Major Structures of the Spinal Cord

Question 1

anterior median fissure

Answer 1

runs the length of the anterior spinal cord and partially divide it into right and left halves

Question 2

cauda equina

Answer 2

composed of the dorsal and ventral roots of spinal nerves L2-S5 that extend beyond the end of the spinal cord

Question 3

central canal

Answer 3

continuous with the ventricles of the brain; contains cerebrospinal fluid

Question 4

cervical enlargement

Answer 4

enlargement of the spinal cord in the cervical region; location where nerves serving the upper limbs arise

Question 5

conus medullaris

Answer 5

tapered, cone shaped end of the spinal cord in the L1-L2 region

Question 6

epidural space

Answer 6

space between the bony wall of the vertebral column and the spinal dural sheath; filled with fat (padding) and a network of veins

Question 7

lumbar enlargement

Answer 7

enlargement of the spinal cord in the lumbar region; location where nerves serving the lower limbs arise

Question 8

posterior median sulcus

Answer 8

runs the length of the posterior spinal cord and partially divide it into right and left halves

Question 9

gray matter

Answer 9

a mixture of neuron cell bodies, their unmyelinated processes and neuroglia

Question 10

gray commissure

Answer 10

gray matter surrounding the central canal and connective the gray matter on each side of the spinal cord

Question 11

anterior (ventral) horn

Answer 11

anterior projections of the gray matter; contains nerve cells bodies of somatic motor neurons and some interneurons

Question 12

lateral horn

Answer 12

lateral projections of the gray matter; found only in the thoracic and superior lumbar segments of the spinal cord; contains nerve cell bodies of visceral motor neurons

Question 13

posterior (dorsal) horn

Answer 13

posterior projections of the gray matter; consists entirely of inter-neurons receiving somatic and visceral input from sensory neurons

Question 14

white columns (funiculi)

Answer 14

groups of myelinated and unmyelinated nerve fibers that allow communication between different parts of the spinal cord and between the spinal cord and the brain; named according to their location

Question 15

dorsal root

Answer 15

contains only sensory (afferent) axons carrying signals from the body to the spinal cord; these sensory axons may synapse with interneurons in the posterior (dorsal) horn or enter the posterior funiculus directly and travel up the spinal cord

Question 16

dorsal root ganglion

Answer 16

bulge on the dorsal root; contain cell bodies of sensory neurons

Question 17

ventral root

Answer 17

contains only motor axons of somatic motor neurons in the anterior horns of the spinal cord and visceral motor neurons in the lateral horns of the spinal cord

Question 18

dorsal rami

Answer 18

innervate the posterior body trunk; each ramus innervates a narrow strip of muscle and skin in line with its emergence point

Question 19

ventral rami

Answer 19

innervate the majority of the body trunk (except the posterior) and the arms and legs; form nerve plexi

Question 20

gray rami communicantes

Answer 20

postganglionic axons pass from the sympathetic chain ganglia to the ventral via this structure

Question 21

white rami communicantes

Answer 21

preganglionic axons pass from the ventral ramus to the sympathetic chain ganglia via this structure

Question 22

cervical plexus

Answer 22

formed by ventral rami of C1-C4; innervates skin of neck, back of head and shoulders; innervates muscles of anterior neck

Question 23

phrenic nerve

Answer 23

a branch of the cervical plexus; innervates the diaphragm

Question 24

brachial plexus

Answer 24

formed by central rami of C5-T1; innervates shoulders and arms; very complex

Question 25

lumbar plexus

Answer 25

formed by ventral rami of L1-L4; innervates the anterior and medial thigh and some abdominal wall muscles

Question 26

sacral plexus

Answer 26

formed by ventral rami L4-S4; innervates pelvic region, perineum, and all of lower limb except the anteromedial thigh

Question 27

sciatic nerve

Answer 27

largest branch of sacral plexus; innervates the entire lower limb except the anteromedial thigh

Question 28

intercostal (thoracic) nerves

Answer 28

formed by the ventral rami T1-T12; do not form a nerve plexus; innervate the intercostals muscles, muscles and skin of anterolateral thorax and most of the abdominal wall