peripheral nervous system Flashcards
(112 cards)
1
Q
what is the central nervous system divided into?
A
- central nervous system (brain and spinal cord)
- peripheral nervous system
2
Q
what does the peripheral nervous system consist of?
A
- neurones carrying info to (affector neurones) or from (effector neurones) the CNS
3
Q
what is the neuron?
A
- specialised cell type
- functional unit of nervous system
4
Q
what 3 parts does the neuron consist of?
A
- axon
- cell body
- dendrites
5
Q
what does the axon do?
A
- carry information away from cell body
- axons of one neurone connects with dendrites of other at synapses
6
Q
what does the cell body contain?
A
- nucleus
- organelles required for cell metabolism
7
Q
what do the dendrites do?
A
- carry information to the cell body
8
Q
how is information electrically relayed?
A
- along axons and dendrites through movement of ions
9
Q
what do synapses occur between?
A
- neurones and target cells
10
Q
what are the target cells?
A
- other neurones
- muscle cells
- secretory cells
11
Q
where does electrical transmission through axons terminate?
A
- at synapses
12
Q
how is it relayed to the next cell?
A
- via chemical messengers (neurotransmitters)
13
Q
where are the chemical messengers stored?
A
- in vesicles in pre synaptic neurone
14
Q
what happens when an action potential reaches these vesicles?
A
- contents are released into synaptic cleft
- bin to receptors on post synaptic membrane
15
Q
what does this stimulate?
A
- depolarisation or hyperpolarisation in post synaptic neurone
- contraction in post synaptic muscle cells
- secretion in post synaptic secretory cells
16
Q
what does the spinal cord consist of?
A
- ascending and descending neurones
- carry info to and from the brain
17
Q
where does the spinal cord end in children?
A
- L3 vertebrae
18
Q
what happens to spinal cord at L1?
A
-no longer a single cord
- made of several spinal nerves all running through vertebral canal
19
Q
what is the spinal cord protected by?
A
- vertebral column (spine)
20
Q
what is the vertebral column made up of?
A
- individual vertebrae
21
Q
what are the individual vertebrae divided into?
A
- 8 cervical nerve pairs
- 12 thoracic nerve pairs
- 5 lumbar nerve pairs
- 5 sacral nerve pairs
- 1 coccygeal nerve
22
Q
what does each vertebra consist of?
A
- vertebral body
- vertebral arch
23
Q
what do the vertebral body and arch form together?
A
- vertebral foramen (area where spinal cord resides)
24
Q
how is the vertebral canal formed?
A
- when several vertebra are stacked
- vertebral foramina align
25
what is the purpose of the canal?
- contains spinal cord
- provides protection
26
what is the vertebral arch formed of?
- two pedicles
- two lamina
- two transverse processes
- one spinous process
- four articular processes
27
what do the intervertebral discs form?
- fibrocartilaginous joint (symphysis)
- between 2 adjacent vertebrae
28
what does the fibrocartilaginous joint allow?
- slight movement
- acts as shock absorbers and holds the two together
29
what does the disc contain?
- annulus fibrosus
- nucleus pulposus
- layer of hyaline cartilage
30
what is the annulus fibrosus?
- outer fibrous ring made up of laminae of fibrocartilage to withstand compression
31
what is the nucleus pulposus?
- gel like centre that helps distribute pressure evenly across disc to act as shock absorber
32
what is the outer section of the spinal cord formed of?
- white matter
- consists of axons of neurones that form ascending or descending pathways
33
what do the ascending pathways do?
- travel from body to brain
- carry sensory information (touch, pain, proprioception)
34
what do the descending pathways do?
- travel from brain to body
- carry motor instructions
- initiate and control movement
35
what is the inner section of the spinal cord formed from?
- grey matter
- where cell bodies of neurones are located
- where synapses occur
36
where do nerves from the body enter through?
- dorsal roots (dorsal horn)
37
where do nerves exit the body through?
- ventral root (ventral horn)
38
what do the ascending and descending tracts carry?
- somatic nerves
39
where do the autonomic nerves run?
- alongside spinal cord in separate chain or neurones and ganglia
40
what does the dorsal column contain?
- ascending sensory neurones carrying fine touch
- proprioception information from limbs
41
what does the lateral column contain?
- descending motor tracts from cerebral cortex
42
what does the anterolateral fasciculus contain?
- ascending sensory neurones carrying pain and temperature fibres
43
what are the two main divisions of the peripheral nervous system?
- autonomic
- somatic
44
what is the autonomic nervous system?
- subconscious control of our bodies
- innervating smooth muscle of tissues or glands
45
what is the autonomic nervous system involved within?
- temperature control (sweating and vasomotor)
- continence
- secretions
- gastric motility
46
where do the autonomic neurones arise from?
- brain
- spinal cord
47
how many neurones does it take the autonomic system to reach its target?
- 2 (pre ganglionic and post ganglionic)
48
what can the autonomic nervous system be divided into?
- sympathetic
- parasympathetic
49
what does the sympathetic nervous system do?
- prepares body for intense physical activity
- fight or flight
50
what does the parasympathetic nervous system do?
- relaxes body
- inhibits high energy functions
- rest and digest
51
what happens in parasympathetic stimulation?
- decreased heart rate
- decreased force of contraction
- increased stomach motility
- increased gastric secretions
- airway smooth muscle contraction
- pupil constriction
- increased digestion and gut motility
52
what happens with sympathetic stimulation?
- increased heart rate
- increased force of contraction
- decreased gut motility
- reduced peristalsis
- relaxation of airway smooth muscle
- dilation of pupil
53
where are sympathetic cell bodies present?
- thoracic and lumbar spinal cord segments
54
what do these connect to?
- paravertebral ganglion chain
- sympathetic chain
- individual ganglia that are distant from target organs
55
where do parasympathetic neurones arise from?
- cranial nerves
- limbo-sacral spinal cord
56
where are the parasympathetic ganglia located?
- close to target organ
57
what is the somatic nervous system responsible for?
- conscious control of bodies and corresponding feedback
58
what are the somatic afferent nerves?
- sensory
- detect pain, temperature, touch, proprioception
59
what are the somatic efferent nerves?
- motor to effector skeletal muscles
60
what happens to the somatic neurones once they leave CNS?
- don't synapse
- project directly to target cell via single neurone
61
what are the two types of somatic nerves?
- spinal nerves (arise from spinal cord)
- cranial nerves (arise directly from brain)
62
what are the spinal nerves?
- peripheral nerves
- carry axons of neurones of somatic and autonomic nervous systems to and from spinal cord
63
where do the spinal cords leave the vertebral column?
- below each vertebra
- except cervical region as exit superior to vertebrae
64
where are the spinal nerves on vertebra C7?
- above (c7 nerve)
- below (c8 nerve)
65
how many spinal nerves are there?
- 31
(additional root from coccyx)
66
where do the spinal nerves arise from?
- spinal cord
67
what are the dorsal roots?
- usually afferent or sensory
- carries information from periphery to CNS
68
what are the ventral roots?
- usually efferent or motor
- carry information from CNS to periphery in somatic motor and autonomic neurones
69
what do they unite to form?
- mixed (motor and sensory) spinal nerve
69
what could this spinal nerve continue to be?
- nerve plexus
- single peripheral nerve
70
what does plexus mean?
- network or tangle
71
what are dermatomes?
- distinct area of skin that each spinal nerve supplies
72
what is a myotome?
- distinct group of muscles that each spinal nerve supplies
73
how many cranial nerves are there?
- 12
74
what do the cranial nerves innervate?
- structures of the head and neck
75
what do the cranial nerves supply?
- special senses (eg. taste)
76
what is cranial nerve 1 (CNI)?
- olfactory nerve
77
what does the olfactory nerve do?
- sensory nerve
- receives smelling senses and sends info to brain
- special sense
78
what is cranial nerve 2 (CNII)?
- optic nerve
79
what does the optic nerve do?
- sensory nerve
- special sense
- afferent for vision from retina
80
what is cranial nerve 3 (CNIII)?
- oculomotor nerve
81
what does the oculomotor nerve do?
- arises from midbrain
- motor nerve
- supplies muscles of eyeballs
- innervates cilia muscles of eye
82
what does somatic division of oculomotor nerve control?
- eye movement
- eyelid control
83
what does autonomic division of oculomotor nerve control?
- motor to pupil constrictors
84
what is cranial nerve 4 (CNIV)?
- trochlear
85
what does the trochlear nerve do?
- somatic
- motor to one muscle that moves eye
- arises from midbrain
86
what is cranial nerve 5 (CNV)?
- trigeminal
87
what does the trigeminal nerve do?
- sensory and motor
- somatic: afferent from surface of face
- senses touch from skin (dermatomes of face)
- motor efferent to muscles of mastication (myotomes)
88
what is cranial nerve 6 (CNVI)?
- abducent
89
what does the abducent nerve do?
- motor nerve
- motor efferent to one muscle of the eye
- arises from pons
90
what is cranial nerve 7 (CNVII)?
- facial nerve
91
what does the facial nerve do?
- motor
- special sense (taste from anterior tongue and palate)
- helpful in facial expression
- supplies secretory glands in face
92
what is the somatic division of the facial nerve?
- motor efferent to muscles of facial expression (myotomes)
93
what is the autonomic division of the facial nerve?
- motor efferent to glands that secrete saliva
94
what is cranial nerve 8 (CNVIII)?
- vestibulocochlear nerve
95
what does the vestibulocochlear nerve do?
- special sense
- hearing from cochlea of ear
- balance from vestibular apparatus of ear
96
what is cranial nerve 9 (CNIX)?
- glossopharyngeal nerve
97
what does the glossopharyngeal nerve do?
- special sense - taste from posterior tongue
98
what is the somatic division of CNIX?
- motor efferent to help with swallowing
- afferent sensation from external ear
99
what is the autonomic division of CNIX?
- secretomotor to one saliva gland (parotid)
100
what is cranial nerve 10 (CNX)?
- vagus nerve
101
what does the nerve nerve do?
- supply structures beyond head and neck
102
what is the somatic division of CNX?
- motor to muscles of pharynx, larynx and palate
103
what is the autonomic division of CNX?
- parasympathetic innervation of smooth muscle in trachea, bronchi, GI tract and cardiac muscles
- afferent sensation from GI tract, heart and airways
104
what is cranial nerve 11 (CNXI)?
- accessory nerve
105
what does the accessory nerve do?
- motor nerve
- to two muscles in neck
106
what is cranial muscle 12 (CNXII)?
- hypoglossal nerve
107
what does the hypoglossal nerve do?
- motor
- to muscles of the tongue
108
what is bells palsy?
- facial nerve paralysis
- idiopathic (unknown cause)
109
what does bells palsy result in?
- unilateral (one sided) facial paralysis
110
what is one of the causative agents to bells palsy?
- herpes simplex virus
111
what does bells palsy cause?
- failure to close eye (watery or dry)
- unable to wrinkle forehead or blow out cheeks
