Human Anatomy

1
Human Anatomy

• Central Nervous System
• CNS
• Part II

2
CNS

• Consists of 2 anatomical components

Brain Spinal cord
3
The Spinal Cord

• Only about 18 inches long in adult
• Ends at L1 or L2
• As infant, spinal cord is as long as spinal
  column
• About 4 yo, spinal column grows faster than
  spinal cord
• Result spinal column longer than cord

4
Spinal Cord
5
Spinal Cord

• Has 2 enlargements
• Cervical enlargement
• Neurons innervate skeletal muscles of upper
  extremities
• Lumbar enlargement
• Neurons innervate skeletal muscles of lower
  extremities

6
Spinal Cord

• Ends at L1 L2 in a cone shaped structure called
  the conus medullaris
• Spinal nerves below L1 L2 must
• continue descending within
• the column until they exit at the correct
  level. The aggregation of these spinal nerve is
  called the cauda equina

7
Spinal Cord
8
Spinal Cord Meninges
9
Internal Anatomy of Spinal Cord

• Partitioned into centrally located gray matter
  and outer region of white matter

10
Spinal Cord

• What is the composition of gray matter?
• Gray matter is the non-myelinated parts of the
  neurons.dendrites and cell bodies or
  non-myelinated axons
• What is the composition of white matter?
• White matter is the myelinated part of the
  neurons.axons of oligodendrocytes
• White matter is organized into tracts

11
Spinal Tracts
12
Spinal Cord Tracts

• There are two types of tracts
• Ascending (sensory) tracts coming from body,
  ascending the spinal cord and reaching the brain
  for processing of electrical information
• Descending (motor) tracts originating in brain,
  descending the spinal cord and reaching a target
  organ to cause some effect of receivng electrical
  information

13
Spinal Tracts