W5 - Somatic NS Flashcards
What does the somatic NS act on?
Skeletal muscles
What are the two parts of the upper motor neurons?
Motor cortex - planning/initiating movements, BRainstem centres - basic movements/posture
Where does the signal go to from the UMN to reach the skeletal muscles (via integration centres)?
The lower motor neurons (LMN)
What receptors are present on the skeletal muscles? (ACh works in the somatic NS)
Nicotinic receptors
What is the different between ANS and SNS in terms of the junctions from the spinal cord to the target organ?
Ganglia (where junctions are) in ANS but no junctions from the SC to the target organ in the SNS
5 steps of a somatic (involuntary) reflex
- Sensor 2. Afferent pathway to SC or Bst 3. Integrating centre (grey matter of SC or Bst) 4. Efferent pathway to muscle 5. Effector creates response
What happens to the extensor and the flexor during the patella reflex?
Extensor (quads) - impulses cause contraction, Flexor (hamstring) - impulses inhibit contraction to relax the muscle
What is the Jendrassik manoeuvre?
Pulls hands apart while clenching teeth to occupy CNS so it doesn’t interfere with the patella reflex
Muscle spindles are an organ, what do they sense?
Sense the length of the muscle
What is proprioception?
The sense of your body in space
Describe the structure of a muscle spindle (intra/extrafusal fibres and neurons)
They’re made up of multiple intrafusal muscle fibres with primary sensory nerve fibres wound around them, muscle spindles are surrounded by extrafusal muscle fibres
What is the purpose of intrafusal and extrafusal muscle fibres?
Intra - contract along with extra so you know the muscle has shortened, Extra - move the body
What surrounds the muscle spindles intra fibres?
Capsule
What efferent and afferent neurons are associated with the intra fibres?
Gamma motor and Grp I / II sensory
What efferent neurons are associated with extrafusal muscle fibres?
Alpha motor neurons
