1.Human anatomyMedium
Which spinal nerve roots form the brachial plexus?
- AC3 to C7
- BC1 to C4
- CC5 to T1
- DT1 to T5
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
After a fracture of the midshaft of the humerus, a patient cannot extend the wrist and fingers ("wrist drop"). Which nerve is most likely injured?
- ARadial nerve
- BAxillary nerve
- CUlnar nerve
- DMedian nerve
3.Human physiologyMedium
Besides lowering glucose, insulin moves which ion into cells, an effect used to treat hyperkalaemia?
- APotassium
- BChloride
- CSodium
- DCalcium
4.Human physiologyHard
A patient has taken high-dose prednisolone for a year. What is the state of the hypothalamic–pituitary–adrenal axis?
- AACTH is normal and cortisol production is increased
- BThe adrenal medulla has stopped making adrenaline and noradrenaline
- CACTH is high and the adrenal cortex is enlarged
- DACTH is suppressed and the adrenal cortex has atrophied
2Solutions
1.Human anatomy
Answer: C · C5 to T1
Why this is the answer
The brachial plexus is formed by the ventral rami of C5, C6, C7, C8 and T1. It gives rise to the main nerves of the arm.
Answer
C · C5 to T1
2.Human anatomy
Answer: A · Radial nerve
Why this is the answer
The radial nerve runs in the radial (spiral) groove of the humeral shaft. It supplies the wrist and finger extensors, so injury causes wrist drop.
Answer
A · Radial nerve
3.Human physiology
Answer: A · Potassium
Why this is the answer
Insulin stimulates the Na⁺/K⁺-ATPase and shifts potassium into cells. Insulin with glucose is therefore used to lower dangerously high plasma potassium.
Answer
A · Potassium
4.Human physiology
Answer: D · ACTH is suppressed and the adrenal cortex has atrophied
Why this is the answer
Exogenous glucocorticoid suppresses CRH and ACTH, so the adrenal cortex atrophies. Stopping the drug suddenly can cause an adrenal crisis, so it is tapered.
Answer
D · ACTH is suppressed and the adrenal cortex has atrophied
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