The Dura mater extends from the level of the foramen magnum to the level of:

Correct Answer: C

Rationale: S2 . The dura mater is the tough, outermost layer of the meningthat surrounds the brain and spinal cord. In the spinal column, it forms a sac called the dural sac, which extends from the foramen magnum (at the base of the skull) down to approximately the second sacral vertebra (S2) in adults, where it tapers off. Choice A, L2, is incorrect because the dura mater extends beyond the second lumbar vertebra, typically ending lower at S2. Choice B, S1, is closer but still incorrect as the dura mater consistently reachS2. Choice D, S3, is wrong because the dura mater donot extend this far inferiorly; it ends at S2, after which the filum terminale continues. Therefore, S2 accurately reflects the anatomical termination of the dura mater, making C the correct answer.

Correct Answer: D

Rationale: Ventral and dorsal roots come together in the intervertebral foramina to form the spinal nervwhich then subsequently branch into ventral and dorsal rami . This accurately describspinal nerve formation: ventral (motor) and dorsal (sensory) roots unite in the intervertebral foramina to form spinal nerves, which then split into rami. Choice A is incorrect (CSF is in the subarachnoid space, not subdural). Choice B is wrong (correct order is dura, arachnoid, pia). Choice C is false (cauda equina includboth ventral and dorsal roots). Thus, D is the only true statement, making it the correct answer.

Correct Answer: C

Rationale: It is the most common disk . Herniation at the L4 root (typically L3-L4 disc) affects the L4 nerve, impacting knee jerk (via quadriceps, A), sensation in the anteromedial leg , and knee extension , all correct. However, the most common disc herniation is at L5-S1, not L3-L4 or L4-L5, due to greater mechanical stress lower in the spine. Thus, C inaccurately claims L4 is the most common site, making it the wrong statement and the correct answer.

Correct Answer: B

Rationale: L4-L5 . The symptoms gluteal pain, sensory loss in the anterolateral leg, and inability to stand on heels (weak tibialis anterior) indicate L5 nerve root compression, most commonly from an L4-L5 disc herniation. Choice A (L3-L4) affects L4, causing medial leg sensory loss and knee weakness. Choice C (L5-S1) affects S1, causing posterior leg/calf issuand tiptoe weakness. Choice D (S1-S2) affects S2, unrelated to these symptoms. Thus, L4-L5 matchthe L5 root symptoms, making B correct.

Correct Answer: C

Rationale: Nucleus proprius . Laminae III and IV of the spinal cord gray matter contain the nucleus proprius, which processsensory input like fine touch and pressure, relaying it to ascending pathways. Choice A (intermedio-medial nucleus) is in lamina VII, for visceral functions. Choice B (intermedio-lateral nucleus) is in lamina VII (T1-L2), for sympathetic neurons. Choice D (substantia gelatinosa) is in lamina II, for pain and temperature. Thus, C correctly identifithe nucleus proprius in laminae III-IV, making it the right answer.