Chapter 12 Spinal Cord and Spinal Nerves

Spinal cord location

Extends from foramen magnum to between L1-L2

Cervical Enlargement

Give rise to to nerves that innervate the upper extremities through the Brachial plexus

Lumbar Enlargement

Give rise to nerves that innervate lower extremities through the Lumbosacral plexus

Conus medullaris

Cone-shaped taper inferior end

Film terminale

Anchors the spinal cord to the coccyx

Number of spinal nerve pairs

31 pairs of spinal nerves

Epidural space

Location for epidural anesthesia

Subdural space

Space with serous fluid

Subarachnoid space

Space to extract that has CSF to test for meningitis

Dorsal root

Root that has sensory (afferent) neuron

Ventral root

Root that has motor (efferent) neuron

Location of multipolar neuron cell bodies

Anterior grey horn

Location of Autonomic (Sympathetic) neuron cell bodies

Lateral grey horn

Integration center

Space in the spinal cord where the action potential is carried to, involves an interneuron and synapses with motor neuron

Simple reflexes do not involve

an interneuron

Specific motor neurons

Gamma motor neurons (small diameter) that control sensitivity of muscle spindle

Alpha motor neurons

Motor neurons of the spinal cord that cause the muscle to contract after being signaled by specific motor neurons

Excitation of the alpha motor neuron

Results in contraction of the flexor muscles

Nicotinic

Receptors that bind to Acetinocholine

Spinal nerves connective tissues

Endoneurium, Perineurium, Epineurium

Endoneurium

Surround individual neurons (inside)

Perineurium

Surround axon groups to form fascicles (middle)

Epineurium

Surround the entire nerve (outside)

Pairs of Cervical spinal nerves

8 pairs

Pairs of Thoracic spinal nerves

12 pairs

Pairs of Lumbar spinal nerves

5 pairs

Pairs of Sacral spinal nerves

5 pairs

Pairs of Coccygeal spinal nerves

1 pair

Dermatome map

mapping of innervation to muscles

Innervation of upper limbs and head

Cervical nerves (C1-C8)

Innervation of rib movement/breathing/posture

Thoracic nerves (T1-T12)

Innervation of hip movement

Thoracic and Lumbar nerves (T11-L2)

Innervation of Lower limb movement

Lumbar and Sacral nerves (L2-S5)

Cervical plexus

C1-C4 innervates neck and posterior portion of head

Phrenic nerve

C1-C3, innervates diaphragm

Brachial Plexus

C5-T1, give rise to nerves of the upper extremities

Posterior cord

Axillary nerve and Radial nerve

Lateral cord

Musculocutaneous nerve and ½ of the Median nerve

Medial cord

Ulnar nerve and ½ of Median nerve

Axillary nerve

Innervates deltoid and Teres minor muscle

Axillary nerve sensory innervation

Inferior and lateral part of shoulder

Radial nerve

Innervates the triceps brachii

Musculocutaneous nerve motor innervation

Innervates the biceps brachii

Ulnar nerve

Innervates the flexor carpi ulnaris

Ulnar nerve

Palm side: pinkie and ½ ring finger

Back side: pinkie ½ ring finger and part of middle

Median nerve

Thumb, pointer, middle, ½ ring. 2/3 of the palm

Carpal tunnel syndrome

Median nerve gets squeezed causing numbness of tingling in thumb-middle fingers

Lumbar plexus

L1-L4, innervation to groin, thigh, leg and lower abdomen

Sacral plexus

L4-S4, sensory innervation to butt, back leg, lower leg, and foot

Obturator nerve

Medial and superior aspect of inner thigh

Femoral nerve

Anterior aspect of the thigh and medial aspect of leg

Tibial nerve

Soler of foot and lateral and posterior 1/3 of leg

Fibular nerve

Lateral surface of knee and front portion of lower leg

Autonomic (sympathetic) neurons

Specialized nerve cells within the autonomic nervous system (ANS) that control involuntary "fight-or-flight" responses

Multipolar somatic neurons

the most common type of nerve cell, characterized by one axon and multiple dendrites, responsible for carrying voluntary commands from the brain/spinal cord directly to skeletal muscles, controlling movement and muscle tone