Structure and 0rganisation
of the Human Brain
Dr. Yogita Chudasama
Stewart Biology, Room N8/4
An imaginary line that runs along
the length of the CNS
! Anterior (rostral)
Front end or toward the head
! Posterior (caudal)
! Dorsal ‘(back’) surface
Top of the head and towards the
! Ventral (‘belly’) surface
Front surface that faces the ground
Toward the side
Toward the middle
1 “Geography” of the brain
Medial (toward midline)
Lateral (away from midline)
(toward (away from
More useful terms
Structures on opposite side of the body
(e.g. left cerebral cortex controls movement of the contralateral hand
means that it controls movement of the RIGHT hand.
Structures on same side of body
(e.g. olfactory bulb sends axons to the ipsilateral hemishere means that the
left olfactory bulb sends axon to the left hemisphere and the right olfactory
bulb sends its axons to the right hemipshere.
2 The Meninges
! The brain is encased in a bony skull and floats in a pool of cerebrospinal fluid (CSF).
! The brain is chemically guarded by the blood-brain barrier.
! The brain receives a large supply of blood because it is unable to store it’s own fuel.
! The meninges are the tough, protective connective tissues that surround the brain.
a) The dura mater is a outer thick, tough but unstretchable tissue.
b) The arachnoid membrane is the middle soft, spongy layer. It has a weblike
c) The third layer that sits closest to the brain in the pia mater which comprises
! The arachnoid space between is filled with CSF.
The Ventricular System of the Brain
! The ventricles are interconnected hollow spaces filed with CSF.
! The lateral ventricles (comprise the first and second ventricle) are the largest.
! The cerebral aqueduct is a long, tube like structure that connects the third
ventricle to the fourth ventricle.
! The CSF is produced continuously by the
! The CSF is replaced every three hours
! CSF leaves the fourth ventricle and flows
through the subarachnoid space where it is
reabsorbed into the blood supply.
3 Anatomical Divisions of the Brain
Early development of brain
Different swellings of the neural tube represent
different phases of embryological development.
Telencephalon Mesecephalon Metencephalon
5 major divisions of the adult brain
Cerebral cortex Tectum Cerebellum
Basal ganglia Tegmentum Pons
Limbic system Medulla Oblongata
(Forebrain) (Midbrain) (Hindbrain)
The Forebrain: Cerebral Cortex
The cerebral cortex is highly convoluted with sulci (small grooves), fissures (large
or major grooves) and gyri (ridges between sulci or fissures). The convolutions
increase the surface area of the cortex.
The cerebral cortex consists mainly of glial cells, axons, dendrites and a high
concentration of cell bodies. It is referred to as gray matter.
The white matter (beneath the gray matter) consists of a large concentration of
myelinated interconnecting axons.
4 Different views of the Cerebral Cortex
The central sulcus
provides a good
fissure separates separating the
rostral and caudal
the two divisions of the
The lateral fissure
from the temporal
The two hemispheres are connected by a band of axons called the Corpus Callosum
The primary sensory areas of the Cerebral Cortex
The primary visual cortex receives visual information, the primary auditory cortex
receives auditory information, the insular cortex receives gustatory information and
the somatosensory cortex receives information about the body senses
Different regions of the somatosensory cortex receive information from different parts
of the body (e.g. feet, hands, fingers).
5 Cytoarchitectonic analysis
(Cellular organisation of the cortex)
! The cortex contains up to six
cell layers (laminae)
! Cell structure and
organisation varies between