Anatomy Prelab 4

The deep matter of the spinal cord is considered

Gray matter

Gray matter description

Contains neuronal cell bodies, dendrites, and local circuitry; organizes into Doral, ventral, and lateral horns

The superficial matter in the spinal cord is the __

White matter

White matter description

Primarily myelinated axons organized into funiculi; carries ascending sensory and descending motor information

Which spinal cord horn is thinner and pointier

Dorsal horn

Dorsal horn function

Receives/ processes sensory information entering through dorsal roots

Which horn is larger, like butterfly wings

Ventral horn

Ventral horn function

Contains somatic motor neuron cell bodies whose axons leave through ventral roots

Lateral horn

Visceral motor/autonomic region, especially prominent in T1-L2 spinal cord segments for sympathetic outflow

Central canal

Small CSF containing channel within the spinal cord, lined by ependymal cells

Posterior, anterior, and lateral funiculi

White matter regions containing ascending and descending tracts; recognize organization rather than individual tract detail

Posterior rootlets

Sensory axons enter the spinal cord through posterior rootlets and diverge from the dorsal root

Posterior rootlets

Posterior root

Carries afferent sensory fibers toward the spinal cord

Dorsal root ganglion

Contains sensory neuron cell bodies; enlargement on the dorsal root. A lesion may affect sensory input without directly interrupting ventral root motor neurons

Anterior rootlets

Motor axons leave the spinal cord through anterior rootlets and converge into the ventral root

Anterior root

Carries efferent motor fibers away from spinal cord

Mixed spinal nerve

formed by union of dorsal and ventral roots; contains sensory, somatic motor, and autonomic fibers that form just distal to DRG

Posterior ramus

Mixed branch supplying intrinsic back muscles, vertebral joints, and overlying skin

Anterior ramus

Mixed branch supplying anterolateral trunk and limbs, forms major nerve plexuses except in much of the thoracic region

Spinal cord

CNS structure connecting brain and peripheral nerveser

Cervical enlargement

Increased neural tissue associated with upper-limb innervation and the brachial plexus

Lumbosacral enlargement

Increased neural tissue associated with lower limb innervation and the lumbar/sacral plexuses

Conus medullaris

Tapered inferior end of the adult spinal cord, typically near L1-L2

Cauda equina

Descending lumbar and sacral nerve roots inferior to the conus; roots travel within the lumbar cistern before exiting

Filum terminale

Slender continuation from the conus that contributes to longitudinal stabilization of the spinal cord

Lumbar cistern

CSF-containing subarachnoid region containing cauda equine: lumbar puncture is performed below the adult cord to reduce risk of cord injury

Meningeal branch

Re-enters the vertebral canal to supply structures within/around the canal

Intervertebral foramen

Passage through which spinal roots and associated vessels enter or leave the vertebral canal; clinically relevant to nerve-root compression

Peripheral nerve

Bundle of PNS axons carrying sensory, motor, and autonomic signals between the CNS and peripheral targets

Nerve fascicle

Bundle of axons within a peripheral nerve

Endoneurium

Connective tissue surrounding individual peripheral nerve fibers eriP

Perineurium

Connective tissue sheath surrounding a nerve fascicle; contributes to the protected internal environment of the fascicle

Epineurium

Outer connective tissue sheath surrounding the entire peripheral nerve and its fascicles

Cervical plexus

Network formed primarily by anterior rami of upper cervical spinal nerves; recognize as a ventral-ramus plexus

Brachial plexus

Anterior-ramus plexus distributing spinal nerve fibers to the upper limb

Lumbar plexus

Anterior ramus plexus contributing peripheral nerves to the lower trunk and limb

Sacral plexus

Anterior-ramus plexus contributing major peripheral nerves to the pelvis and lower limb

Neuron cell body

Metabolic/integrative region containing the nucleus; motor neuron somata may be recognized in spinal gray matter

Dendrites

Receive synaptic input and conduct graded signals toward the cell body

Axon

Conducts action potentials away from the cell body toward another neuron or effector

Myelin sheath

Electrical insulation around selected axons that increases conduction efficiency

Node of ranvier

Gap between myelin segments where action potentials are regenerated during saltatory conduction

Schwann cell

PNS glial cell responsible for myelination/ensheathment of peripheral axons

Oligodendrocyte

CNS glial cell responsible for myelinating CNS axons

Satellite cell

PNS glial cell surrounding neuronal cell bodies in peripheral ganglia, including the dorsal root ganglion

Astrocyte

CNS support cell involved in structural/ metabolic support and regulation of the neural environment

Microglia

Resident immune/phagocytic cells of the CNS

Ependymal cells

Line the ventricles and central canal; specialized ependymal cells contribute to choroid plexus CSF production tL

Lateral horn/intermediolateral cell column

Contains preganglionic sympathetic neuron cell bodies in T1-L2

White ramus communicans

Carries myelinated preganglionic sympathetic fibers from a spinal nerve into the sympathetic trunk; present at only T1-L2

Sympathetic trunk

Paired longitudinal chains alongside the vertebral column that allow sympathetic fibers to synapse, ascend, or descend

Sympathetic trunk ganglion

Contains sympathetic postganglionic neuron cell bodies

Gray ramus communicans

Carries unmyelinated postganglionic sympathetic fibers from the sympathetic trunk back to a spinal nerve; gray rami occur at all spinal nerve levels

Thoracic splanchnic nerve

Carries primarily preganglionic sympathetic fibers toward pre vertebral ganglia; distinguish from gray rami returning fibers toward spinal nerve

Prevertebral ganglion

Sympathetic ganglion anterior to the vertebral column/aorta where many abdominopelvic preganglionic fibers synapse

Adrenal medulla

Modified sympathetic ganglion receiving preganglionic sympathetic fibers directly; releases catecholamines into bloodstream