anatomy : ascending pathways

Question 1

two types of senses

Answer 1

special : localised by their respective sensory organ

general: senses spread all over body

Question 2

what are the 5 special senses and what nerve are they carried in

Answer 2

1. olfaction - olfactory nerve
2. vision - optic nerve
3. taste -facial , glossopharyngeal
4. hearing - vestibulocochlear nerve
5. vestibular- vestibulocochlear nerve

Question 3

types of general senses

Answer 3

interoception
exteroception
propioception

Question 4

what is interoception

Answer 4

perceptions of sensations (pain, temperature, touch pressure) from viscera (inside body)

Question 5

exteroception

Answer 5

perception of sensations (‘’) from external world

Question 6

propioception

Answer 6

bodys ability to sense its location , movements and actions

Question 7

information is detected by;
nociceptors
Thermoreceptors
mechanoceptors

Answer 7

• monitor tissue damage
• monitor temp (found in skin muscle liver and hypothalamus)
• monitor contact and pressure

Question 8

information is detected by;
chemoreceptors
baroreceptors

Answer 8

• monitor chemical composition of body fluids (02 AND C02 ect)
• subset of mechanoreceptors , monitors changes in pressure in tubular organs such as vessels and bowels

Question 9

what are dermatomes

Answer 9

area of SKIN supplied by a particular spinal nerve

each corresponds to the entry or exit point of ventral (motor) and dorsal (sensory) rootlets

Question 10

how many dermatomes

Answer 10

31 dermatomes - 31 spinal segments

Question 11

different types of ascending somatosensory pathway in the

spinal cord

Answer 11

• spinothalamic (anterolateral)- collection of neurons that carry info to brain about pain and temp, crude touch
• medial leminiscus - large ascending bundle of myelinated axons that decussate in medulla oblongata , carry info to brain ab fine touch and conscious proprioception

Question 12

types of ascending somatosensory pathway in the spinal cord

Spinocerebellar

Answer 12

proprioception

Question 13

three orders of neurons in ascending pathways

Answer 13

1st- pns -dorsal root ganglia
2nd- cns- spinal cord
3rd- cns- thalamus

Question 14

divergence of pathway depends on sensory modality

• pain and temperature, crude touch
• fine touch and proprioceptive pathways

Answer 14

-decussate in spinal cord and ascend contrallaterally via the STT to the
primary somatosensory cortex

-ascend ipsilaterally via the Fg and Fc before decussating in the
brainstem to ascend contrallaterally via the MLP to the primary somatosensory cortex

Question 15

Trigeminothalamic tract

Answer 15

All enter brainstem and synapse at trigeminal nuclear complex (midbrain, pons and medulla)

decussate before ascending to post central gyrus