BSC2085L E.14 The Spinal Cord, Spinal Nerves, Reflexes, and the Autonomic Nervous System

Developed for the Broward College course BSC2085/L Anatomy and Physiology I.

epidural space

• The space deep to the vertebral canal and superficial to the dura mater.
• Filled with fat.

meninges

• Three layers of protective membrane that surround the spinal cord.
• Composed of the dura mater, arachnoid mater, pia mater.

dura mater

• The outer layer of the meninges.
• Deep to the epidural space and superficial to the arachnoid mater.

arachnoid mater

• The intermediate layer of the meninges.
• Deep to the dura mater and superficial to the subarachnoid space.

subarachnoid space

• The space deep to the arachnoid mater and superficial to the pia mater.
• Contains cerebrospinal fluid.

pia mater

• The inner layer of the meninges.
• Deep to the subarachnoid space and superficial to the spinal cord.
• Emerges denticulate ligaments.

denticulate ligament

Lateral folds of the pia mater that holds the spinal cord.

cervical enlargement

• Located at C3-T1 of the spinal cord.
• A bulge that houses the neurosomas whose fibers supply the upper limbs.

lumbar enlargement

• Located at T9-T12 of the spinal cord.
• A bulge that houses the neurosomas whose fibers supply the lower limbs.

conus medullaris

• Located at L1-L2 of the spinal cord.
• The cone-shaped tip termination of the spinal cord.

cauda equina

• Located beyond the conus medullaris.
• The continuation of nerves from the spinal cord extending downward from the conus medullaris.

filum terminale

• Located beyond the conus medullaris.
• Fibrous extensions of the pia mater that continue to S2, located on the midline.

ventral horns

• Gray matter in the spinal cord.
• Located on the ventral (anterior) side of the spinal cord.
• Contains somatic motor neurosomas.
• Also called anterior horns.

dorsal horns

• Gray matter in the spinal cord.
• Located on the dorsal (posterior) side of the spinal cord and contacts the surface.
• Contains the axon terminals of peripheral sensory neurons and their synapses with interneurons.
• Also called posterior horns.

lateral horns

• Gray matter in the spinal cord.
• Located laterally on the spinal cord only in the thoracic region.
• Contains visceral motor neurosomas.

gray commissure

• Gray matter in the spinal cord.
• The bridge connecting the gray matter on both sides of the spinal cord.
• Surrounds the central canal.

central canal

• Located in the gray commissure of the spinal cord.
• Channels cerebrospinal fluid.

ventral median fissure

• Located between the ventral columns on the ventral side of the spinal cord.
• The larger of the two grooves in the spinal cord.
• Also known as the anterior median fissure.

ventral column

• White matter in the spinal cord.
• Located on the ventral (anterior) side of the spinal cord.

lateral column

• White matter in the spinal cord.
• Located laterally on either side of the spinal cord.

dorsal column

• White matter in the spinal cord.
• Located on the dorsal (posterior) side of the spinal cord.

dorsal median sulcus

• Located between the dorsal columns on the dorsal side of the spinal cord.
• The smaller of the two grooves in the spinal cord.
• Also known as the posterior median sulcus.

dorsal root

• A division of the spinal nerves external to the spinal cord.
• Connects to the dorsal horns of the spinal cord.
• Contains sensory fibers.
• Also known as the posterior root.

ventral root

• A division of the spinal nerves external to the spinal cord.
• Contains motor fibers.
• Also known as the anterior root.

dorsal root ganglion

• A bulge of the dorsal root external to the spinal cord.
• Contains sensory neurosomas bringing information from the periphery to the spinal cord.

cervical plexus

• A branched network of spinal nerves C1-C5.
• Innervates muscles of the shoulder and neck.
• Gives rise to the phrenic nerve.

brachial plexus

• A branched network of spinal nerves C5-T1.
• Innervates muscles and skin of the shoulder and upper limbs.
• Gives rise to the axillary, radial, median, and ulnar nerves.

lumbar plexus

• A branched network of spinal nerves L1-L4.
• Innervates the lower abdominopelvic region and anterior thigh.
• Gives rise to the femoral nerve.

sacral plexus

• A branched network of spinal nerves L4-S4.
• Innervates the rear pelvis. posterior side of thigh, and the lower limbs.
• Gives rise to the sciatic, common fibular, and tibial nerve.

phrenic nerve

• A nerve arising from the cervical plexus.
• Travels downward and innervates the diaphragm.

axillary nerve

• A nerve arising from the brachial plexus.
• Wraps around the head of the humerus.

radial nerve

• A nerve arising from the brachial plexus.
• The lateral of the three major nerves innervating the upper limbs.

median nerve

• A nerve arising from the brachial plexus.
• The intermediate of the three major nerves innervating the upper limbs.

ulnar nerve

• A nerve arising from the brachial plexus.
• The medial of the three major nerves innervating the upper limbs.

femoral nerve

• A nerve arising from the lumbar plexus.
• Travels anterior to the coxal bone and innervates the anterior thigh.

sciatic nerve

• A nerve arising from the sacral plexus.
• Travels down the posterior leg and divides into the common fibular and tibial nerves.

common fibular nerve

• A nerve arising from the sacral plexus.
• The lateral of the two nerves innervating the lower leg.
• Best seen on the posterior side.

tibial nerve

• A nerve arising from the sacral plexus.
• The medial of the two nerves innervating the lower leg, travelling along the tibia.
• Best seen on the posterior side.