Lecture 9 Flashcards
Describe how sensory info comes in
Have sensory receptors in the periphery, sensory systems carrying different modalities
What are the main types of sensory modailities?
-Proprioception
-Superficial touch
-Deep touch
- Vibration
- Pain
- Temperature
Receptors carrying proprioception
muscle spindles and glogi tendon organs from muscle stretch
Receptors for superificial touch
meissner’s corpuscle and merkle receptors
Receptors for deep touch, vibration
pacinian corpuscle, ruffini ending
Receptors for pain and temperature
bare nerve endings
Dermatome
Cutaneous region associated with a spinal segment
Trigeminal nerve innervates the
face region
Cutaneous region associated with with cervical cord
back of head, neck and upper half of arms
Cutaneous region associated with with thoracic cord
lower half of arms and trunk and thorax
Cutaneous region associated with with lumbar cord
front and sides of legs
Cutaneous region associated with with sacral region of cord
back of legs, feet
C5 nerve innervates
lateral part of upper arm/deltoids
C6 nerve innervates
upper half of the lower arm
C6, C7, C8 nerve innervates
hand
T1 nerve innervates
lower half of lower arm, including over elbow
How trunk is innervated
upper trunk levels innervates high up, lower thoracic level innervates lower trunk
level of spinal cord innervates around nipples
T4
level of spinal cord innervates at level of umbilicus
T10
Above nipples in trunk innervates by
T2, T3, T4
Below nipples and above umbilicus innervates by
T5-T10
L2 innates
upper part of thighs
L3 innervates
Knees
L4 innervtes
Medial aspect of leg
L5 innervates
lateral aspect of leg
S1 innervates
achillies tendon
Two main ascending sensory pathways (once info enters into spinal cord) that carry info to sensory regions of cortex
- posterior column-medial lemniscus pathways (PCML)
- Antero-lateral pathway
How are ascending pathways named
for where they travel
- PCML- travel in posterior column of SC, through medial leminiscus higher up
- Anterlateral pathways travel in anterolateral column of SC
Info that Posterior column-medial lemniscus pathways carries
vibration, proprioception, light touch information (good sensations)
Info that antero-lateral pathway carries
pain, temperature, crude touch info (bad sensations)
Describe pathway of PCML tract (first order neuron)
- Involves three neurons
- Receptor in periphery, sends action portential through mixed nerve until gets to intervertebral formen where it splits and enters dorsal root. Bulge (dorsal root ganglion) contain cell bodies for primary sensory neurons. From cell bodies have second axon (of primary sensory neuron) through dorsal root into dorsal horn. Axons buifurface, one branch to nuclei at level of spinal cord- e.g. if simple stretch reflex pathways innervate to motor nuclei back out to muscle. Other branch enters posterior column of white mater and ascends.
Describe the organsiation of upper and lower motor neurons in PC-ML pathway
- Lower body- primary sensory neurons travel in fasciculus gracilis
- Upper body- primary sensory neurons travel in fasciculus cunateatus
- Maintains somatotopic organisation:
- Leg= medial
- Arms-lateral
Describe PC-ML tracts from first order neuron
travels to caudal medulla. Axons of fascuculus gracilis synapse on nucleus gracilis (medial nuclei). Axons in fasciculus cunateatus synapse on nucleus cuneatus (lateral nuclei). Second order neurons travels from nucli and cross midline in caudal medulla and synapse in thalamus (contralteral side they originated). This tract in called medial lemniscus. Third order sensory neurons from thalamus go to somatosensory cortex
Identify this pathway
Posterior Column-Medial Lemniscus pathway
