Spinal cord
- Long tube of neurons and support cells
- Extends from brainstem to the lumbar region
- Acts as highway for the flow of information between the brain and body
Grey matter
- Consists of nerve cell bodies, short interneurons and glial cells
- Contains a central canal filled with CSF
- Can be divided into regions called horns
White matter
- Contains bundles of axons
- Each bundle is connected to a specific region of the brain to transmit information
Whats located in the ventral horn?
Cell bodies of efferent motor neurons
Whats located in the lateral horn?
Cell bodies for the autonomic efferent fibres
Whats located in the dorsal root ganglia?
The cell bodies for the afferent nerves
Cell bodies for the afferent nerves function
Receive information from the periphery and relay it to the interneurons of the dorsal horn within the spinal grey matter
2 different pathways that connect the dorsal root ganglia to the spinal cord
- The dorsal root containing the afferent input
- The ventral root containing the efferent output
Structure of a nerve
- Bundle of peripheral afferent and efferent axons, covered in connective tissues
- Contains several nerve fascicles
What are nerve fascicles?
Bundles of myelinated or unmyelinated axons in connective tissues and blood vessels
Cervical nerves
8 pairs of nerves that emerge from the neck
Thoracic nerves
12 pairs of nerves that emerge from the chest
Lumbar nerves
5 pairs of nerves that emerge from the abdomen
Sacral nerves
5 pairs of nerves that emerge from the pelvis
Coccygeal nerves
1 pair of nerves that emerge from the tailbone
Function 1 of the spinal cord
The medium for transmitting information between the brain and the periphery
Function 2 of the spinal cord
- Integrating certain afferent inputs and efferent outputs which bypass the brain
- Called spinal reflexes and can either be simple or acquired reflexes
Simple reflexes
- Unlearned response
- Ex: pulling hand away from something hot
Acquired reflexes
- Result of practice, training, conditioning
- Ex: Salivating over favourite food
The reflex arc
- Neuronal pathways for reflexes
- Comprised of 5 components
- Receptors in skin - reflex arc
Receptor senses a physical or chemical change in environment and produces an action potential
- Afferent neuron - reflex arc
Action potential is transmitted from the receptor to the integrating centre
- Interneuron - reflex arc
- Generally within the CNS
- Simple reflexes are integrated within spinal cord or brainstem
- Acquired reflexes are processed in higher brain centres
- Once signal is processed, response is initiated
- Efferent neuron - reflex arc
Response is transmitted away from CNS
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Module 1: Section 1 + 256
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Module 1: Section 316
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Module 1: Section 413
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Module 1: Section 531
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Module 2: Section 120
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Module 2: Section 216
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Module 2: Section 332
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Module 2: Section 451
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Module 2: Section 511
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Module 4: Section 127
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Module 4: Section 235
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Module 4: Section 333
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Module 4: Section 426
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Module 4: Section 59
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Module 4: Section 628
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Module 5: Section 115
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Module 5: Section 234
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Module 5: Section 352
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Module 5: Section 47
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Module 5: Section 533
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Module 5: Section 67
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Module 6: Section 121
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Module 6: Section 223
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Module 6: Section 344
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Module 6: Section 428
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Module 6: Section 512
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Module 6: Section 613
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Module 6: Section 743
