CompTIA
Checkpoint
ISC
HP
Dell
EC-Council
EXIN
Fortinet
ITIL®
Juniper
PMI
Microsoft
VMware
Avaya
Google
Salesforce
Amazon
Palo Alto Networks
Certiport
ISC2
All Vendors
  2. Home
  3. Exams
  4. USMLE
  5. STEP1

Free STEP1 Exam Braindumps (page: 14)

Page 13 of 213
PDF with 845 Questions

A patient has been admitted for hematemesis (vomiting of blood). Endoscopic examination reveals bleeding esophageal varices resulting from portal obstruction. These varices represent anastomoses between branches of which of the following?

  1. inferior vena cava with a patent ductus venosus
  2. left gastric, azygos, and hemiazygos veins
  3. right gastric vein and the inferior vena cava
  4. superior, middle, and inferior rectal veins
  5. veins running on the ligamentum teres and the epigastric veins

Answer(s): B

Explanation:

Obstruction of the portal vein results in an increase in the collateral circulation between veins that normally drain to the portal vein and those that drain to the systemic veins. Choices A, B, D, and E all represent possible collateral venous circulation in case of portal obstruction. Choice A is rare because the ductus venosus closes after birth. Choice B is correct because varicose veins in this region give rise to esophageal varices. Choice D results in varicose veins in the rectal region. Choice C is incorrect because there is no connection between the right gastric vein and the inferior vena cava. In choice E, enlargement of the epigastric veins results in varicose veins radiating from the umbilicus, the caput medusae.



A 15-year-old high school football player is brought to the emergency room. On examination, his right lower limb is deformed and swollen around the knee. At full extension, there is valgus instability, suggestive of knee dislocation. The patient is in great pain and there is a concern for concomitant vascular and nervous injuries. Palpation of the dorsalis pedis artery reveals a normal pulse. However, neurological examination reveals impaired dorsiflexion of the foot with decreased sensation in the space between digits 1 and 2.
Which of the following nerves is affected?

  1. deep peroneal (fibular) nerve
  2. femoral nerve
  3. saphenous nerve
  4. superficial peroneal (fibular) nerve
  5. tibial nerve

Answer(s): A

Explanation:

The deep peroneal (fibular) nerve innervates the muscles responsible for dorsiflexion in the anterior compartment of the leg. It also provides for the cutaneous innervation of the space between digits 1 and 2. The femoral nerve (choice B) innervates muscles in the anterior compartment of the thigh and the skin of the medial aspect of the leg by a continuing branch, the saphenous nerve (choice C). The superficial peroneal (fibular) nerve (choice D) innervates the lateral compartment of the leg and muscles responsible for foot eversion. The tibial nerve (choice E) innervates the posterior compartment of the leg and the muscles responsible for plantar flexion.



In the central auditory pathways, second-order neurons are located in which of the following?

  1. cochlear (spiral) ganglion
  2. cochlear nuclei
  3. inferior colliculi
  4. nuclei of lateral lemniscus
  5. superior olivary nuclei

Answer(s): B

Explanation:

Second-order neurons in the central auditory pathways are located in the dorsal and ventral cochlear nuclei. They receive afferents from the first-order neurons located in the cochlear (spiral) ganglion (choice A). Secondorder fibers from the cochlear nuclei project in turn to the inferior colliculi (choice C), nuclei of lateral lemniscus (choice D), and superior olivary nuclei (choice E).



Arrow 2 in following figure points to which of the following structures?

  1. glomerulus
  2. juxtaglomerular cells
  3. lacis cells
  4. macula densa
  5. vascular pole of the renal corpuscle

Answer(s): D

Explanation:

The macula densa indicated by arrow 2 is a modified segment of the distal tubule at the site of its passage adjacent to the vascular pole of the renal corpuscle. The name arises from the close spacing of nuclei of the epithelial cells forming this part of the distal tubule. These cells are thought tosense the chloride content in the passing filtrate and generate signals that regulate the caliber of the afferent arteriole. The glomerulus (choice A, arrow 1) is a network of capillaries derived from the afferent arteriole and suspended within Bowman's capsule by its vascular pole. The juxtaglomerular cells (choice B) form a cuff around the afferent arteriole prior to its entrance into the glomerulus and they secrete renin. Lacis cells (choice C, arrow 4) are extraglomerular mesangial cells with an uncertain function. The vascular pole (choice E, arrow
3) feeds blood to the glomerulus and carries blood away from it. As part of the juxtaglomerular apparatus, it is closely apposed to the macula densa.






Post your Comments and Discuss USMLE STEP1 exam with other Community members:

STEP1 Discussions & Posts