Part 5: Peripheral & autonomic nervous systems Flashcards
Brain splits into ___ (3 parts)
-Forebrain
-Midbrain
-Hindbrain
Cranial Nerves emerge from ____
brain stem
spinal Nerves emerge from ____
spinal cord
Peripheral Ganglia are (2)
-somatic sensory cell bodies
-autonomic ganglia (postganglionic neuronal cell
bodies)
somatic nervous system Supplies ____
somatic (body wall) structures
- Skin, muscle, bone, parietal membranes
somatic nervous system: sensory (what it senses?)
- Pain (direct pain arising from the site of injury, Sharp, focused and well-localized (pin-prick, cut, burn)
- Temperature
- Touch
- Proprioception
motor somatic nervous system controls ____
skeletal muscle (exception - reflex arc)
autonomic nervous system supplies ____
-viscera (internal organs)
- Glands, smooth muscle, cardiac muscle, visceral membranes
- Involuntary or autonomous control
autonomic nervous system: sensory (what it senses?)
-stretch or ischemia (lack of oxygen) at the organs
- vague, ill-defined and ache-like (menstrual cramps, indigestion)
- perceived as indirect or referred pain
- Usually referred to the dermatomes
autonomic nervous system: motor controls___
sympathetic, parasympathetic
2 Classification of Spinal Nerves
General Afferents
General Efferents
spinal nerves: general afferents two types
Somatic Afferents (GSA)
- Visceral Afferents (GVA)
spinal nerves: Somatic Afferents (GSA) sense ____
-pain, temperature, touch, proprioception from
body wall
spinal nerves: - Visceral Afferents (GVA) sense _____
pain, distension, chemical from visceral
structures
spinal nerves: general efferents two types
Somatic Efferents (GSE)
Visceral Efferents (GVE)
spinal nerves: Somatic Efferents (GSE) sense ____
motor neurons in ventral horn projecting to
skeletal muscles
spinal nerves: Visceral Efferents (GVE) sense ____
autonomic fibres innervating smooth muscle, cardiac muscle, and glands
typical spinal nerve
dorsal root + ventral root=spinal nerve split into dorsal/ventral primary ramus
Intervertebral Foramen
where spinal nerve passes through
what’s in a nerve?
purple: spinal nerve
orange: Blood vessels
yellow: EPINEURIUM around entire nerve
green: Fascicle (bundle of nerve fibers in PNS)
blue: PERINEURIUM around individual fascicle
pink: axon
black: ENDONEURIUM around individual axon
dermatome
an area of skin that is mainly supplied by a single spinal nerve (C1 has no dermatome)
3 Somatic Nerve Plexuses
-Brachial Plexus
-Lumbar Plexus
-Lumbosacral Plexus
Brachial Plexus where?
Ventral primary rami (mixed nerves carrying both motor and sensory fibers) of spinal nerves C5, C6, C7, C8 and T1
Brachial Plexus creates __ main nerves: ____
5 (five)
1. Axillary (shoulder)
2. Musculocutaneous (biceps)
3. Median (forearm flexors, thenar)
4. Radial (posterior arm and forearm)
5. Ulnar (hand muscles)
Lumbar Plexus where?
Ventral primary rami of spinal nerves
L1, L2, L3, and L4
Lumbar Plexus creates __ main nerves: ____
6 (six)
1. Iliohypogastric
2. Ilioinguinal
3. Genitofemoral
4. Lateral Femoral Cutaneous
5. Femoral (anterior compartment thigh)
6. Obturator (adductors)
Lumbosacral Plexus where?
Ventral primary rami of spinal nerves
L4, L5, S1, S2, and S3
Lumbosacral Plexus creates __ main nerves: ____
6 (six)
1. Tibial (posterior thigh, toe muscles)
2. Common Peroneal (lateral leg, ‘foot drop’)
3. Superior Gluteal
4. Inferior Gluteal
5. Pudendal
6. Posterior Femoral Cutaneous
Reflex arc steps
Step 1:Arrival of stimulus and activation of receptor
Step 2: Activation of a sensory neuron
Step 3:Dorsal root + interneuron + ventral root- processing in CNS
Step 4:Activation of a motor neuron
Step 5: Response by effector
Autonomic Motor Nerves: Sympathetic (where in spinal cord, action)
-Thoracolumbar
- T1 – L2
- Fright, Flight, Fight
Autonomic Motor Nerves: Parasympathetic (where in spinal cord, action)
-Craniosacral
- CN III, VII, IX, X
- S2, S3, S4
- Rest, Relax, Regenerate
Somatic Motor System: “Common Final
Pathway”
One axon emerges from the CNS and travels to the effector site
Autonomic Motor System:Preganglionic fibre from the ____ to ____
CNS to the autonomic ganglion
Autonomic Motor System: Postganglionic fibre from the ____ to
autonomic ganglion to the effector site
sympathetic preganglionic fibre are ____ than parasympathetic preganglionic fibre
shorter
sympathetic preganglionic fibre synapses on _____ (releases?)
sympathetic ganglion (acetylcholine)
adrenal medulla
sympathetic postganglionic fibre synapses on _____ (releases?)
target (norepinephrine)
blood vessels (epinephrine/norepinephrine)
parasympathetic preganglionic fibre synapses on _____ (releases?)
parasympathetic ganglion (acetylcholine)
parasympathetic postganglionic fibre synapses on _____ (releases?)
target (acetylcholine)
Sympathetic Nervous System: Cervical sympathetic ganglia
Superior (eye)
Middle (salivary gland)
Inferior (+ T1-3)- heart and lungs
Sympathetic Nervous System: Sacral splanchnic nerve
-from below L2
Sympathetic Nervous System: Greater splanchnic n and Lesser splanchnic n.
-greater: long preganglionic fiber to kidney (T5-10)
-lesser (T11-12)
Sympathetic Actions
Eye (pupil dilation)
Trachea and Bronchioles (dilation)
Ureters and Bladder (relax detrusor m. contract trigone and sphincter)
Genitalia (Male – stimulates ejaculation, Female – relaxes uterus )
Heart ↑rate (↑contractility)
Gastrointestinal (↓motility and tone,contract sphincter)
Blood Vessels (skeletal muscle – dilate, viscera - constrict )
Skin innervation + Thoracic Innervation (heart)
similarities
Preganglionic sympathetic neuron – T1 to L2
(Grey + white ramus communicantes)
Sympathetic innervation of abdominal viscera
( by ____Splanchnic nerves)
Splanchnic nerves
Cutaneous and visceral sensory neurons share
_____
the same ascending tracts
Referred Pain
Brain perceives visceral pain as coming from spinal
nerve
REFERRED PAIN (and dermatome levels)
heart: T1-5 (arm)
stomach: T7-9
Appendix: T10
small intestine:T9-11
colon:T11-12
Pelvic splanchnic nn. part of ____
parasympathetic
Parasympathetic Nervous System nerves
CN III, VII, IX, X
Pelvic splanchnic nn
Parasympathetic Actions
Eye (pupil constriction accommodation reflex)
Trachea and Bronchioles (constrict, ↑secretion)
Ureters and Bladder (contract detrusor m.
relax trigone and sphincter)
Genitalia (stimulates erection)
Lacrimal Glands (stimulate tears)
Salivary Glands (copious watery secretion)
Heart (↓rate ↓contractility)
Gastrointestinal (↑motility and tone)
Autonomic Motor Command Structure
hypothalamus (small formations of grey matter that controls autonomic system)
