WEEK 6: Peripheral Nervous System Flashcards
Describe a peripheral nerve
This is a nerve composed of many nerve fibres which are arranged in bundles (fasicles) that are surrounded by connective tissue
what are the connective tissue layers surrounding the peripheral nerve?
Endoneurium: surrounds each nerve fibres and myelin sheath
Perimeurium: surrounds the fasicles
Epineurium: surrounds the whole nerve
which cells form the myelin sheath?
schwann cells
What are the type of branches in peripheral nerves?
Cutaneous- skin
muscular- skeletal muscle
articular- joints
vascular- blood vessels
what are the fibre types present in the muscular and cutaneous branches?
Muscular:
GSE: to skeletal muscle to cause contration
GSA: sensory info from skeletal muscle
GVE: to the smooth muscle in blood vessels
Cutaneous:
GSA: sensory information from the skin eg temp
GVE: innervating smooth muscle in the skin eg muscles that make hair stand up
label the figure 1 diagram in week 6 of the orange book
… remember GSE and GSA neurons
what does the dorsal primary ramus supply?
supplies the back
what does the ventral primary ramus supply?
everthing other than the back (somatic)
which root carries motor information and which one carries sensory information?
ventral root- motor info
dorsal- sensory info
if a muscle got injured in the back how would the nerve travel?
Ventral root
spinal nerve
dorsal ramus
what is a nerve plexus?
this is a network or interjoining of nerves by means of numerous communicating branches
what are the types of nerve plexi and what is an example of each?
Somatic nerve plexi: these generally supply limb(s) which has many nerves supplying the different tissues and region of that limb
eg lumbar plexus: supplies lower limbs
Autonomic plexus: supply internal organs
eg Cardiac plexus: plexus that controls the heart which i combined with the sympathetic and parasympathetic system
what are dermatomes and myotomes?
Dermatomes innervate specific areas of the skin, different dermatomes in the spine relate to different areas of the skin.
Myotomes are the spinal segments that innervate specific blocks of muscle
why does the knee jerk reflex movement not require involvement from higher brain centres?
A nerve impulse still travels to the brain but this is only a sensory impulse to identify the tapping, yes this happens without even realising as the simple movement of knee flexion is given out by the spinal cord.
GSA neuron is sent to spinal cord
GSE neuron is sent to the muscle
brain is not required as by the time you have realised there is pain your leg has already moved
what is an example of a withdrawal reflex and is it poly or monosynaptic?
- quickly removing your hand off a hot surface
- polysynaptic
