Internal anatomy of the spinal cord

Gray matter
Deeper layer; contains all the nerve cell bodies; at the center of the cord; cell bodies are organized by function and are organized in nuclei

Dorsal horn
contains SENSORY cell bodies

Lateral horn
contains VISCEROMOTOR neurons and is only present from T1-L2 and S2-S4

Ventral horn
contains SOMATOMOTOR cell bodies for skeletal muscles

White Matter
Superficial layer; contains only AXONS; axons are organized into tracts which allows brain and brainstem to communicate with spinal cord and different levels of the spinal cord.

Posterior, lateral, and anterior funiculus
Continuous with each other and are divided by an imaginary line that extends out from the ventral horn of gray matter.

Dorsal root
“DAVE”; Dorsal=afferent; Sensory info; collection of axons entering spinal cord with sensory information.

Dorsal Root Ganglion
Collection of cell bodies with a common purpose.

Ventral Root
“DAVE”; Ventral= efferent; Motor info; axons are sent from lateral and ventral horns to the ventral root; synapses on a 2nd neuron along the way.

Spinal Nerve
All SENSORY information going in and all MOTOR info going out

Dorsal Ramus
First branches of spinal neurons; innervates muscles of skin and back.

Ventral Ramus
First branches of spinal neurons; innervates everything else.

What are the three fibers of spinal nerves?
Sensory, Somatomotor, and visceromotor

Encloses the entire nerve.

Around a fasicle of axons.

Around a single axon.

Monosynaptic stretch reflex=simplest; a muscle is stretched, a receptor in that muscle senses the stretch, and sends a signal to the somatomotor neurons causing contraction- effector.

What can’t neurons fire without?
an input

Where are the bodies located?

Pathways that carry info to and from the brain.



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