Medial Lemniscus

Question 1

What are the highly myelinated alpha/A receptos

Answer 1

sensory from mm spindles

Question 2

What are the highly myelinated beta receptors

Answer 2

Sensory from tendons, fuffini endings, meissners, pancian corpuscles, large hair follicles, flower spray from mm spindle

Question 3

What are the low myelinated delta receptors

Answer 3

sensory from mm spindle small hair follicles, free nerve endings for temp and pain

Question 4

what are the first order neurons of the medial lemniscus pathway

Answer 4

located in the DRG of every level- connected to various receptors in the periphery

Question 5

What do meisners, pacinian and ruffini endings detect

Answer 5

meisners- fine touch ( Alpha)

Pancian- vibration (alpha)

Ruffini- skin strech + jt deformaion (alpha)

Question 6

What do fasic fibers and tonic fibres detect

Answer 6

fasic (chain)- stretch of mm (alpha)

Tonic (flower spray)- detecting length of mm (beta)

Question 7

How posterior column of medial lemnsicus is formed

Answer 7

axons pass thru DRG and bundle into post white column (gracilis-LL medial, cunateous- UL lateral)

Question 8

Blood supply of posterior column

Answer 8

Post spinal aa

Question 9

Where is the second order neurons of medial lemniscus

Answer 9

Gracilis and cunateus nuclei in medulla

Question 10

Path thru medulla and blood supply

Answer 10

will cross thru sensorry decussation and form medial lemniscus (lower limb more ant)

Medullary branches of vertebral aa

Question 11

Path of medial lemniscus through the pons and blood supply

Answer 11

travel through the tegmentum of pons (lower limb more lateral now

pontine branches of basilar aa

Question 12

path of medial lemniscus through the midbrain and blood supply

Answer 12

ascends further (lower limb now more post)

Post cerebral aa

Question 13

where is the third order neuron of the medial lemniscus

Answer 13

Vent post lat nucleus of the thalmus

Question 14

Path of medial lemniscus after the thalmus and blood suuply

Answer 14

travel thru post limb (middle cerebellar aa)

Question 15

What is the end target of the medial lemniscus and blood supplies

Answer 15

post central gyrus + paracentral gyrus (LL)

postcentral- middle cerebelar

paracentral- cortical br of ant cerebreal aa (colosomarginal aa)

Question 16

lesion in post spinal cord would cause what

Answer 16

IL loss of prop, driscrimitive touch, vibration

Question 17

What would a lesion in cut 3/4 of the medulla cause (3)

Answer 17

• Cl prop, fine touch vib
• CL motor loss (spastic)
• Il toung weakness

Question 18

What would a lesion in cut 5/6 of pons cause (5)

Answer 18

• CL prop, fine touch, vib
• loss of discrim touch, pain, temp on IL face (trigeminal )
• paralysis of masticatory mm
• IL facial and lateral rectus
• Horners syndrome IL

Question 19

What would a lesion in cut 7 or 8 of midbrain cause (2)

Answer 19

• CL prop, fine touch, vibration

- CL loss of pain temp

Question 20

What could a lesion at the thalamus cause (2)

Answer 20

• CL prop, fine touch, vibration

- CL loss of pain temp

Question 21

What is brown sequard syndrome and what would it cause

Answer 21

Spinal cord hemisection

• IL loss of vib, fine touch , prop
• IL motor loss
• CL pain and temp loss starting two levels below lesion