LEC 15: Nervous system (Spinal cord, ANS & PNS)

A comprehensive set of vocabulary flashcards covering spinal cord anatomy, meninges, nerve organization, dermatomes, plexuses, major nerves, clinical notes, and CSF procedures.

Spinal cord

The neural tissue extending from the brainstem to around the L1 vertebral level, with cervical and lumbosacral enlargements.

Conus medullaris

Tapered end of the spinal cord, typically at the level of L1.

Cauda equina

Bundle of spinal nerve roots inferior to the conus medullaris that descend within the vertebral canal.

Filum terminale

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

Cervical enlargement

Region of the spinal cord with more neurons supplying the upper limbs.

Lumbar enlargement

Region of the spinal cord with more neurons supplying the lower limbs.

Cervical part

The uppermost portion of the spinal cord containing the cervical nerves (8 pairs).

Thoracic part

Midsection of the spinal cord containing the thoracic nerves (12 pairs).

Lumbar part

Section of the spinal cord containing lumbar nerves (5 pairs).

Sacral part

Section of the spinal cord containing sacral nerves (5 pairs).

Coccygeal part

Inferior tip of the spinal cord with 1 coccygeal nerve pair.

Anterior (ventral) horn

Gray matter region containing somatic motor neuron cell bodies.

Posterior (dorsal) horn

Gray matter region housing sensory neuron axons and interneurons.

Lateral horn

Gray matter region (present T1–L2) containing autonomic motor neuron cell bodies.

Gray matter

Nerve cell bodies, dendrites, and unmyelinated fibers in the spinal cord.

White matter

Myelinated axons forming tracts that transmit information to and from the brain.

Central canal

CSF-filled channel running through the spinal cord’s center.

Anterior median fissure

Front groove that divides the spinal cord along its length.

Posterior median sulcus

Back groove that divides the spinal cord along its length.

Posterior funiculus

White matter region containing sensory tracts between the posterior horns and the posterior median sulcus.

Lateral funiculus

White matter region on the sides of the spinal cord containing ascending and descending tracts.

Anterior funiculus

White matter region between the anterior horns and the anterior median fissure.

Dorsal root ganglion

Cluster of sensory neuron cell bodies on the dorsal root.

Posterior root

Dorsal root carrying sensory (afferent) fibers into the spinal cord.

Anterior root

Ventral root carrying motor (efferent) fibers from the spinal cord.

Spinal nerve

Mixed nerve formed by the fusion of dorsal and ventral roots, enclosed in an epineurium.

Epineurium

Dense connective tissue outer layer surrounding a spinal nerve.

Rami communicantes

Autonomic nerve branches that link a spinal nerve to the sympathetic trunk.

Sympathetic trunk ganglion

Ganglia forming the sympathetic trunk adjacent to the vertebral column.

Denticulate ligament

Lateral extensions of pia that help suspend the spinal cord.

Arachnoid trabeculae

Fibrous extensions of the arachnoid mater spanning the subarachnoid space.

Subarachnoid space

Space between arachnoid and pia containing CSF.

Dura mater

Tough outermost meningeal layer stabilizing the spinal cord.

Arachnoid mater

Web-like middle meningeal layer surrounding the brain and spinal cord.

Pia mater

Delicate innermost meningeal layer adherent to the spinal cord; gives rise to denticulate ligaments and the filum terminale.

Epidural space

Space between dura mater and vertebra containing fat, connective tissue, and vessels.

Subdural space

Potential space between dura and arachnoid mater.

Lumbar puncture (spinal tap)

Procedure to collect CSF by inserting a needle through skin, muscles, ligaments, dura, and arachnoid into the subarachnoid space.

Thecal sac

Dural sac surrounding the spinal cord and cauda equina containing CSF.

Phrenic nerve

C3–C5 ventral rami supply the diaphragm; essential for breathing.

Intercostal nerves

Anterior rami of spinal nerves T1–T11; T12 is subcostal.

Dermatome

Skin region innervated by a single spinal nerve.

Dermatome map

Illustration showing skin areas supplied by each spinal nerve; useful for localizing nerve injury.

Trigeminal dermatome (CN V)

Facial skin areas represented in a dermatome map (cranial nerve involvement).

Brachial plexus

Network of nerves from C5–T1 that innervates the upper limb; includes trunks, divisions, and cords.

Axillary nerve

Deltoid and teres minor innervation; sensation from superolateral arm.

Median nerve

Most forearm flexors and thenar muscles; sensory from lateral palm and fingertips.

Musculocutaneous nerve

Anterior arm muscles; sensory from lateral forearm.

Radial nerve

Posterior arm and forearm muscles; sensory from posterior arm/forearm and dorsolateral hand.

Ulnar nerve

Most intrinsic hand muscles; sensory from medial fingers.

Femoralar nerves - Femoral nerve

Innervates anterior thigh muscles; sensory from anterior/medial thigh and medial leg.

Obturator nerve

Innervates medial thigh muscles; sensory from superomedial thigh.

Sciatic nerve

Largest nerve; splits into tibial and common fibular divisions near the knee.

Tibial nerve

Part of the sciatic nerve; innervates posterior thigh/leg and sole; plantar nerves originate here.

Common fibular (peroneal) nerve

Part of the sciatic nerve; divides into deep and superficial fibular nerves; sensory from dorsum of foot.

Pudendal nerve

Sensation from external genitalia and perineum; controls anal/urogenital function.

Superior gluteal nerve

Innervates gluteus medius/minimus and tensor fasciae latae.

Inferior gluteal nerve

Innervates gluteus maximus.

Nerve to piriformis

Innervates the piriformis muscle.

Cervical plexus

Anterior rami of C1–C4 (C5 contributes) forming nerves including the phrenic nerve.

Phrenic nerve (C3–C5)

Diaphragmatic nerve essential for breathing.

Ansa cervicalis

Loop of nerves from C1–C3 supplying infrahyoid muscles.

Intercostal nerves (T1–T11)

Anterior rami of thoracic spinal nerves; T12 is subcostal.

Lumbar plexus

Anterior rami of L1–L4; gives rise to femoral, obturator, and other nerves.

Sacral plexus

Anterior rami of L4–S4; includes sciatic, pudendal, and gluteal nerves.

Sciatic nerve divisions

Tibial and common fibular divisions of the sciatic nerve near the popliteal fossa.

Pudendal nerve (S2–S4)

Sensation from external genitalia and perineum; supports pelvic floor muscles.

Dermatomes example: T10

Around the umbilicus; illustrates segmental skin innervation by a spinal nerve.

Shingles (Varicella zoster)

Reactivation of latent Varicella zoster virus in dorsal root ganglia causing a dermatomal rash.

Dorsal root ganglion vs dorsal root

Dorsal root carries sensory fibers; dorsal root ganglion houses sensory neuron cell bodies.

Grey commissure

Horizontal gray matter band around the central canal connecting left and right sides.

Intervertebral foramina

Openings through which spinal nerves exit the vertebral column.

Nerve plexus

Networks of intersecting ventral rami that supply limbs and trunk.