Week 13: Anatomy of the Peripheral nervous system

Question 1

Somatic nervous system

Answer 1

Transmitting sensory information + voluntary movement

Question 2

Somatic nervous system pairs of nerves

Answer 2

12 cranial, 31 spinal

Question 3

Cranial nerves

Answer 3

emerge direct from brain, supply skin of face, muscles of face, special sense in head, vision, smell, balance

Question 4

Spinal nerves regions

Answer 4

Cervical:8, Thoracic:12, Lumbar:5, Sacral:5, coccygeal:1

Question 5

Where is the most excitable part of an axon?

Answer 5

Near axon Hillock

Question 6

Resting potential

Answer 6

-70mV

Question 7

Threshold potential

Answer 7

-55mV

Question 8

When are action potentials triggered

Answer 8

When membrane potential increases above -55mV

Question 9

What happens during action potential (to the membrane potential)

Answer 9

Shoots up, the abruptly down

Question 10

What info goes along unmylenated fibres?

Answer 10

pain from skin, motor fibres controlling BV and heart

Question 11

What info travels along myelinated fibres?

Answer 11

fine touch from skin, joint positon. motor fibres - skeletal muscle

Question 12

Pacinian corpuscles

Answer 12

Found in areaas of skin sensitive to touch e.g. fingertips - When deformed, nerve fibre emits sodium and an action potential is triggered

Question 13

Nociceptors

Answer 13

pain! Found in many places, part in skin. = FREE-nerve endings - chemical, thermla or mechanical changes cause AP

Question 14

what detects Skin stretch

Answer 14

Corpuscle of Ruffini

Question 15

What detects Pressure, position and features such as shapes and edges

Answer 15

Corpuscle of Merkle

Question 16

What is sensitive to light touch

Answer 16

Meissner’s corpuscle

Question 17

Where does Spinal cord extend to

Answer 17

Space between L1 and L2

Question 18

Spinal cord functions

Answer 18

Cpndiut of motor info -travelling caudially. Conduit of sensory info - rostrally. Centre for coordinating reflexes.

Question 19

Gray matter

Answer 19

Ventral, dorsal, lateral horns

Question 20

Ventral horn

Answer 20

Cell bodies - motor neurons

Question 21

Dorsal horn

Answer 21

Axons and terminals of somatosensory neurons

Question 22

Lateral horn

Answer 22

T1-L2/L3 - Cell bodies of sympathetic neurons

Question 23

White matter

Answer 23

Contains axons of ascending and descending fibre tracts.

Question 24

Dorsal column tract

Answer 24

A. same side. carry: discriminatory touch, proprioception, pressure and vibration.

Question 25

Spinothalamic tract

Answer 25

Lateral to ventral horn - nociceptor and temperature. Cross spinal cord - A. on op side

Question 26

Corticospinal tract

Answer 26

Lateral to dorsal horn. D. carries motor nerons - (skeletal muscles) info from brain. Crosses op side at brainstemish level - terminate in ventral horn

Question 27

Which tract is located lateral to dorsal horn

Answer 27

Corticospinal tract

Question 28

Loss of fine touch - where lesion ?

Answer 28

Dorsal column tract

Question 29

Loss of pressure and vibration - where lesion ?

Answer 29

dorsal column tract

Question 30

Loss of pain and temperature on op side body - where lesion?

Answer 30

Spinothalamic tract

Question 31

Loss of voluntary motor control on same side - Where lesion?

Answer 31

Corticospinal tract