EXTROCEPTIVE SYSTEM FOR MECHANORCEPTION
- Means the structures and pathways that detect mechanical stimuli from the external environment providing information about touch , pressure , vibration & proprioception.
Componants :
1. Sensory receptors (mechanoreceptors)
- Are specialized sensory receptors that respond to mechanical stimuli.
- Types :
- Merkel cells - in the epidermis (light touch & light)
- Meissner's Corpuscles.
2. Peripheral Nerves :
- Carry signals from mechanoreceptors to the (CNS.)
3. Spinal cord :
Enter the spinal cord & synapse with seconed -order neuron in the dorsal horn.
4. Ascending pathways :
The dorsal column - medial lemniscus pathway is particularly involved in transmitting fine touch , pressure....
4. Brainstem
5. Thalamus
6. Primary Somatosensory cortex
- Sensation reaching the cerebral cortex → conscious.
- " terminate elsewhere → unconscious.
2 Types of sensory system :
1. General :
- A. General somatic afferent.
Provides sensations from skin , joints , muscles , tendons
- Pain - temp - light touch.
- Proprioception and discriminative touch.
- B. General visceral Afferent
senses info from internal organs , blood vessles & glands.
2. Special :
These systems are highly specialized for specific senses.
- Sight
- Sound
- Smell
- Taste
- Balance.