Cutaneous perception

Question 1

What are the sensory modalities?

Answer 1

Light, sound, taste, temperature, pressure and smell

Question 2

What does a mechanoreceptor detect?

Answer 2

Touch, pressure, vibration, proprioception

Question 3

What do thermoreceptors detect?

Answer 3

Changes in temperature

Question 4

What do nociceptors detect?

Answer 4

Pain resulting from physical or chemical change

Question 5

What do free nerve endings detect?

Answer 5

Pain, thermal, tickle, itch, some touch

Question 6

What do encapsulated nerve endings detect?

Answer 6

Touch, pressure, vibration

Question 7

Characteristics of encapsulated nerve endings

Answer 7

Large axon diameter

Myelinated A fibers

Question 8

Characteristics of free nerve endings

Answer 8

Small axon diameter

Unmyelinated C fibers

Question 9

What are the two touch modalities?

Answer 9

Crude and fine touch

Question 10

What is crude touch?

Answer 10

No information about location, size, shape, texture

Question 11

What are the two types of receptors?

Answer 11

Rapidly acting and slowly acting

Question 12

What are the two rapidly adapting receptors?

Answer 12

Meissner corpuscle

Hair root plexus

Question 13

Where are Meissner corpuscles found?

Answer 13

Hairless skin, e.g. hands, lips, tongue etc

Question 14

Where are hair root plexuses found?

Answer 14

Around hair follicles

Question 15

What are the two types of slowly adapting receptors?

Answer 15

Merkel discs

Ruffini corpuscles

Question 16

Characteristics of Merkel discs

Answer 16

Detect fine touch

Free nerve endings, found in epidermis

Question 17

Characteristics of Ruffini corpuscle

Answer 17

Encapsulated nerve endings
Deep in dermis
Sensitive to stretching during movement

Question 18

Which receptors detect pain?

Answer 18

Nociceptors

Question 19

Where are nociceptors found?

Answer 19

Everywhere except the brain

Question 20

Characteristics of nociceptors

Answer 20

Free nerve endings, little adaptation

Question 21

When are nociceptors activated?

Answer 21

Intense mechanical, thermal or chemical stimuli capable of causing damage

Question 22

Characteristics of fast pain

Answer 22

Within 0.1 sec, acute and sharp pain, carried by myelinated A-delta which are precisely located, very fast AP

Question 23

Characteristics of slow pain

Answer 23

More than a second, chronic and burning pain, carried by unmyelinated C fibers (AP is slower), diffusely located, intensity increases over time

Question 24

Function of proprioceptors

Answer 24

Prevent tissue damage from excessive muscle extension

Information on body position (muscle contraction, tension in tendons, position of joints)

Question 25

Function of muscle spindle

Answer 25

Detect changes in muscle stretch

Question 26

Function of Golgi tendon organs

Answer 26

Detect changes in tendon tension and protect from excessive tension

Question 27

Function of joint kinaesthetic receptors

Answer 27

Monitor stretch in synovial joints and provide information about joint position and movement

Question 28

Characteristics of thermoreceptors

Answer 28

Free nerve endings, rapidly adapting but sustain firing at low frequencies

Question 29

Characteristics of cold receptors

Answer 29

Abundant, can have myelinated A-delta or unmyelinated C fibers, activated between 10-40 degrees

Question 30

Characteristics of warm receptors

Answer 30

Unmyelinated C fibres, activated between 32-48 degrees

Question 31

Characteristics of dorsal column-medial lemniscal

Answer 31

Discriminative touch, crossover in medulla, cuneate nucleus (upper body), gracile nucleus (lower body)

Question 32

Characteristics of corticospinal tract

Answer 32

Motor (descending), crossover in spinomedullary junction

Question 33

Characteristics of spinocerebellar tract

Answer 33

Proprioception, no functional crossover

Question 34

Characteristics of spinothalamic tract

Answer 34

Pain and temperature, crossover in spinal cord

Question 35

What impact does decussation have?

Answer 35

The RHS of the bra

Question 36

Function of spinothalamic tract

Answer 36

Routes pain information from spinal cord to brainstem and thalamus, information then relayed to somatosensory cortex (pain perception)

Question 37

Function of spinofeticular tract

Answer 37

Emotional response to pain, descending modulation of pain processing

Question 38

Effect of thalamic lesion

Answer 38

Sensory loss throughout opposite side

Question 39

Effect of brain stem lesion

Answer 39

Contralateral sensory loss below face and ipsilateral on face

Question 40

Effect of central cord lesion

Answer 40

Areas of loss, often asymmetrical and dissociated

Question 41

Effect of unilateral cord lesion/hemisection

Answer 41

Contralateral spinothalamic loss; ipsilateral corticospinal muscle weakness and dorsal column (touch) loss

Question 42

Effects of tranverse cord lesion

Answer 42

Loss of all sensory and motor modalities below the lesion