sensory information from the skin and musculoskeletal systems. 

Musculoskeletal (stretch, tension on tendon, position of joint, deep vibration) and pain 

Mechanoreceptors: respond to touch, pressure, stretch or vibration

   -Chemoreceptors: respond to substances released by cells (do chemoreceptors move afferently and efferently? no)

   -Thermoreceptors: respond to heating or cooling  

   -nocioceptor: responds to pain 

  outside the spinal cord in the dorsal root ganglia or outside the brain in cranial nerve ganglia

- Distal Axon: conducts messages from receptor to the cell body.

- Proximal Axon: projects from the cell body into the spinal cord or brain 

   Classified according to diameter

      - Ia, Ib, II or AB, A8 (cant find the weird symbol), C 

Proprioception 

receptor: muscle spindles

Stimulus: Muscle Stretch 

-large myelinated 

- 130 m/sec

proprioception

Receptors: golgi tendon organs, ligament receptors 

Stimulus: tendon tension, ligament tension

120 m/sec

large myelinated  

Proprioception 

Receptors: muscle spindles, paciniform and ruffini-type receptors in joint capsules

Stimulus: muscle stretch, joint movement 

speed: 90 m/sec

type: medium myelinated 

Cutaneous and subcutaneous touch and pressure 

Stimulus: touch, vibration, skin stretch, pressure 

Size: Medium Myelinated 

Speed: 90 m/sec

Pain and temperature 

receptors: free nerve endings

stimulus: tissue damage, temperature, course touch

size: Small myelinated

speed: 45 m/sec

Pain and temperature 

Receptors: free nerve endings

stimulus: tissue damage, temperature, tickle, itch 

Size: small unmyelinated

speed: 2 m/sec 

 small receptive field allowing resolution to closely spaced stimuli. Transmits information on the A(beta) afferents.  

Sensation of tickle and itch, pleasant touch or pressure - free nerve endings throughout the skin  

 Sensory organ in the muscle - consists of muscle fibers, sensory endings and motor endings. (quick and tonic stretch are registered by Ia afferents, tonic stretch is monitored by type II afferents) 

free nerve ending 

respond to warm or cold 

A(delta) or C afferents 

 Specialized muscle fibers inside the spindle 

Tension in tendon is relayed

information is transferred to the spinal cord by Ib afferents.

 respond to mechanical deformation of the joint capsule and ligament 

gamma dynamic axons: adjust the sensitivity of primary afferents

gamma static axons: tune the sensitivity of both primary and secondary afferents. 

the ability to use touch and proprioception to identify an object without looking. 

--- muscle spindles, joint receptors and cutaneous mechanoreceptors.   

divergent ascending network of neurons associated with pain. affects emotional, autonomic and social function.   

 receptors that receive/transmit information about pain. 

brings information about location and type of stimulation to the cerebral cortex. 

-high fidelity 

-discriminative touch, conscious proprioception  (dorsal column/medial lemniscus)

discriminative pain and temperature (spinothalamic)

maintained throught the second and third order neurons 

-means that each specific part of the body corresponds with a specific location in the somatosensory (primary) cortex

fast pain; travels on the lateral pain system (termination of the spinothamalic tract in the lateral thalamus) 

- conscious relay pathway 

analyzes information from the primary sensory area and the thalamus

-provides stereogenosis and memory of the tactile and spatial environment 

Conveys less localized information than is conveyed by the dorsal column/medial lemniscus 

-transmitted by C-fibers from low-threshold mechanoreceptors 

- vital for perceiving pleasant touch and pleasant skin-to-skin contact. 

type of pain

-slow, aching pain 

-divergent pathway 

conveys information from the receptor to the medulla 

conveys information from the medulla to the thalamus

 conveys information from the thalamus to the cerebral cortex. 

Transmits information to many locations in the brainstem and cerebrum.  

 Involved in turning the head and eyes towards the source of pain. 

synapse in the reticular formation ( Reticular formation: neural network in the brainstem that regulates sleep/wake cycle, arousal and attention.) Severe pain commands attention and interferes with sleep. 

transmits slow pain information to the thalamus. 

monitor activity of the spinal interneurons and descending motor signals 

anterior spinocerebellar tract

rostrospinocerebellar tract

 bilateral projection 

-automatic coordination of lower limb activities  

results in delayed motor development and clumsy movement 

(monkey experiemnt page 122) 

lowest intensity of a stimulus that can be percieved

evaluate the function of the peripheral nerve. 

-uses measures of latencies (delay), amplitudes (change in pressure), conduction velocities (speed).

-compared with unaffected nerves 

proprioceptive pathway lesion 

incoordination that is not due to weakness 

3 types (sensory, vestibular and cerebellar) 

peripheral nerves are subject to trauma and disease 

peripheral nerve severence: results in lack of sensation in the distribution of the nerve; pain may occur; sensory and motor changes are accompanied by reflex loss 

compression of peripheral nerve 

(sensory loss order)

1. conscious proprioception and discriminative touch

2. cold

3. fast pain

4. heat

5. slow pain

spinal region lesions 

(transection) 

results in preventing all sensation one or two levels below the level of the leasion from ascending to higher levels of the cord. 

-voluntary motor control is also lost 

interupts pain and temp. sensation from the contralateral body 

and discriminative touch and proprioception is lost ipsilaterally 

senses of conscious proprioception, two point discrimination and vibration sense are lost below the lesion. 

if lesion is above C6 there is an inability to recognize objects by palpating because of information from the hand being Lost. 

usually cause a mix of ipsilateral and contralateral signs. 

-ipsilateral face 

cerebral region lesions 

(thalamic)

-contralateral 

-decreas or loss of discriminative sensation (conscious proprioceptionm two-point discr., stereogenosis, localization of touch and pinprick. 

loss of sensation only evident when symmetric body parts are tested bilaterally. 

ex. if both hands are touched the person may be aware of the stimulation only on the same side of the body as the cortical lesion. if not touched simultaneously, stimulus can be felt of either side of the body. 

when tissue is injured or ischemic, biochemicals are released that awaken sleeping nociceptors. 

-awakened nociceptors are excessivly reactive to stimuli. 

coming from a site distict from the actual site of origin. 

ex. heart attack pain ...arrises from the skin of the medial left arm. 

consists of brain structures that process and regulate pain information 

parts of the (brainstem, amygdala, hypothalamus, thalamus, areas of the cerebral cortex) 

effect of the pain experience on emotions and behavior, including increased arousal and avoidance. 

(spinolimbic and spinoreticular tracts) 

why we respond by applying pressure to injured thumb 

- inhibits pain transmission 

endogenous or naturally occurring substances that activate antinociceptive mechanisms 

-enkephalins, dynorphins, Beta-endorphins)

substances are those that originate from within an organism, tissue, or cell

stress induced antinociception 

sites of antinociception 

(level I)

periphery 

topical methol, capsaicin, asprin

(prevents abnormal axon generated action potentials, decreasing pain)

Level II 

(antinociception)

occurs in the dorsal horn

-local inhibitory neurons (releasing enkephalin or dynorphin)

- counterirritant effects (low intensity TENS)

level III 

antinociception

fast acting neuronal system 

occurs in the hormonal system 

-low frequency TENS may act on this level 

Level V

Antinociception 

Glutamate acts on AMPA, NMDA and g-protein receptors to increase CA2+ 

neuropeptides act via second messager system to increase activity of kinases. 

- leads to gene activation and increase of cellular activity.

SO, nocioceptive information is not simply delivered to the brain but can change the structure and function of the CNS

C-fiber axons withdraw from the dorsal horn, A(beta)-fiber axon stop growing/connecting w/C-fibers

- A(beta)-fibers form connections with central nociceptive neurons, these synapses are percieved as pain.

- reorganization also happens in the cortex. 

the periphery (Ex. nerve compression in carple tunnel syndrom)

-the CNS in response to deafferenation 

-the dorsal horn 

partial nerve damage can cause allodynia 

-ephaptic transmission 

-ectopic transmission

-ectopic foci (in nerve stump, areas of myelin damage, in the dorsal root ganglion somas) 

can be partial or complete deafferentation. 

- neurons that use to recieve information from the body part may become abnormally active

ALL people, in amputation when sensation seems to originate from the missing limb (phantom limb sensation) 

- SOME people report Phantom pain in the missing limb 

caused by a Lesion of the CNS and is usually localized to the area of the body deafferented by the lesion. 

- spinal cord injury, stroke, Multiple Scerosis 

produces partial deafferentation and central sensitization 

- ex. diabetic neuropathy, Guillain-Barré syndrome 

Top-down regulation of pain is disturbed. 

-antinociception is reduced and/or pronociception os intensified. 

-tenderness of muscles and adjacent soft tissues, stiffness of muscles and aching pain. 

-pain shows a regional rather than dermatomal or peripheral nerve distribution. 

-perception of pain without any painful stimuli. 

-pain inhibition is impaired. 

 -main symptom: cronic widespread pain. 

-affects the somatosensory, autonomic and motor systems. 

- pain, vascular changes and atrophy 

- often follows surgery, fracture, crush injury or sprain. 

-severe, spontaneous pain out of proportion with the injury. 

-splintingm tactile stimulation, functional activities. 

-mirror therapy (modified, with the affected limb hidden)

DMSO cream

-surgury to implant stimulating electrode by the spinal cord or drug pump delivering opiords or local anesthetics directly to the spinal fluid. 

causalgia

-sudeck's atrophy

-sympathetically maintained pain 

- reflex sympathetic dystrophy 

sensitive to chemical concentrations in the blood. 

-located in the cartoid and aortic bodies. 

in the hypothalamus respont to small changes in temp. of cerculating Blood.

-cutaneous thermoreceptors respond to external temperature changes 

VII facial

IX glossopharyngeal

X vagus 

most visceral information entering the brainstem via cranial nerves converge here. 

- the main visceral sensory nucleus 

regulate hear rate, respiration, vasoconstriction and vasodialation 

master controller of homeostasis, maintains equilibrium in the interior of the body 

- influences cardiorespiratory, metabolic, water reabsorbtion and digestive activity by sending info to the pituitary gland, control centers in the brainstem and spinal cord

projects visceral information to the limbic system

-ANS responses ex. increased heart rate due to anxiety, blushing with embarrassment and crying

neurons that secrete (ACh) Acetylcholine. 

-include: all preganglionic neurons 

-postganglionic neurons of the parasympathetic system

-located in the mombranes of effectors 

- muscarine: a poison derived from mushrooms

-g protein mediated response 

-excitatory (EPSP) or Inhibitory (IPSP)

-regulate glands, smooth muscles, and heart rate 

-nicotine: derived from tobacco 

- located on postsynaptic autonomic neurons and the adrenal medulla

-excitatory (ESPS) 

 -also activates acetylcholine receptors on skeletal muscle membrane and limbic areas of the brain

receptors that bind to epinephrine and norepinephrine

-most sympathetic postganglionic neurons release norepinephrine 

- two groups (Alpha) and (Beta) 

-influence heart blood vessles and bronchi 

Adrenal medula: release transmitter into the bloodstream 

-Alpha and Beta 

skeletal muscle veins and venules. 

-blood pools in these vessles when their walls are relaxed 

- brief loss of consciousness due to inadequate blood flow to the brain.

-blood flow is restored when person is horizontal

can happen from emotion, prolonged bed rest, or painful stimuli  

fainting because of powerful emotions 

what happens: 

-vasodialation of intramuscular arterioles, causes precipitous fall in blood pressure

-blood flow to the head is lost

-