D5 - Mesencephalon, diencephalon

Question 1

Define mesencephalon

Answer 1

Midbrain

Question 2

Mesencephalon

Structures to mention

Answer 2

• Aqueductus mesencephali (canal between 4^th and 3^rd ventricle)
• Periaqueductal gray matter (PAG)
• Tectum mesencephai (roof of midbrain, dorsal to tegmentum)
  
  • Rostral colliculus (related to visual pathway)
  • Caudal colliculus (related to auditory pathway)
• Tegmentum mesencephali (dorsal part of pedunculus cerebri, core of the midbrain, contains the motor and parasymp. nucleus of n. oculomotorius, n. trochlearis and nucl. ruba)
• Substantia nigra (under nucl. ruba)
• Crus cerebri (carries pyramidal and pontine tracts)
• N. oculomotorius (emerges to the ventromedial aspect of the cerebral pedunculus)
• N. trochlearis (leaves the midbrain dorsally)

Question 3

Mesencephalon

Location

Answer 3

Between pons and diencephalon

Made up of pedunculus cerebri and tectum

Question 4

Mesencephalon

Function

Answer 4

• Coordination of voluntary motor function
• Muscle tone, body posture, locomotion
• Reflex centers for hearing and vision

Question 5

Mesencephalon

Draw mesencephalon, lateral aspect

Answer 5

Question 6

Mesencephalon

Draw mesencephalon, ventral aspect

Answer 6

Question 7

Mesencephalon

Draw mesencephalon, crossection

Answer 7

Question 8

Define diencephalon

Answer 8

Caudal (posterior) part of the forebrain

Consists of:

1. Epithalamus
2. Thalamus
3. Hypothalamus
4. Metathalamus
5. 3^rd ventricle

Question 9

Diencephalon

Structures to mention

Answer 9

• 3^rd ventricle
• Epithalamus
  
  • ​Pineal gland
  • Habenula (white matter anchoring pineal gland to thalamus)
    
    • Commisura habenularum (fibers connecting nucl. habenularis)
• Thalamus (most ventral component of diencephalon)
• Hypothalamus
  
  • N. opticus
  • Chiasma opticus
  • Optic tract
  • Corpus mamillare
• Lateral geniculate body (nucleus)
• Medial geniculate body (nucleus)

Question 10

Diencephalon

What does diencephalon consists of?

Answer 10

1. Hypothalamus
2. Thalamus
   
   • ​Subthalamus
   • Dorsal thalamus
3. Epithalamus
4. Metathalamus

Question 11

Diencephalon

Epithalamus

Answer 11

• Comprises:
  
  • Pineal gland
  • Habenula (important in olfactory pathway, white matter anchoring pineal gland to thalamus)
    
    • Commisura habenularum (fibers connecting nucl. habenularis)

Question 12

Diencephalon

Thalamus

Answer 12

• The largest part of diencephalon
• On both sides of 3^rd ventricle, developed in lateral wall of 3^rdventricle
• Can be subdivided into:
  
  • Subthalamus
  • Dorsal thalamus
• The left and right thalamus is connected by interthalamic adhesion

Question 13

Diencephalon

Hypothalamus

Answer 13

• Floor and walls of the 3^rd ventricle
• Separated from thalamus by sulcus hypothalamus
• Consists of:
  
  • Chiasma opticus (rostrally)
  • Corpus mamillare (caudally to tuber cinerum)
  • Tuber cinereum (in between, grey tuber of the 3^rd ventricle, gives rise to infundibulum)
  • Infundibulum (suspend hypophyse below brain)
• Lateral hypothalamus controls:
  
  • Hunger center
  • Thirst center
  • Sataity center
• Nuclei:
  
  • Regio hypothalamus rostralis
    
    1. ​​Nucl. okpraopticus ??
    2. Nuc. paraventricularicularis
    3. Nucl. suprachiasmaticus
  • Regio hypothalamus intermeida
    
    • _​_Nucl. hypothalamus dorsomedian
    • Nucl. hypothalamus ventromedian
    • Nucl. infundibilaris
• Hypophysis​ (link between hypothalamus and endocrine glands)
  
  1. ​Neurohypophysis
  2. Adenohypophysis

Question 14

Diencephalon

Metathalamus

Answer 14

• Consists of:
  
  • Corpus geniculatum mediale
    
    • ​Connected to colliculus caudalis
    • Part of auditory pathway: receive acustic fibers and relay acustic information to the cerebral cortex
  • Corpus geniculatum laterale
    
    • ​Connected to colliculus rostralis
    • Fibers from tractus opticus terminate in the corpus geniculatum laterale. It sends fibers to the optic areas of the cortex

Question 15

Diencephalon

Function

Answer 15

• Pineal gland: Biological clock
• Hypothalamus: Controls the hypophysis and thus the endocrine system