MOH Anatomy & Physiology 1 — Questions and Answers
Question 1: Which nerve is responsible for the motor innervation of the diaphragm?
- Vagus nerve (CN X)
- Phrenic nerve (C3, C4, C5) (Correct answer)
- Intercostal nerves
- Accessory nerve (CN XI)
Correct answer: Phrenic nerve (C3, C4, C5)
The phrenic nerve, arising from cervical roots C3, C4, and C5, provides the primary motor innervation to the diaphragm, the principal muscle of inspiration.
Question 2: The left recurrent laryngeal nerve loops around which structure?
- Aortic arch (Correct answer)
- Right subclavian artery
- Trachea
- Carotid artery
Correct answer: Aortic arch
The left recurrent laryngeal nerve loops under the aortic arch before ascending to the larynx; this long course explains why left-sided lesions (e.g., aortic aneurysm, lung tumors) commonly cause hoarseness.
Question 3: Which valve separates the left atrium from the left ventricle?
- Tricuspid valve
- Pulmonary valve
- Mitral (bicuspid) valve (Correct answer)
- Aortic valve
Correct answer: Mitral (bicuspid) valve
The mitral (bicuspid) valve, consisting of two leaflets, separates the left atrium from the left ventricle and prevents backflow during ventricular systole.
Question 4: The blood supply to the SA node is most commonly from which artery?
- Left anterior descending artery
- Circumflex artery
- Right coronary artery (Correct answer)
- Left main coronary artery
Correct answer: Right coronary artery
The SA node receives its blood supply from the SA nodal artery, which arises from the right coronary artery in approximately 60% of individuals.
Question 5: Which portion of the nephron is primarily responsible for glucose reabsorption?
- Collecting duct
- Loop of Henle
- Proximal convoluted tubule (Correct answer)
- Distal convoluted tubule
Correct answer: Proximal convoluted tubule
Virtually all filtered glucose is reabsorbed in the proximal convoluted tubule via sodium-glucose cotransporters (SGLT2), up to the renal threshold of approximately 180 mg/dL.
Question 6: The normal adult resting heart rate range is:
- 40–60 bpm
- 60–100 bpm (Correct answer)
- 100–120 bpm
- 50–80 bpm
Correct answer: 60–100 bpm
A normal resting heart rate in adults is defined as 60–100 beats per minute; rates below 60 are bradycardia and above 100 are tachycardia.
MOH Anatomy & Physiology 1
Which nerve is responsible for the motor innervation of the diaphragm?