Key Terms in Spinal Cord Anatomy and Reflexes

Spinal reflexes

Responses that do not involve the brain; fast reaction to a stimulus.

Conus medullaris

Tapered, inferior end of the spinal cord.

Cervical enlargement

Contains neurons that innervate the upper limbs.

Lumbar enlargement

Contains neurons that innervate the lower limbs.

Epineurium

Connective tissue wrapping around the entire nerve.

Perineurium

Connective tissue wrapping around each fascicle.

Endoneurium

Connective tissue wrapping around each individual axon.

Cauda equina

Bundle of spinal nerve roots arising from the end of the spinal cord.

Posterior ramus

Smaller branch that innervates the back.

Anterior ramus

Larger branch that innervates limbs and anterior trunk.

Plexuses

Networks of spinal nerves that allow redundancy and coordination.

Meninges

Three protective membranes: dura mater, arachnoid mater, pia mater.

Denticulate ligaments

Extensions of pia mater anchoring spinal cord laterally.

Posterior horn

Contains sensory neurons receiving signals from the PNS.

Anterior horn

Contains motor neurons sending signals to skeletal muscle.

Lateral horn

Contains autonomic motor neurons; found in thoracic and upper lumbar.

Gray commissure

Connects left and right sides of spinal cord gray matter.

Funiculus

Region of white matter in spinal cord: anterior, lateral, or posterior.

Dermatome

Skin area innervated by a single spinal nerve.

Reflex arc

Neural pathway for a reflex; includes 5 steps from stimulus to response.