Anatomy_Key Terms_Ch14 Flashcards
sensory receptors
pick up stimuli from inside and outside the body and then initiate impulses in sensory axons, which carry the impulse to the CNS
nerves
bundles of peripheral axons
motor endings
terminal boutons of motor neurons that innervate the effector organs, muscles, and glands
peripheral sensory receptors
structures that pick up sensory stimuli and then initiate signals in the sensory axons; most fit into two main categories: free nerve endings of sensory neurons and complete receptor cells
exteroceptors
sensitive to stimuli arising outside the body; most located at or near the body surface and include receptors for touch, pressure, pain, and temperature in the skin and most receptors of the special sense organs
interoceptors
aka veseroceptors, receive stimuli from the internal viscera e.g. digestive tube, bladder, and lungs; different ones monitor a variety of stimuli, including changes in chemical concentration, taste stimuli, the stretching of tissues, and temperature; their activation causes us to feel visceral pain, nausea, hunger, orfullness
proprieceptors
located in the musculoskeletal organs, e.g. skeletal muscles, tendons, joints, and ligaments; monitor the degree of stretch of these locomotory organs and send input on body movemeents to the CNS
mechanoreceptors
respond to mechanical forces such as touch, pressure, stretch, and vibrations
baroreceptor
mechanoreceptor that monitors blood pressure
thermoreceptors
respond to temperature changes
chemoreceptors
respond to chemicals in solution (such as molecules tasted or smelled) and to changes in blood chemistry
photoreceptors
in the eye respond to light
nociceptors
(noci=harm), respond to harmful stimuli that result in pain
general sensory receptors
nerve endings of sensory neurons that monitor touch, pressure, vibration, stretch, pain, temperatur, and proprioception; two broad groups: free nerve endings and encapsulated nerve endings surrounded by a capsule of connective tissue
free nerve endings
invade almost all tissues of the body but are particularly abundant in epithelia and in the connective tissue that underlies epithelia; primarily nociceptors and thermoreceptors; monitor the affective sense, those to which people have an emotional response
epithelial tactile complexes
aka Merkel discs, lie in the epidermis of the skin; each consists of a disc-shaped tactile epithelial cell innervated by a sensory nerve ending
slowly adapting mechanoreceptors
continue to respond and send out action potentials even after a long period of contiual stimulation
hair follicle receptors
free nerve endings that wrap around hair follicles, mechanoreceptors for light touch that monitor the bending of hairs (rapidly adapting)
rapidly adapting
sensation disappears quickly even if the stimulus is maintained
encapsulated nerve endings
consist of one or more end fibers of sensory neurons enclosed in a capsule of connective tissue
tactile corpuscles
“aka Meissner’s corpuscle, a few spiraling nerve endings are surrounded by Schwann cells, which in turn are surrounded by an egg-shaped capsule of connective tissue; occur in the dermal papillae beneath the epidermis; rapidly adapting receptors for fine, discriminative touch; mainly occur in sensitive and hairless areas of the skin e.g. soles, palms, fingertips, nipples, lips”
lamellar corpuscles
aka Pacinian corpuscles, scattered throughout the deep connective tissues of the body e.g. in the subcutaneous tissue deep to the skin; respond only to the initial application of pressure before they tire and stop firing (rapidly adapting receptors), best suited to moitory vibration; ~0.5-1mm wide and 1-2mm long
bulbous corpuscles
aka Ruffini endings, located in the dermis and elsewhere, contain an array of nerve endings enclosed in a thin, flattened capsule; adapt slowly and thus can monitory continuous pressure placed on the skin
proprioceptors
virtually all are encapsulated nerve endings that monitor stretch in the locomotory organs; include muscle spindles, tendon organs, and joint kenesthetic receptors
muscle spindles
(neuromuscular spindles), measure the changing length of a muscle as that muscle contracts and is stretched back to its original length; an average muscle contains 50-100, which are embedded in the perimysium between tho fascicles
intrafusal muscle fibers
(intra=within, fusal=the spindal), each spindle contains several modified skeletal muscle fibers surrounded by a connective tissue capsule
extrafusal muscle fibers
(extra=outside), the ordinary muscle cells outside the spindles, have more striations that the intrafusal muscle fibers
anulospiral endings
aka primary sensory endings, twirl around the noncontractile middle of the intrafusal fibers innervating the spindle center; these receptors are stimulated by the rate and degree of stretch of the muscle spindle
flower spray endings
(secondary sensory endings), monitor the spindle ends (the only contractile parts of the spindle) and respond only to degree of stretch
alpha efferent neurons
spinal motor neurons that cause the entire muscle (extrafusal fibers) to generate conractile force and resist further stretch
gamma efferent neurons
neurons preset the sensitivity of the spindle to stretch, most active when balance reflexes must be razor sharp
tendon organs
aka Golgi tendon organs, proprioceptors located near the muscle-tendon junction, where they monitor tension within tendons; each consists of an encapsulated bundle of tendon fibers (collagen fibers) whithin wihch sensory nerve endings are intertwined; relaxation reflex is important in motor activities that involve rapid alternation between flexion and extension
joint kinesthetic receptors
”"”movement feeling””, proprioceptors that monitor stretch in the synovial joints, specifically, they they are sensory nerve endings within the joint capsules”
lamellar (Pacinian) corpuscles
these rapidly adapting stretch receptors are idal for measuring acceleration and rapid movement of the joints
bulbous corpuscles (Ruffini endings)
these slowly adapting stretch receptors are ideal for measuring the positions of nonmoving joints and the stretch of joints that undergo slow, sustained movements
free nerve endings (joints)
may be pain receptors
receptors resembling tendon organs
their function in joints is not known
cranial nerves
“12 pairs that attach to the brain and pass through various foramina in the skull; numbered from I through XII in a rostral to coudal direction; first two pairs attach to the forebrain, the rest to the brain stem<br></br>"”Oh, Oh, Oh, To Touch And Feel Very Good Velvet, AH!”””
I. Olfactory
this is the sensory nerve of smell
II. Optic
because it develops as an outgrowth of the brain, this sensory nerve of vision is not a true nerve at all; it is more correctly called a brain tract
III. Oculomotor
”"”eye mover””, this nerve innervates four of the extrinsic eye muscles–muscles that move the eyeball in the orbit”
IV. Trochlear
”"”pulley””, this nerve innervates an extrinsic eye muscle that hooks through a pulley-shaped ligament in the orbit”
V. Trigeminal
”"”threefold””, which refers to this nerve’s three major branches; the nerve provides general sensory innervation to the face and motor innervation to the chewing muscles”
VI. Abducens
this nerve was so named because it innervates the muscle that abducts the eyeball (turns the eye laterally)
VII. Facial
this nerve innervates the muscles of facial expression as well as other structures
XIII. Vestibulocochlear
This sensory nerve of hearing and equilibrium was once called the auditory nerve
IX. Glossopharyngeal
”"”tongue and pharynx””, structures that this nerve helps to innervate”
X. Vagus
”"”vagabond”” or ““wanderer””, this nerve ““wanders”” beyond the head into the thorax and abdomen”
XI. Accessory
once called the spinal accessory nerve; originates from the cervical region of the spinal cord, enters the skull through the foramen magnum, and exits the skull with the vagus nerve; carries motor innervation to the trapezius and sternocleidomastoid muscles
XII. Hypoglossal
”"”below the tongue””, this nerve runs inferior to the tongue and innervates the tongue muscles”
cranial sensory ganglia
lie along some cranial nerves (V, VII-X) just external to the bran; directly comparable to the dorsal root ganglie on teh spinal nerves
primarily or exclusively sensory nerves
(I, II, VIII) that contain special sensory fibers for smell (I), vision (II), and hearing and equilibrium (VIII)
primarily motor nerves
(III, IV, VI, XI, XII) that contain somatic motor fibers to skeletal muscles of the eye, neck, and tongue
mixed (motor and sensory) nerves
(V, VII, IX, X), these mixed nerves supply sensory innervation to the face (through general somatic sensory fibers) and to the mouth and viscera (general visceral sensory), including the taste buds for the sense of taste (specialy visceral sensory); these nerves also innervate pharyngeal arch muscles (somatic motor), such as the chewing mucles (V) and the muscles of facial expression (VII)
spinal nerves
thirty-one pairs, each containing thousands of nerve fibers, attach to the spinal cord; named accourding to their paint of issue from the vertebral column: 8 pairs of cervical nerves, 12 pairs of thoracic nerves, 5 pairs of lumbar nerves, 5 pairs of sacral nerves, 1 pair of coccygeal nerves (Co1)
rootlets
attach along the whole length of the corresponding spinal cord segment
dorsal root
contains the axonal processes of sensory neurons arising from cell bodies in the dorsal root ganglion
ventral root
contains the axonal processes of motor neurons whose cell bodies are located in the ventral gray column of the spinal cord
dorsal ramus/i
supply the dorsum of the neck and the back
ventral ramus/i
supply the anterior and lateral regions of the neck and trunk, and all regions of the limbs
intercostal nerves
supply the intercostal muscles, the skin of the anterior and lateral thorax, and most of the abdominal wall inferior to the rib cage
nerve plexus
network of nerves; the ventral rami of all spinal nerves except T2-T12 branch and join one another lateral to the vertebral column, forming __(es)
cervical plexus
buried deep in the neck, under the sternocleidomastoid muscle, and extends into the posterior triangle of the next; formed by the ventral rami of the first four cervical nerves; forms an irregular series of interconnecting loops from which branches arise
sutaneous nerves
(cutane=skin), carry sensory impulses from the skin (cervical plexus: skin of the neck, the back of the head, and the most superior part of the shoulder)
phrenic nerve
receives fibers from spinal nerves C3, C4, and C5, courses inferiorly through the thorax and innervates the diaphragm, providing somatic motor and sensory innervation to this most vital respiratory muscle
brachial plexus
lies partly in the neck and partly in the axilla (armpit) and gives rise to almost all of the nerves that supply the upper limb; formed by the wentral rami of cervical nerves C5-C8 and most of the ventral ramus of T1, may recive small contributions from C4 or T2
roots of the brachial plexus
ventral rami C5-T1, lie deep to the sternocleidomastoid; at the lateral border of this muscle, these rami unite to form the upper, middle, and lower trunks, each of which branches into and anterior and posterior division
lateral cord
anterior divisions from the upper and middle trunks give rise to the _
medial cord
anterior division from the lower trunk forms the _
posterior cord
composed of the posterior divisions of all three trunks (upper, middle, lower)
musculocutaneous nerve
main terminal branch of the lateral cord, courses within the anterior arm
median nerve
innervates most muscles of the anterior forearm and the lateral palm
ulnar nerve
branches off the medial cord of the brachial plexus, then descends along the medial side of the arm
axillary nerve
branch of the posterior cord, runs posterior to the surgical neck of the humerus and innervates the deltoid and teres minor muscles; its sensory fibers supply the capsule of the shoulder joint and the skin covering the inferior half of the deltoid muscle
radial nerve
a contiuation of the posterior cord, is the largest branch of the brachial plexus, innervating almost the entire posterior side of the uper limb, including all the limb extensor muscles
