Somatosensory Pathyways

Question 1

The somatosensory pathways include descending or ascending pathways?

Answer 1

Ascending pathways

Question 2

What are the two tracts that are a part of the somatosensory pathway in the rostral, caudal midbrain, middle, caudal pons, and rostral medulla?

Answer 2

Medial lemniscus
Spinothalamic tract

Question 3

What are the tracts and nuclei that are a part of the somatosensory pathway in the caudal medulla,

Answer 3

Ascending pathways: Gracile tract, cuneate tract, internal arcuate fibers, medial lemniscus, spinothalamic tract
Nuclei: gracile nucleus, cuneate nucleus

Question 4

What tracts are part of the ascending pathway in the cervical spinal cord?

Answer 4

Gracile tract
Cuneate tract
Spinothalamic tract

Question 5

What is the purpose of the posterior column-medial lemniscus pathway?

Answer 5

Carry peripheral information to the brain

Question 6

What is the definition of somatosensory?

Answer 6

All sensations arising from the skin, connective tissue, voluntary muscles, periosteum and teeth

Question 7

What are the touch sensations?

Answer 7

Discriminative touch
Pressure
Vibration
Conscious proprioception

Question 8

There are 3 types of discriminative touch. What are they?

Answer 8

Two-point discrimination: telling 2 points apart
Stereognosis: ID objects via touch only
Graphesthesia: ID writing on skin by touch only

Question 9

What are pain and temperature sensations?

Answer 9

Pain (nociception)
Temperature
Nondiscriminative touch

Question 10

What is proprioception?

Answer 10

Conscious and nonconscious information from structures including muscle spindles and golgi tendon organs regarding position sense and movement
Ability to consciously know where body parts are, knowing about position sense and movement

Question 11

Peripheral components: some somatosensory neurons are associated with ____ while others are ___ nerve endings

Answer 11

Receptors
Free nerve endings

Question 12

What are the three categories of somatosensory receptors?

Answer 12

Mechanoreceptors (tactile sensation)
Pain receptors
Thermoreceptors

Question 13

The posterior column-medial lemniscus pathway conveys which sensations

Answer 13

Discriminative touch
Conscious proprioception

Question 14

The cuneate tract of the posterior column-medial lemniscus pathway is responsible for

Answer 14

Upper limb

Question 15

The gracile tract of the posterior column-medial lemniscus pathway is responsible for

Answer 15

Lower limb

Question 16

Posterior column-medial lemniscus pathway: first order neurons structure locations

Answer 16

Cell bodies: posterior root ganglia
Central processes: gracile tract (lower limb), cuneate tract (upper limb)

Question 17

Posterior column-medial lemniscus pathway: second order neurons structure locations

Answer 17

Cell bodies: gracile and cuneate nuclei
Axons: medial lemniscus

Question 18

Posterior column-medial lemniscus pathway: third order neurons structure locations

Answer 18

Cell bodies: VPL nucleus of thalamus
Axons: posterior limb of internal capsule

Question 19

Vascular territories of PCML pathway: Spinal cord is supplied by

Answer 19

Posterior spinal artery

Question 20

Vascular territories of PCML pathway: Medulla is supplied by

Answer 20

Anterior and posterior spinal artery

Question 21

Vascular territories of PCML pathway: Pons is supplied by

Answer 21

Paramedian artery (basilar)

Question 22

Vascular territories of PCML pathway: Midbrain is supplied by

Answer 22

Quadrigeminal artery
Posterior cerebral artery

Question 23

Spinothalamic (anterolateral) pathway conveys which sensations

Answer 23

Pain
Temperature
Nondiscriminative touch

Question 24

Spinothalamic pathway: First order neurons structure locations

Answer 24

Cell bodies: posterior root ganglia
Central processes: posterior roots

Question 25

Spinothalamic pathway: Second order neurons structure location

Answer 25

Cell bodies: posterior horn Axons: anterior white commissure and spinothalamic tract

Question 26

Spinothalamic pathway: third order neurons structure location

Answer 26

Cell bodies: VPL nucleus of thalamus Axons: posterior limb of internal capsule

Question 27

Vascular territories of the spinothalamic pathway: spinal cord supplied by

Answer 27

Anterior spinal artery

Question 28

Vascular territories of the spinothalamic pathway: medulla supplied by

Answer 28

Vertebral artery

Question 29

Vascular territories of the spinothalamic pathway: pons supplied by

Answer 29

ACA, long circumferential artery

Question 30

Vascular territories of the spinothalamic pathway: midbrain supplied by

Answer 30

PCA, quadrigeminal artery

Question 31

What part of the internal capsule is associated with the spinothalamic pathway

Answer 31

Posterior limbs Axons from VPL of thalamus go through post limb of internal capsule to somatosensory cortex

Question 32

What is the somatosensory association cortex responsible for?

Answer 32

Higher level processing of sensory information

Question 33

Review of blood supply to cerebrum: MCA supplies ... PCA supplies ... ACA supplies ....

Answer 33

MCA: lateral cerebral hemispheres PCA: medial temporal and occipital lobes ACA: medial frontal and parietal lobes

Question 34

Posterior column-medial lemniscus pathway is ...

Answer 34

Touch pathway

Question 35

Spinothalamic pathway is ....

Answer 35

Pain and temperature pathway

Question 36

The cranial touch pathway conveys ....

Answer 36

Sensation for discriminative touch and conscious proprioception

Question 37

Information to the cranial touch pathway primarily comes from ....

Answer 37

Trigeminal nerve

Question 38

The cranial touch pathway is also called the ___ pathway

Answer 38

Trigeminal

Question 39

Cranial touch pathway: first order neurons structure location

Answer 39

Cell bodies: trigeminal ganglion Central processes in trigeminal nerve

Question 40

Cranial touch pathway: second order neurons structure location

Answer 40

Cell bodies: principal sensory trigeminal nucleus Axons: trigeminothalamic tract

Question 41

Cranial touch pathway: third order neurons structure location

Answer 41

Cell bodies: VPM nucleus of thalamus Axons: posterior limb of internal capsule

Question 42

What sensations are conveyed by the cranial pain and temperature pathway?

Answer 42

Pain Temperature Non discriminative touch

Question 43

Damage of the cranial touch pathway at the level of the pons and above leads to

Answer 43

Loss of touch only

Question 44

Damage at the cranial touch/pain and temp pathway below the pons leads to

Answer 44

Loss of pain and temp

Question 45

Decussation occurs at the level of the ___ in the cranial touch and cranial pain and temp pathway

Answer 45

Medulla

Question 46

Cranial pain and temp pathway: first order neurons structure locations

Answer 46

Cell bodies: trigeminal ganglion Central processes: CN V, spinal trigeminal tract

Question 47

Cranial pain and temp pathway: second order neurons location

Answer 47

Cell bodies: spinal trigeminal nucleus Axons: trigeminothalmic tract

Question 48

Cranial pain and temp pathway: third order neuron structure location

Answer 48

Cell bodies: VPM nucleus of thalamus Axons: posterior limb of internal capsule

Question 49

Where is the point of decussation of the cranial pain and temperature pathway?

Answer 49

Second order neuron