Spinal Cord

Vocabulary flashcards covering spinal cord anatomy, meninges, spinal nerves, gray and white matter structures, and reflex physiology.

Central Nervous System (CNS)

Comprises the brain and spinal cord; responsible for integrating sensory information and coordinating motor output.

Spinal Cord

Location: CNS structure extending from the foramen magnum C1 → L2 vertebra

Function: conducts impulses to/from the brain and mediates spinal reflexes.

Conus Medullaris

The tapered, cone-shaped end of the spinal cord around L1–L2.

Anterior median fissure aka cleavage

Anterior deep crevasse in the middle of the spine

Posterior median sulcus aka butt crack

Posterior shallow depression in the middle of the spine.

Filum Terminale

A thread-like extension of pia mater that anchors the spinal cord to the coccyx.

Cauda Equina

A bundle of spinal nerve roots below L2 resembling a horse’s tail; site for lumbar puncture (spinal tap).

Cervical Enlargement

Widened region of the spinal cord

Function: gives rise to nerves supplying the upper limbs.

Lumbosacral Enlargement

Widened region of the spinal cord

Function: gives rise to nerves supplying the lower limbs.

3 Layers of the spinal cord, meninges

1. Dura mater

2. Arachnoid mater

3. Pia mater

Dura Mater

Location: most superficial spinal meninx

Structure: dense irregular CT

Function: support and structure

Arachnoid Mater

Location: Middle meninx

Structure: dense irregular CT and elastic fibers

Function: support

Pia Mater

Location: deepest meninx

Structure: areolar CT

Function: metabolic support.

Denticulate Ligaments

Triangular extensions of pia mater that laterally anchor the spinal cord to the dura mater.

Epidural Space

Space between vertebrae and dura mater filled with adipose tissue; site of epidural injections.

Subdural Space

Potential space between arachnoid mater and dura mater.

Subarachnoid Space

Space between arachnoid and pia mater containing cerebrospinal fluid (CSF) for metabolic support and buoyancy.

Spinal roots

nerves stemming from spinal cord surface

Bunch of axons

Rootlets

Smaller spinal roots

Project from the surface of spinal cord

Ventral Rootlets

Small bundles of motor neuron axons exiting the spinal cord surface from the front; merge to form a ventral root.

Ventral Root

Bundle of ventral rootlets carrying efferent (motor) axons from the spinal cord.

Dorsal Rootlets

Small bundles of sensory neuron axons entering the spinal cord from the back; merge to form a dorsal root.

Dorsal Root

Bundle of dorsal rootlets carrying afferent (sensory) axons to the spinal cord; contains the dorsal root ganglion.

Spinal root

Contains both ventral and dorsal roots

Spinal Nerve

Mixed nerve formed by union of a dorsal and ventral root; there are 31 pairs named by vertebral region.

Regions of spinal nerves that stick out

1. Cervical spinal nerves

2. Thoracic spinal nerves

3. Lumbar spinal nerves

4. Sacral spinal nerves

5. Coccygeal spinal nerves

2 types of tissue make up the spinal cord

1. Grey matter

2. White matter

Gray Matter

Location: Inner spinal cord tissue

Structure: butterfly containing neuron cell bodies and unmyelinated interneurons; arranged in ‘horns.’

Gray Commissure

Cross-bar of gray matter connecting the two spinal cord wings; surrounds the central canal.

Central Canal

CSF-filled channel in the center of the spinal cord lined by ependymal cells.

Divided regions of the grey matter, horns

1. Ventral grey horn

2. Dorsal grey horn

3. Lateral grey horn

Ventral Horn

Location: Gray matter region of spinal cord

Structure: houses somatic motor neuron cell bodies. multipolar neurons

Function: send motor output to skeletal muscle. Somatic motor output.

Dorsal Horn

Location: Gray matter region of spinal cord

Structure: unipolar sensory neurons with cell bodies living in the dorsal root

Function: receive sensory input from the body but not from special senses: eyes, ears, or taste buds

Dorsal root ganglion

A collection of cell bodies of sensory neurons

Lateral Horn

Location: Gray matter region between T1–L2

Structure: contains autonomic multipolar motor neuron cell bodies

Function: send output to cardiac muscle, smooth muscle, and glands

White Matter

Location: Outer spinal cord tissue

Structure: composed of tracts organized into funiculi. Like cables

Function: axons transmit information to and from the brain

Funiculus (White Column)

One of three major regions (anterior, lateral, posterior) of spinal cord white matter carrying ascending/descending tracts.

Tract

Bundle of myelinated axons within the CNS transmitting specific information.

Nucleus (CNS)

Cluster of neuron cell bodies within the central nervous system gray matter.

Ganglion (PNS)

Cluster of neuron cell bodies located outside the CNS, e.g., dorsal root ganglion.

Reflex

A rapid, automatic motor response to a specific sensory stimulus.

Reflex Arc

Neural pathway of a reflex involving a sensory neuron, integration center (± interneuron), and motor neuron.

3 components of reflex

1. Sensory neuron talking to interneuron

2. Interneuron takes information and decides what to do

3. Interneuron tells motor neuron what to do

2 types of reflex

1. Somatic

2. Autonomic

Somatic Reflex

Reflex that activates skeletal muscle, such as stretch and withdrawal reflexes.

Autonomic Reflex

Reflex that activates cardiac muscle, smooth muscle, or glands

Stretch Reflex

Muscle contraction in response to muscle stretching; prevents overstretching (e.g., knee-jerk).

Withdrawal Reflex

Muscle contraction pulling a limb away from painful stimuli; protects tissues from damage.