Chapter 13

cranial nerve VI

Abducens, motor, lateral movement of eyeball

What is magnitude estimation?

Ability to detect stimulus intensity. Perception increases and intensity increases.

What is perceptual detection?

Ability to detect that a stimulus has occurred. Imput from several receptors must be summed for perceptual detection to occur.

What is quality discrimination?

Ability to differentiate the subcategories of a particular sensation. Ex. Taste- bitter or sweet

What is pattern recognition?

Ability to take in scene around and recognize a familiar pattern, unfamiliar pattern, or one that has special meaning. Ex. Dots that make up a picture.

cranial nerve XI

Accessory, motor, controls some swallowing movements, movement of head. Innervates trapezius and sternocleomastoid muscles

What types of nerves are afferent? Efferent? Both?

Afferent: Sensory.. Somatic, visceral Efferent: Motor.. Somatic, visceral Both: sensory and motor, most nerves, autonomic nerves

What is spatial discrimination?

Allows us to identify site and pattern of stimulus.

Describe a Merkel disc and what stimuli it can detect.

Associated with large disc shaped basal layer epidermis. Tactile and receptor for light.

Which ventral rami comprise the cervical plexus?

C1-C4

What important structure does the phrenic nerve innervate?

C3, 4, 5 keep the diaphragm alive

Which ventral rami comprise the brachial plexus?

C5-T1

Describe a Ruffini ending and what stimuli it can detect.

Capsule enclosed branched receptors that lie in deep in dermis, hypodermis, and joint capsule. Respond to deep and continuous pressure.

What is adaptation, with respect to receptors?

Change in sensitivity and nerve impulse generation in the presence of a constant stimulus.

What type of stimulus does a photoreceptor detect?

Changes in light, retina

What type of stimulus does an exteroreceptor detect?

Changes outside the body, touch, pressure, pain, temperature receptors in the skin and most special senses receptors.

What type of stimulus does a chemoreceptor detect?

Chemicals in solution, smelled, taste, changes in blood or interstitial fluid chemistry.

Describe a Pacinian corpuscle and what stimuli it can detect.

Deep, subcutaneous underlying skin. Only respond at pressures first touch. Best monitoring vibrations.

Through what opening do spinal nerves exit the spine?

Dorsal and ventral roots exit at intervertebral foramen. Lumbar and sacral nerves exit at cauda equine.

Which spinal nerve root carries sensory neurons?

Dorsal root

Where are sensory neuron cell bodies found?

Dorsal root ganglion

What are two pain inhibitors?

Endorphins and enkephalins

What structures do dorsal rami supply?

Entire somatic region of body, skeletol muscle, and skin form neck down

cranial nerve VII

Facial, mixed, facial expression, secretion of saliva and tears, taste (2/3 of tongue)

Describe a hair follicle receptor and what stimuli it can detect.

Free nerve endings wrap around follicle. Light touch receptor.

cranial nerve IX

Glossopharyngeal, mixed, secretion of saliva, swallowing, taste (posterior 1/3 tongue), control blood pressure.

What information does frequency of action potentials provide?

Greater the frequency the stronger the stimulus.

Which chemicals can trigger pain?

Histamine, K, ATP, acids, bradykinin, inflammatory prostaglandins.

cranial nerve XII

Hypoglossal, motor, movement of tongue, during speech and swallowing.

What actions does the lateral reticulospinal tract direct?

Impulses concerned with muscle tone, and many visceral motor functions. May control most unskilled movements.

What is phantom pain?

Intense pain strengthens neural connections with spinal cord and it "learns" hyperalgesia (pain syndrome)

What type of stimulus does an interoreceptor detect?

Internal changes, from viscera and blood vessels.

What type of stimulus does a proprioceptor detect?

Internal stimuli, skeleton muscles, tendons, joints, ligaments, and CT covering bones and muscles. Advise brain of body position and movement.

Which ventral rami comprise the lumbar plexus?

L1-L4

Which ventral rami comprise the sacral plexus?

L4-S4

What is feature abstraction?

Mechanism where a neuron or circuit is tuned to one feature in preference to others. Enables us to identify more complex aspects of a sensation.

What is a generator potential?

Membrane that depolorizations that summate and directly lead to generation of AP in an afferent fiber.

cranial nerve III

Oculomotor, motor, opening eyelid, papillary reaction.

cranial nerve I

Olfactory, sensory, smell

How do oligodendrocytes and astrocytes prevent nerve healing in the CNS?

Olidodendrocytes release inhibitory protein, nogo, and astrocytes lay down scar tissue which blocks axonal growth.

cranial nerve II

Optic, sensory, visual impulse from eye to optic cortex, pupillary reaction

What is a receptive field?

Particular area monitored by a receptor. The smaller the more accurate.

What is the difference between phasic and tonic receptors?

Phasic are fast acting, often give burst and initiation and ending. Report changes of internal and external environment. Ex, pacinian, meissner. Tonic provide sustained response with little to no adaption to stimulus. Protective importance. Ex. Nociceptors and most proprioceptors.

What type of stimulus does a nociceptor detect?

Potentially damaging stimuli resulting in pain. Excess of thermoreceptors, mechanoreceptors, chemoreceptors.

What type of stimulus does a mechanoreceptor detect?

Respond to mechanical force. Touch, pressure, blood pressure, vibration, stretch.

Describe a Meissner's corpuscle and what stimuli it can detect.

Small Encapsulated surrounded by Schwann cells, dermal papillae. Numberous in sensitive areas, ie nipples, finger tips, soles,

What is a fascicle (as pertains to nerves)?

Small bundles of nerve fibers enclosed by perineurium, bundled together in a larger group.

What substances do sensory axons release to transmit pain?

Substance P and glutamate that activate second order sensory neurons.

What is the endoneurium?

Surrounds axon and myelin sheath (neurilemma)

What is the epineurium?

Surrounds entire nerve

What is the perineurium?

Surrounds fascicle

What type of stimulus does a thermoreceptor detect?

Temperature. Hot, cold stimulus.

cranial nerve V

Trigeminal, mixed, lateral rectus, chewing, impulses of temperature, pain, and touch from face and teeth. Sensory from face and scalp, oral, and nasal cavity, and cornea.

cranial nerve IV

Trochlear, motor, superior oblique, movement and proprioception of eyeball.

What structures do ventral rami supply?

Trunk and limbs

Describe a free nerve ending and what stimuli it can detect.

Unencapsulated unmyelinates, small diameter, knob-like distal end swellings, mainly respond to temperature and painful stimuli but also tissue movements.

cranial nerve X

Vagus, mixed, controls smooth muscles and glands of GI tract, sensation from viscera.

Which spinal nerve root carries motor neurons?

Ventral root

Where are motor neuron cell bodies found?

Ventral root ganglion

cranial nerve VIII

Vestibulocochlear, sensory, hearing and balance

Describe a muscle spindle and what stimuli it can detect.

fusiform, spindle shaped, proprioceptors found in perimysium of skeletol muscles. Bundles of intrafusal fibers, detect stretch and start a reflex that resist the stretch.

How is a dead axon cleaned out after nerve damage?

phagocytized

Describe a Golgi tendon organ and what stimuli it can detect.

proprioceptors in tendons close to muscle insertion. Capsule enclosed layer of tendon (collagen) fibers that inhibit contraction and cause muscle to relax when the nerve endings activated by compression from stretch.

What type of stimulus do joint kinesthetic receptors detect?

proprioceptors that monitor synovial joint articulations ( joint position and movement). Pacinian corpuscles, ruffini endings, free nerve endings, golgi tendon looking receptors all aid kinesthetic receptors.