Lecture XV

• Pia Mater. Hugs surface of spinal cord and brain
• Pia Mater. Areolar like connective tissue
• Pia Mater. Held in place by astrocytes
• Pia Mater. Denticulate ligaments stabilize left and right movements
• Dorsal Root Ganglion. Contains sensory neuron cell bodies
• Dorsal Root Ganglion. Keeps insufficient (weak) sensory signals from reaching spinal cord
• Dorsal Root Ganglion. Laterally, neurons merge with the ventral root motor fibers
• D. Spinal Nerves

  • always mixed: sensory and motor
  • come out from intervertebral foramina
• D. Spinal Nerves. 1. Function and Structure. a. Mixed Nerves

  • ventral ramus: thicker, more neurons go through
  • dorsal ramus: thinner, fewer neurons go through
• D. Spinal Nerves. 1. Function and Structure. a. Connective Tissue

  • adipose surrounds most nerves protect, cushion, insulate
• D. Spinal Nerves. 1. Function and Structure. a. Connective Tissue

  • epineurium: dense irregular connective tissue
• D. Spinal Nerves. 1. Function and Structure. a. Connective Tissue

  • epineurium: dense irregular connective tissue
• D. Spinal Nerves. 1. Function and Structure. a. Connective Tissue

  • Epineurium. Continuous with dura mater
  • Epineurium. Same functions as dura mater, but different location (CNS or PNS)
• D. Spinal Nerves. 1. Function and Structure. a. Connective Tissue

  • perineurium: organizes neurons, ensures things go to right place
• D. Spinal Nerves. 1. Function and Structure. a. Connective Tissue

  • Perineurium. Dense irregular connective tissue
  • Perineurium. Creates fascicles
• D. Spinal Nerves. 1. Function and Structure. a. Connective Tissue

  • endoneurium: covers schwann cell and axon
• D. Spinal Nerves. 1. Function and Structure. a. Connective Tissue

  • Endoneurium. Areolar connective
• Added Notes:

  • Ventral ramus lead to more connections to limbs
• Added Notes:

  • Label RED: nerve
  • Label ORANGE: epineurium
  • Label YELLOW: perineurium
  • Label GREEN: endoneurium
  • Label LIGHT BLUE: unmyelinated axon
  • Label DARK BLUE: myelinated axon
  • Label PINK: fascicle

  
• Added Notes:

  • Endoneurium: covers neuron and glial cell (schwann cell)
• D. Spinal Nerves. 2. Dermatomes

  • areas of spinal nerves monitor (sensation) a specific region of the body
• D. Spinal Nerves. 2. Dermatomes

  • useful to assess spinal cord injuries
• II. Reflexes

  • cranial reflex: integrated in brain (acquired, cranial nerves, complex)
  • spinal reflex: integrated in spinal cord (innate, simple)
  • one of which, the spinal reflex, is rapid and poorly adaptive
• II. Reflexes. A. Synapse Number. 1. Monosynaptic: one CNS synapse

  • often spinal cord
  • simple response
  • fast time
• II. Reflexes. A. Synapse Number. 2. Polysynaptic: many synapse

  • uses interneurons
  • brain and spinal cord
  • complex response
  • adaptable
  • slow time
• II. Reflexes. B. Acquired vs Innate

  • innate: born with a reflex that is often vital
  • acquired: learned over time with memory repetition
• II. Reflexes. C. Somatic vs Visceral

  • somatic: control skeletal muscle
  • visceral: smooth muscle, cardiac muscle, gland, adipose