The spinal cord is about the diameter of your little finger at its larges (where it connects to the brain) and tapers to a point at its end
The filum terminale
All information from the brain to the body goes through the spinal cord
All information from the body to the brain goes through the spinal cord.
Reflex pathways within the
White matter contains __________ and ________ tracts.
ascending (sensory); descending (motor)
Gray matter is where
neural information is processed.
Posterior horn- dorsal horn(gray matter)
processes sensory information.
*cell body in posterior root ganglion
Anterior horn- ventral horn(gray matter)
contains cell bodies of neurons which control the voluntary muscles.
*motor neuron cell body is a red dot in this schematic
The spinal cord ends in a bundle of nerves called the
cauda equina- the nerves float in CSF enclosed in a sac of dura and arachnoid
If we introduce a needle into the vertebral column, then the nerve roots float out of the way and we can sample cerebrospinal fluid. (the L3/L4 intervertebral space is the most common location. This is called
Lumbar puncture or spinal tap
To relieve pain in the lower body anesthetic agent is infected around the nerves as they exit the dural sleeve. Because this goes on top of the dura mater, it is called
The size and shape of the spinal cord changes from superior to inferior
Cervical is largest, sacral is smallest
Less and less white matter as we descend
-fewer sensory tracts going up (they haven't "jumped on" yet)
-fewer motor tracts going down (they've "jumped off" already)
Spinal cord (gray matter, white matter)
white matter outside
gray matter inside
Brain (gray matter, white matter)
white matter inside
gray matter outside
Gray matter =
cell bodies; reception, processing
white matter =
axons; sent long distances
Dorsal root ganglion
contains the cell bodies of sensory neurons.
plural: dorsal root ganglia
also called posterior root ganglion
also called posterior root.
also called anterior root
mixed: both motor and sensory information
innervates one segment or "slice" of body
nerves connecting spinal nerve to sympathetic ganglion.
Interconnected nerves that combine and split and recombine lateral to the spinal cord.
When a collection of neuron cell bodies occurs in the peripheral nervous system, it is called
List the four spinal nerve plexi
Cervical plexus is
in the neck. It receives nerves from the C1 through C5 spinal cord segments, and gives rise to several important nerves.
What is the most important nerve involved with the cervical plexus?
phrenic nerve, which innervates the diaphragm and makes breathing possible.
Brachial plexus receives contributions from __-__ and __. Its major exiting nerves are the
C5-C8 and T1; radial nerve (thumb, nearby structures), the median nerve (middle finger), and ulnar nerve (little finger)
The lumbar plexus is associated with the lumbar spinal cord
(roots L1-L5) and innervates the upper thigh.
The sacral plexus receives contributions from __-__ and __-__. One huge nerve, the larges in the body, emerges from the sacral plexus: the _____ _____.