8. Organisation of the Peripheral Nervous System Flashcards

1
Q

Define DERMATOME and MYOTOME

A

Dermatome: a SLICE of SKIN

Myotome: a SLICE of MUSCLE

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2
Q

which SPINAL ROOT is SENSORY (and where is it going into)

A

DORSAL / POSTERIOR

into DORSAL / ALAR HORNS of GREY MATTER - pointy

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3
Q

which SPINAL ROOT is MOTOR (and where is it coming from)

A

VENTRAL / ANTERIOR

from VENTRAL / BASAL HORNS of GREY MATTER

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4
Q

which part of PNS is in ROSTRO-CAUDAL AXIS (top to bottom)

A

CRANIAL NERVES

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5
Q

in PNS SPINAL NERVE ROOT -> SPINAL NERVE for OVER THE TRUNK

how is it for LIMBS

A

ROOT -> PLEXUS -> NERVE

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6
Q

Name the 2 GANGLIA of the PNS

A
  • DORSAL ROOT GANGLION : where cell bodies of sensory neurones are
  • AUTONOMIC GANGLION (SYMPATHETIC) : contains cell bodies of the post ganglionic autonomic axon
    (contain the ONLY SYNAPSES in the PNS)
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7
Q

SENSORY system uses what type of nerve cells

A

UNIPOLAR cells in the DRG

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8
Q

MOTOR system uses what

A

(ALPHA) MOTOR NEURON in the ANTERIOR / VENTRAL HORN

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9
Q

AUTONOMIC system uses what

A

AUTONOMIC GANGLIA and PRE/POST FIBRES

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10
Q

where is the place that has the ONLY SYNSAPSES in the PNS

A

AUTONOMIC GANGLIA

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11
Q

which CRANIAL NERVES arise from the BRAINSTEM

therefore these are PERIPHERAL

A

3 - 12

Occulomotor
Trochlear
Trigeminal
Abducens
Facial
Vestibulocochlear
Glossopharyngeal
Vagus
Accessory
Hypoglossal

(all EXCEPT Olfactory and Optic)

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12
Q

which CRANIAL NERVES come from the MIDBRAIN

A

3 & 4

OCCULOMOTOR & TROCHLEAR
(eye movement)

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13
Q

which CRANIAL NERVES come from the PONS

A

5, 6, 7, 8

TRIGEMINAL, ABDUCENS, FACIAL, VESTIBULOCOCHLEAR

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14
Q

which CRANIAL NERVES come from the MEDULLA

A

9, 10, 11, 12

GLOSSOPHARYNGEAL, VAGUS, ACCESSORY, HYPOGLOSSAL

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15
Q

where does FACIAL NERVE arise from

A

PONS

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16
Q

where does TROCHLEAR NERVE arise from

A

MIDBRAIN

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17
Q

where does VAGUS NERVE arise from

A

MEDULLA

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18
Q

where does ABDUCENS NERVE arise from

A

PONS

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19
Q

where does TRIGEMINAL NERVE arise from

A

PONS

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20
Q

where does the GLOSSOPHARYNGEAL NERVE arise from

A

MEDULLA

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21
Q

where does VESTIBULOCOCHLEAR NERVE arise from

A

PONS

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22
Q

MIDBRAIN consists of what for processing

A
  • CORTICOSPINAL TRACTS,
  • S. NIGRA
  • AUDITORY & VISUAL REFLEX CENTRES
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23
Q

PONS consists of what for processing

A

CEREBRO-CEREBELLAR RELAYS

also Apneustic and Pneumotaxic centres for respiration

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24
Q

MEDULLA consists of what for processing

A
  • LONG TRACTS
  • RESPIRATORY and CARDIAC CENTRES
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25
Q

what GANGLIA are CRANIAL (not in PNS)

A
  • SENSORY GANGLIA (drg equivalents)
  • PARASYMPATHETIC GANGLIA (pns has sympathetic)
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26
Q

what does RAMUS mean

A

BRANCH

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27
Q

RAMI of the SPINAL NERVE that come after the roots

A

VENTRAL RAMI (important) - lateral and ventral (anterior)
DORSAL RAMI - supplies skin and muscles of the back (posterior)

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28
Q

what GANGLIA exist on VENTRAL ROOTS

A

AUTONOMIC GANGLION
aka SYMPATHETIC GANGLION

29
Q

AUTONOMIC (SYMPATHETIC) GANGLION CONNECT to the SPINAL ROOTS via which ADDITIONAL RAMI

A

RAMI COMMUNICATES

  • can be WHITE RAMI (more myelinated) or GREY RAMI
30
Q

what do RAMI COMMUNICATES do (white or grey)

A

CONNECT the SYMPATHETIC GANGLION to the SPINAL ROOTS

31
Q

example of a PLEXUS: BRACHIAL PLEXUS

what are the SPINAL ROOTS

A

C5-T1

C5,C6,C7,C8,T1

32
Q

NERVES that arise from the BRACHIAL PLEXUS (C5-T1)

A
  • RADIAL NERVE
    wrist and finger Extensors
  • MEDIAN NERVE
    muscles of Thenar Eminence (base of thumb) and lateral hand sensation
  • ULNAR NERVE
    most muscles of Hand, Medial hand sensation

also MUSCULOCUTANEOUS,
Cutaneous nerves of arm/forearm
Axillary nerve

33
Q

NERVES that arise from the LUMBAR SACRAL PLEXUS

A
  • FEMORAL NERVE (L2-L4)
    knee Extension, Anterior thigh sensation
  • SCIATIC NERVE (L4-S2)
    Hip Extension, Knee Flexion
    branches:
    -> COMMON PERONEAL / FIBULAR NERVE
    Ankle Dorsiflexion & Eversion, Lateral Leg sensation
    -> TIBIAL NERVE
    Ankle Plantarflexion & Inversion
34
Q

LAYER SURROUNDING the AXONS in a nerve:

A

ENDONEURIUM

35
Q

LAYER SURROUNDING the FASCICLES (bundles of axons) in a nerve:

A

PERINEURIUM

36
Q

OUTERMOST LAYER that SURROUNDS PERIPHERAL NERVES

A

INTERNAL & EXTERNAL EPINEURIUM

37
Q

how are SCHWANN CELLS in MYELINATED AXONS

A

series of schwann cells LINED UP ALONG the AXON

each one having a WRAPPED COATING of MYELIN insulating the axon

  • each AXONAL SEGMENT is ENCASED in WRAPPED LAYERS of LIPID MEMBRANE of the SCHWANN CELL
38
Q

how are SCHWANN CELLS in UNMYELINATED AXONS

A

unmyelinated axons in PNS are ENCASED BY SCHWANN CELL CYTOPLASM

but no wrapped coating of myelin surround axons

  • SUPPORTED BY SCHWANN CELLS
39
Q

how do DIVIDE NERVES into TYPES
by their…

A
  • FUNCTION
  • DIRECTIONALITY (Afferent or Efferent)
  • MYELINATION STATUS
  • AXONAL DIAMETER - A, B, C Fibres
40
Q

how are A NERVE FIBRES

A

LONGEST DIAMETER
MYELINATED
FAST

  • alpha, beta, gamma (efferent) and delta (afferent) types
41
Q

how are B NERVE FIBRES

A

SMALL DIAMTER (middle)
MYELINATED
*SLOW

mostly PRE-GANGLIONIC AUNTONOMIC FIBRES

42
Q

how are C NERVE FIBRES

A

SMALLEST DIAMETER
*UNMYELINATED
FAST

mostly POST-GANGLIONIC ANS
and some PAIN fibres - SLOW PAIN

43
Q

PRE-GANGLIONIC ANS FIBRES are normally what type

A

B

small, myelinated, slow

44
Q

POST-GANGLIONIC ANS FIBRES are normally what type

A

C

smallest, unmyelinated, slow

45
Q

which NERVE FIBRES transmit SLOW PAIN

A

C FIBRES

46
Q

what type of NEURONS are used in PNS SENSORY SYSTEM

A

PSEUDOUNIPOLAR DRG Neurons

Cell Bodies as an expansion of the Dorsal Root

47
Q

PNS SENSORY SYSTEM.
PROXIMAL BRANCHES of DRG NEURON enter either:

A
  • DORSAL (posterior) COLUMN OF CORD (white matter)
    dosal column/medial lemniscus pathway
    carries complex somatosensory information ie movement
    ASCENDS
  • DORSAL (posterior) HORN OF CORD (white matter)
    Spinothalamic pathway, 2nd order neuron
48
Q

where are CUTANEOUS RECEPTORS and what are they

A

SENSORY RECEPTORS in the SKIN

that permit a range of SOMATOSENSORY SUB-MODALITIES to be DETECTED

49
Q

those CUTANEOUS RECEPTORS that DETECT MOVEMENT have RAPIDLY-ADAPTING SIGNAL TRANSDUCTION PATHWAYS and transmit it to the CNS VIA…

A

FAST ABETA AFFERENTS
- well myelinated

50
Q

those CUTANEOUS RECEPTORS that TRANSMIT SUBMODALITIES ie PAIN use what..

A

SMALLER AXONS

SLOW NOCICEPTIVE FREE ENDINGS that transmit via C-FIBRES

  • to encourage animal to protect an injured part
51
Q

MOTOR NEURON CELL BODIES are LOCATED where

A

in the VENTRAL (anterior) HORN of the GREY MATTER of the cord

their AXONS transverse the White Matter of cord, form BUNDLES (FASCICLES) and then EXIT the cord as a VENTRAL ROOT

VENTRAL & DORSAL ROOTS JOIN after the DRG at the exit point of the INTERVERTEBRAL FORAMEN

52
Q

the MUSCLES CORRESPONDING to a SPINAL CORD are a..

A

MYOTOME

53
Q

what is a MOTOR UNIT (consist of)

A

a MOTOR NEURON, its AXON, AXONAL BRANCHES, their TERMINATIONS and CONNECTED MYOFIBRILS

54
Q

HIGHER BRAIN CENTRES (CNS) influence the OUTPUT of PARASYMPATHETIC ANS
- major play in this is the…

A

HYPOTHALAMUS

55
Q

where are the CELL BODIES of the PREGANGLIONIC NEURONS in the PARASYMPATHETIC NERVOUS SYSTEM

A

in the CRANIAL NERVE NUCLEI
in the BRAINSTEM and SACRAL CORD

(autonomic fibres are particularly in cranial nerves 3, 7, 9, 10 nuclei)

56
Q

where are the CELL BODIES of the PREGANGLIONIC NEUROS in the SYMPATHETIC NERVOUS SYSTEM

A

in the CENTRAL GREY - INTERMEDIOLATERAL HORN

in CERVICAL, THORACIC & LUMBAR REGIONS

57
Q

which REGIONS have the LATERAL HORN on the CENTRAL GREY

A

CERVICAL
THORACIC
LUMBAR

58
Q

the MOST ROSTAL (superior) SYMPATHETIC OUTFLOW is at what spinal level

A

T1

(parasympathetic is higher)

59
Q

what are in the VENTRAL HORNS of CENTRAL GREY

A

MOTOR NEURON CELL BODIES

60
Q

how are the CAROTID ARTERY and the VAGUS NERVE OPPOSITE?

A

CAROTID ARTERY - Carries SYMPATHETIC outflow UP to head

VAGUS NERVE - Carries PARASYMPATHETIC outflow DOWN from brainstem

61
Q

how does CAROTID ARTERY carry SYMPATHETIC OUTFLOW (from, to..) in its wall

A

FROM THORACIC CORD
- TO HEAD

UP

62
Q

how does VAGUS NERVE carry PARASYMPATHETIC OUTFLOW (from, to..)

A

FROM BRAINSTEM
- TO TRUNK

DOWN

63
Q

where is SYMPATHETIC OUFLOW FROM in the CAROTID ARTERY

A

from THORACIC TRUNK up to head

64
Q

AFFERENTS can also exist from .. as ..

A

INTERNAL ORGANS as VISCERAL AFFERENTS

65
Q

where are the PRE-GANGLIONIC NEURONS in the SYMPATHETIC vs PARASYMPATHETIC

A

Sympathetic: CERVICAL, THORACIC, LUMBAR Cord
(THORACO-LUMBAR OUTFLOW)

Parasympathetic: BRAINSTEM (mostly) and SACRAL CORD

66
Q

where are SYMPATHETIC GANGLIA vs PARASYMPATHETIC GANGLIA

And so how are their PRE-GANGLIONIC FIBRE LENGTHS?

A

Sympathetic: NEAR CNS

Parasympathetic: NEAR/WITHIN the END ORGAN (not near CNS)

Sympathetic: SHORT PRE-GANGLIONIC

Parasympathetic: LONG PRE-GANGLIONIC (post-ganglionic are short)

67
Q

POST GANGLIONIC NEURONS use what CHEMICAL in SYMPATHETIC vs PARASYMPATHETIC

A

Sympathetic: NORADRENERGIC (noradrenaline)

Parasympathetic: CHOLINERIC (Acetylcholine)
(act as MUSCARINIC RECEPTORS)

68
Q

what use FAST ABETA AFFERENTS

A

CUTANEOUS RECEPTORS that transmit the DETECTION OF MOVEMENT