Overview of the PNS Flashcards
what are sensory axons in the limbs and body known as? [1]
where do sensory axons enter the spinal cord? [1]
where do motor axons leave the spinal cord? [1]
what are sensory axons in the limbs and body known as? [1]
sensory nerve fibres
where do sensory axons enter the spinal cord? [1]
dorsal root
where do motor axons leave the spinal cord? [1]
ventral root
what happens if the dorsal roots are severed between the dorsal root ganglion and spinal cord? [1]
what happens if the dorsal roots are severed between the dorsal root ganglion and spinal cord? [1]
sensory axons cannot regenerate into the spinal cord - creates paralysis
how can we tell whether loss of sensation is due to injury in spinal or nerve or dorsal root ganglion or a peripheral nerve? [2]
what can be a reason that a whole dermatome is damaged? [1]
how can we tell whether loss of sensation is due to injury in spinal nerve or dorsal root ganglion or a peripheral nerve? [2]
spinal nerve / dorsal root ganglion = whole dermatome affected
not a whole dermatome = damgae due to peripheral nerve
what can be a reason that a whole dermatome is damaged? [1]
fracture or slipped disc can crush a dorsal root ganglion
What is A, B & C? [3]
by which procedure do you collect CSF? [1]
at what vertebral level do you conduct ^? [1]
by which procedure do you collect CSF? [1]
lumbar puncture
at what vertebral level do you conduct ^? [1]
L3 or L4 (spinal cord stops at L1/2, so after this)
what is endoneurium?
what is endoneurium?
CT - thin protective membrane that surrounds individual or motor nerve fibres
what is perineurium?
CT - that wraps around fasicles of nerves
what is epineurium?
CT - the external connective-tissue sheath of a nerve trunk.
label A-D
what type of sensory receptors are present in body? [2] which responds to pain? [1]
what determines the kind of stimulus that sensory nerve endings will be sensitive to? [1]
what type of sensory receptors are present in body? which responds to pain? [1]
free nerve endings [1] = pain [1]
encapsulated nerve endings [1]
what determines the kind of stimulus that non-pain sensory nerve endings will be sensitive to? [1]
capsule surrounding the encapulated nerve ending
which of the following is Pacinian corpsucle?
A
B
C
D
E
which of the following is Pacinian corpsucle?
A
B
C
D
E
which of the following is Meissner corpuscle
A
B
C
D
E
which of the following is Meissner corpuscle
A
B
C
D
E
which of the following is a free nerve ending?
A
B
C
D
E
which of the following is a free nerve ending?
A
B
C
D
E
which of the following is a ruffini ending?
A
B
C
D
E
which of the following is a ruffini ending?
A
B
C
D
E
which of the following is a merkels disc?
A
B
C
D
E
which of the following is a merkels disc?
A
B
C
D
E
what causes, during development , the differentiated nerve fibre capsules? [1]
what causes, during development , the differentiated nerve fibre capsules? [1]
cytokines are released from the bare end of the nerve fibre and stimulate local CT to for a capsule around it
which of the following are rapidly-adapting, encapsulated neurons that responds to low-frequency vibrations and fine touch;
Ruffini endings
Pacinian corpuscles
Meissner’s corpuscles
Merkel’s disk
which of the following are rapidly-adapting, encapsulated neurons that responds to low-frequency vibrations and fine touch;
Ruffini endings
Pacinian corpuscles
Meissner’s corpuscles
Merkel’s disk
what is a receptive field? [1]
where do you find bigger receptive fields in the body? [1]
what is a receptive field? [1]
sensory nerve fibre bracnhes when it reaches the skin and supplies a small set of the same receptors in localised skin
where do you find bigger receptive fields in the body? [1]
larger on skin regions not used for tactile discrimination - e.g back
how does the brain precisely localise a sensory stimulus? [1]
what does this mean if get damage to a single senosry fibre? [1]
how does the brain precisely localise a sensory stimulus? [1]
receptive fields overlap [1]
what does this mean if get damage to a single senosry fibre? [1]
damage to a single fibre does not leave any region of skin anaesthetic
get less overlap
explain mechanism of what occurs after nerve injury xox
- peripheral nerve is cut
- schwann cell wraps around distal part to form continuous line of cells (and make a tunnel)
- proximal end: nerve fibres form growth cones: grow back down inside the sheath
- in growth cone, have filopodia, (contain actin)
- filopodia adhere to the cell adhesion molecules on inner surface of schwann cells, contract and pull forward along tunnel
- schwann cells wrap myeline around nerve fibre
- nerve fibres regen at 1.5mm/ day
