MCAT Anatomy 4 — Questions and Answers
Question 1: Which structure forms the posterior boundary of the epiploic foramen (foramen of Winslow)?
- Hepatoduodenal ligament
- Inferior vena cava (Correct answer)
- Portal vein
- Common bile duct
Correct answer: Inferior vena cava
The inferior vena cava forms the posterior boundary of the epiploic foramen, allowing access to the lesser sac.
Question 2: Wrist drop results from injury to which nerve?
- Median nerve
- Ulnar nerve
- Radial nerve (Correct answer)
- Musculocutaneous nerve
Correct answer: Radial nerve
Radial nerve injury causes wrist drop due to loss of innervation to the wrist and finger extensors.
Question 3: The moderator band (septomarginal trabecula) is found in which cardiac chamber and carries which structure?
- Left ventricle; left bundle branch
- Right ventricle; right bundle branch (Correct answer)
- Right atrium; SA node fibers
- Left atrium; pulmonary vein orifices
Correct answer: Right ventricle; right bundle branch
The moderator band crosses the right ventricle and carries the right bundle branch of the cardiac conduction system.
Question 4: The thoracic duct begins at the cisterna chyli and drains into which venous junction?
- Right subclavian and right internal jugular junction
- Left subclavian and left internal jugular junction (Correct answer)
- Superior vena cava directly
- Azygos vein
Correct answer: Left subclavian and left internal jugular junction
The thoracic duct empties into the left venous angle (junction of left subclavian and left internal jugular veins).
Question 5: The dentate (pectinate) line in the anal canal marks a transition between which two types of epithelium?
- Simple columnar to stratified squamous (Correct answer)
- Stratified squamous to transitional
- Pseudostratified columnar to simple columnar
- Simple squamous to stratified squamous
Correct answer: Simple columnar to stratified squamous
Above the dentate line the mucosa is simple columnar epithelium; below it transitions to non-keratinized stratified squamous epithelium.
Question 6: Which muscle is the primary medial rotator and adductor of the arm?
- Infraspinatus
- Teres minor
- Subscapularis (Correct answer)
- Supraspinatus
Correct answer: Subscapularis
The subscapularis is the largest rotator cuff muscle and the primary medial rotator of the humerus; it also adducts the arm.
Question 7: The appendix most commonly arises from the cecum at which taenia coli convergence point?
- Taenia libera
- Convergence of all three taeniae coli (Correct answer)
- Taenia mesocolica
- Taenia omentalis
Correct answer: Convergence of all three taeniae coli
The three taeniae coli converge at the base of the appendix, making this anatomical landmark useful for locating the appendix surgically.
MCAT Anatomy 4
Which structure forms the posterior boundary of the epiploic foramen (foramen of Winslow)?