Anatomy and Physiology Lecture Notes

Introduction

• Lecture by Professor Long
• Videos due to coronavirus shutdown
• Informal style, no editing
• Lecture for A&P 2401 students, Lecture Test 6

Previous Lecture Recap

• Covered ventricles, meninges, and cerebrospinal fluid (CSF)
• Issue of hydrocephalus (blocked interventricular foramen)
  • Leads to enlarged ventricles and swollen skulls in infants
  • Requires shunts to drain fluid

Spinal Tap Procedure

• Used to sample cerebrospinal fluid
• Needle inserted between vertebrae into subarachnoid space
• Must be performed by skilled anesthesiologists

Anatomy of the Spinal Cord

Structure

• Starts as a mass, folds into anterior and posterior median sulcus
• Central canal through which CSF flows
• Grey matter (inside, forms horns) and white matter (outside)

Grey Matter

• Grey matter forms horns: anterior, posterior, and lateral
• Central canal in the middle
• Grey Commissures: Unmyelinated axons crossing spinal cord

White Matter

• Anterior Median Fissure: Wide gap on anterior side
• White Columns: Myelinated axons; tracts for sensory and motor
• White Commissures: Myelinated axons crossing spinal cord

Functional Anatomy

Sensory and Motor Nuclei

• Posterior Grey Horn:
  • Somatic and visceral sensory nuclei
  • Sensory neurons synapse here
• Lateral Grey Horn:
  • Visceral motor nuclei
• Anterior Grey Horn:
  • Somatic motor nuclei

Spinal Nerves

• 31 pairs, mixed (sensory and motor)
• Dorsal Root: Sensory axons
• Dorsal Root Ganglion: Soma of sensory neurons
• Ventral Root: Motor axons leaving spinal cord

Spinal Cord Segmentation

• Segments aligned with vertebrae
• Cervical, thoracic, lumbar enlargements for innervation of limbs
• Conus Medullaris: End of spinal cord
• Cauda Equina: Nerve roots extending from conus medullaris

Pathways and Functions

• Sensory Pathways: Afferent neurons enter dorsal root, synapse in grey horns
• Motor Pathways: Efferent neurons exit through ventral root

Clinical Relevance

• Understanding of spinal anatomy aids in diagnosing nerve issues
• Knowledge assists in determining MRI or CT scan focus areas
• Differentiation between dorsal and ventral roots informs sensory/motor issues

Nerve Mapping

• Nerve exit order: Cervical nerves before vertebra; thoracic/lumbar nerves after
• Dermatomes: Skin areas innervated by specific spinal nerves
• Clinical tests for sensory and motor damage

Conclusion

• Importance of spinal anatomy knowledge in medicine
• Sets up for more detailed study of spinal tracts in future lectures