SOMATOSENSORY SYSTEMS I LAB #4: SOMATOSENSORY SYSTEMS I

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

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

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

LAB EXERCISE: DORSAL COLUMN/MEDIAL LEMNISCUS SYSTEM

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

Haines 5-1 Gracile Fascicle Cuneate Fascicle Sacral Level

Haines 5-2 Gracile Fascicle Cuneate Fascicle Lumbar Level

Haines 5-3 Dorsal Intermediate Sulcus Gracile Fascicle Cuneate Fascicle Starts @T6 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

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

Haines 5-5 Gracile Fascicle Cuneate Fascicle C1 Level

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

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

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

Haines 5-17 Medial Lemniscus Caudal Pons Level

Haines 5-18 Medial Lemniscus Rostral Pons Level

Haines 5-20 Medial Lemniscus Rostral Pons Level

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

Haines 5-23 Medial Lemniscus Caudal Midbrain Level

Haines 5-25 Medial Lemniscus Rostral Midbrain Level

Haines 5-26 Medial Lemniscus Midbrain/Dienceph jctn

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

Haines 4-6

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

Radiology

Black Board 28 Dorsal Columns

Black Board 29 DCML

Black Board 30 DCML

Black Board 31 DCML

Black Board 33 Posterior limb of internal capsule