Cortex Somatosensory Flashcards
What are the 6 layers of the cortex from outer to inner?
- Molecular
- External granular
- External pyramidal
- Internal granular
- Internal pyramidal
- Multiform
What types of fibers enter the external granular layer?
Long associative fibers
What types of fibers are found throughout the external granular layer?
- Short associative fibers
What types of fibers exit the external pyramidal layer?
Long associative
What types of fibers are found within the external pyramidal layer?
- Short associative
- Commissural
What types of fibers are found within the internal granular layer?
- Corticalpetal (go everywhere)
- Thalamocortical radiations
What types are found in the internal pyramidal layer?
Corticofugal fibers from:
- Striatum
- Brainstem
- Spinal cord
What layer has reciprocal connections to the thalamus?
Multiform
What gyrus makes up the Sensory cortex?
Postcentral gyrus
Is the sensory cortex hetero or homotypical?
Hetero
What are the 4 portions of the sensory cortex from anterior to posterior
3a, 3b, 1, 2
From what structure do 3a and 3b receive most of their projections?
Thalamus
What types of fibers does 3b receive? What sensory information do they carry?
Fast and slow adapting cutaneous receptors (texture, and size and shape of objects)
What types of fibers does 3a receive?
Proprioception
What areas do 3a and 3b project to?
Areas 1 and 2
What are the 5 largest areas of the sensory homunculus?
- Lips
- Tongue
- Feet
- Hand
- Face
How are individual modalities of S1 arranged within the cortex?
In columns (one for fast adapting, one for slow adapting fibers)
What are the 2 pathways of S1?
- What
- Where
Which pathway sends information to S2?
What
Which pathway works with the posterior parietal cortex?
Where
What structures does the What pathway connect with?
- Insula
- Parietal operculum
- S2
What areas make up the Where pathway?
5, 6, 7
Which pathway can recognize objects with visual aid?
What
Which pathway can determine where an object is in space?
Where
What will a lesion to 3b cause?
Loss of discrimination of texture, shape, and size
What will a lesion to 1 cause?
Inability to assess texture
What will a lesion to 2 cause?
Inability to assess shape and size
Why are pain, temperature, and crude touch not affected by a lesion to S1?
The LSTT negates the loss
How does S2 connect with S1?
Via the Treanscallosal Connection
What are the 5 functions of S2?
- Bimanual coordination
- Rapid transfer of acquired tactile skills
- Texture and shape discrimination
- Acute pain
- Localizes
What 2 effects will a lesion of S2 cause?
- Severe impairment of discernment of shape and texture
- Inability to learn tactile discrimination based on shape
Is the associative somatosensory cortex homotypical or heterotypical?
Homotypical (most common)
What complex plays a large role in the Associative cortex?
Posterior parietal complex
What 3 functions does the posterior parietal complex perform?
- Perception and intrepretation of spatial relationships
- Accurate body image
- Learning tasks related to coordination of bod yin psace
What function does Area 5 perform in the Associative cortex?
Integrates tractile info from mechanoreceptors in skin and prorioception from muscles and joints
What sensory information does area 7 of the associative cortex integrate?
- Vision
- Tactile information
- Propriocpetive information
Aligns body coordinate system with the environment
What 5 strange disorders result from lesions to the Associative cortex?
- Tactile agnosia
- Astereognosia
- Amorphognosia
- Ahylognosia
- Neglect syndrome
What is tactile agnosia?
- Can’t recognize objects, but can describe them through touch
What is astereognosia?
Can’t recognize object through feel
What is amorphognosia?
Can’t recognize object through form
What is ahylognosia?
Can’t feel: weight, texture, or density
What is neglect syndrome?
- Ignore portion of body or world
Is the motor cortex granular or agranular?
Agranular
Is the motor cortex heterotypical or homotypical?
Heterotypical
What functions does the insula perform?
- Determines quality and intensity of stimulus
- Affective aspects of pain
- Deals with homeostasis
What is the function of the Anterior Cingulate Cortex?
- Generates/ controls emotions
- Unsettling/ unpleasant pain activate
What 2 structures make up the parabrachial nucleus?
- Amygdala
- Hypothalamus
Where is the allocortex found?
Deep temporal lobe
How many layers is the allocortex?
3
What are the 3 layers of the allocortex?
- Molecular
- Pyramidal/ granule
- Polymorphic
What 4 structures make up the allocortex?
- Subthalamus
- Hippocampus
- Dentate gyrus
- Parahypocampal gyrus
