Neural control of micturition

Nerve control of the bladder

  1. Sympathetic: hypogastric nerve (T10-L2), involuntary control of bladder neck and intrinsic sphincter
  2. Parasympathetic: pelvic nerve (S2-S4), involuntary contraction of detrusor
  3. Somatic: pudendal nerve (S2-S4), voluntary contraction/relaxation of external sphincter

Spinal Cord Syndromes

There are 4 main spinal cord syndromes, plus 2 sort-of-spinal-cord syndromes. Some are not common, but a favourite of examiners because they’re just so darn cool in that they really demonstrate where things cross (like in Brown-Sequard syndrome). Cauda equina syndrome is also an important one to know because if you see it acutely, the damage can actually be temporary (otherwise the person is stuck with permanent bowel and bladder dysfunction, which is really no fun).

Neural tube folding and migration

This cross-section shows the migration of cells to form the dorsal root ganglia, melanocytes, sympathetic ganglia and adrenal medulla.

Periaquaductal grey pain modulation pathway

The periaquaductal grey pathway is the descending pathway that helps modulate pain. There are so many double/triple/quadruple negatives in this pathway it makes the head spin. Who knew that the activation of the inhibitory interneuron would inhibit the other inhibitory interneuron, releasing inhibition of another neuron only to inhibit pain?

Muscles groups for the ASIA exam

ASIA stands for the American Spinal Injury Association. As part of their oh-so-standardized grading for spinal injuries, they devised the muscle groups you need to test corresponding to each nerve root.

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