Anatomy Bones and Muscles · MU Pleven

151. Circulation of the cerebro-spinal fluid. Cerebral cisternae.

Covers the 31 pairs of spinal nerves, spinal ganglia and how anterior and posterior roots form a spinal nerve, then the five components of the reflex arc with monosynaptic and polysynaptic examples. Moves on to the motor system, tracing corticospinal and corticobulbar pathways, the facial and hypoglossal exceptions to bilateral control, and the medial and lateral extrapyramidal tracts, ending with an upper-to-lower motor neuron summary.

Inside: 13 sections · 10 labelled pictures · 10 flashcards · 12 min

Topic 150 of 236 in the MU Pleven syllabus for Anatomy Bones and Muscles (Medicine, Year 2). The free AceMed note covers it in 13 sections, about 1,770 words (12 min of reading), with 10 flashcards.

In this note

  1. SPINAL NERVES
  2. Spinal Ganglia :
  3. Formation of spinal Nerves:
  4. Reflex Arch :
  5. MOTOR SYSTEM
  6. Pyramidal System :
  7. Extrapyramidal tract :
  8. Corticonuclear (Corticobulber) system :
  9. Corticospinal :
  10. Oculomotor :
  11. Medial pathway : (Extrapyramidal). → Both ipsilateral & contralateral
  12. Lateral pathway :
  13. Summary:

SPINAL NERVES

  • Spinal nerves emerge intermittently from the spinal cord, exiting the vertebral canal.
  • There are a total of 31 pairs of spinal nerves.
  • These pairs are categorized based on their locations:
  • Cervical nerves (C1–C8): These exit the neck region.
  • Thoracic nerves (T1–T12): They exit the torso region.
  • Lumbar nerves (L1–L5): These exit the lower back.
  • Sacral nerves (S1–S5): They exit from the base of the spine.
  • Coccygeal nerve pair: This exits from the tailbone (coccyx).

Spinal Ganglia :

  • Structure: Ganglia are oval in shape and contain neuronal cell bodies (somata), satellite cells (a type of glial cell), and a protective connective tissue layer.
  • Neuron Types:
  • Sensory ganglia usually contain unipolar or pseudo-unipolar neurons.
  • Autonomic ganglia contain multipolar neurons.

– Can be broadly categorized into 2 groups :

  1. 1. Sensory Ganglia:
  • Dorsal Root Ganglia: These are associated with spinal nerves. Each dorsal root ganglion is located at the proximal end of each posterior root. They contain the cell bodies of sensory nerve fibers 1 .
  • Sensory Ganglia of Cranial Nerves: These are found in selected cranial nerves.
  1. 2. Autonomic ganglia :
  • Sympathetic
  • Parasympathetic

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