Functions and Anatomy of the Spinal Cord

A compilation of flashcards to review vocabulary and concepts related to the anatomy and physiology of the spinal cord.

Spinal Cord

Connection between brain and body; acts as a two-way pathway for messages.

Sensory Input

Nerve signals that travel up to the brain.

Motor Commands

Nerve signals that travel down to the body.

CNS

Central Nervous System, consisting of the brain and spinal cord.

PNS

Peripheral Nervous System, consisting of nerves outside the brain and spinal cord.

Spinal Reflexes

Automatic responses to stimuli that do not involve the brain.

Reflex Example

Pulling your hand back after touching something hot.

Cervical Region

Uppermost region of the spinal cord, controlling upper limbs.

Thoracic Region

Middle region of the spinal cord, contains thoracic spinal nerves.

Lumbar Region

Lower back region of spinal cord controlling lower limbs.

Sacral Region

Lowest region of spinal cord, below lumbar.

Conus Medullaris

Cone-shaped end of the spinal cord around L1 vertebra.

Cauda Equina

Bundle of spinal nerves below conus medullaris, resembling a horse's tail.

Spinal Nerves

31 pairs of mixed nerves containing both sensory and motor axons.

Rootlets

Small nerve fibers that merge into roots.

Posterior Root

Contains sensory neurons and has a posterior root ganglion.

Anterior Root

Contains motor neurons without a ganglion.

Epineurium

Connective tissue layer that surrounds the entire nerve.

Perineurium

Connective tissue layer that surrounds fascicles or bundles of axons.

Endoneurium

Connective tissue layer that surrounds individual axons.

Vertebral Column

Bone structure that protects the spinal cord.

Meninges

Three protective layers surrounding the spinal cord.

Pia Mater

Innermost layer of the meninges attached directly to the cord.

Denticulate Ligaments

Stabilize the spinal cord laterally.

Filum Terminale

Anchors the spinal cord to the coccyx.

Arachnoid Mater

Middle web-like layer of the meninges.

Subarachnoid Space

Space containing cerebrospinal fluid (CSF).

Dura Mater

Outermost tough layer of the meninges.

Epidural Space

Space between dura and vertebra that holds fat, vessels, and nerves.

Lumbar Puncture

Procedure to collect CSF for testing.

Gray Matter

Region of the spinal cord containing neuron cell bodies and unmyelinated axons.

Posterior Horns

Part of gray matter housing sensory neurons and interneurons.

Anterior Horns

Part of gray matter housing somatic motor neurons.

Lateral Horns

Part of gray matter that contains autonomic motor neurons (T1-L2).

Gray Commissure

Connects the two sides of gray matter, surrounding central canal.

White Matter

Outer portion of the spinal cord composed of myelinated axons.

Funiculi

Groups of white matter tracts in the spinal cord.

Ascending Pathways

Carry sensory information from body to brain.

Descending Pathways

Carry motor commands from brain to body.

Decussation

Crossing over of tracts; one side of the brain controls the opposite side of the body.

Posterior Funiculus-Medial Lemniscal Pathway

Pathway for fine touch, vibration, and proprioception.

Anterolateral Pathway

Pathway for crude touch, pain, and temperature.

Spinocerebellar Pathway

Pathway for muscle and joint position, ending in cerebellum.

Corticospinal Tracts

Major motor pathways that control voluntary movement of skeletal muscles.

Direct Pathway

Begins in the primary motor cortex, controlling voluntary movements.

Indirect Pathway

Originates in brainstem, controls posture, tone, and reflexes.

Plexuses

Networks of nerves that innervate specific body regions.

Dermatomes

Specific skin areas innervated by spinal nerves; overlap slightly.

Cervical Plexus

Innervates neck muscles and skin, including the phrenic nerve.

Brachial Plexus

Controls upper limbs, with major nerves like ulnar and radial.

Lumbar Plexus

Innervates lower trunk and limbs, including femoral and obturator nerves.

Sacral Plexus

Innervates lower limbs; includes the sciatic nerve.

Reflex Arc

Neural pathway responsible for generating a reflex response.

Monosynaptic Reflex

Reflex with one synapse; fast response (e.g., knee-jerk).

Polysynaptic Reflex

Reflex with multiple synapses; involves interneurons.

Stretch Reflex

Muscle contracts when stretched, such as knee-jerk response.

Golgi Tendon Reflex

Muscle relaxes when tension is too high; prevents damage.

Withdrawal Reflex

Pulls body part away from pain, activating flexor muscles.

Crossed-Extensor Reflex

Opposite limb supports weight during withdrawal.

Hypoactive Reflexes

Weak or absent reflexes indicating potential spinal or muscle issues.

Hyperactive Reflexes

Overly strong reflexes indicating potential brain or spinal damage.

Neural Tube

Developmental structure from which spinal cord develops.

Sulcus Limitans

Divides motor (anterior) and sensory (posterior) areas during development.

Cauda Equina Formation

Caused by spinal cord growth lagging behind vertebral growth.

Cerebrospinal Fluid (CSF)

Fluid in subarachnoid space providing cushioning to the spinal cord.

Nerve Roots

The initial portions of spinal nerves before they combine into spinal nerves.

Anterior Ramus

Branch of spinal nerve that supplies trunk and limbs.

Posterior Ramus

Branch of spinal nerve that supplies muscles and skin of the back.

Rami Communicantes

Connects spinal nerves to the sympathetic chain ganglia.

Clinical View

Medical procedures and observations related to spinal cord anatomy.

Shingles

Reactivation of chickenpox virus in sensory ganglia following dermatome.

Sciatica

Pain caused by compression of the sciatic nerve.

Dura

The outermost layer of the meninges that protects the spinal cord.

Filum Terminale

Connective tissue cord anchoring spinal cord to coccyx.

Coccyx

The tailbone, to which the filum terminale anchors the spinal cord.

Interneuron

Neurons that process signals in the spinal cord, optional in reflex arcs.

Effector

Muscle or gland that responds to a motor neuron command.

Receptor

Structure that detects stimulus for reflex response.

Somatic Reflexes

Reflexes that involve skeletal muscle responses.

Visceral Reflexes

Reflexes that involve smooth muscle or glandular responses.

Innate Reflexes

Reflexes present at birth.

Acquired Reflexes

Reflexes that are learned through experience.

Initial Reflex Response

The body's automatic, rapid reactions to a stimulus.

Plasticity

The ability of the nervous system to adapt or change in response to experience.