1.Human anatomyMedium
Which cranial nerve supplies the lateral rectus muscle of the eye?
- ATrochlear nerve (IV)
- BOptic nerve (II)
- CAbducens nerve (VI)
- DOculomotor nerve (III)
Anatomy and Physiology: cram pack
Formula sheets, the key method steps for every topic and 4 practice problems, with full solutions at the back.
1Practice problems
2.Human anatomyHard
A large central disc prolapse at L4–L5 causes saddle anaesthesia, urinary retention and bilateral leg weakness. Which structure is compressed?
- AThoracic spinal cord
- BFemoral nerve
- CSciatic nerve in the buttock
- DCauda equina
3.Human physiologyMedium
What is the main effect of vagus nerve stimulation on the heart?
- AIt increases ventricular contractility strongly
- BIt slows the heart rate
- CIt increases the heart rate
- DIt constricts the coronary arteries
4.Human physiologyHard
Which substance's clearance is used as the gold standard to measure glomerular filtration rate?
- AGlucose
- BInulin
- CCreatinine
- DUrea
2Solutions
1.Human anatomy
Answer: C · Abducens nerve (VI)
Why this is the answer
The abducens nerve (VI) supplies lateral rectus. A lesion stops the eye moving outwards and causes horizontal double vision.
Answer
C · Abducens nerve (VI)
2.Human anatomy
Answer: D · Cauda equina
Why this is the answer
Below L1–L2 the canal holds the cauda equina. Central compression of these lumbar and sacral roots causes cauda equina syndrome, a surgical emergency.
Answer
D · Cauda equina
3.Human physiology
Answer: B · It slows the heart rate
Why this is the answer
The vagus releases acetylcholine on muscarinic receptors in the SA and AV nodes, slowing pacemaker firing and AV conduction.
Answer
B · It slows the heart rate
4.Human physiology
Answer: B · Inulin
Why this is the answer
Inulin is filtered freely and is not reabsorbed or secreted, so its clearance equals GFR exactly. Creatinine is slightly secreted, so it overestimates GFR a little.
Answer
B · Inulin
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