Diencephalon

Question 1

Projections to the Thalamus

Answer 1

sensory periphery, sp cd, brainstem, cbm, BG, hypothalamu

Question 2

Where does the retina input info to the thalamus

Answer 2

LGN

Question 3

Diencephalon location

Answer 3

‘tween the telencephalon and the mesencephalon,

medial to the internal capsue

Question 4

Relation of the thalamus to the sub

Answer 4

Thalamus is superior to the subthalamus , which is superior to the hypothalamus

Question 5

BG and subthal ?

Answer 5

Subthalamus is implicated in the BG

Question 6

Hypothalamus

Answer 6

Implicated in ANS, endocrine and pleasure and pain in the body

Question 7

Thalamus to anterior commissure

Answer 7

Posterior to anterior commissure and optic chaism

Question 8

Thal to lentiform nucleus

Answer 8

Thalamus is above the lentiform nucleus of the BG. It is medial to the internal capsule.

Question 9

Is the subthalamus part of the BG

Answer 9

yes

Question 10

Fornix rln to septum pellucidum

Answer 10

Fornix is the very posterior end of the septum pellucidum that divides the lateral ventricles.

Question 11

Epithalamus

Answer 11

Structure that is above the epithalamus in development and in the adult.

Question 12

Structures of the Epithalamus

Answer 12

1) Habenular nuclear complex
2) Pineal gland
3) Posterior commissure

Question 13

Dorsal thalamus

Answer 13

Bulk of the diencephalon and contains thalamic nuclei that receive input from various sources and usually relays it to the brain.

Question 14

External medullary lamina

Answer 14

Myelinated fibers that encase the thalamus

Question 15

Internal medullary lamina

Answer 15

Myelinated fibers that bisect each thalamus into its medial and lateral halves

Question 16

Ventral thalamus

Answer 16

Ventral to the dorsal

Question 17

Components of ventral thalamus

Answer 17

1) Reticular nucleus of thalamus
The reticular nucleus exists OUTSIDE of the external medullary lamina
2) Ventral Lateral Geniculate Nucleus
The VGN is NOT ventral to the dorsal thalamus, but insanely small

Question 18

Subthalamus

Answer 18

Composed of:

1) Zona Incerta
2) Subthalamic Nucleus (Luys)

Question 19

Hypothalamus

Answer 19

Beneath the subthalamus beneath the hypothalamus

Question 20

Infundibulum

Answer 20

Connects the hypophysis to the posterior pit, which is a downgrowth of the brain.

Question 21

Hypophyseal portal system

Answer 21

Also connects the hypophysis to the hypothalamus. This way hormones from the hypothalamus can influence the posterior pituitary.

Question 22

Blood supply to the DNCPLN

Answer 22

The circle of WIllis

• the ant comm a
• the post comm a
• the ACA
• the PCA and
• the ICA

Question 23

Location to posterior limb of IC

Answer 23

Medial . At the bend of the IC is the genu where the face motor section is located.

Question 24

Major functions of the thal

Answer 24

A) Relays:
1) All sensory information to the cerebral cortex. (Olfactory input to the thlamus is from the piriform cortex).
2) Info about motor activities to the cerebral cortex
3) Relays emo and affective info to the cortex
B) Intimately involved in the control of alertness, arrousal , and sleep.
C) Integrates sensory information from different modalities and projects to association cortex
D) Part of “Papez circuit” of the Limbic System, projects to limbic cortex
E) Under direct cortical feedback and control: reciprocal connections between thalamus and cortex.

Question 25

Major Subdivisions of the thalamus

Answer 25

1) Anterior nuclear gp 2) Lateral-Ventral tier 3) Lateral -Dorsal tier 4) Medial gp

Question 26

Anterior nuclear gp of thal

Answer 26

Surrounded by the internal medullary lamina ao is more medial to the internal medullary lamina The other nuclei are lateral to the internal medullary lamina

Question 27

Components of the Anterior nuclear gp of the thal

Answer 27

The afferent is the mammilary body , the efferent is the cingulate gyrus and it functions in the limbic system. This is the mammillo thalamic tract. It's output goes to the cingulate gyrus, which is just on top of the corpus collossum, and has limbic fnx.

Question 28

Lateral-Ventral tier components

Answer 28

``` VA VL VPL VPM LGN MGN ```

Question 29

Lateral-Dorsal tier

Answer 29

LD LP Pulvinar

Question 30

Medial GP:

Answer 30

The medial gp is ALSO medial to the interior medullary laminar similar to the anterior gp. MD: Afferent: Amygdala, Olf, Hyp Efferernt: Prefrontal cortex FX: Limbic

Question 31

Subdvisions of the lateral gp

Answer 31

1) Dorsal tier | 2) Ventral tier

Question 32

Ventral anterior tier

Answer 32

Receives input from the BG, specifically the GP for motor output, and it projects to Broadman's area 6 or the premotor area. So it has total motor functions

Question 33

The Venterolateral aspect

Answer 33

Receives input from the cbm, specifiaclly the dentate nucleus. It not only pojects to the premotor cortex, area 6, but also the 1* motor cortex, or area 4, total motor.

Question 34

VPL

Answer 34

Sensation from the body. Recives input from the dorsal column medial lemniscus system, and the spinothalamic tract, so light touch/ vibration and then pain/temp resspectilvey from the body. This will project to the postcentral gyrus, or Broadmann's 312

Question 35

VPM

Answer 35

Sensation from the face. From the 3geminothalamic and trigeminal lemniscus so pain/temp and light tough for the face respectiley. thi swill again project to the 1* sensory cortex , Brodmann's 312, just like VPL

Question 36

LGN

Answer 36

Visual Relay. It is very posterior and receives input from the retina and projects it to Broadmann's area 17, the 1* visual cortex, so totally visual.

Question 37

MGN

Answer 37

Also posterior and medial to the LGN. It will receive input from the inferior colliculus, which is linked to hearing and projects to areas 41 and 42 in the superior temporal lobe, so for auditory processing.

Question 38

LD

Answer 38

The lateral dorsal receives input and output from the cingulate gyrus, so reciprocal rlnx, especially in its most medial aspects. This is associated with emotional expression.

Question 39

LP

Answer 39

Lateral posterior will receive input and output from teh the parietal cortex. This is associated with sensory integration. So it integrates visual, auditory, somatosensory inputs in order to give you a sense of your surrounding.

Question 40

Pulvinar

Answer 40

The large structure that is the most developed in humans among animals. It receives input from teh superior colliculs (visions) and the parieto-occipo-temporal cortex (sensation and hearing). It will project back to the POT for senseory integration much like the LP.

Question 41

Medial Gp

Answer 41

The single medial gp is ENTIRELY medial to the internal medullary lamina. It receives input from the amygdala, the hypothalamus, and the olfactory cortex. It has a MAJOR connection to the PFC. It has a mjaor connection with the limbic system.

Question 42

Diffuse nuclei

Answer 42

These nuclei are very much NONSPECIFIC relays in teh brain. This is made up of the midline nuclei that is a thin sheet of nuclei that line the lateralmost border of the third ventricles. The intralaminar nuclei are surrounded by the internal medullary lamina; and the reticular nucleus that is on the outside of the major dorsal nuclei. All of these are diffuse which means that they are associated with keeping you awake and attentive.

Question 43

Midline nuclei of the diffuse nuclei

Answer 43

The midline nuclei receive input from the reticular formation of the brainstem and the hypothalamus and it projects to the basal forebrain, and its major functions are limbic.

Question 44

The Intralaminar nuclei of the Diffuse projection nuclei can be divided into 3 parts

Answer 44

Centromedian Centrolateral and parafasiculus

Question 45

Centromedian nuclei of the Intralaminar nuclei of the Diffuse nuclei

Answer 45

Centro-median nuclei of the Intralaminar nucle of the Diffuse nuclei. This is the main nucleus of the Intralaminar nuclei because it is implicated with pain as well as with the BG. RECALL THAT THE CM IS THE THALAMIC NUCLEUS THAT IS IMPLICATED IN THE SPINORETICULAR PWY FOR PAIN ATTENTION. SO THE CM WILL TAKE INFO FROM THE RAS TO THE CORTEX.

Question 46

Centrolateral nuclei of the Intralaminar nuclei of the Diffuse nuclei

Answer 46

Receive info from teh reticular formation, but also pain input from the spinothalamic tract. The motor input from the GP and some extracortical input. They project back to the BG. what is important is that these project to not only the BG but to WIDE areas of the cortec tna this ish how it is involved in keeping us alert and attentive. So roles in pain and sleep and wakefulness.

Question 47

Location of the reticular nucleus

Answer 47

Outside the major dorsal nuclei. It receives a lot of input from the cortex, and also from teh neighboring specific nuclei in the thalamus, and from the reticular formation of the brainstem. The Reticular nucleus projects back to the thalamic nuclei in order to modulate the activity of the brain.

Question 48

Main Fxn of the diffuse nuclei

Answer 48

They are involved with the reticular formation of the brainstem and the RAS. Especially the intralaminar nuclei will project to wide areas of the brain. The overall fx of the diffuse nuclei is to keep you awake and alert.

Question 49

Thalamic neuronal circuit

Answer 49

Affernt input from the periphery will go to the thalamic neuronal circuit. This circuit will in turn project to the cerebral cortex, which will also give feedback to the thalamus to modulate its output. There will also be thalamic interneuron that MODIFY this thalamic INPUT b4 it legit gets to the thalamus, and therefore modulate the output neurons that project to the cortex. Therefore there is modulation that is actually going on inside the thalamus.

Question 50

Thalamic syndrome

Answer 50

Usually caused by a lesion or a tumor that occurs in the thalamus, but RARE. Thalamic syndrome usually involves damage to the most lateral parts of the thalamus, specifically the VPL.

Question 51

Symptoms of Thalamic Syndrome

Answer 51

Initially a transient hemianalgesia, so loss of snsation on the contra side of the body. But painful sensations will appear with noxious stimuli, so different pwy. Later, the pain will be elicited with non noxious stimuli like light touch or vibration or pressure. In time, there will be a CONSTANT or PAROXYSMAL (comes and goes) of pain that is NOT provoked by anything, and this a DYSESTHESIA or abnormal sensation.

Question 52

Are neurons sensitized in Thalamic Syndrome

Answer 52

No. The threshold for pain is NOT LOWER. However, the threshold is actually RAISED but onece the threshold is reached, you get this STRONG emotional response. So the pain becomes UNBEARABLE.