1.Human anatomyMedium
Which spinal nerve roots form the brachial plexus?
- AC5 to T1
- BC3 to C7
- CT1 to T5
- DC1 to C4
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 stab wound cuts the left half of the spinal cord at T10. Which pattern of loss is expected below the lesion?
- ALeft-sided weakness and loss of proprioception, right-sided loss of pain and temperature
- BLoss of pain and temperature on both sides only
- CLoss of all sensation and movement on the left only
- DRight-sided weakness and loss of proprioception, left-sided loss of pain and temperature
3.Human physiologyMedium
Where does the final activation step of vitamin D (1-alpha hydroxylation) take place?
- ASmall intestine
- BSkin
- CLiver
- DKidney
4.Human physiologyHard
A pulmonary embolus blocks blood flow to a well-ventilated region of lung. How does the ventilation–perfusion (V/Q) ratio of that region change?
- AIt becomes low, like in pneumonia
- BIt becomes very high, acting as dead space
- CIt becomes zero, acting as a shunt
- DIt stays normal because ventilation falls too
2Solutions
1.Human anatomy
Answer: A · 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
A · C5 to T1
2.Human anatomy
Answer: A · Left-sided weakness and loss of proprioception, right-sided loss of pain and temperature
Why this is the answer
In Brown-Séquard syndrome the corticospinal tract and dorsal columns are lost on the same side, while the spinothalamic tract, which crosses near entry, causes contralateral pain and temperature loss.
Answer
A · Left-sided weakness and loss of proprioception, right-sided loss of pain and temperature
3.Human physiology
Answer: D · Kidney
Why this is the answer
Vitamin D is made in the skin or eaten, hydroxylated in the liver, and then activated to calcitriol in the kidney. Kidney failure therefore causes vitamin D deficiency.
Answer
D · Kidney
4.Human physiology
Answer: B · It becomes very high, acting as dead space
Why this is the answer
Ventilation without perfusion gives a very high V/Q ratio (dead space). A shunt, such as in pneumonia, is the opposite: perfusion without ventilation.
Answer
B · It becomes very high, acting as dead space
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