Topic 19 -peripheral nervous system Flashcards
(31 cards)
cranial nerves all 12 pairs
1 olfactory 2 optic 3 oculomotor 4 Trochlear 5 Trigeminal 6 Abducens 7 Facial 8 Vestibulocochlear 9 Glossopharyngeal 10 Vagus 11 Accessory 12 Hypoglossal
which cranial nerves are associated with the forebrain
1 olfactory
2 optic
which cranial nerves are associated with the midbrain
3 oculomotor
4 trochlear
which cranial nerves are associated with the pons
5 trigeminal
6 abducens
7 facial
8 vestibulocochlear
which cranial nerves are associated with medulla oblongata
9 glossopharyngeal
10 vagus
11 accessory
12 hypoglossal
2 pairs of cranial nerves are only Sensory
sensory
1 olfactory
2 optic
1 pair of cranial nerves is mainly sensory
sensory
8 vestibulocochlear
9 pairs of cranial nerves are
mixed nerves
- carry both sensory + motor neurons
- motor neurons ⇒ cell bodies in brainstem nuclei
- sensory neurons ⇒ cell bodies in ganglia of PNS
- e.g. trigeminal (V)
- motor function = chewing
- sensory function = conveys general sensations (touch, pressure, pain, temperature etc) from face to CNS
Spinal nerves
- 31 pairs = all mixed nerves
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
spinal nerves exit at
exit via intervertebral foramina (except 1st - between atlas + occipital bone
each spinal nerve has two points of attachment to spinal cord:
a) Dorsal Root
- sensory; cell bodies in dorsal root ganglion
b) Ventral Root
- autonomic and somatic motor neurons; cell bodies in ventral or lateral horn
- spinal nerve = joining of dorsal + ventral roots
- immediately divides into branches = rami:
a) dorsal ramus
innervates skin + muscles of back
b) ventral ramus
- forms thoracic nerves (T2 - T12) OR further branch + join up forming nerves plexuses (= nerve networks)
c) rami communicantes
- connect ventral ramus to sympathetic trunk
- contain autonomic nerve fibres (neurons)
cervical plexus
C1-C5
phrenic (innervates diaphragm)
brachial plexus
C5-C8, T1
Axillary, radial,ulnar, median, musculocutaneous
Lumbar plexus
L1-L4
femoral
Sacral
L4-S4
sciatic => divides into tibial and common fibular
Peripheral Nervous system: Sensory (Afferent) Division
consists of
stimulus -> receptor -> CNS
Receptors
First order Neurons
Receptors
detect changes in environment classified by location type of stim received structure of receptor
receptors classified by location
i) exteroceptors
- stimulus in external environment = receptors at body surface e.g. touch, most special senses)
ii) interoceptors
- stimulus in internal environment (in viscera, blood vessels etc)
iii) proprioceptors
- located in joints, skeletal muscles etc
- monitor body position (stretch receptors, muscle spindles) – balance + movement
receptors classified based on type of stim received
i) mechanoreceptor- mechanical stimuli (e.g. pressure, touch, hearing)
ii) thermoreceptors- temperature
iii) chemoreceptors- chemical
iv) photoreceptors- light
v) nociceptors - pain`
receptors based on structure
i) free nerve endings - terminal dendrites of unipolar sensory neurons e.g. pain, root hair plexus
ii) encapsulated nerve endings - terminal dendrites enclosed in CT
e. g. Meissner’s + Pacinian corpuscles
First Order Neurons = sensory neurons
Cell bodies where
Axon terminates where
- unipolar neurons attached to or associated with receptor
- axon located in cranial/spinal nerves to CNS
- cell bodies in:
a) sensory ganglia of cranial nerves
b) dorsal root ganglia of spinal cord-
axon terminals in:
a) brain nuclei
b) dorsal horn of spinal cord
Peripheral system: Motor (efferent) Division
CNS => effector (E)
2 subdivisions
somatic
autonomic
Somatic peripheral nervous system
- effector = skeletal muscle
- consists of lower motor neurons (= motor neurons):
= single multipolar neuron:
a) cell body in ventral horn of spinal cord to effector
b) cell body in motor nuclei of brain stem to effector (e.g. facial motor nucleus for cranial nerve VII)
