Flashcards in CNS Ch 12 Deck (56):
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Sensory receptors
Specialized to respond to changes in environment called stimuli
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Classification by stimulus type
Mechanoreceptors
Thermoreceptors
Chemoreceptors
Photoreceptors
Nociceptors
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Mechanoreceptors
Respond to mechanical force such as touch, pressure, vibration, and stretch
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Photoreceptors
Respond to light, such as those in the retina.
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Chemoreceptors
Respond to chemicals in solution ( molecules smelled or tasted, or changes in blood or interstitial fluid chemistry)
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Nociceptors
Respond to potentially damaging stimuli that result in pain (extremes of cold and heat, excessive pressure and inflammatory chemicles
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Classification by location
Exteroceptors: Outside the body
Internoceptors: Within the body
Proprioceptors:
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Proprioceptors
Occure in skeletal muscles, tendons, joints, ligaments and connective tissues or bones and muscles
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Simple receptors of general sences
Non-encapsulated (free) nerve endings
Encapsulated nerve endings
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Non-encapsulated nerve endings
Non-mylinated, small diameter and have knob like distal ends
Nearly everywhere, abundant in epithelial and connective tissue.
Examples: Tactile (merkel) disk in skin and Hair follicle receptors
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Encapsulated nerve endings
ONe or more fiber terminal enclosed in connective tissue capsule
Tactile corpuscles
Lamellar corpuscle
Bulbous corpuscles
Muscle spindles
Tendon organs
Joint kinethetic receptors
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Somatosensory system
Part of the sensory system serving the ody wall and limbs. Receives input from exteroceptors, interoceptors and proprioceptors
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3 levels of neural integration
Receptor level: sensory receptors
Circuit level: processing in ascending pathways
Perceptual level: processing in cortical sensory areas
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Perceptual detection
Ability to detect that stimulus has occured
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Magnitude estimation
Ability to detect how intense the stimuli is
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Spatial discrimination
Ability to identify the site and pattern of stimuli
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Feature abstration
The ability to identify multiple features of an object
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Quality discrimination
Ability to identify submodalities of a sensation, eg. sweet or bitter.
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Patter recognition
Ability to recognize a familiar or unfamiliar pattern, or a special significance.
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Visceral Pain
Results from noxious stimulation of receptors in thorax or abdomen.
Vague, dull, aching or burning
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Referred pain
Arises from one part of the body but is perceived in another part.
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Nerve
Cord like organ, consists of multiple fascicles full of axons and a blood supply
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Nerve structure
Endoneurium: encloses each axon
Perineurium: surrounds each fascicle
Epineurium: encloses all fascicles, outer sheath of nerve.
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Regeneration of PNS nerves
1. Axon fragments at injury site
2. Macrophages clean out the dead axon
3. Schwann cells form regeneration tube and axon sprouts grow through tube.
4. Axon regenerates and new myelin sheath forms
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I Olfactory
Tiny nerve filaments of sense of smell
SENSORY ONLY
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II Optic
SENSORY ONLY, nerve of vision, outgrowth of the brain so it is actually a tract.
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III Oculomotor
MOTOR ONLY, "eye mover", supplies the 4 extrinsic muscles that move the eyeball up down and inward.
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IV Trochlear
MOTOR ONLY, "pulley" innervaed the extrinsic eye muscle that rotate eye inferolaterally
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V Trigeminal
SENSORY & MOTOR to the face and chewing muscles
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VI Abducens
MOTOR. Controls eye abduction
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VII Facial
MOTOR & SENSORY, controls muscles of facial expression
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VIII Vestibulocochlear
SENSORY, for balance and hearing.
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IX Glossopharyngeal
SENSORY & MOTOR for tongue and pharynx
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How many spinal nerve pairs are there
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8 cervical (C1-C8)
12 thoracic (T1-T12)
5 lumbar (L1-L5)
5 sacral (S1-S5)
1 coccygeal (C0)
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DAVE
Dorsal root = Afferent, Ventral root = Efferent
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Nerve Plexis
Ventral rami branch and join one another laterally forming complicated interlacing nerve networks
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Cervical Plexus
C1-C4
Under SCM
mostly supply cutaneous nerves
and muscles of anterior neck
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Phrenic nerve
Fibers from C3, C4 & C5
motor and sensory for the diaphragm
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Brachial Plexus
Nerves that innervate upper limb
C5-C8 and T1
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Really Tired Drink Coffee
Brachial plexus branches from medial to lateral:
1) Roots
2) Trunks
3) Divisions
4) Cords
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Nerves of brachial plexus
Axillary
Musculocutaneus
Median
Ulnar
Radial
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Axillary
innervated deltoid, teres minor, shoulder skin and joint
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Musculocutaneus
Biceps brachii, brachialis and coracobrachialis
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Median
5 muscles of lateral palm, pronates foreare, flex wrist and thumb and index finger
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Ulnar
Medial part of forearm and the last 3 fingers, flexors not supplied by median nerve
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Radial
Extend the elbow, supinate forearm, extend wrist and fingers, and abduct the thumb.
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Lumbosacral Plexus
L1-L4
Within Psoas major muscle
Innervates abdominal wall and psoas muscle, anterior and medial thigh
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Femoral nerve
Largest terminal nerve in lumbar plexus
Innervates quadriceps and knee extensors.
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Obturator nerve
innervates adductor muscles through obturator foramen
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Sacral plexus
L4-S4
Innervates butt ox lower limb pelvic structures and perineum
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Sciatic nerve
Largest nerve in sacral plexus
thickest and longest in the body
supplies entire lower limb except anteromedial thigh.
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Hilton's Law
Any nerve serving a muscle that produces movement also innervates the joint and skin over the joint.
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Hierarchy of motor control
Precommand
Projection
Segmental
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Precommand level
Highest level, cerebellum and basal nuclei, programs and instructions.
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Projection level
Middle level, motor cortex and brain stem nuclei (vestibular and reticular formation ect)
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