BSC2085L Lesson 10 Spinal Cord Anatomy and Nerve Plexuses Overview

Conus medullaris

Cone-shaped end of spinal cord at L1-2.

Cauda equina

Bundle of spinal nerves below L2, resembles horse tail.

Meninges

Three protective membranes covering the spinal cord.

Pia mater

Innermost meningeal layer, extends to coccyx.

Denticulate ligaments

Pia mater extensions securing spinal cord to vertebrae.

Gray matter

Region containing neuron cell bodies in spinal cord.

Dorsal horns

Contain interneurons and sensory fibers from ganglia.

Ventral horns

Contain motor neurons for somatic nervous system.

Lateral horns

Contain sympathetic motor neurons of autonomic nervous system.

Gray commissure

Connects left and right gray matter horns.

White matter

Region containing myelinated axons in spinal cord.

Dorsal funiculus

Carries proprioception and fine touch information.

Lateral funiculus

Transmits proprioception, pain, temperature, and motor info.

Ventral funiculus

Relays pain, temperature, and motor control information.

Dorsal (posterior) median sulcus

Shallow groove on dorsal side of spinal cord. (note: it's a sulcus, not a fissure)

Ventral (Anterior) median fissure

Deep groove on ventral side of spinal cord. (DAM fissure - Deep Anterior Median fissure)

Spinal nerves - how many pairs?

31 pairs of mixed sensory and motor nerves.

Ventral rami

Branches forming nerve plexuses, except thoracic nerves.

Cervical plexus

Nerve network from C1-C5, serves neck and shoulder.

Phrenic nerve

Major motor branch of cervical plexus, innervates diaphragm.

Brachial plexus

Nerve network from C5-T1, serves upper limb.

Lumbar plexus

Nerve network from L1-L4, serves lower abdomen and legs.

Sacral plexus

Nerve network from L4-S4, serves pelvic region.

Brachial Plexus

Network serving shoulder, arms, and hand.

Axillary Nerve

Innervates shoulder muscle and skin area.

Radial Nerve

Supplies extensor muscles of arm and forearm.

Median Nerve

Innervates flexor muscles of forearm and hand.

Musculocutaneous Nerve

Serves forearm flexors and lateral forearm skin.

Ulnar Nerve

Innervates hand muscles and medial hand skin.

cords of brachial plexus

Divisions of brachial plexus leading to nerves.

Femoral Nerve

Innervates anterior thigh muscles.

Saphenous Nerve

Branch of femoral nerve serving skin.

Sciatic Nerve

Largest nerve, serves lower limb.

Common Fibular Nerve

Branch of sciatic nerve serving leg.

Tibial Nerve

Branch of sciatic nerve serving foot.

Lumbar Plexus

Serves lower abdominopelvic region and thigh.

Sacral Plexus

Serves buttock, thigh, leg, and foot.

Ventral Rami

Nerve roots contributing to plexuses.

Femoral Nerve

Major nerve at the front of the leg.

Saphenous Nerve

Nerve descending after femoral nerve branches.

Tibial Nerve

Nerve on the medial side of the leg.

Common Fibular Nerve

Nerve on the lateral side of the leg.

Sciatic Nerve

Large nerve at the back of the leg.

Autonomic Nervous System (ANS)

Controls involuntary bodily functions.

Preganglionic Neuron

Neuron in CNS before synapsing in ganglion.

Ganglionic Neuron

Neuron located in ganglion outside CNS.

Sympathetic Division

ANS division for fight or flight response.

Parasympathetic Division

ANS division for rest and digestion.

Sympathetic Trunk Ganglia

Bulges along sympathetic trunk nerve chain.

Norepinephrine

Neurotransmitter released by sympathetic postganglionic axons.

Acetylcholine

Neurotransmitter released by parasympathetic postganglionic axons.

Lateral Horn

Part of spinal cord with sympathetic neurons.

Paravertebral Ganglion

Ganglion alongside vertebral column for sympathetic neurons.

Terminal Ganglion

Ganglion close to target organ in parasympathetic.

Intramural Ganglion

Ganglion located within the target organ.

Cardiac Muscle

Muscle type controlled by the ANS.

Smooth Muscle

Muscle type in blood vessels, controlled by ANS.