1
Q
Functions of the Thalamus
A
- 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
2
Q
Reciprocal Connections Between Thalamus and Cortex
A
3
Q
VA (thalamus-cortex connections)
A
Frontal Cortex
4
Q
VL (thalamus-cortex connections)
A
Motor and Premotor Cortex
5
Q
VPL & VML (thalamus-cortex connections)
A
Somatosensory Cortex*
6
Q
MD &. Pulvinar (thalamus-cortex connections)
A
Parieto-Occipital Cortex
7
Q
LGN (thalamus-cortex connections)
A
Visual Cortex
8
Q
MGN (thalamus-cortex connections)
A
Auditory Cortex
9
Q
Main Categories of Thalamic Nuclei
A
- Relay Nuclei
- Intralaminar Nuclei
- Reticular Nuclei
10
Q
Relay Nuclei (Thalamic Nuclei)
A
- 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
11
Q
Intralaminar Nuclei (Thalamic Nuclei)
A
- Lies within internal medullary lamina
- Main inputs and outputs with basal ganglia
- Alertness and consciousness
12
Q
Reticular Nucleus (Thalamic Nuclei)
A
- Thin sheet lateral to thalamus and medial to internal capsule
- Does not project to cortex
- Inputs and outputs are within the thalamus
13
Q
Main Nuclear Divisons of the Thalamus
A
14
Q
Ascending Pathways Overview
A
- Posterior/Dorsal Column Medial Lemiscal: Facilulus Gracilis & Faciculus Cuneatus)
- Anterolateral System: Spinothalamic, Spinoreticular, & Spinomesencephalic Tract)
- Ventral & Dorsal Spinocerebellar Tract
- Cuneocerebellar
15
Q
■ Spinothalamic (ALS)
A
-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)
16
Q
Spinoreticular (ALS)
A
- Adds emotional/arousal component (“Ouch, that shit hurts”)
- Located in Pons
- C Pain (chronic & slow)
17
Q
Spinomesencephalic (ALS)
A
- Identifies that pain is feeling better (pain modulation)
- Located in Midbrain
18
Q
Sensory and Motor Spinal Cord Pathways
A
19
Q
Somatotropic Organization of Posterior Column and Anterolateral Pathways in the Spinal Cord
A
PCML (vibration, proprioception, fine touch) -UE: Lateral (faciculus cuneatus) -LE: Medial (faciculus gracilis) ALS (pain, temp, crude touch) -UE: Medial -LE: Lateral
20
Q
Sensory Neuron Fiber Types
A
Group 1: A-alpha
Group 2: A-beta
Group 3: A-delta
Group 4: C
21
Q
Group 1: A-alpha Fibers (Sensory Neuron Fiber Types)
A
- Found in: Spinocerebellar Tract
- Receptors: Muscle Spindles & Golgi Tendon Organs
- Modalities: Proprioception
22
Q
Group 2: A-beta Fibers (Sensory Neuron Fiber Types)
A
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
23
Q
Group 3: A-delta Fibers (Sensory Neuron Fiber Types)
A
Found in: Anterolateral Spinothalmic Tract (ALS)
Receptors: Bare Nerve Ending
Modalities: Pain (sharp), Temp (cold), Itch
24
Q
Group 4: C Fibers (Sensory Neuron Fiber Types)
A
Found in: Lateral Spinothalmic Tract (ALS)
**ONLY FIBERS NOT MYELINATED
Receptors: Bare Nerve Ending
Modalities: Pain (dull/achy), Temp (warm), Itch
25
Posterior/Dorsal Column Medial Lemiscal Pathway (PCML/DCML-Main Long Tracts)
Fibers: I & II
Function: Vibration, Joint Proprioceptiotion, Fine Touch
Starts in: Spinal Cord (T6&below: Gracilis, T6&above: Cuneatus)
Decussation: Internal arcuate fibers in caudal (lower) medulla)
-Synapses: in VPL of thalamus
Stops: Primary Somatosensory Cortex
26
Anterolateral System (ALS-Main Long Tracts)
Fibers: III & IV
Function: Pain, Temp, Crude Touch (Key role in pain: esp sharp, acute)
Decussation: Anterior Commissure (spinal cord)
27
Lateral Spinothalamic Pathway (of the ALS)
Function: Identifying Pain, Temp, Crude Touch, Itch, Tickle
-Starts: Spinal cord
-Decussates: Immediately in the anterior white commissure of sc
-Synapses: in VPL of the thalamus (a pain: sharp, acute pain, c pain: chronic pain "ouch" sensation)
Stops: Primary somatosensory cortex
28
Lateral Corticospinal Tract- LCST (Lateral Motor System)
Functions: Contralateral extremity control (control all voluntarty, fine, skilled movements of opp extremities
Starts: Primary Motor Cortex
Decussations: Pyramidal Decussation at cervicomedullary junction (caudal medulla)
Ends: Entire cord
2 Neuron Pathway: 1st order (UMN), 2nd order (LMN/alpha motor neuron)
Lesions above (UMN): Contralateral weakness
Lesions below: Ipsilateral Weakness
Descends down to the brainstem, then 85-90% of fubers cross over to the contralateral sidem at the pyramidal decussation located at the cervicomedullary junction (forament magnum) to enter the lateral portions of the SC (remaining 10-15% goes to the anterior corticospinal tract)
29
Anterior Corticospinal Tract (Medial Motor System)
Functions: Motor of bilateral neck and trunk (tone, posture, extension, control of neck; Voluntary movements of biaxial and girdle musculature (proximal muscles)
Starts: Primary motor cortex (precentral gyrus)- ACT is remaining 10-15% of LCST fibers that did not cross over at pyramidal
*Bifurcates: in Spinal Cord (remains ipsilateral until it bifurcates at spinal cord to innervate both sides of the trunk muscles)
Ends: Upper thoracic region
30
Reticulospinal Tract (Medial Motor System)
Functions: Pontine (extensor muscles)/Medullary (flexor muscles) (both posture & gait)
Starts: Pontine & Medullary Reticular Formations (reciprocally)
Decussations: DOES NOT!
Ends: Entire Cord
-Both descend ipsilateral through entire cord
-Enter anterior horn and synapse on medial LMN (alpha motor neurons that go to muscles)
31
Tectospinal Tract
Functions: Coordination of head/eye
Starts: Superior Colliculus (Tectum of the midbrain)
Descends: Contrallaterally, endters anterior horn
Decussations: Dorsal Tegmental Decussation
Ends: Cervical Region
32
Rubrospinal Tract (Lateral Motor System)
Functions: UE FIne Motor (fast finger movement)
Starts: Red Nucleus
Decussations: IMMEDIATELY at Ventral Tegmental Decussation
Ends: Cervical Region
(Descends through pons and medull, then into lateral spinal cord to enter the anterior horn and synapse with LMN
-Lesions to one entire half of the midbrain would result in bilateral deficits
-Lesion below the decussation - Ipsilateral to lesion has weakness
33
Lateral Vestubulospinal Tract (Medial Motor System)
```
Functions: Balance
Starts: Lateral Vestibulospinal nucleus
*Bifurcates: DOES NOT
Spilts and descends: Iipsilaterally
Ends: Entire cord
```
34
Medial Vestubulospinal Tract (Medial Motor System)
```
Functions: Head/neck control
Starts: Medial Vestibulospinal nucleus
*Bifurcates: IMMEDIATELY at medial vestibular nucleus
Spilts and descends: Bilaterally
Ends: Cervical region
```
35
Weird Image (probz should figure out wtf it means)
36
Spinal Cord Syndromes
1. Transverse Cord Lesion
2. Hemicord/Brown-Sequard
3. Central Cord Lesion (small vs. large)
4. Posterior Cord Lesion
5. Anterior Cord Lesion
37
Transverse Cord Lesion (Spinal Cord Syndromes)
- Complete lesion
- Everything below the lesion DOES NOT work
- NO sensory going UP, NO motor coming DOWN
- Occurs from fractures and falls
- Most severe
- DCML, ALS and Movement ALL affected
38
Hemicord/Brown-Sequard (Spinal Cord Syndromes)
- IPSILATERAL DCML and Motor Loss (movement)
- CONTRALATERAL ALS (pain/temp) Loss
- Zone of Leisure: Sprouting above and below lesion
39
Central Cord Lesion- small vs. large (Spinal Cord Syndromes)
Affects anterior commissure (decussation site of ALS)
- Small: Bilateral suspended sensory loss of pain and temp (ALS affected)
- Large: More corticospinal involvement & DCML (ALS, DCML, and movement affected)
- Can occur from a tumor
- More UE involvement if small lesion
- All body involvement if large lesion (with sacral sparing) *anal wink
40
Posterior Cord Lesion (Spinal Cord Syndromes)
-Loss of DCML
41
Anterior Cord Lesion (Spinal Cord Syndromes)
- AFFECTS ALS bilaterally
- DOES NOT affect DCML
- Hits some corticospinal tracts
- Injury to anterior spinal artery
42
CVA
- Damage to 3rd order neuron
- Presents w/ contralateral symptoms
- UMN
43
Above vs. Below Decussation
Above Decussation: CONTRALATERAL
| Below Decussation: IPSILATERAL
44
Brainstem Lesion
- Above Medulla: Contralateral Symptoms
| - Below Medulla: Ipsilateral Symptoms
45
```
Functions: Head/neck control
Starts: Medial Vestibulospinal nucleus
*Bifurcates: IMMEDIATELY at medial vestibular nucleus
Spilts and descends: Bilaterally
Ends: Cervical region
```
