Somatosensory Pathways Flashcards
The closest mechanoreceptors to the surface
Merkel’s Disc and Meissner Corpuscles
Somatosensory information goes through the…
Dorsal Column - Medial Lemniscus Pathway
Higher [Mechanoreceptors]
Meissner
Fast adapting mechanoreceptors are
Meissner and Pacinian
Smallest RF
Merkel
Smaller Receptor Fields are Found in
Fingers and upper lip
Nerve Territory vs Dermatome
NT = Area of skin that provides sensory information to a specific Nerve Dermatome= Area of skin supplied by a nerve root
then endings of the mechanoreceptors are free nerve fibres T/F
F, encapsulated by connective tissue
where are located the gracile and cuneate fasciculli
Dorsal Funiculus
how many neruons comprise the DC- ML pathway and from where to where they go
1 Mechanoreceptor to Cuneate/Gracile Nucleus (Lower medulla)
2 Lower medulla to Lateral Ventral Posterior Nuclei [Lateral VPN] (Thalamus)
3 Thalamus to Sensory Cortex
neurons cross the midline at the level of the medulla via
Internal Arcuate Fibre
at the level of the spine more medial equals more distal T/F
T, same at the cortex
but at the medulla is the other way around
Most of the information received is analysed by which part of the cortex
Area 3b of the primary somatosensory cortex
Most medial part of the somatosensory cortex is the 1 and the most lateral is the 2
1 Genitalia
2 Chin and lower lip
Parts of the Dorsal Column - Medial Lemniscus Pathway
1 Dorsal Column
2 Dorsal Funiculus
3 Caudal Medulla (Gracile/Arcuate Nucleus)
4 Internal Arcuate Fibres
5 Medial Lemniscus Pathway
6 Ventral Posterolateral Nucleus of the Thalamus
7 Internal Capsule
8 Sensory Cortex
Gracile Nucleus takes info from which level of the spinal cord and below
T7
Up to what level does the spinal cord reaches
L1-L2
thus site for lumbar puncture is L3-L4
H is the spinal cord is made of which type of matter
Grey
which horn of the spinal cord is for somatosensory information
Dorsal Horn
what are the 3 types of pathways found in the spinal cord
Ascending
Descending
Propiospinal
Nociception travels within 1
Decussates at the level of 2
via the 3
Towards the 4
1 Dorsal Horn
2 (1/2) levels above or below
3 Anterior White Commissure
4 Anterolateral System
Muscle spindles are not found in the
Extraocular muscles of the eye
What are muscle spindles?
Terminal Neurons capsulated in connective tissue able to detect STRETCH
What is a motor Unit?
Muscle Fibres inervated by 1 alpha motor Neuron
Define Motor Neuron Pool
All the motor neurons that innervate 1 muscle
Muscle spindles are innervated by
Gamma Motor neurons that gives them
What type of sensory apparatus is in parallel with the muscle fibres
Muscle Spindles
1 - Type of sensory organ found in the tendons of muscles
2 - WHat do they sense
1 - Golgi Tendon Organs
2 - Force