Sensation and brain

Receptive field

the spatial region where application of a stimulus causes a sensory neuron to respond.

Sensory unit

a primary afferent and the receptors that define its receptive field.

Superficial pain

activation of the Aδ fibres sharp, circumscribed and well localized, fast conduction

Deep pain

resulted in the activation of C type fibres, diffuse, hard to localize, and concomitant vegetative reactions can be seen

Nociceptors

free nerve endings, small diameter, not or “less” myelinated axon → slow conduction velocity

modality specific nociceptors

reacts to a mechanical or chemical stimulus

polymodal nociceptors

nociceptors are activated by strong stimuli of different modalities

Endogenous opioid system

inhibits neurotransmission (opioid therapy).

Acupuncture

release of endogenous opioids

TENS

pain relief and decrease of muscle spasm

Icing

inhibition of nociception

Pain

Pain is conducted by the spinothalamic tract.

Visceral pain

hard to localise, long-lasting, diffuse pain evoked by the mechanical or other stimuli in the internal organs.

Ischemic pain

evoked by hypoxia in the tissues. Characteristic symptom is the angina pectoris which derives from the poor blood supply to the heart

Claudication intermittent

ischemic pain in the lower extremities which occurs during exercise, such as walking, and is relieved by a short period of rest.

Referred pain

pain perceived at a location other than the site of the painful stimulus

Défense musculaire

protective mechanism, spasm of the skeletal muscle originated from the same somite than the internal organ affected by injury (inflammation, irritation)

Aα motor neurons

innervates muscle fibers

Aγ motor neurons

innervates intrafusal fibers

Pyramidal system

voluntary control, the implementation of the fine, highly resolved movements, learn the new movement elements and influences the muscle tone

Extrapyramidal system

Carry impulses from the neocortex, the subcortical ganglia, the vestibular apparatus, the reticular formation of the brainstem, and indirectly from the cerebellum. Regulation of automatic movements (programmed movements), regulation of muscle tone, regulation of rough movements

Reflex

Stimuli → receptors → local response → action potential → afferent branch → reflex center: data processing → efferent branch → effector

Somatic reflexes

proprioceptive ("sense of self") reflexes
myotatic reflex (stretch reflex)
inverse myotatic reflex

exteroceptive reflexes

flexor reflexes
crossed flexor-extensor reflex

Role of the cerebellum

Coordination of the eye movements
Regulation of the reflex movement of the head
To keep the balance
Control of the running movements
Regulation of the muscle tone
Planning and starting the movements
Coordination of movements