Chapter 12 (lecture)

Question 1

Connective tissue membranes surrounding spinal cord and brain

Answer 1

Dura mater - tough outer layer

Arachnoid mater - thin middle

Pia mater - bound tightly to surface of brain/spinal cord (forms film terminale)

Question 2

Spinal cord spaces

Answer 2

Epidural - where anesthesia is injected. Contains blood vessels/areolar CT and fat

Subdural - beneath dura

Subarachnoid - contains blood vessels

Question 3

Gray matter

Answer 3

Posterior horn

Lateral horn

Anterior horn

Question 4

White matter

Answer 4

Dorsal column

Ventral column

Lateral column

Question 5

Cross section of spinal cord

Answer 5

Anterior median fissure and posterior median sulcus - deep clefts partially separating left and right halves

Question 6

Commissures

Answer 6

• connect left and right halves
• gray matter contains central canal

Question 7

Spinal nerves and roots

Answer 7

Dorsal contains dorsal root ganglion - contains sensory neurons

Ventral root - contains motor neurons

Question 8

Afferent neurons

Answer 8

Sensory

Travel through dorsal root and live in ganglion

Travel to gray matter where they synapse into interneurons

Question 9

Reflex components

Answer 9

1. action potentials produced in sensory receptors detect stimuli, transmitted to
2. sensory neurons to
3. Interneurons which can be excitatory or inhibitory. Then to
4. Motor Neurons which leave the ventral root and leave spinal cord out of the
5. Effector Organ which responds with a reflex

Question 11

Stretch Reflex

Answer 11

• muscles contract in response to stretching force.
• unique because no interneuron
• receptor is the muscle spindle: specialized muscle cells that respond to stretch
• gamma motor neurons regulate sensitivity of the muscle spindle

Question 12

Golgi Tendon Reflex

Answer 12

• prevents contracting muscles from applying excessive force in tendons
• receptor is the golgi tendon organ: encapsulated nerve endings in tendon near muscle that detect excessive stretch and tension placed on the tendon
• produces sudden relaxation of the muscles

Question 13

Withdrawal Reflex

Answer 13

• functions to remove body limb or other part from painful stimulus
• Reciprocal innervation causes relaxation of extensor muscle when flexor muscle contracts
• Crossed extensor reflex: when a withdrawal reflex is initiated in one limb, this causes extension of opposite limb.

Question 14

Organization of Spinal Nerves

Answer 14

• 31 pairs of spinal nerves
• 1st pair exit through vertebral column between skull and atlas
• Last 4 exit through sacrum

Cervical Nerves - C1 through 8

Thoracic Nerves - T1 through 12

Lumbar Nerves - L1 through 5

Question 15

Cervical Plexus

Answer 15

Exits from C1-4

Includes Phrenic Nerve from C3-C5.

Innervates diaphragm/superficial neck structures/skin of neck/posterior head

Question 16

Brachial Plexus

Answer 16

C4, C5-T1

Nerves included: axillary/radial/ulnar/etc

Question 17

Lumbosacral Plexus

Answer 17

Lumbar: ventral rami of L1-L4

Sacral: ventral rami of L4-S4

Includes sciatic nerve

Question 18

Peripheral Nerves

Answer 18

Consists of: Axon bundles/Schwann cells/CT

Endoneurium surrounds individual neurons
Perineurium surrounds axon groups to form fascicles
Epineurium surrounds the entire nerve

Question 20

Dermatomal Map

Answer 20

Skin area map of sensory nerve distribution by letter and number