BPK 105 Study Guide - Midterm Guide: Dorsal Root Ganglion, Cauda Equina, Dorsal Root Of Spinal Nerve
27 Apr 2018
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Module 4 - Objectives - Part 4
● Describe a cross section of the spinal cord.
Refer to figure 8.16 in textbook.
- spinal cord extends from the foramen magnum at the base of the skull to the second
lumbar vertebra (figure 8.15).
- Spinal nerves communicate between the spinal cord and the body. The inferior end of
the spinal cord and the spinal nerves exiting there resemble a horse’s tail and are
collectively called the cauda equina.
- the spinal cord consists of a superficial white matter portion and a deep gray matter
portion.
- white matter: myelinated axons
- gray matter: mainly a collection of neuron cell bodies.
- white matter in each half of the spinal cord is organized into three columns, called the
dorsal (posterior), ventral (anterior), and lateral columns.
- Each column of the spinal cord contains ascending and descending tracts, or pathways.
- Ascending tracts consist of axons that conduct action potentials toward the brain, and
descending tracts consist of axons that conduct action potentials away from the brain.
- The gray matter of the spinal cord is shaped like the letter H, with posterior horns and
anterior horns. Small lateral horns exist in levels of the cord associated with the
autonomic nervous system. The central canal is a fluid-filled space in the center of the
cord.
- Spinal nerves arise from numerous rootlets along the dorsal and ventral surfaces of the
spinal cord.
- The ventral rootlets combine to form a ventral root on the ventral (anterior) side of the
spinal cord, and the dorsal rootlets combine to form a dorsal root on the dorsal
(posterior) side of the cord at each segment.
- The ventral and dorsal roots unite just lateral to the spinal cord to form a spinal nerve.
The dorsal root contains a ganglion, called the dorsal root ganglion (a swelling or
knot).
- cell bodies of pseudounipolar sensory neurons are in the dorsal root ganglia (figure
8.16b
).
- axons of these neurons originate in the periphery of the body. They pass through spinal
nerves and the dorsal roots to the posterior horn of the spinal cord gray matter.
- In the posterior horn, the axons either synapse with interneurons or pass into the white
matter and ascend or descend in the spinal cord.
- The cell bodies of motor neurons are located in the anterior and lateral horns of the
spinal cord gray matter.
Document Summary
Describe a cross section of the spinal cord. Refer to figure 8. 16 in textbook. spinal cord extends from the foramen magnum at the base of the skull to the second lumbar vertebra (figure 8. 15). Spinal nerves communicate between the spinal cord and the body. White matter in each half of the spinal cord is organized into three columns, called the gray matter: mainly a collection of neuron cell bodies. dorsal (posterior), ventral (anterior), and lateral columns. Each column of the spinal cord contains ascending and descending tracts, or pathways. Ascending tracts consist of axons that conduct action potentials toward the brain, and descending tracts consist of axons that conduct action potentials away from the brain. The gray matter of the spinal cord is shaped like the letter h, with posterior horns and anterior horns. Small lateral horns exist in levels of the cord associated with the autonomic nervous system.
