Unit 6: Tutoring Flashcards
Functions of the Thalamus
- Integration and relay of sensory information
- Integration and relay of motor control information from cerebellum and basal ganglia to the motor cortex
- Gaiting of the passage of sensory and motor info
- Transmit states of consciousness from brainstem to cortex
Reciprocal Connections Between Thalamus and Cortex
VA (thalamus-cortex connections)
Frontal Cortex
VL (thalamus-cortex connections)
Motor and Premotor Cortex
VPL & VML (thalamus-cortex connections)
Somatosensory Cortex*
MD &. Pulvinar (thalamus-cortex connections)
Parieto-Occipital Cortex
LGN (thalamus-cortex connections)
Visual Cortex
MGN (thalamus-cortex connections)
Auditory Cortex
Main Categories of Thalamic Nuclei
- Relay Nuclei
- Intralaminar Nuclei
- Reticular Nuclei
Relay Nuclei (Thalamic Nuclei)
- Specific relay nuclei: Project to primary sensory and motor areas (nuclei located mainly in the thalamus)
- Widely projecting (non-specific) nuclei: Project to large regions of association corticies involved in behavior orientation
Intralaminar Nuclei (Thalamic Nuclei)
- Lies within internal medullary lamina
- Main inputs and outputs with basal ganglia
- Alertness and consciousness
Reticular Nucleus (Thalamic Nuclei)
- Thin sheet lateral to thalamus and medial to internal capsule
- Does not project to cortex
- Inputs and outputs are within the thalamus
Main Nuclear Divisons of the Thalamus
Ascending Pathways Overview
- Posterior/Dorsal Column Medial Lemiscal: Facilulus Gracilis & Faciculus Cuneatus)
- Anterolateral System: Spinothalamic, Spinoreticular, & Spinomesencephalic Tract)
- Ventral & Dorsal Spinocerebellar Tract
- Cuneocerebellar
■ Spinothalamic (ALS)
-Identifies that there is pain (“I’m stepping on something sharp”)
-Located in Cortex
-A Pain (fast & acute)
● Location & intensity of pain/temperature (noxious stimuli)
Spinoreticular (ALS)
- Adds emotional/arousal component (“Ouch, that shit hurts”)
- Located in Pons
- C Pain (chronic & slow)
Spinomesencephalic (ALS)
- Identifies that pain is feeling better (pain modulation)
- Located in Midbrain
Sensory and Motor Spinal Cord Pathways
Somatotropic Organization of Posterior Column and Anterolateral Pathways in the Spinal Cord
PCML (vibration, proprioception, fine touch) -UE: Lateral (faciculus cuneatus) -LE: Medial (faciculus gracilis) ALS (pain, temp, crude touch) -UE: Medial -LE: Lateral
Sensory Neuron Fiber Types
Group 1: A-alpha
Group 2: A-beta
Group 3: A-delta
Group 4: C
Group 1: A-alpha Fibers (Sensory Neuron Fiber Types)
- Found in: Spinocerebellar Tract
- Receptors: Muscle Spindles & Golgi Tendon Organs
- Modalities: Proprioception
Group 2: A-beta Fibers (Sensory Neuron Fiber Types)
Found in: DCML tract Receptors/Modalities -Muscle Spindle: Proprioception -Meissner's Corpuscle: Superficial Touch -Merkel's Receptor: Superficial Touch -Pacinian Corpuscle: Deep touch, Vibration -Ruffini Ending: Deep touch, Vibration -Hair Receptor: Touch, Vibration
Group 3: A-delta Fibers (Sensory Neuron Fiber Types)
Found in: Anterolateral Spinothalmic Tract (ALS)
Receptors: Bare Nerve Ending
Modalities: Pain (sharp), Temp (cold), Itch
Group 4: C Fibers (Sensory Neuron Fiber Types)
Found in: Lateral Spinothalmic Tract (ALS)
**ONLY FIBERS NOT MYELINATED
Receptors: Bare Nerve Ending
Modalities: Pain (dull/achy), Temp (warm), Itch