Somatic NS Flashcards
What is the functioning unit for the nervous system?
Neurons
Name the three main parts of a neuron.
Axon, cell body, dendrite
What are the three major types of neuron?
Bipolar
Multipolar
Pseudounipolar.
What are the four main types of cells found in the CNS?
Astrocytes, microglial cells, ependymal cells, and oligodendrocytes.
What is myelin?
Protein and lipid substance
What does a myelin sheath do?
Increase velocity of impulse conduction (insulation)
Why are peripheral nerves resilient?
Protected by three layers of connective tissue coverings
What is a dermatome?
Area of skin supplied by a single spinal nerve
What is a myosome?
Part of muscle supplied by a single spinal nerve
What is the clinical relevance of dermatomes and 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 is a motor end plate?
A neuromuscular junction
RECAP- what makes up the CNS?
Brain and spinal cord
RECAP- what makes up the PNS?
Cranial nerves, Spinal nerves and peripheral ganglia
How many pairs of cranial nerves are there?
12
How many pairs of spinal nerves are there?
31
What are the two components of the somatic NS?
Motor and sensory
What is controlled by the somatic motor system?
Voluntary control
Skeletal muscle
What is controlled by somatic sensory system?
Pain/ touch/temperature/ proprioception etc., skin
What does a somatic motor fibre do?
Regulates voluntary control of body movements via skeletal muscle.
What do somatic sensory fibres do?
Transmits general sensation to the CNS
What would happen if there was damage to the anterior/ventral root?
Motor loss
What would happen if there was damage to the posterior/dorsal root?
Sensory loss
What would happen if there was damage to ventral ramus>
Motor and sensory loss of anterolateral trunk and limbs
What would happen if there was damage to the dorsal ramus?
Motor and sensory loss at the back
What do spinal nerves also carry?
Sympathetic fibres
Where does the spinal nerve exit through?
Intervertebral foramen
What is a Somatic Reflex Arc?
Sensory detection
Interpretation of sensory input in the CNS
Motor response
What is the function of the muscles at the back of the arm and forearm?
Back of arm- extensors of the elbow
Forearm- extensors of the wrist
Which nerve supplies the muscles at the back of the arm and forearm?
Radial nerve
What does damage to lower motor neuron cell bodies or their peripheral axons result in?
Paralysis
Weakness of affected muscles
