Spinal Cord- Structure and Function Pages 252-255 The Nervous System Spinal Cord- Structure and Function Pages 252-255

Review of nervous system terms Neurons = nerve cells Nerve cell bodies = ganglia (ganglion is singular) Bundles of nerve fibers: In the CNS = tracts In the PNS = nerves

Spinal Cord Begins at the foramen magnum of the skull Terminates around first or second lumbar vertebra conduction pathway Approaching/Exiting the brain Afferent vs. Efferent 31 pairs of spinal nerves arise from the spinal cord Cauda equina (horse’s tail) a dense collection of spinal nerves at the inferior end Meninges cover the spinal cord © 2015 Pearson Education, Inc.

Figure 7.20 Anatomy of the spinal cord, posterior view. Cervical spinal nerves C8 Dura and arachnoid mater Thoracic spinal nerves T12 End of spinal cord Lumbar spinal nerves Cauda equina L5 End of meningeal coverings S1 Sacral spinal nerves S5

Figure 7.21 Spinal cord with meninges (three-dimensional view). White matter Dorsal (posterior) horn of gray matter Dorsal root ganglion Central canal Lateral horn of gray matter Spinal nerve Ventral (anterior) horn of gray matter Dorsal root of spinal nerve Ventral root of spinal nerve Pia mater Arachnoid mater Dura mater ANTERIOR

Spinal Cord Anatomy Gray Matter: Horns of the spinal cord Collection of neuron cell bodies Dorsal (posterior) horns (SENSORY) house interneurons Receive sensory info from neurons in the dorsal root Anterior (ventral) horns (MOTOR) house somatic (voluntary) motor neurons Send motor information out ventral root White Matter: myelinated axons the central canal is filled with CSF

Figure 7.21 Spinal cord with meninges (three-dimensional view). White matter Dorsal (posterior) horn of gray matter Dorsal root ganglion Central canal Lateral horn of gray matter Spinal nerve Ventral (anterior) horn of gray matter Dorsal root of spinal nerve Ventral root of spinal nerve Pia mater Arachnoid mater Dura mater ANTERIOR