains three layers and is responsible for churning.

Which part of the bladder is at the base of the trigone?

The neck of the bladder leads to the urethra at the trigone.

The oblique sinus of the pericardium is superior to what landmark?

The oblique sinus of the pericardium is superior to the inferior vena cava.

Which paired visceral branching of the abdominal aorta forms an anastomosis with the uterine artery?

The ovarian arteries arise from this structure and form an anastomosis with the uterine artery to supply the fallopian tubes.

Which portion of the pericardium forms a space with the parietal layer to house pericardial fluid?

The parietal layer (fibrous layer) and the serous layer (visceral layer) form the pericardial cavity, a space containing pericardial fluid.

What is facilitated by the cavity formed between layers of the pericardium?

The pericardial cavity is filled with liquid, providing a frictionless space for gliding movement.

Which of the following is one of the functions of the pericardium?

The pericardium acts as a separating barrier for the heart and encircling mediastinal tissue.

What is facilitated by the pericardium?

The pericardium facilitates ventricular interdependence through its structure. The pericardium prevents ventricular dilation.

What orientation does the pylorus of the stomach display in relation to the superior mesenteric artery?

The pylorus of the stomach is anterior to the superior mesenteric artery.

What is enclosed by the rectus sheath?

The rectus sheath encloses the pyramidalis and the rectus abdominis.

What supplies the upper portion of the ureters?

The renal arteries supply the upper portion of the ureters.

Two atria are superior to two ventricles. Which of these characteristically contains the crista terminalis?

The right atrium characteristically contains the crista terminalis.

What is adjacent to the right kidney?

The right kidney is adjacent to the second part of the duodenum.

Extensions of the trachea serve as branches of the bronchial tree, distributing air throughout the lungs. Subdivision of the primary two bronchi yields another secondary segment per lobe. How many secondary segments does the right lung contain?

The right lung has 3 lobes and contains 3 secondary segmental bronchi. The left lung has 2 lobes and contains 2 secondary segmental bronchi.

Vascular and bronchial structures compose the attachment between the lungs and the mediastinum. These structures are located on which surface of the lung?

The root of the lung lies at the center of the medial surface of the lung.

What supplies blood to the proximal segment of the duodenum?

The superior pancreaticoduodenal artery supplies the proximal segment of the duodenum.

The thoracic musculature works in unison to support respiration. The superior portion of which part of this group inserts on ribs 2 through 5?

The serratus posterior superior inserts on ribs 2 through 5.

Which segment of the large intestine precedes the rectum?

The sigmoid colon precedes the rectum.

The spleen is located between the fundus of the stomach and what other structure?

The spleen is located between the diaphragm and the fundus of the stomach.

Which component of the spleen surrounds the central arteriole?

The splenic artery enters the spleen through the hilum. The artery branches and eventually produces a central arteriole surrounded by white pulp.

Five vertebrae compose a region of the vertebral column. What aspect of these structures is directed backward and is oval-shaped?

The structure is a lumbar vertebra. The pedicle of lumbar vertebrae is oval-shaped and is directed backward.

A nerve inferior to the aortic arch controls the intrinsic muscles of the larynx, excluding the cricothyroid muscle. This structure is located in which region of the mediastinum?

The structure is the left recurrent laryngeal nerve, which is located within the superior mediastinum.

A structure prevents stomach contents from entering the esophagus body. What is directly inferior to this structure?

The structure is the lower esophageal sphincter (LES). The LES sits at the junction between the esophagus and the stomach, just inferior to the diaphragm in the peritoneal space of the abdomen. The cardia of the stomach is the portion that interfaces with the LES, which by definition would mean that it must sit directly inferior to the LES.

A major vessel of the heart originates from the right ventricle and branches into the right and left pulmonary arteries. This structure is located in which region of the mediastinum?

The structure is the pulmonary trunk, located in the middle mediastinum.

An organ of the digestive system is 3-5 meters long. What provides blood to the longest portion of this structure?

The structure is the small intestine. The ileum is the longest portion of the small intestine. Vasa recta of the superior mesenteric artery provide blood to the ileum.

A soft bilobed gland is relatively large during early years and becomes comparatively smaller throughout adulthood. This structure is located in the superior portion of which region of the mediastinum?

The structure is the thymus, which is found in the superior portion of the anterior mediastinum.

Structures protecting the spinal cord form foramina between discrete bodies, arches, and pedicles. Which of these structures is characterized by having a large cone-shaped transverse process?

The structures are vertebrae. L5 is characterized by a large cone-shaped transverse process; L2, L3, and L4 are not characterized this way due to the sacrovertebral articulation.

Which layer of the stomach contains blood vessels, nerves, and lymphatic vessels?

The submucosa of the stomach contains blood vessels, nerves, and lymphatic vessels.

Which segment of the duodenum extends transversely from right to left?

The third segment of the duodenum extends transversely from right to left.

What orientation does the uterus display in relation to the bladder?

The uterus is posterior to the bladder.

What percentage of blood supply does the hepatic portal system provide to the liver?

The veins convening at the portal vein provide approximately 75% of the blood supply of the liver. The other 25% is provided by the hepatic artery.

The vertebral canal is smallest in which region of the vertebral column?

The vertebral canal is smallest in the thoracic region as it changes shape with the vertebral column.

What grouping of vertebrae displays a heart-shaped body?

Thoracic vertebrae are characterized by a heart-shaped body.

Structures in the vertebral column increase in size as the column descends. Which part of these structures forms the walls of the spinal canal?

Vertebrae increase in size as the column descends. The vertebral arch forms the walls of the foramen (spinal canal).

Venous drainage of the gastrointestinal organs convenes at the portal vein. Within the portal sheath, the vein is located posterior to what structure?

When the portal vein enters the triad, it travels posteriorly to the hepatic artery; it enters the liver inside the hepatoduodenal ligament.