The cerebrum is divided into halves longitudinally by a deep cleft. Each half is called a cerebral hemisphere.
Both hemispheres are connected by the corpus callosum-a tract of nerve fibres.
The cerebral hemispheres are hollow internally.
The walls of the cerebrum have an outer cortex and an inner medulla.
The cerebral cortex contains cell bodies of neurons and hence appears greyish. It is called grey matter.
The grey matter is thrown into many grooves and folds called sulci and gyri, respectively.
A higher number of convolutions leads to greater intelligence.
The cerebral cortex contains motor areas, sensory areas and association areas. Association areas are neither sensory nor motor.
These areas are responsible for complex functions such as memory, communication and intersensory associations.
The cerebral medulla consists of axons of nerve fibres and appears whitish. It is called white matter.
The inner part of the cerebral hemispheres and a group of associated deep structures such as hippocampus and amygdala form a complex structure called the limbic lobe or limbic system.
Functions:
The cerebrum is the centre of intelligence, memory, consciousness, will power and voluntary actions.
Thalamus:
It is made of grey matter.
It is situated superior to the midbrain.
Functions:
The thalamus relays motor and sensory impulses to the cerebrum.
It also regulates the manifestation of emotions and recognises heat, cold and pain.
Hypothalamus:
It lies at the base of the thalamus.
It consists of the optic chiasma, a point where the fibres of optic nerves cross to opposite sides.
Behind the optic chiasma is the infundibulum. It is a greyish protuberance of the hypothalamus.
The infundibulum holds the pituitary gland.
Functions:
The hypothalamus contains the centres which control body temperature, blood pressure and homeostasis.
It contains the centres to control hunger, thirst, sleep, fatigue, emotions, anger, pleasure and penance.
The neurosecretory cells of the hypothalamus secrete certain hormone or releasing factors which control the activity of the pituitary hormones.
The hypothalamus along with the limbic system is involved in the regulation of sexual behaviour.