Sensory and motor inputs

Question 1

What are the 3 basic functions of neurones?

Answer 1

1. sensory input - collect info about external and internal environments
2. integration - recieve sensory input, analyse it and decide on an appropriate response
3. motor output - effects on organs or muscles

Question 2

How are receptors classified?

Answer 2

1. Anatomically - encapsulated or non-encapsulated
2. Location - exteroreceptor (near body surface, change in external environment) or proprioceptors (sensitive to movement of muscles, tendons and joints)or internoceptors (within viscera, change in internal environment)

Question 3

How is the sensory portion of the PNS classified?

Answer 3

1. Somatic afferent - dendritic zone on/near body surface

2. Visceral afferent - dendritic zone in walls of body viscera

Question 4

How can somatic afferent fibres be subdivided?

Answer 4

1. General somatic afferent (GSA) - touch, temp., proprioception and noxious stimuli. Cranial nerve V and spinal nerves
2. Special somatic afferent (SSA) - vision (cranial nerve II) and hearing (cranial nerve VIII)

Question 5

How are visceral afferent fibres subdivided?

Answer 5

1. General visceral afferent (GVA) - organ content, distension and chemicals (cranial nerve VII, IX, X to viscera in head; cranial nerve X and spinal nerves to body viscera)
2. Special visceral afferent (SVA) - taste (cranial nerves VII, IX, X) and olfaction (cranial nerve I)

Question 6

Name the 4 sensory spinal tracts and their function

Answer 6

Fasciculus gracilis - proprioceptive input from pelvic limbs
Fasciculus cuneatus - proprioceptive info from thoracic limbs
Dorsal/ventral spinocerebellar tracts - info from cerebellum from coordination
Spinothalmic tracts - info from thalamus about pain, itch, touch and temp

Question 7

How are the motor neurones of the NS classified?

Answer 7

Lower motor neurones (LMN) - neurones located in ventral horn of spinal cord/ cranial nerve of brainstem nuclei with motor function
Upper motor neurone (UMN) - originate in motor area of cerebral cortex or brainstem. Carry info to LMN

Question 8

How is the motor part of the PNS classified?

Answer 8

1. General somatic efferent (GSE) - dendritic zone in striated muscle (all cranial nerves except I, II, VIII; ventral nerve roots and spinal nerves)
2. General visceral efferent (GVE) - dendritic zone in involuntary smooth muscle of viscera (cranial nerves III, VII, IX, X, XI; spinal nerves)

Question 9

Name the 5 motor spinal tracts and their function

Answer 9

1. Corticospinal tracts (pyramidal) - motor info directly from cerebral cortex
2. Rubrospinal tracts (extrapyramidal) - motor info from red nucleus in brainstem
3. Reticulospinal tracts (extrapyramidal) - motor info from reticular formation in brainstem
4. vestibulospinal tracts (extrapyramidal) - motor info from vestibular nuclei in brain stem
5. Tectospinal tracts (extrapyramidal) - motor info from tectal region in brainstem

Question 10

Explain the grading of spinal injuries

Answer 10

0 - normal
1 - pain (no neurological deficits)
2 - ambulatory paresis
3 - non-ambulatory paresis
4 - plegia
5 - plegia with absent deep pain sensation