Peripheral Nervous System Part II Study Guide Flashcards
12 cranial nerves
I Olfactory (S): smell
II Optic (S): vision
III Oculomotor (M): eye movement, pupil reflex
IV Trochlear (M): eye movement
V Trigeminal (B): facial sensation; mastication
VI Abducens (M): eye abduction
VII Facial (B): facial expression; taste sensation
VIII Vestibulocochlear (S): equilibrium, balance, hearing sensation
IX Glossopharyngeal (B): movement of tongue + pharynx; taste sensation
X Vagus (B): parasympathetic efferents, sensory afferents of the viscera
XI Accessory (M): movement of trapezius + SCM
XII Hypoglossal (M): movement of tongue
All spinal nerves are _______ nerves.
mixed
nerve plexus
except for some in the thoracic region, all ventral rami branch and join one another lateral to the vertebral column – this creates cervical, brachial, lumbar, and sacral nerve plexuses
phrenic nerve
(C3-C5): innervates the diaphragm
median nerve
(C8 -T1 + C5-C7): innervates the flexor muscles of the forearm and the intrinsic muscles of the lateral hand; sensation of the lateral hand
ulnar nerve
(C8-T1): innervates the flexor muscles of the forearm and most of the intrinsic muscles of the hand; sensation of the medial hand
femoral nerve
sensation of anterior and medial thigh + medial leg and foot; motor innervation of quadriceps, sartorius, pectineus
sciatic nerve
(L4-L5, S1-S2): widespread sensation and motor function of the thigh, leg, and foot
nervous system is primarily responsible for maintaining homeostasis
Autonomic nervous system
effectors of the somatic nervous system
innervates skeletal muscles
effectors of the autonomic nervous system
innervates cardiac + smooth muscle and glands
efferent pathway of the somatic nervous system
a motor neuron’s cell body is in the cns; a single, thick, myelinated group A axon extends directly to skeletal muscle
efferent pathway of the autonomic nervous system
uses a 2-neuron chain to reach effectors
- Preganglionic Neuron: cell body resides in the CNS with a thin, lightly myelinated preganglionic axon extending to a ganglion
- Postganglionic (Ganglionic) Neuron: cell body synapses with preganglionic axon in the autonomic ganglion; a nonmyelinated postganglionic axon extends to the effector organ
- Impulse conduction through the autonomic efferent chain is slower than conduction in the somatic motor system
ganglion
a collection of neuronal bodies found in the voluntary and autonomic branches of the peripheral nervous system (PNS)
All somatic motor neurons release acetylcholine at their targets, and its effect is always _________.
stimulatory
In the autonomic nervous system, preganglionic fibers release ___________. Postganglionic fibers release either ___________________ or _____________.
- ACh
- norepinephrine (NE)
- ACh
Running through the woods to get away from a bear is an example of the overlap between somatic and autonomic function. Describe the somatic roles in this process. Describe the autonomic roles.
- active skeletal muscles require more Oxygen and glucose, so the ANS speeds up HR and dilates the airways
- SNS to contract muscles to run, ANS to supply oxygen and glucose by contracting heart faster and moving blood from gut into legs —
The parasympathetic division of the ANS promotes _____________________-___________________________
maintenance functions and conserves energy.
the sympathetic division of the ANS
mobilizes the body during activity
Dual innervation
almost all visceral organs are served by both divisions, but the divisions cause opposite effects (dynamic antagonism) this tightly controls our viscera
dynamic antagonism
one division produces an excitatory response and the other system produces an inhibitory response (think heart rate) the divisions go against each other to maintain homeostasis (only rarely dominate each other, which would be in an emergency situation)
physiological symptoms of parasympathetic activation
Blood pressure, heart rate, and respiratory rate are low
GI tract activity is high
Pupils are constricted, lenses accommodated for close vision