Unit 2: IFS - Spinal Cord and Sensory Pathways

This set of flashcards covers spinal cord anatomy, neurotransmission in muscle movement, and the major ascending and descending pathways including DCML, ALST, and LCST.

Efferent

A term describing motor fibers of the spinal cord that carry impulses away from the central nervous system.

Afferent

A term describing sensory fibers located in the posterior of the spinal cord that carry impulses toward the central nervous system.

Cauda equina

The termination point of the spinal cord below $L2$, where it consists of free-floating nerves resembling a horse's tail.

Meninges

The three protective layers of the spinal cord, consisting of the dura pia and arachnoid.

Gray matter vs. White matter

White matter columns are located on the outside of the spinal cord, while grey matter is located on the inside.

Anterior horn

The part of the spinal cord's grey matter that contains motor neurons.

Ventral rootlets

Structures that contain only motor information.

Anterior spinal artery

The artery that supplies the anterior cord and carries motor information.

Posterior spinal artery

The artery that supplies the posterior cord and carries sensory information.

Precentral gyrus

The location of the upper motor neuron that generates the actual impulse for movement, such as kicking a ball.

Lateral corticospinal tract (LCST)

The primary movement pathway, responsible for $80\%-90\%$ of movement.

Acetylcholine

The neurotransmitter used to excite muscle tissue when an impulse is sent by a lower motor neuron.

Sarcoplasm

The part of the muscle that provides calcium to open the gate allowing acetylcholine to flow into the space.

Power stroke

The process in the sliding filament theory where ATP binds to the myosin head to grab the actin and shorten the sarcomere.

Rexed laminae

The system used to map different areas of the dorsal horn's grey matter to specific sensations like pain, touch, and temperature.

Meissners corpuscles

Sensory receptors densely located in areas requiring two-point discrimination, such as for reading braille.

DCML (Dorsal column medial lemniscal)

The ascending sensory pathway for light touch, proprioception, and vibration.

VPL in the Thalamus

The Ventral posterior lateral nucleus, described as the most confused nucleus in the body and the third neuron stop in the DCML pathway.

Internal arcuate fibers

The fibers at the medulla where the DCML pathway crosses to the other side of the body.

ALST (Anterior lateral spinothalamic)

The sensory pathway for pain, temperature, and crude touch containing slow unmyelinated fibers.

Dermatomes

A map of the nerve root levels that control sensation for specific areas of the skin.

Nociception

The medical term for the perception of pain.

Gate theory

The theory that pain can be overridden by stimulating fast sensory fibers (like touch) to reach the brain faster than slow pain fibers.