Somatic Nervous System Flashcards
What are the structural divisions in the nervous system?
- CNS (brain & spinal cord)
- PNS (12 cranial & spinal nerves)
How many pairs of spinal nerves are there?
31
How many regions is there?
5 (named after associated vertebrae)
Where does the C1 spinal nerve exit?
Between skull and atlas
What is the fibre distribution in spinal nerves?
- Sensory/afferent
- Motor/efferent
What is the process for when motor fibres don’t synapse?
CNS —> Skeletal muscle
What is the process for when motor fibres synapse?
CNS -(presynaptic)-> Ganglion -(postsynaptic)-> smooth muscle, cardiac muscle, glands
What is a dermatome?
Area of skin supplied by a single spinal nerve
What is a neuron?
The functional unit of the nervous system
What are the parts of a neuron?
- Cell body
- Dendrites
- Axon
What are the major types of neuron?
- Bipolar
- Multipolar
- Pseudounipolar
What are the 4 types of neurological cells found in the CNS?
- Astrocytes
- Microglial cells
- Ependymal cells
- Oligodendrocytes
What is myelin?
Lipid and protein substance that is secreted by Schwann cells (glial cell) around some axons
What is a myotome?
Part of muscle supplied by a single spinal nerve
What is the clinical relevance of dermatomes/myotomes?
Useful to test motor or sensory loss of one or more spinal nerves/segments by testing joint movements or an area of skin in neurological disorders
What level is the nipples and belly button?
T4 - nipples
T10 - belly button
What is the function of the somatic motor fibres?
Regulates voluntary control of body movements via skeletal muscles
What is the function of somatic sensory fibres?
Transmits general sensation (pain, touch, temperature, proprioception etc.) to the CNS
If the dorsal root is damaged, what function is lost?
Sensory
If ventral root is damaged, what function is lost?
Motor
If the spinal nerve is damaged, what function is lost?
Both motor and sensory
If the ventral ramus is damaged, what function is lost?
Motor and sensory loss of anterolateral trunk and limbs
If the dorsal ramus is damaged, what function is lost?
Motor and sensory loss of the back
Where does the spinal nerve exit through?
The intervertebral foramen
