brain ( encephalon) · midbrain,pons & medulla • described with cranial nerves lectures....

Dr . Nirajan Neupane

Brain ( Encephalon)

• Covered by meninges ( PAD) subarachnoid space contains CSF

• Cavity is called ventricles ( 4 in no.) filled with CSF

• Weight : 1.4 kg

• Divided into Forebrain , midbrain & hindbrain

Forebrain/ prosencephalonTelencephalon & Diencephalon

CerebrumLargest part of brain

• Gyri & sulcus / fissure

• Divided into two cerebral hemisphere by longitudinal fissure(dura - falx cerebri) & connected by corpus callosum

• Each cerebral hemisphere is divided into F-POT lobe by 3 prominent sulci viz central , paraieto-occipital & lateral

DiencephalonCavity : 3rd ventricle

• Thalamus -2

• Hypothalamus

• Epithalamus

• Subthalamus -2

Thalamus

• Major relay station of all the sensory neurons except olfactory nerve (to cortex)

• Feedback from basal ganglia/nuclei & cerebellum (to cortex)

Hypothalamus: (SEAT)2

-Extended from upper part of midbrain to optic chiasm

-Consists gray sheets around 3rd venticle,median eminence & 2 mammillary bodies

-Makes lateral wall & floor of 3rd ventricle

Epithalamus -Consists of a pineal body & 2 habenular nuclei

-Pineal body contains pinealocytes , glial cells but no neuron ; secretes serotonin & melatonin ( from Tryptophan amino acid)

• Subthalamus : part of basal ganglia indirect pathway

• Lie below each thalamus

Limbic system : emotional brain : cortex = cingulate gyrusHippocampus

Amygdala

Septal nuclei

Anterior & DM nuclei of thalamus

Mammillary bodies of hypothalamus

Functions

Smell

Sex drive

Memory / learning

Behavior & emotion

Basal nucleiPlanning & programming of voluntary movement through direct or indirect pathway

Feedback circuit to cortex

Striatum : caudate & putamen

Globus pallidus

Substantia nigra

Subthalamic nuclei

Brain stemMidbrain,pons & medulla

• Described with cranial nerves lectures

Cerebellum Little brain

• Part of hind brain( Rhombencephalon)

• Derived from Metencephalon

• Located dorsal to the pons & medulla

• Tentorium cerebelli ( dura)

• Connected to brain stem by 6 cerebellar peduncle

• Consists of a midline vermis and 2 lateral cerebellar hemisphere

• Internally , outer cortex & inner core (deep seated nuclei & white matter in the pattern of tree called arbor vitae)

• Only axons of purkinje cell leave the cerebellar cortex

• Functions :

• Posture & balance

• Co -ordination of voluntary motor activity