Transcript 12 DiencephalonI

Dr. Ahmed Fathalla Ibrahim
DIENCEPHALON
• ORIGIN: from prosencephalon
• COMPONENTS: from dorsal to ventral:
epithalamus, thalamus, subthalamus &
hypothalamus
• CAVITY: third ventricle
EPITHALAMUS
•
SITE: above superior colliculus,
dorsal to thalamus
• COMPONENTS:
1. Pineal gland: secretes melatonin that
regulates onset of puberty
2. Habenular nuclei: a part of limbic
system
THALAMUS
SHAPE:
• An oval mass of grey matter
• Both thalami are joined by
interthalamic adhesion
RELATIONS OF THALAMUS
THALAMUS
RELATIONS:
• Superior:
1. Its lateral part is related to caudate nucleus
2. Its medial part forms the floor of lateral
ventricle
• Inferior: hypothalamus & subthalamus
• Medial: forms the lateral wall of third
ventricle
• Lateral: posterior limb of internal capsule
separating it from lentiform nucleus
SUBDIVISIONS OF THALAMUS
CONNECTIONS OF THALAMUS
ANTERIOR GROUP OF NUCLEI:
• A part of limbic system
• Concerned with recent memory,
emotion, behavior
Anterior group
Cingulate gyrus
Mammillary body
Hippocampus
CONNECTIONS OF THALAMUS
MEDIAL GROUP OF NUCLEI:
• A part of limbic system
• Concerned with control of mood &
emotion
Hypothalamus
Medial group
Prefrontal cortex
Prefrontal cortex
CONNECTIONS OF THALAMUS
LATERAL GROUP OF NUCLEI:
• Specific nuclei
• Non specific nuclei
SPECIFIC NUCLEI
VENTRAL POSTERIOR:
• VENTRAL POSTERIOR LATERAL (VPL)
• VENTRAL POSTERIOR MEDIAL (VPM)
LATERAL GENICULATE BODY (LGB)
MEDIAL GENICULATE BODY (MGB)
VENTRAL ANTERIOR (VA)
VENTRAL LATERAL (VL)
SPECIFIC NUCLEI
Medial leminiscus
VPL
Spinal leminiscus
Sensory cortex
Trigeminal leminiscus
VPM
Taste fibres
SPECIFIC NUCLEI
Optic tract
Inferior
colliculus
Globus
pallidus
LGB
Visual cortex
MGB
Auditory cortex
VA
VL
Premotor &
Motor cortex
NON SPECIFIC NUCLEI
• LATERAL DORSAL
• LATERAL POSTERIOR
• PULVINAR
They are connected to wide areas of
cerebral cortex
CONNECTIONS OF THALAMUS
INTRALAMINAR NUCLEUS (IL):
• Control all level of activities of cerebral
cortex
Reticular formation
Specific thalamic nuclei
IL
All cortical areas
CONNECTIONS OF THALAMUS
RETICULAR NUCLEUS (RN):
• Control mechanism of cerebral cortex
over thalamus
All cortical areas
RN
All thalamic nuclei
THALAMIC LESION
THALAMIC SYNDROME:
• Contralateral hemianaesthesia
• Occurrence of spontaneous pain
• Contralateral hemiparesis
• Choreoathetosis