Lecture 7

Question 1

Spinal Cord Dermatomes

Answer 1

Area of the skin innervated by a single spinal nerve, divided into groups based on what part of the spine that nerve comes from
Partially overlapping with adjacent ones

Cervical: arms and back of the head
Thoracic: back and stomach 
Lumbar: lower back and front of legs
Sacral: buttocks and back of legs
Coccyx: pelvis and groin

Question 2

Spinal Nerves

Answer 2

31 pairs

Relays information to and from different regions of the body

Question 3

Spinal Cord Protection

Answer 3

Bony vertebrae and meninges

Question 4

Transduction

Answer 4

conversion of energy from one form into another

sensory systems transduce some energy into an action potential

Question 5

Types of Somatosensory Receptors

Answer 5

Discriminative Touch (pressure, vibration, texture): mechanoreceptors in skin send signal through dorsal column 
Proprioception (position of joints and limbs): mechanoreceptors in muscle and tendons send signals through dorsal column
Pain and Temperature (tissue damage, heat, cold): chemoreceptors in the skin travel via spinothalamic tract (anterolateral)

Question 6

Discriminative Touch

Answer 6

pressure, vibration, texture; mechanoreceptors in skin send signal through dorsal column

Question 7

Proprioception

Answer 7

position of joints and limbs; mechanoreceptors in muscle and tendons send signals through dorsal column

Question 8

Pain and Temperature

Answer 8

tissue damage, heat, cold; chemoreceptors in the skin travel via spinothalamic tract (anterolateral)

Question 9

Dorsal Horn

Answer 9

gray matter of spinal cord; contains sensory interneurons

Question 10

Ventral Horn

Answer 10

gray matter of spinal cord; contains motor neurons

Question 11

Ascending Tracts

Answer 11

myelinated axons in white matter that carry signals from spinal cord to brain
Two main ones:
Dorsal Column-touch and proprioceptive information
Anterolateral (Spinothalamic)-relays pain and temperature info to the brain

Question 12

Descending Tracts

Answer 12

myelinated axons in white matter that carry signals from brain to spinal cord

Question 13

A alpha axon

Answer 13

proprioception function
muscle spindle receptors
thickest diameter
fastest speed

Question 14

A beta axon

Answer 14

touch function
receptors: Pacinian corpuscles, Ruffini’s endings, Merkel’s discs, Meissner’s corpuscles
somewhat large diameter, somewhat fast speed

Question 15

A delta axon

Answer 15

pain, temperature function
free nerve ending receptors
somewhat small, somewhat slow

Question 16

C-fiber axon

Answer 16

temperature, pain, itch
free nerve ending receptors
small and slow
uses unmyelinated, slow active conduction all the way down the axon
SCN9A is important in C-fibers