week 9

Question 1

Proprioception (sense of oneself)

Answer 1

Information from the musculoskeletal system

Question 2

Exteroception (sense of external world)

Answer 2

➢ Information from the skin is superficial or cutaneous (e.g., touch, pain, temperature)

Question 3

➢ Interoception (organ system sense)

Answer 3

➢ Information from internal organs (e.g., stretch of the bladder / stomach)

Question 4

Mechanoreceptors

Answer 4

are sensitive to physical distortion such as touch, pressure, stretch, or vibration

Question 5

Nociceptors

Answer 5

are sensitive to pain.

Question 6

Thermoreceptors

Answer 6

are sensitive to changes in temperature.

Question 7

Chemoreceptors

Answer 7

are sensitive to chemical changes in the body e.g., blood pH, oxygen.

Question 8

Muscle Spindles

Answer 8

are the sensory receptors/organs
(mechanoreceptors) within the skeletal muscle belly

Question 9

muscle spindles are compromised by

Answer 9

Numerous intrafusal muscle fibers

Question 10

Muscle spindles respond to

Answer 10

muscle stretch.

Question 11

Golgi Tendon Organs (GTOs

Answer 11

are found in tendons near the musculotendinous junction.

Question 12

Golgi Tendon Organs GTOs detect

Answer 12

force / muscle tension generated during muscle contraction
This force / tension is detected by stretch of the
tendon

Question 13

Joint receptors respond to

Answer 13

mechanical deformation of joint capsules and ligaments.

Question 14

Rods & Cones special sensory receptors for

Answer 14

vision

Question 15

Hair cells special sensory receptors

Answer 15

hearing & balance

Question 16

Chemoreceptors special sensory receptors

Answer 16

taste, olfaction

Question 17

Large diameter fibres (nerve fibres)

Answer 17

Course touch, pressure, vibration, fine/light touch (tactile discrimination), proprioception
- transmitt signal faster

Question 18

• Small diameter fibres (nerve fibres)

Answer 18

• pain & temperature
• transmit signals slower

Question 19

Receptive Field

Answer 19

the receptive field of a sensory neuron is the cutaneous (skin) area which, if stimulated, leads to activity in the neuron

Question 20

Large receptor fields sensitivity

Answer 20

low sensitivity

Question 21

small receptor fields sensitivity

Answer 21

high sensitivity

Question 22

distally and proximally receptor feilds are

Answer 22

disatlly= smaller
proximal= larger

Question 23

dorsal root ganglion

Answer 23

conveys Somatosensory information from the bodies skin, muscles, joint capsules, and viscera

Question 24

Primary somatosensory cortex area number

Answer 24

3,1,2

Question 25

Nerve fibres carrying proprioception information go to what area

Answer 25

area 3 of Primary Somatosensory Cortex

Question 26

* Nerves fibres carrying texture/size/shape information go to what areas

Answer 26

area 1 & 2 Primary Somatosensory Cortex

Question 27

secondary somatosensory cortex area

Answer 27

area 40

Question 28

secondary somatosensory cortex function

Answer 28

a receives connections from the primary sensory cortex. * This responds to sensory stimuli bilaterally * with much less precision than the primary somatosensory cortex. * lesions to this area can impair sensory discrimination.

Question 29

somatosensory association cortex area number

Answer 29

area 5 and 7

Question 30

somatosensory association cortex where and function

Answer 30

is directly posterior to the sensory cortex in the superior parietal lobes. ➢receives synthesized connections from the primary and secondary sensory cortices. ➢neurons respond to several types of inputs and are involved in complex associations. * Stereognosis (tactile gnosis) / haptic perception

Question 31

Ascending Tracts 3 types

Answer 31

* Conscious relay * Divergent relay * Nonconscious (unconscious) relay

Question 32

Ascending Tracts function

Answer 32

bring somatic sensory information to the brain

Question 33

Conscious Relay Tracts

Answer 33

* Transmit information about the location and type of stimulus with high fidelity. ➢high level of, and accurate details ➢allows discrimination of information = discriminative

Question 34

Conscious Relay Tracts 3 neuron relay to the cortex:

Answer 34

1º neuron (1 st order neuron): * Cell body in a dorsal root ganglion; one axon connected to a sense organ (receptor) and the other travels into the spinal cord/or brainstem. 2º neuron (2 nd order neuron): * Cell body in the spinal cord/or brainstem; axon crosses(decussates) and goes to the contralateral Thalamus. 3º neuron (3 rd order neuron): * Cell body in the Thalamus; axon travels up to the primary sensory cortex (via the internal capsule).

Question 35

Conscious Relay Tracts * Somatic conscious sensations ascend in the spinal cord via two routes

Answer 35

➢ Dorsal column medial lemniscus tracts (DCML) ➢ Spinothalamic / Anterolateral tracts (STT)

Question 36

Dorsal Column Medial Lemniscus Tract

Answer 36

* Transmits information about fine touch, vibration, pressure, proprioception, and two-point discrimination 1º neuron - enters and ascends in dorsal column of spinal cord. Some collaterals head off in spinal cord and may contribute to motor control, or influence activity in other neurons in sensory systems, or that influence autonomic control 2º neuron: * Cell bodies located in the nucleus gracilis or cuneatus (in dorsal medulla) * Axons cross the midline (decussate) then ascend to the thalamus 3º neuron: * Cell bodies located in the Thalamus send their axons to the cortex via the Internal Capsule * Synapse to cells in the primary somatosensory cortex corresponding to the body area they originated from

Question 37

Spinothalamic / Anterolateral Tract

Answer 37

* Transmits information about fast pain, and temperature * 1º neuron (1 st order neuron): ➢brings information into the posterior horn (grey matter) of the spinal cord. * 2º neuron (2 nd order neuron): ➢have cell body in the posterior grey area of the spinal cord ➢axons of secondary neurons cross the midline and ascend from the spinal cord to the thalamus (anteriolaterally). * 3º neuron (3 rd order neuron): ➢have cell bodies in the Thalamus ➢axons project from the Thalamus to the cerebral cortex (via Internal Capsule)

Question 38

Mesencephalic nucleus

Answer 38

unconscious proprioception from muscle spindles of the face (e.g., prevents excessive biting, receives information about stretch from muscles of mastication)

Question 39

Main sensory nucleus

Answer 39

touch, vibration, 2-point discrimination, fine touch, and conscious proprioception senses

Question 40

Spinal nucleus:

Answer 40

pain & temperature, and crude touch

Question 41

Sensation of the face tracts

Answer 41

* The Trigeminal nerve (CN V) carries sensory information from the face to nuclei in the brainstem (Pons region) * 2º neurons (2 nd order neuron) then transmit the information to the Thalamus * 3º neuron (3 rd order neuron) takes from the Thalamus it to the cortical areas

Question 42

Divergent Tracts

Answer 42

* Transmission of slow pain. ➢Nociceptive sensations that are non descriptive * Information is transmitted to many locations in the brainstem and cortex. * is not localized * input is involved in arousal, attentional, motivational, sleep /wake and reflexive functions

Question 43

Nonconscious (unconscious) relay Tracts

Answer 43

* Transmits unconscious movement-related information to the cerebellum. * Unconscious proprioceptive information, as well as sensory information from muscles, joints and ligaments. * Spinocerebellar tracts: * This information is critical for automatic adjustment of movements and posture. * Not consciously perceived.

Question 44

DCML tract damage

Answer 44

* A lesion of the DCML tract causes a loss of proprioception and fine touch. * A hemi-section of the spinal cord * Ipsilateral loss below the level of the lesion * A somatosensory cortex lesion * Contralateral sensory loss

Question 45

STT tract

Answer 45

* Transmits information about pain & temperature * 1º neuron (1 st order neuron) enters the spinal cord * 2º neuron (2 nd order neuron) decussates immediately in the spinal cord at the level it enters and ascends contralaterally in the anterior column * 3º neuron (3 rd order neuron) travels from the Thalamus to the primary sensory cortex

Question 46

STT tract damage

Answer 46

* Damage to the STT will cause a loss of pain and temperature sensation. * A hemi-section of the spinal cord * Contralateral loss below the level of the lesion * A somatosensory cortex lesion * Contralateral sensory loss