nervous system Flashcards
cranial nerve #1
Olfactory. sensory only
cranial nerve #2
Optic. sensory only
cranial nerve #3
Oculomotor. motor only.
cranial nerve #4
Trochlear. eye muscles. motor only.
cranial nerve #5
Trigeminal. motor AND sensory. general sensation and chewing musces.
cranial nerve #6
Abducens. motor only. moves eye laterally.
cranial nerve #7
Facial. motor AND sensry. taste and muscles of facial expression
cranial nerve #8
Acoustic/Vestibulocochlear. sensory and some motor. hearing and balance.
cranial nerve #9
Glossopharyngeal. motor AND sensory. taste and muscles of pharynx and tongue.
cranial nerve #10
Vagus. Extends to thorax and abdomen. Sensory AND motor. taste.
cranial nerve #11
Accessory. motor only. back of the neck muscles.
cranial nerve #12
Hypoglossal. motor only. under the tongue and in tongue muscles.
list all cranial nerves in order
I. Olfactory II. Optic III. Oculomotor IV. Trochlear V. Trigeminal VI. Abducens VII. Facial VIII. Acoustic/Vestibulochochlear IX. Glossopharyngeal X. Vagus XI. Accessory XII. Hypoglossal
How many pairs of cranial nerves?
12
How many pairs of spinal nerves?
31
dorsal roots
contain sensory fibers
ventral roots
contain motor (efferent) fibers
dorsal rami
smaller of the two, supply the posterior body trunk only. contain both sensory and motor fibers.
ventral rami
larger of the two. supply all of the body except the head and the posterior part of the trunk. Contain both sensory and motor fibers.
plexus
a network formed by ventral rami. they primarily supply the limbs. Occur in cervical, brachial, lumbar, and sacra regions (NOT thoracic)
phrenic nerve
nerve in the cervical plexus. supplies the diaphragm.
median nerve
allows grabbing. damaged in carpal tunnel.
wrist drop
result of trauma to the radial nerve. will also interfere with forearm extension.
mechanoreceptors
respond to mechanical force such as touch, pressure (including blood pressure), vibration, and stretch.
thermoreceptors
respond to temperature changes.
photoreceptors
such as those of the retina of the eye, respond to light.
chemoreceptors
respond to chemicals in solution (molecules smelled or tasted, or changes in blood or interstitial fluid chemistry).
Nociceptors
respond to potentially damaging stimuli that result in pain. For example, searing heat, extreme cold, excessive pressure, and inflammatory chemicals are all interpreted as painful. These signals stimulate subtypes of thermoreceptors, mechanoreceptors, and chemoreceptors.
exteroceptors
are sensitive to stimuli arising outside the body (extero = outside), so most exteroceptors are near or at the body surface. They include touch, pressure, pain, and temperature receptors in the skin and most receptors of the special senses (vision, hearing, equilibrium, smell, and taste).
interoceptors
also called visceroceptors, respond to stimuli within the body (intero = inside), such as from the internal viscera and blood vessels. Interoceptors monitor a variety of stimuli, including chemical changes, tissue stretch, and temperature. Sometimes their activity causes us to feel pain, discomfort, hunger, or thirst. However, we are usually unaware of their workings.
proprioceptors
ike interoceptors, respond to internal stimuli. However, their location is much more restricted. Proprioceptors occur in skeletal muscles, tendons, joints, and ligaments and in connective tissue coverings of bones and muscles. (Some authorities include the equilibrium receptors of the inner ear in this class.) Proprioceptors constantly advise the brain of our body movements by monitoring how much the organs containing these receptors are stretched.
Nonencapsulated (Free) Nerve Endings
mostly small and nonmyelinated. respond to pain, heat, and cold, and itch.
merkel cells and discs
AKA Epithelial tactile complexes. light pressure receptors between the dermis and epidermis. a type of free nerve ending.
encapsulated nerve endings
consist of one or more fiber terminals of sensory neurons enclosed in a connective tissue capsule. Most are mechanoreceptors but a few are proprioceptors; they vary greatly in shape, size, and distribution in the body. They include tactile corpuscles, lamellar corpuscles, bulbous corpuscles, muscle spindles, tendon organs, and joint kinesthetic receptors
tonic receptors
provide a sustained response with little or no adaptation. Nociceptors and most proprioceptors are tonic receptors because of the protective importance of their information.
phase receptors
fast adapting, often giving bursts of impulses at the beginning and the end of the stimulus. Phasic receptors report changes in the internal or external environment. Examples are lamellar and tactile corpuscles.
origin of parasympathetic fibers
the brain or sacral spinal cord
origin of sympathetic fibers
the lumbar or thoracic spinal cord
which are longer: postganglionic or preganglionic fibers?
In the parasympathetic system, preganglionic fibers are longer. in the sympathetic system, postganglionic fibers are longer
are preganglionic and postganglionic fibers myelinated?
Preganglionic fibers are lightly myelinated. Postganglionic fibers are not myelinated.
