Lecture 9

Question 1

Describe how sensory info comes in

Answer 1

Have sensory receptors in the periphery, sensory systems carrying different modalities

Question 2

What are the main types of sensory modailities?

Answer 2

-Proprioception
-Superficial touch
-Deep touch
- Vibration
- Pain
- Temperature

Question 3

Receptors carrying proprioception

Answer 3

muscle spindles and glogi tendon organs from muscle stretch

Question 4

Receptors for superificial touch

Answer 4

meissner’s corpuscle and merkle receptors

Question 5

Receptors for deep touch, vibration

Answer 5

pacinian corpuscle, ruffini ending

Question 6

Receptors for pain and temperature

Answer 6

bare nerve endings

Question 7

Dermatome

Answer 7

Cutaneous region associated with a spinal segment

Question 8

Trigeminal nerve innervates the

Answer 8

face region

Question 9

Cutaneous region associated with with cervical cord

Answer 9

back of head, neck and upper half of arms

Question 10

Cutaneous region associated with with thoracic cord

Answer 10

lower half of arms and trunk and thorax

Question 11

Cutaneous region associated with with lumbar cord

Answer 11

front and sides of legs

Question 12

Cutaneous region associated with with sacral region of cord

Answer 12

back of legs, feet

Question 13

C5 nerve innervates

Answer 13

lateral part of upper arm/deltoids

Question 14

C6 nerve innervates

Answer 14

upper half of the lower arm

Question 15

C6, C7, C8 nerve innervates

Answer 15

hand

Question 16

T1 nerve innervates

Answer 16

lower half of lower arm, including over elbow

Question 17

How trunk is innervated

Answer 17

upper trunk levels innervates high up, lower thoracic level innervates lower trunk

Question 18

level of spinal cord innervates around nipples

Answer 18

T4

Question 19

level of spinal cord innervates at level of umbilicus

Answer 19

T10

Question 20

Above nipples in trunk innervates by

Answer 20

T2, T3, T4

Question 21

Below nipples and above umbilicus innervates by

Answer 21

T5-T10

Question 22

L2 innates

Answer 22

upper part of thighs

Question 23

L3 innervates

Answer 23

Knees

Question 24

L4 innervtes

Answer 24

Medial aspect of leg

Question 25

L5 innervates

Answer 25

lateral aspect of leg

Question 26

S1 innervates

Answer 26

achillies tendon

Question 27

Two main ascending sensory pathways (once info enters into spinal cord) that carry info to sensory regions of cortex

Answer 27

- posterior column-medial lemniscus pathways (PCML) - Antero-lateral pathway

Question 28

How are ascending pathways named

Answer 28

for where they travel - PCML- travel in posterior column of SC, through medial leminiscus higher up - Anterlateral pathways travel in anterolateral column of SC

Question 29

Info that Posterior column-medial lemniscus pathways carries

Answer 29

vibration, proprioception, light touch information (good sensations)

Question 30

Info that antero-lateral pathway carries

Answer 30

pain, temperature, crude touch info (bad sensations)

Question 31

Describe pathway of PCML tract (first order neuron)

Answer 31

- Involves three neurons - Receptor in periphery, sends action portential through mixed nerve until gets to intervertebral formen where it splits and enters dorsal root. Bulge (dorsal root ganglion) contain cell bodies for primary sensory neurons. From cell bodies have second axon (of primary sensory neuron) through dorsal root into dorsal horn. Axons buifurface, one branch to nuclei at level of spinal cord- e.g. if simple stretch reflex pathways innervate to motor nuclei back out to muscle. Other branch enters posterior column of white mater and ascends.

Question 32

Describe the organsiation of upper and lower motor neurons in PC-ML pathway

Answer 32

- Lower body- primary sensory neurons travel in fasciculus gracilis - Upper body- primary sensory neurons travel in fasciculus cunateatus - Maintains somatotopic organisation: - Leg= medial - Arms-lateral

Question 33

Describe PC-ML tracts from first order neuron

Answer 33

travels to caudal medulla. Axons of fascuculus gracilis synapse on nucleus gracilis (medial nuclei). Axons in fasciculus cunateatus synapse on nucleus cuneatus (lateral nuclei). Second order neurons travels from nucli and cross midline in caudal medulla and synapse in thalamus (contralteral side they originated). This tract in called medial lemniscus. Third order sensory neurons from thalamus go to somatosensory cortex

Question 34

Identify this pathway

Answer 34

Posterior Column-Medial Lemniscus pathway