Somesthesis Flashcards
Somesthesis
general term referring to body sensibility or somatosensory capacity.
Exteroceptors
respond to external stimuli impinging on the skin
proprioceptors
located more deeply in muscles, joints, ligaments, and the vestibular system. Signal the status of muscle, joints, and tendons
interoceptors
located within viscera, respond to changes in the internal environment- mechanical or chemical nature of viscera and body wall.
Mechanoreceptors
transduce mechanical energy into electrical signals propagated along axons to the central nervous system
Rapidly adapting afferents
signal transient events such as a stimulus contact and movement or high frequency events like vibration
Slowly adapting afferents
signal maintained events such as light pressure
Nociceptors
pain
Dorsal column system
Detailed discrimination that is involved in sensory perception and fine movements.
Spinocerebellar system
Proprioception
Spinothalmic tract
location and intensity of painful stimuli. Projects to VCL and other thalamic nuc
spinoreticular tract
affective qualities of painful stimuli through projections to thalamus and other regions. Ends in brainstem reticular formation and IL
Motor nucleus of V
Contains motor neurons that innervate muscles of mastication.
Principal sensory nucleus of V
Receives touch input from the face and oral cavity. Dorsal zone: oral cavity Ventral zone: face
Mesencephalic nucleus of V
Innervation to proprioceptors of the muscles of mastication and periodontal ligaments. Jaw closing reflexes
Spinal nucleus of V
Subnucleus oralis mediates oral cav reflexes. Interpolaris receives touch inputs and projects to the VCM. CAUDALIS relays pain and thermal sensations to the intralaminar nuclei of thalamus
Trigeminothalamic tract
info from face. Terminates at VCM
Medial lemniscus
Info from the trunk and limbs. Terminates at VCL
Lateral system
Spinocervical thalamic, lat spinothalamic, and dorsal column tracts, provide sesnory-discriminative aspect of pain
Medial system
Spinoreticular, medial spinothalamic, propriospinal tracts, provide motivational-affective aspect of pain
A fiber
First superficial pain myelinated
C fiber
Second deep pain unmyelinated
