Spinal cord and Spinal nerves

The_________ extends from the foramen magnum at the base of the skull to the second lumbar vertebra.

spinal cord

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 white matter in each half of the spinal cord is organized into three columns, called the _________________________

dorsal (posterior), ventral (anterior), and lateral columns.

___________________ consist of axons that conduct action potentials toward the brain.

Ascending tracts

________________ consist of axons that conduct action potentials away from the brain.

Descending tracts

The gray matter of the spinal cord is shaped like the letter H, with __________________

posterior horns and anterior horns.

Small ______________ exist in levels of the cord associated with the autonomic nervous system

lateral horns

The _________________ is a fluid-filled space in the center of the cord.

central canal

The ventral rootlets combine to form a ___________ on the ventral (anterior) side of the spinal cord

ventral root

the dorsal rootlets combine to form a ____________ on the dorsal (posterior) side of the cord at each segment.

dorsal root

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.

The cell bodies of _______________________________ are in the dorsal root ganglia.

pseudo-unipolar sensory neurons

The simplest reflex is the_______________ , in which muscles contract in response to a stretching force applied to them

stretch reflex

The _______________ , or patellar reflex, is a classic example of the stretch reflex. When the patellar ligament is tapped, the quadriceps femoris muscle tendon and the muscles themselves are stretched.

knee-jerk reflex

The ____________ arise along the spinal cord from the union of the dorsal roots and ventral roots.

spinal nerves

All the spinal nerves contain axons of both sensory and somatic motor neurons and thus are called ___________

mixed nerves.

A ____________ is the area of skin supplied with sensory innervation by a pair of spinal nerves.

dermatome

Most of the spinal nerves are organized into three major __________ where neurons of several spinal nerves come together and intermingle.

plexuses

In addition to the major plexuses, the small__________________ supplies motor innervation to the muscles of the pelvic floor and sensory cutaneous innervation to the skin over the coccyx

coccygeal plexus