Spinal Cord Anatomy and Function

These flashcards cover key terminology and concepts related to spinal cord anatomy, function, and reflex actions for easy review and study in preparation for the exam.

Spinal Cord

Extends from the brain's medulla through the vertebral canal, ending at the L1 vertebra with the conus medullaris.

Cervical Enlargement

A region in the spinal cord that contains neurons innervating the upper limbs.

Lumbar Enlargement

A region in the spinal cord that contains neurons innervating the lower limbs.

Conus Medullaris

The tapered ending of the spinal cord at the L1 vertebra.

Cauda Equina

A bundle of spinal nerves extending from the lower end of the spinal cord.

Filum Terminale

A thin strand of pia mater anchoring the conus medullaris to the coccyx.

Pia Mater

The delicate inner layer of the meninges adhering to the spinal cord.

Arachnoid Mater

The web-like middle layer of the meninges lying above the pia mater.

Dura Mater

The tough outermost layer of the meninges that stabilizes the spinal cord.

Subarachnoid Space

The area between the arachnoid and pia mater where cerebrospinal fluid (CSF) flows.

Epidural Space

The space between the dura mater and the vertebra that contains adipose and blood vessels.

Gray Matter

Made up of neuron cell bodies, dendrites, and unmyelinated axons; located centrally in the spinal cord.

White Matter

Composed of myelinated axons that carry signals to and from the brain.

Anterior Horn

Contains cell bodies of somatic motor neurons.

Posterior Horn

Contains axons of sensory neurons and cell bodies of interneurons.

Lateral Horn

Contains cell bodies of autonomic motor neurons; present only in T1-L2 segments.

Gray Commissure

A horizontal band of gray matter surrounding the central canal.

Sensory Neurons

Transmit impulses from sensory receptors to the spinal cord.

Motor Neurons

Transmit impulses from the spinal cord to muscles and glands.

Reflex Arc

The neural pathway involved in reflex actions, including sensory neurons, interneurons, and motor neurons.

Monosynaptic Reflex

A reflex involving one synapse between the sensory neuron and motor neuron.

Polysynaptic Reflex

A reflex involving one or more interneurons connecting sensory and motor neurons.

Stretch Reflex

A reflex that causes a muscle to contract in response to being stretched.

Withdrawal Reflex

A reflex that moves a limb away from a painful stimulus.

Crossed-Extensor Reflex

A reflex that stabilizes the body when an opposite limb withdraws from a painful stimulus.

Sensory Pathway

Pathways that carry sensory information from the body to the brain.

Motor Pathway

Pathways that carry motor commands from the brain to the body.

Dermatome

A segment of skin supplied by a single spinal nerve.

Nerve Plexus

A network of intersecting nerves formed by the anterior rami of spinal nerves.

Cervical Plexus

A nerve plexus formed by the anterior rami of C1-C4 cervical nerves.

Brachial Plexus

A nerve plexus formed by the anterior rami of C5-T1 spinal nerves.

Lumbar Plexus

A nerve plexus formed by the anterior rami of L1-L4 spinal nerves.

Sacral Plexus

A nerve plexus formed by the anterior rami of L4-S4 spinal nerves.

Phrenic Nerve

Innervates the diaphragm originating from the cervical plexus.

Sciatic Nerve

The largest nerve in the body, formed from the sacral plexus.

Femoral Nerve

Innervates anterior thigh muscles; part of the lumbar plexus.

Obturator Nerve

Innervates medial thigh muscles; part of the lumbar plexus.

Axillary Nerve

Innervates deltoid and teres major muscles; part of the brachial plexus.

Median Nerve

Innervates most anterior forearm muscles and lateral lumbricals; part of the brachial plexus.

Ulnar Nerve

Innervates most intrinsic hand muscles; part of the brachial plexus.

Radial Nerve

Innervates posterior arm and forearm muscles; part of the brachial plexus.

Anterior Rami

Branches of spinal nerves that form peripheral nerves.

Posterior Rami

Branches of spinal nerves that innervate the back.

Rami Communicantes

Branches of autonomic fibers connecting spinal nerves to the sympathetic trunk.

Central Canal

The fluid-filled space in the center of the spinal cord.

Cerebrospinal Fluid (CSF)

Fluid that circulates through the subarachnoid space and central canal.

Denticulate Ligaments

Extensions of the pia mater that anchor the spinal cord.

Neural Tube

The embryonic structure developing into the spinal cord and brain.

Basal Plates

Anterior structures of the spinal cord that develop into anterior horns.

Alar Plates

Posterior structures of the spinal cord that develop into posterior horns.

Sulcus Limitans

The groove in the neural tube that separates basal and alar plates.

Intervertebral Foramen

The openings between vertebrae through which spinal nerves exit.

Hypoactive Reflex

A diminished reflex response indicating possible nerve damage.

Hyperactive Reflex

An exaggerated reflex response suggesting possible spinal cord damage.

Nociceptor

A sensory receptor that responds to painful stimuli.

Interneuron

A neuron that connects sensory and motor neurons in the spinal cord.

Excitatory Synapse

A synapse that increases the likelihood of firing an action potential.

Inhibitory Synapse

A synapse that decreases the likelihood of firing an action potential.

Anterior Median Fissure

The longitudinal groove on the anterior surface of the spinal cord.

Posterior Median Sulcus

The indentation on the posterior surface of the spinal cord.

Spinal Nerves

31 pairs of nerves that emerge from the spinal cord, forming part of the peripheral nervous system.

C1 Spinal Nerve

The only spinal nerve that exits above its corresponding vertebra.

C8 Spinal Nerve

The spinal nerve that exits below the C7 vertebra.

Lumbar Puncture

A procedure to collect cerebrospinal fluid for diagnostic purposes, performed below L1.

Adipose Tissue

A connective tissue that resides in the epidural space to cushion the spinal cord.

Spinal Cord Injury

Injury that may result in loss of sensation or motor function.

Neural Stem Cells

Cells that have the potential to develop into different types of neural cells.

Pulmonary Infections

Infections in the lungs that can arise post-spinal cord injury.

Urinary Infections

Infections that can occur due to impaired bladder control after spinal injury.

Clinical Examination

A physical assessment to evaluate reflexes as indicators of spinal cord health.

Tendons

Connective tissues that attach muscle to bone, involved in the golgi tendon reflex.

Proprioceptors

Sensory receptors that detect body position, movement, and tension.

Spinal Reflex Testing

A procedure to assess the function of the nervous system based on reflex responses.

Pathway Decussation

The crossing over of axons from one side of the nervous system to the other.

Nerves

Bundles of axons that transmit signals between the brain and body.

Motor Control

The ability of the nervous system to manage physical actions and movements.

Inguinal Region

The area of the body located in the groin, innervated by nerves from the lumbar plexus.

Anterolateral Pathway

A sensory pathway that conveys pain and temperature sensations.

Posterior Funiculus

A white matter region that carries sensory information regarding touch and proprioception.

Spinocerebellar Pathway

A sensory pathway that carries proprioceptive information to the cerebellum.

Lateral Spinothalamic Tract

A tract that carries information about pain and temperature.

Medial Lemniscus

A high-order sensory pathway that carries signals about touch and proprioception.

Direct Pathway

Motor pathways that directly connect the primary motor cortex to lower motor neurons.

Indirect Pathway

Motor pathways that involve multiple synapses, regulating involuntary muscle actions.