1. SOMATOSENSORY SYSTEMS I
LAB #4:
SOMATOSENSORY SYSTEMS I

2. Summary of DCML Midbrain Pons Rostral Medulla Caudal Medulla
L4 Spinal Level
Midbrain
Pons
Rostral Medulla
Caudal Medulla
Cervical Vertebra
Lumbar vertebra
Discriminative Touch,
Vibration
Concious Proprioception
Graphesthesia

3. Carries proprioceptive, tactile receptive and motor neuron pool activity information
Cerebellum then modifies actions of different muscle groups so that movements are performed smoothly and accurately.
Not conciously aware of this process.
Disorders of this tract  ataxia = motor incoordination of extremities
Clinically impossible to distinguish problems in this tract
Spinocerebellar
System Overview
IPSILATERAL path to cerebellum via cerebellar peduncles

4. Discriminative touch,
Concious proprioception
Vibration
body trunk and limbs
Large diameter fibers
Cell bodies in DRG
Central processes ascend in Dorsal Columns
Terminate in Gracile and Cuneate Nuclei in Caudal medulla
Send axons across midline in caudal medulla
Ascend in medial lemniscus
Synapapse in VPL of thalamus
Sends fibers through posterior limb of internal capsule
To poscentral gyrus (S1)
Cortex processing  perception, recognition and localization

5. LAB EXERCISE: DORSAL COLUMN/MEDIAL LEMNISCUS SYSTEM

8. Gracile and Cuneate Tubercles are the first processing centers for the DCML

9. Haines 5-1
Gracile Fascicle
Cuneate Fascicle
Sacral Level

10. Haines 5-2
Gracile Fascicle
Cuneate Fascicle
Lumbar Level

11. Haines 5-3 Dorsal Intermediate Sulcus Gracile Fascicle
Cuneate Fascicle
Spinocerebellar Tracts
Unconcious Proprioception
(Anterior and posterior)
Travels all the way up the lateral side of the spinal columns until it synapses in the Rostral Medulla
Cerebellum
Is concerned with modulating reflex activity and modifying outgoing motoro commmands from other brain regions based on ongoing motor actions.
Thoracic Level

12. Haines 5-4 Dorsal Intermediate Sulcus Gracile Fascicle
Cuneate Fascicle
C7 Level

13. Haines 5-5
Gracile Fascicle
Cuneate Fascicle
C1 Level

14. Haines 5-9 Gracile Nucleus Cuneate Nucleus Caudal Medulla Level
Sensory Decussation
Caudal Medulla Level
Beginning of Medial Lemniscus

15. Note: Fibers of the Medial Lemniscus are only foud in the lower part of the outlined area between the inferior olivary nuclei.
Haines 5-11
Medial Lemniscus
Midrostral Medulla Level

16. Haines 5-12 Inferior Cerebellar Peduncle Spinocerebellar tract
Sends spinocerebellar fibers to the cerebellum
Spinocerebellar
tract
Medial Lemniscus
Rostral Medulla Level

17. Haines 5-17
Medial Lemniscus
Caudal Pons Level

18. Haines 5-18
Medial Lemniscus
Rostral Pons Level

19. Haines 5-20
Medial Lemniscus
Rostral Pons Level

20. Haines 5-22
Note: In the midbrain the Medlial lemnsicus moves dorsally to enter the Thalamus
Medial Lemniscus
Pons/midbrain jctn Level

21. Haines 5-23
Medial Lemniscus
Caudal Midbrain Level

22. Haines 5-25
Medial Lemniscus
Rostral Midbrain Level

23. Haines 5-26
Medial Lemniscus
Midbrain/Dienceph jctn

24. Note: Within the thalamus, the VPL is in a ventral group of nuclei, in the lateral mass. Within the ventral group it is posterior

25. Haines 4-6

26. Haines 5-30 Ventral Posterolateral (VPL) nucleus of Thalmus Thalmus
Posteror Limb of Internal Capsule
Thalmus

27. Radiology

28. Black Board 28
Dorsal Columns

29. Black Board 29
DCML

30. Black Board 30
DCML

31. Black Board 31
DCML

32. Black Board 33
Posterior limb of internal capsule