OT Anatomy & Physiology 4 — Questions and Answers
Question 1: Which neurotransmitter is primarily released at the neuromuscular junction to initiate muscle contraction?
- Dopamine
- Norepinephrine
- Acetylcholine (Correct answer)
- Serotonin
Correct answer: Acetylcholine
Acetylcholine is released from motor neuron terminals and binds to nicotinic receptors on the motor end plate, triggering muscle fiber depolarization.
Question 2: In the context of hand therapy, the A1 pulley is located at the level of which structure?
- Proximal phalanx
- Middle phalanx
- Metacarpophalangeal joint (Correct answer)
- Distal interphalangeal joint
Correct answer: Metacarpophalangeal joint
The A1 pulley overlies the metacarpophalangeal joint and is the site most commonly involved in trigger finger (stenosing tenosynovitis).
Question 3: Which phase of the cardiac cycle represents ventricular filling?
- Isovolumetric contraction
- Ventricular systole
- Diastole (Correct answer)
- Isovolumetric relaxation
Correct answer: Diastole
During diastole, the ventricles relax and fill with blood from the atria through the open atrioventricular valves.
Question 4: The zona pellucida is associated with which anatomical structure?
- Kidney nephron
- Ovarian follicle/oocyte (Correct answer)
- Adrenal cortex
- Liver lobule
Correct answer: Ovarian follicle/oocyte
The zona pellucida is a glycoprotein layer surrounding the oocyte and early embryo, playing a critical role in fertilization and implantation.
Question 5: A client has difficulty extending the wrist and fingers following a humeral shaft fracture. Which nerve is most likely injured?
- Median nerve
- Ulnar nerve
- Musculocutaneous nerve
- Radial nerve (Correct answer)
Correct answer: Radial nerve
The radial nerve winds in the spiral groove of the humerus and is vulnerable to injury with humeral shaft fractures, causing wrist drop and loss of finger extension.
Question 6: Which type of muscle fiber predominates in postural muscles like the soleus?
- Type IIb (fast-twitch glycolytic)
- Type IIa (fast-twitch oxidative)
- Type I (slow-twitch oxidative) (Correct answer)
- Type IIx (intermediate)
Correct answer: Type I (slow-twitch oxidative)
Type I slow-twitch fibers predominate in postural muscles like the soleus because they are fatigue-resistant and rely on oxidative metabolism for sustained contractions.
Question 7: Which cranial nerve provides motor innervation to the muscles of facial expression?
- Cranial nerve V (trigeminal)
- Cranial nerve VII (facial) (Correct answer)
- Cranial nerve IX (glossopharyngeal)
- Cranial nerve XII (hypoglossal)
Correct answer: Cranial nerve VII (facial)
The facial nerve (CN VII) provides motor innervation to all muscles of facial expression; damage causes ipsilateral facial paralysis (Bell's palsy).
OT Anatomy & Physiology 4
Which neurotransmitter is primarily released at the neuromuscular junction to initiate muscle contraction?