THALAMUS Flashcards
What are the 4 major divisions of the diencephalon?
- Epithalamus (pineal gland,etc)
- DORSAL THALAMUS (true)
- Subthalamus
- Hypothalamus
What are the 4 major divisions of the THALAMUS itself?
- Internal Medullary Lamina
- Intralaminal Nuclei.
- Thalamic Reticular Nucleus
- Midline Nuclei
What are the 3 functional groups of the thalamus?
- Specific/relay
- Association
- Non -Specific
What various nuclei fall within the 3 functional groups of the thalamus?
- Specific/Relay
- Association
- Non-specific
- VPL, VPM, VA/VL, MEDIAL GENICULATE, LATERAL GENICULATE, LD (lateral dorsal)
- Lateral Posterior
- Pulvinar
- Dorsomedial
- Intralaminar & Reticular
What is the function of the RETICULAR NUCLEUS OF THE THALAMUS? Which thalamic functional group does it fall in?
HiGHLIGHT certain novel/new sensory info, and ignore background info
(relays to other areas)
- NON -SPECIFIC group
(does not relay directly to cortex, only relay to THALAMUS)
Which nucleus does not relay directly to the CORTEX, but ONLY to the THALAMUS?
RETICULAR NUCLEUS
What are the afferents for the following THALAMIC NUCLEI, where do these nuclei project?
- VA/VL
- VPL
- VPM
- Medial Geniculate
- Lateral Geniculate
- Anterior
- Basal Ganglia/Cerebellum
- Medial Lemniscus/ STT of the BODY
- Medial Lemniscus/ STT of the FACE
- Inferior Colliculus
- Optic tract (Superior Colliculus)
- Mamillothalamic Tract
Where do these nuclei project? (efferents)
- VA/VL
- VPL
- VPM
- Medial Geniculate
- Lateral Geniculate
- Anterior
- Motor Areas (pre-central gyrus + frontal area)
- Somatosensory cortex
(AREA 312 of Post-central gyrus) - Somatosensory cortex
(AREA 312 of Post-central gyrus) - Auditory cortex (Transverse temporal gyri)
- Visual Cortex (occipital lobe –> calcarene fissure area 17)
- CINGULATE gyrus
What is the auditory cortex of the brain?
Transverse Temporal Gyrus
What is the only sensory information NOT traveling through the Thalamus?
SMELL
What is the function of the cerebellum?
coordinates voluntary movements such as posture, balance, coordination, and speech, resulting in smooth, balanced muscular activity.
- makes sure that motor functions you want to do HAPPEN (monitors & adjusts motor function)
What is the function of basal ganglia?
Coordination of motor activity between agonist and antagonist
ex: activates the bicep (agonist), i& inactivates the function of the tricep (antagonist)
What is the function of the thalamus?
Receives sensory information & passes this on either DIRECTLY or INDIRECTLY
- decides what info to pass on
What are the majority of thalamic neurons?
MAJORITY = PROJECTION
rest = inhibitory
What type of inputs exist into the THALAMUS? Which of these 2 is the MAJOR input?
- Specific (ex: medial lemniscus pathway)
- use GLUTAMATE - REGULATORY
= MAJORITY!!
What is the major output and input of the thalamus?
Output = PROJECTION neurons
Input = REGULATORY
control thalamus & turn parts of it on/off
which nuclei of the thalamus is split into ANTERIOR, MEDIAL, & LATERAL and forms a Y SHAPE?
INTERNAL MEDULLARY LAMINA
- collection of myelinated fibers
The thalamus forms the wall of which structure?
3rd ventricle
What is the nuclei that is referred to as the “thin sheet draped over the thalamus”
THALAMIC RETICULAR NUCLEUS
c-shape around the image of the thalamus like a bean
Which nuclei are embedded in the Internal medullary Lamina?
INTRALAMINAR Nuclei
The thalamus lies behind what structure? it forms the wall of which structure?
- behind the INTERVENTRICULAR FORAMEN
2. walls of the 3rd VENTRICLE
What is the pineal gland responsible for?
Circadian Rhythms, melatonin
What separates the thalamus from the lentiform nucleus?
INTERNAL CAPSULE
What structures compose the lentiform nucleus? What does it look like?
Putamen & Globus Pallidus
- it is the ball at the end of the CAUDATE
(part of basal ganglia)
What makes the decision of which possible behaviors to execute at any given time? (motor function)
LENTIFORM NUCLEUS
Which functional group of the thalamus has clear inputs & projections & ALOT OF TOPOGRAPHIC organization?
Specific/Relay Nuclei
Which thalamic nuclei is used to project visual info to the visual cortex of the brain (occipital lobe)? Which Brodman’s zone is this?
- LATERAL GENICULATE
(SLO AIM)
AREA 17 - Calcarene fissure
In the thalamus, which Specific/Relay nucleus shows somatotopic organization in regards to the face & the body?
VPM (FACE) & VPL(body)
- face is more medial
Which nuclei can perform higher level of analysis?
ASSOCIATION NUCLEI
- Lateral Posterior
- Pulvinar
- Medial Dorsal Nuclei
Where do the ASSOCIATION NUCLEI receive input from? Do they receive input from sensory info?
DIRECTLY FROM CORTEX
- NO INPUT FROM PRIMARY SENSORY INFO
(does not project to spinal cord; no SUBCORTICAL organs)
- only talks back & forth to cortex
Which functional nuclei of the thalamus is responsible for consciousness, emotional state etc? 1. Specific 2. Association 3. Non-specific Which nuclei are within this category?
NON-SPECIFIC NUCLEI
- Intralaminar (alertness, sensory awareness)
- Thalamic Reticular Nuclei
Which Non-specific nuclei project ONLY to the thalamus? (not to the cortex or anywhere else)
THALAMIC RETICULAR FORMATION*
- can inhibit or excite
(look at name)
What is the function of the Reticular Formation of the Thalamus?
serves as a FILTER
- highlights certain sensory info, turns off info around the area
= control flow of info IN & OUT
The top of the internal capsule is called what?
Corona Radiata
fibers connect the lentiform nucleus to the caudate
What are the 3 divisions of the internal capsule?
- Anterior Limb
- GENU (bend)
- Posterior Limb (mostly sensory)
What is the MAIN blood supply to the thalamus?
Posterior Cerebral Artery
PCA
- but SMALL Perforating arteries supply the thalamus from PCA
If there is hypertension in the perforating arteries, what could occur?
- lose function of the THALAMUS
- lose sensory info from contralateral side of the body
What is sensory ataxia?
Loss of proprioception (where the limbs are in relation)
- postiive Romberg’s sign - can’t maintain balance with eyes closed = SENSORY ATAXIA
- not cerebellar ataxia
If the vision is lost in an individual, which THALAMIC NUCLEI is likely responsible?
Lateral Geniculate Nuclei
If a stroke occurs that affects the VPL nucleus? What would be lost?
- loss of PROPRIOCEPTION (vibration/2 pt. touch) on CONTRALATERAL side of the body
- (VPM = same side of face)
What artery is likely occluded in a LATERAL MEDULLARY STROKE? (Wallenburg Syndrome) If the VPM & VPL were damaged, what symptoms would be apparent?
- PICA (posterior inferior cerebellar artery)
- VPM = loss of pain sensation on SAME SIDE of face
VPL = loss of sensation on OPPOSITE SIDE OF BODY
(contralateral)