Peripheral Nervous System & Spinal Cord Vocabulary

Vocabulary flashcards covering foundational terms from the lecture on the peripheral nervous system and spinal cord.

Central Nervous System (CNS)

Comprises the brain and spinal cord; integrates and processes information.

Peripheral Nervous System (PNS)

All neural structures outside the CNS, including 12 cranial nerve pairs and 31 spinal nerve pairs.

Afferent Nerve

Carries sensory information toward the CNS (input).

Efferent Nerve

Carries motor commands away from the CNS (output).

Somatic Nervous System

Voluntary division that controls skeletal muscles and receives conscious sensory input.

Visceral (Autonomic) Nervous System

Involuntary division regulating glands, smooth muscle, and cardiac muscle.

Sympathetic Division

Fight-or-flight branch of the autonomic nervous system.

Parasympathetic Division

Rest-and-digest branch of the autonomic nervous system.

Enteric Nervous System

Intrinsic neural network of the gastrointestinal tract.

General Somatic Afferent (GSA)

Sensory fibers conveying touch, pain, temperature, and proprioception from body wall structures.

General Visceral Afferent (GVA)

Sensory fibers conveying information such as distension or chemical changes from visceral organs.

General Somatic Efferent (GSE)

Motor fibers that stimulate skeletal (somatic) muscles.

General Visceral Efferent (GVE)

Motor fibers supplying smooth muscle, cardiac muscle, and glands (autonomic).

Body Wall

Primarily somatic structures (skin, fasciae, skeletal muscle, bone) forming the outer body framework.

Body Cavity

Region housing visceral organs; innervation is entirely visceral.

Somatic Sensation

Conscious, sharp, well-localized perception such as touch or temperature.

Visceral Sensation

Usually unconscious, dull, poorly localized signals like distension or cramping.

Spinal Cord

CNS structure within vertebral canal that ends around L1–L2 in adults.

Conus Medullaris

Tapered, terminal end of the spinal cord at ~L1–L2 level.

Cauda Equina

Bundle of lumbar and sacral nerve roots descending beyond the conus medullaris.

Spinal Nerve

Mixed nerve formed by union of dorsal and ventral roots; exits through an intervertebral foramen.

Dorsal (Posterior) Root

Contains afferent GSA and/or GVA fibers only.

Ventral (Anterior) Root

Contains efferent GSE and/or GVE fibers only.

Dorsal Ramus

Mixed branch innervating intrinsic back muscles and overlying skin.

Ventral Ramus

Mixed branch innervating limbs, anterolateral trunk, and neck; forms plexuses.

Dorsal Root Ganglion (DRG)

Collection of sensory neuron cell bodies on the dorsal root.

Meninges

Three protective membranes: dura mater, arachnoid mater, and pia mater.

Dura Mater

Outer tough meningeal layer surrounding CNS.

Arachnoid Mater

Middle web-like meningeal layer; forms subarachnoid space.

Pia Mater

Delicate inner meningeal layer adherent to CNS surface.

Epidural Space

Fat-filled space between vertebral canal and dura mater; site for epidural anesthesia.

Subdural Space

Potential space between dura and arachnoid mater.

Subarachnoid Space

CSF-filled space between arachnoid and pia mater; tapped during lumbar puncture.

Lumbar Spinal Puncture

Needle insertion into subarachnoid space below L2 (typically L3–L4) for CSF sampling.

Filum Terminale

Pia mater extension anchoring spinal cord to coccyx.

Denticulate Ligaments

Lateral pia extensions anchoring spinal cord to dura for stability.

Gray Matter

Central spinal cord region containing neuron cell bodies; mediates lateral communication.

White Matter

Outer spinal cord region composed of myelinated tracts ascending and descending.

Dorsal Horn

Gray matter region receiving sensory input.

Ventral Horn

Gray matter region housing motor neuron cell bodies.

Lateral Horn

Gray matter region (T1–L2, S2–S4) containing autonomic motor neurons.

Multipolar Motor Neuron

Efferent neuron type with multiple dendrites and one axon.

Pseudounipolar Sensory Neuron

Afferent neuron type with single process that splits into peripheral and central branches.

Dermatome

Skin area supplied by a single spinal cord segment.

Plexus

Network where ventral rami intermix to form new peripheral nerves.

Brachial Plexus

C5–T1 nerve network that innervates the upper limb.

Segmental Innervation

Pattern of spinal cord segments providing sensory or motor supply to specific body regions.