1.Human anatomyMedium
Which cranial nerve controls most of the muscles of facial expression?
- AOculomotor nerve (III)
- BHypoglossal nerve (XII)
- CTrigeminal nerve (V)
- DFacial nerve (VII)
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
Why is the proximal pole of the scaphoid at risk of avascular necrosis after a waist fracture?
- AIts only artery runs through the lunate
- BIt has no blood supply at all
- CIts blood supply enters mainly from the distal end
- DIt is drained by a single vein that clots easily
3.Human physiologyMedium
Why do myelinated axons conduct action potentials faster than unmyelinated ones?
- AMyelin makes the axon thinner
- BThe impulse jumps between nodes of Ranvier
- CMyelin releases neurotransmitter along the axon
- DMyelin contains more sodium channels
4.Human physiologyHard
In Graves' disease, what thyroid function results are expected and why?
- AHigh T4 and low TSH, because antibodies stimulate the TSH receptor
- BLow T4 and high TSH, because antibodies destroy the gland
- CHigh T4 and high TSH, because the anterior pituitary gland is overactive
- DLow T4 and low TSH, because the hypothalamus fails
2Solutions
1.Human anatomy
Answer: D · Facial nerve (VII)
Why this is the answer
The facial nerve (cranial nerve VII) supplies the muscles of facial expression. Damage causes facial palsy, as in Bell's palsy.
Answer
D · Facial nerve (VII)
2.Human anatomy
Answer: C · Its blood supply enters mainly from the distal end
Why this is the answer
Branches of the radial artery enter the scaphoid mainly distally and flow backwards. A fracture through the waist can cut off the proximal pole, causing avascular necrosis.
Answer
C · Its blood supply enters mainly from the distal end
3.Human physiology
Answer: B · The impulse jumps between nodes of Ranvier
Why this is the answer
Myelin insulates the axon, so action potentials are only generated at the nodes of Ranvier. This saltatory conduction is much faster.
Answer
B · The impulse jumps between nodes of Ranvier
4.Human physiology
Answer: A · High T4 and low TSH, because antibodies stimulate the TSH receptor
Why this is the answer
TSH-receptor antibodies stimulate the thyroid independently of TSH. The resulting high T4 and T3 suppress pituitary TSH by negative feedback.
Answer
A · High T4 and low TSH, because antibodies stimulate the TSH receptor
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