Somatosensory Pathways

Question 1

Spinal nerve root C6-C8

Answer 1

hand and fingers

Question 2

Spinal nerve root T4

Answer 2

Nipples

Question 3

Spinal nerve root T10

Answer 3

Umbilicus

Question 4

Merkel cell

Answer 4

sensation

Question 5

Anterior 2/3 of the tongue is innervated by which nerve?

Answer 5

Trigeminal provides pain, temperature and touch

Question 6

Does the Trigeminal nerve provide motor or sensory innervation?

Answer 6

It provides both

Question 7

Which branch of the Trigeminal nerve has a motor component?

Answer 7

The mandibular nerve it provides motor to the muscles of mastication

Question 8

Where does the trigeminal nerve enter the brain?

Answer 8

In the level of the mid pons

Question 9

Which nerve supplies the TMJ

Answer 9

the auriculotemporal joint (posteriorly)

Question 10

Meissner cells

Answer 10

flutter

Question 11

Two point discrimination

Answer 11

ability of the brain to discriminate between two closely spaced touch stimuli as two separate stimuli

Question 12

Greater the receptor density in a body region, _________ is the distance between two stimuli that the brain can perceive as two separate stimuli.

Answer 12

smaller

Question 13

What receptor type allows us to have proprioception?

Answer 13

Muscle fibers axon type Ia and II

Question 14

Pacinian cells

Answer 14

vibration

Question 15

Axon type of cells providing touch sensory

Answer 15

A-beta

Question 16

What receptor type allows use to feel pain and temperature?

Answer 16

Free nerve endings of axon A-delta

Question 17

Dorsal column-medial lemniscal system (DCML)

Answer 17

Allows us to feel touch and propioception.

Question 18

Anterolateral system (ALS)

Answer 18

Allows us to feel pain and temperature from the neck down.

Question 19

Trigeminothalmic tract

Answer 19

Allows us to feel pain, temperature, touch, propiception from the face, sinus, oral cavity etc.

Question 20

Steps of the DCML

Answer 20

1. mechanoreceptors (spinal cord) from the upper body synapse at the cuneate nucleus (medulla)
2. lower body mechanoreceptors (spinal cord) synapse at the gracilis nucleus (medulla)
3. upper and lower fibers merge to form the medial lemniscus any lesions here or higher will manifest in contralateral issues with touch and propioception
4. Medial lemniscus travels through mid pons, mid brain
5. 2nd order neurons synapse in the VENTRAL POSTERIOR LATERAL NUCLEUS in the somatosensory region of the post central gyrus

Question 21

What fibers synapse in the ventral posterior LATERAL nucleus (thalamus)

Answer 21

fibers from the neck, trunk and extremities

Question 22

What fibers synapse in the ventral posterior MEDIAL nucleus (thalamus)

Answer 22

fibers from the head

Question 23

Where does crossing over happen in the DCML pathway

Answer 23

In the medulla

Question 24

Cuneate nucleus (medulla)

Answer 24

Where fiber from upper extremities synapse (above T6)

Question 25

Cuneate gracilis (medulla)

Answer 25

Where fiber from lower extremities synapse (below T6)

Question 26

Where do 3rd order neurons synapse in the DCML pathway?

Answer 26

In the somatosensory cortex of the post central gyrus

Question 27

Where do the 2nd order neurons synapse in the DCML and AML pathways?

Answer 27

In the ventral posterior lateral nucleus of the thalamus

Question 28

Proprioception fibers follow the same pathway as the DCML pathway except?

Answer 28

Propiocetion fibers below L2 travel to the gracilis nucleus Propioception fibers from L2-T1 (upper extremities) travel to the CLARK NUCLEUS Form the spinocerebellar tract

Question 29

Clark nucleus

Answer 29

Where propioception fibers from L2-T1 (upper) synapse

Question 30

Dorsal spinocerebellar tract

Answer 30

Where crossing over happens in propioception fibers

Question 31

Morphosynthesis

Answer 31

recognition of objects by touching them

Question 32

Graphesthesia

Answer 32

recognition of numbers or letters traced on skin

Question 33

Anterolateral System (ALS)

Answer 33

fibers for pain and and temperature

Question 34

Where does crossing over happen in the ALS

Answer 34

in the dorsal horn of the spinal cord at the anterior white commissure

Question 35

Where does crossing over happen in the DCML pathway?

Answer 35

in the medulla

Question 36

Where does 3rd order neuron synapse in the ALS

Answer 36

Primary somatic sensory cortex

Question 37

Where does all sensory information leave the thalamus?

Answer 37

through the thalamo-cortical projections in the internal capsule (posterior limb)

Question 38

Brown Sequard Syndrome

Answer 38

damage to one side of the spinal cord DCML damage on the same side ALS damage on opposite side Corticospinal tract damage on the same side unable to move limbs Babinski signs

Question 39

Corticospinal tract

Answer 39

motor fibers coming from the PRIMARY MOTOR CORTEX OF THE PRECENTRAL GYRUS the muscles

Question 40

Where does crossing over occur in the corticospinal tract

Answer 40

In the medulla

Question 41

In the cortical tract damage below what will show ipsilateral damage?

Answer 41

damage after the pons will show on the same side. Anything above the pons (medulla, cortex, midbrain) will show on opposing side

Question 42

How to test damage of the cortical spinal tract

Answer 42

with the babinski sign if toes flex down (normal) if toes fan up (damage to the corticospinal tract)

Question 43

Main sensory nuclei in the pons

Answer 43

Pontine trigeminal nucleus for sensory and touch

Question 44

mesencephalic nucleus

Answer 44

propioception

Question 45

nucleus of the the spinal tract

Answer 45

pain and temperature

Question 46

Touch pathway of the face

Answer 46

mechanoreceptors go through the trigeminal ganglion synpase and crossover in the pons

Question 47

Pain fibers in the face

Answer 47

enter through the pons travel down in the the spinal trigeminal tract synapse in the spinal nucleus (medulla) cross over at the trigeminothalmic tract

Question 48

Vertebral artery give rise to what?

Answer 48

Anterior Spinal artery & Posterior Inferior Cerebellar artery

Question 49

Wallenberg syndrome

Answer 49

Stroke that damages PICA damage of the trigeminal nucleus Pain and temperature loss ipsilateral of face contralateral rest of the body