Anatomy - Chapter 17: Spinal Cord and Spinal Nerves

Foramen magnum (Big Hole)

allows the spinal cord to exit the cranial cavity

Cervical (7)

Thoracic (12)

Lumbar (5)

Sacral (5)

sections of the vertebrae

Dura mater, Arachnoid mater, Pia mater (superficial to deep)

The Meninges

Epidural space

Space filled with fat and connective tissue between the vertebral canal and dura mater

Dura mater

dense irregular connective tissue; extends from the foramen magnum to S2; in the cranium separates into two layers (endosteal or periosteal dura, and meningeal dura); continuous with epineurium in peripheral nerves

Subdural Space

Space between dura and arachnoid mater filled with interstitial fluid

Arachnoid mater

weblike middle meningeal, avascular

Subarachnoid space

space between arachnoid and pia mater, filled with CSF

Pia mater

Innermost layer of the meninges

endosteal/periosteal dura and meningeal dura

the two layers of the dura mater

Meningitis

inflammation of the meninges

Spinal tap/lumbar puncture

method used to sample CSF

anterior median fissure

Best way to orient the spinal chord

Columns (white) and horns (grey)

Terms for white and grey mater

Posterior/dorsal grey horns

contains sensory nuclei and interneurons

Anterior/ventral grey horn

contains somatic motor nuclei

Lateral grey horn

contains autonomic motor nuclei

-no ___________ in cervical segment of spinal cord

Autonomic nervous system

Controls smooth muscle and gland (GI tract)

Anterior spinothalamic tract

Tract that begins i spinal chord and ends in thalamus

Sensory

Ascending Tracts = _______

Motor

descending tract = ______

decrease

As you travel from superior to inferior, the ratio of grey to white _______ as the spinal cord size______

L1, L2

Where the spinal cord ends in adults

Cauda equina

"horse's tail", a fan of nerve fibers below the spinal cord

PNS

System containing afferent and efferent fibers

8 cervical

12 thoracic

5 lumbar

5 sacral

1 coccygeal

Pairs of spinal nerves (31)

Plexusues

Interconnected nerves

C1-C5, phrenic nerve: innervates the diaphragm

Cervical Plexus contains

C5-T1, Axillary nerve, Radial nerve, Ulnar Nerve, Median nerve:

Brachial Plexus

Axillary Nerve

innervates the deltoid and teres minor muscles

radial nerve

extension of the elbow, wrist, fingers, and thumb

Ulnar nerve

Funny bone, innervates the flexor carpi ulnaris and flexor digitorum profundus

Median nerve

innervates the forearm pronation, thumb palmar abduction, thumb/index finger/long finger flexion

Subunits of the brachial plexus: Roots, Trucks, Divisions, Cords, Branches

Mnemonic: Risk Takes Don't Cautiously Behave

Femoral Nerve

L1-L4, Lumbar Plexus

Sciatic nerve, tibial nerve

L4-S4 Sacral Plexus

Femoral nerve, Sciatic nerve, Tibial nerve

Lumbosacral Plexus

Femoral nerve

innervates the flexor muscles of the hip join, extensor muscles of the knee joint, the skin of the anterior and medial aspect of thigh, and the skin of the medial side of leg and foot

Sciatic nerve

Tibial nerve and common fibular nerve combined; splits at knee into two divisions

Tibial nerve

Innervates gastrocnemius, plantaris, soleus, popliteus, tibialis posterior, flexor digitorum longus, and flexor hallucis longus