Spinal Cord

What are the two parts of the central nervous system?

The brain and spinal cord.

Where does the spinal cord leave the brain?

Through the foramen magnum.

Where does the spinal cord start and end?

Starts at C1 and ends around L1-L2 at the conus medullaris.

How many pairs of cervical spinal nerves are there?

8 pairs.

How many pairs of thoracic spinal nerves are there?

12 pairs.

How many pairs of lumbar spinal nerves are there?

5 pairs.

How many pairs of sacral spinal nerves are there?

5 pairs.

How many pairs of coccygeal spinal nerves are there?

1 pair.

Why are there 8 pairs of cervical spinal nerves despite only 7 vertebrae?

The first nerve exits above C1, and the 8th pair exits above T1.

What is the cauda equina?

The bundle of spinal nerves coming off the conus medullaris (L2-Coccygeal).

What is the cervical enlargement?

A bump in the spinal cord from C5-T1 caused by a higher abundance of gray matter (presence of lateral nuclei)

What does the lumbar enlargement innervate?

The skeletal muscles of the lower extremities.

What happens to the amount of white matter as you go down the spinal cord?

It decreases.

What happens to the amount of gray matter as you go down the spinal cord?

It increases.

What is located at the very posterior portion of the spinal cord cross-section?

The posterior median sulcus.

What is the anterior median fissure?

A line on the opposite side of the posterior median sulcus.

What are the dorsal gray horns?

The two gray matter horns near the posterior median sulcus.

What is the dorsal funiculus?

White matter located between the two dorsal gray horns.

Where are the lateral gray horns found?

Only in T1-L2, containing preganglionic motor neurons of the sympathetic nervous system.

What is the ventral funiculus?

White matter located between the two ventral gray horns.

What do the dorsal and ventral roots of the spinal cord form?

The spinal nerve.

What does the dorsal rami innervate?

The deep portion of the back.

What is gray matter in a neuron?

The unmyelinated portion.

What is a nucleus in the central nervous system?

A group of cell bodies.

What connects both horns of the spinal cord?

The gray commissure.

What is the primary function of the posterior gray horn?

Sensory function.

What type of function do the anterior horns have?

Somatic motor function.

What is the rex lamina?

A way of organizing the gray matter of the spinal cord by function.

What is located near the central canal?

Lamina 10

What occupies lamina 1?

The posterior marginal nucleus

Which fibers primarily pick up fast pain and temperature sensation, associated with the posterior marginal nucleus

A delta fibers

What tract do A delta fibers lead into?

Anterior/lateral spinothalamic tract

What occupies lamina 2?

The substantia gelatinosa of Rolando

Which fibers are associated with slow pain?

C fibers

What does the nucleus proprius occupy?

Lamina 3 and 4

What types of sensations does the nucleus proprius take?

Pain and temperature sensation (both A-delta), touch/vibration, proprioception (A beta and 1a fibers)

What is the function of lamina 5?

Carries pain and temperature information from the viscera

Where does proprioceptive information go after lamina 6?

It crosses over and goes to the cerebellum via the ventral spinocerebellar tract

What is Clark's column?

Present in C8-L2 section of spinal cord, part of the spinocerebellar tract

What does the interomediomedial nucleus contain?

nuclei that serve as a relay center for viscerla info, and to modulate autonomic function

What does the interomediolateral nucleus contain?

nuclei that mediate sympathetic function

What do the nuclei in lamina 8 serve as?

Relay stations for subcortical tracts

What is the function of lamina 9?

Contains nuclei involved in controlling flexors and extensors

Where is the phrenic nucleus located?

In the C3-C5 section of the spinal cord

What does the accessory spinal nucleus innervate?

Sternocleidomastoid and trapezius

What does Onuf's nucleus control?

External sphincter of the anus and urethra, muscles involved in erection and ejaculation

What is the white matter of the spinal cord?

Myelinated portion of an axon

What is a tract in the CNS?

A bundle of axons

What are the three sections of white matter in the spinal cord?

Dorsal white column, lateral white columns, ventral white column

What is the anterior white commissure?

Where myelinated axons cross the spinal cord

What does the anterior spinothalamic tract carry?

Crude touch and pressure

What does the lateral corticospinal tract stimulate?

Lower motor neurons for voluntary movement of skeletal muscles

What does the dorsal spinocerebellar tract carry?

Proprioception from C8-L2

What is the function of the lateral spinothalamic tract?

Carries pain and temperature

What does the anterior corticospinal tract stimulate?

Lower motor neurons for voluntary control of skeletal muscles