CNS B – Spinal Cord, Tracts and Trauma

Vocabulary flashcards covering spinal cord structure, sensory and motor tracts, injuries, and protective features such as meninges and cerebrospinal fluid.

Spinal Cord

Central nervous system structure extending from C1 to L2, carrying sensory and motor pathways and protected inside the vertebral canal.

Tract

A bundle of axons within the CNS that carries specific information; white-matter pathway.

Ascending Tract

Sensory pathway that carries information from receptors up the spinal cord to the brain.

Descending Tract

Motor pathway that delivers commands from the brain down the spinal cord to skeletal muscles.

Dorsal Column Tract

Ascending tract for proprioception and deep touch; crosses in the medulla.

Spinothalamic Tract

Ascending tract for pain and temperature; crosses immediately in the spinal cord.

Corticospinal Tract

Major descending tract for fine, skilled skeletal-muscle movement; crosses in the medulla.

Myelinated Axon

Nerve fiber covered with myelin that forms the white matter and speeds impulse conduction.

Unmyelinated Cell Bodies

Neuron somata and dendrites that form the gray “butterfly” inside the spinal cord.

Transection

Complete cut of the spinal cord producing total motor and/or sensory loss below the lesion.

Paraplegia

Loss of motor/sensory function in lower limbs due to transection between T1 and L1.

Quadriplegia

Loss of motor/sensory function in all four limbs from cervical spinal cord transection.

Proprioception

Sense of body position carried to the brain by the dorsal column tract.

Pain and Temperature Sensation

Modalities transmitted via the spinothalamic tract.

Upper Motor Neuron

First neuron in a descending pathway; cell body in brain, axon down spinal cord.

Lower Motor Neuron

Neuron whose cell body is in the spinal cord and whose axon exits to skeletal muscle.

Flaccid Paralysis

Limp muscles caused by damage to lower motor neurons; muscles receive no commands.

Spastic Paralysis

Continuous muscle contraction from upper motor neuron damage; reflex arcs intact.

Meninges

Three connective-tissue membranes—dura, arachnoid, pia—that protect brain and spinal cord.

Dura Mater

Outermost, toughest meningeal layer surrounding CNS.

Arachnoid Mater

Middle meningeal layer; web-like and separated from pia by CSF-filled space.

Pia Mater

Delicate innermost meningeal layer adhering to brain and spinal cord surfaces.

Cerebrospinal Fluid (CSF)

Liquid cushioning the CNS, circulating through ventricles and subarachnoid space.

Choroid Plexus

Blood-vessel network in ventricles that produces CSF.

Ventricles

Hollow CNS cavities (lateral, third, fourth) filled with CSF.

Central Canal

CSF-filled channel running through the spinal cord’s center.

Epidural

Anesthesia injected into space above dura to block spinal pain signals.

Epidural Space

Area outside the dura mater used for epidural anesthesia.

Lumbar Puncture

Procedure inserting a needle below L4 through dura and arachnoid to withdraw CSF.

White Matter

Regions of the CNS composed chiefly of myelinated axons (tracts).

Gray Matter

CNS regions rich in neuron cell bodies and dendrites; forms spinal cord ‘butterfly.’

Cauda Equina (nerve bundle)

Collection of spinal nerves below L3 traveling down the vertebral canal after cord ends.