QUESTION: 81

A female patient is diagnosed by sonogram with uterus didelphys (double uterus). The imaging study reveals a bicornuate uterus with a single vagina. During development, the uterus develops from which of the following?

mesonephric ducts
nephrogenic ridge
paramesonephric ducts
urogenital sinus
yolk sac

Answer(s): C

Explanation:

During development, the uterus develops from fusion of the caudal ends of the para-mesonephric ducts.
Failure of fusion results in uterus didelphys. The mesonephric ducts (choice A) give rise to the epididymis, vas deferens, and ejaculatory duct in the male. The nephrogenic ridge (choice B) is the derivative of the urogenital ridge which will give rise to the urinary system. The urogenital sinus (choice D) gives rise to the urinary bladder, urethra, vagina, and associated glands in the female. The yolk sac (choice E) plays a role in transfer of nutrients before uteroplacental circulation is established, in blood development before the liver begins its hemopoietic activity, and is the site of formation of primordial germ cells.

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QUESTION: 82

Anewborn infant suffers from a posterolateral defect on the left side of the body. His abdominal contents have herniated through the defect into the thoracic cavity, and as a result, the infant suffers from pulmonary hypoplasia. His breathing difficulty is life threatening because the herniation has inhibited lung development and inflation. This congenital defect is due to a malformation of which of the following?

mesentery of the esophagus
muscular ingrowth of the body wall
pleuropericardial membrane
pleuroperitoneal membrane
septum transversum

Answer(s): D

Explanation:

congenital defect of the pleuroperitoneal membrane results in an abnormal opening in the posterolateral aspects of the diaphragm. This defect occurs more often on the left side of the body. It is due to the failure of the pleuroperitoneal membrane to form properly and/or to fuse with the other parts of the diaphragm: the mesentery of the esophagus (choice A), the muscular ingrowth of the body wall (choice B), and the septum transversum (choice E). The pleuropericardial membranes (choice C) participate in the formation of the mediastinum and do not contribute to the formation of the diaphragm.

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QUESTION: 83

A 17-year-old male college student is brought to the emergency room, displaying vomiting, fever, and diarrhea. The patient reports that for a period of 24 hours prior to admission, he suffered from abdominal pain first centered around the navel and then moving inferiorly to the right. As the patient talks, you realize that he is gesturing toward McBurney's point. You tentatively diagnose acute appendicits and request emergency surgery. Accurate visual identification of the appendix during surgery can be verified by using which of the following landmarks?

bifurcation of the abdominal aorta
epiploic appendages
haustra
inferior border of the right kidney
taeniae coli

Answer(s): E

Explanation:

The position of the appendix varies depending on the patient. The taeniae coli are three longitudinal bands of smooth muscle running the length of the colon. Since the appendix is part of the colon, the taeniae coli can be accurately followed to this structure. The bifurcation of the abdominal aorta (choiceA) and inferior border of the right kidney (choice D) are retroperitoneal and would not be of value in identification of the appendix. The epiploic appendages (choice B) are small pockets of fatty tissue along the length of the colon, but they are not found on the appendix. The haustra (choice C) are sacculations of the large intestine resulting from contractions of the taeniae coli.

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QUESTION: 84

The efferent limb of the pupillary light reflex is interrupted along with corticospinal and orticobulbar fibers in which of the following clinical entities?

Broca's aphasia
inferior alternating hemiplegia
middle alternating hemiplegia
superior alternating hemiplegia
Wallenberg syndrome

Answer(s): D

Explanation:

Compression of cranial nerve III, in combination with descending corticospinal and corticobulbar fibers, occurs as part of superior alternating hemiplegia. Patients with Broca's aphasia (choice A) typically do not exhibit involvement of the pupillary light reflexes. Inferior alternating hemiplegia (choice B) and middle alternating hemiplegia (choice C) involve cranial nerves XII and VI, respectively, in combination with corticospinal fibers. Wallenberg syndrome (lateral medullary syndrome) (choice E) typically does not include damage to the corticospinal tract.

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QUESTION: 81

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QUESTION: 84

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