Nervous System

Question 1

Classifications of the spinal tracts

Answer 1

1. Spinothalamic (Antero-lateral)
2. Dorsal Column Medial Lemniscus 3. Spinocerebellar
3. Trigemino-thalamic

Question 2

Modalities for spinothalamic tract

Answer 2

Anterior: crude touch, pressure
Lateral: pain and temperature

Question 3

Process for spinothalamic tract

Answer 3

1º neuron at drg

2º neuron at DH of grey matter @ spinal cord, decussates and crosses midline to

3º neuron at thalamus

sensory cortex (post central gyrus) in cerebral cortex (where sensory information is CONSCIOUSLY perceived)

Question 4

Modalities for dorsal column medial lemniscus

Answer 4

1. Fine, discriminative touch
2. Vibration and pressure
3. Conscious proprioception

Question 5

Process for DCML

Answer 5

1º neuron at DRG, receives stimulus from Meissner’s corpuscles, Pacinian corpuscles

2º neuron at MEDULLA OBLONGATA decussates & crosses midline

3º neuron at THALAMUS where sensory information is processed and relayed to

sensory cortex

Question 6

Functions of spinocerebellar system

Answer 6

1. Control muscle tone
2. Coordination
3. Regulate movements

Question 7

Process of spinocerebellar system

Answer 7

1º neuron at DRG

2º neuron at DH @ spinal cord
(1) Dorsal spinocerebellar tract (dominant), DO NOT CROSS –> inferior cerebellar peduncle (cerebellum)

(2) Ventral spinocerebellar tract, DECUSSATES –> superior cerebellar peduncle (cerebellum)

Question 8

What are the 4 cutaneous mechanoreceptors

Answer 8

1. Meissner’s corpuscles
2. Merkel’s disc
3. Ruffini nerve ending
4. Pacinian corpuscle

Question 9

Function of Meissner’s Corpuscle

Answer 9

Changes in texture, slow vibrations

Question 10

Function of Merkel’s disc

Answer 10

Sustained touch and pressure

Question 11

Function of Ruffini’s nerve endings

Answer 11

Sustained pressure

Question 13

Classification of the Somatic Motor Pathways

Answer 13

PYRIMIDIDAL SYSTEM
1. Corticospinal tract
2. Corticobulbar tract (Nuclear)

EXTRAPYRIMIDAL SYSTEM
1. Rubrospinal tract
2. Tectospinal tract
3. Vestibulospinal tract
4. Reticulospinal tract

Question 14

Function and process of rubrospinal tract

Answer 14

1. Neuronal cell bodies of UMNs @ RED NUCLEUS of midbrain
2. VH of spinal cord (synapse)
3. LMNs → FLEXOR MUSCLES

Question 15

Function and process of TECTOspinal tract

Answer 15

1. Neuronal cell bodies of UMNs @ superior colliculus/ TECTUM of midbrain
2. VH of spinal cord
3. LMNs → REFLEX TO VISUAL STIMULI

Question 16

Function and process of vestibulospinal tract

Answer 16

1. Neuronal cell bodies from VESTIBULAR NUCLEI @ PONS
2. (a) MEDIAL → VH of cervical cord → correct position of head and neck

(b) LATERAL → VH of LUMBAR cord → extensor muscle, tone and equilibrium