Anatomy of the Brain

The anatomy of the brain is complex due its intricate structure and function. This amazing organ acts as a control center by receiving, interpreting, and directing sensory information throughout the body. There are three major divisions of the brain. They are the forebrain, the midbrain, and the hindbrain.

Brain Divisions
The forebrain is responsible for a variety of functions including receiving and processing sensory information, thinking, perceiving, producing and understanding language, and controlling motor function. There are two major divisions of forebrain: the diencephalon and the telencephalon. The diencephalon contains structures such as the thalamus and hypothalamus which are responsible for such functions as motor control, relaying sensory information, and controlling autonomic functions. The telencephalon contains the largest part of the brain, the cerebral cortex. Most of the actual information processing in the brain takes place in the cerebral cortex.

The midbrain and the hindbrain together make up the brainstem. The midbrain is the portion of the brainstem that connects the hindbrain and the forebrain. This region of the brain is involved in auditory and visual responses as well as motor function.

The hindbrain extends from the spinal cord and is composed of the metencephalon and myelencephalon. The metencephalon contains structures such as the pons and cerebellum. These regions assists in maintaining balance and equilibrium, movement coordination, and the conduction of sensory information. The myelencephalon is composed of the medulla oblongata which is responsible for controlling such autonomic functions as breathing, heart rate, and digestion.

•Prosencephalon - Forebrain

•Mesencephalon - Midbrain

•Diencephalon

•Telencephalon
•Rhombencephalon - Hindbrain

•Metencephalon

•Myelencephalon

Anatomy of the Brain: Structures
The brain contains various structures that have a multitude of functions. Below is a list of major structures of the brain and some of their functions.

Basal Ganglia
•Involved in cognition and voluntary movement

•Diseases related to damages of this area are Parkinson's and Huntington's
Brainstem
•Relays information between the peripheral nerves and spinal cord to the upper parts of the brain

•Consists of the midbrain, medulla oblongata, and the pons
Broca's Area
•Speech production

•Understanding language
Central Sulcus (Fissure of Rolando)
•Deep grove that separates the parietal and frontal lobes
Cerebellum
•Controls movement coordination

•Maintains balance and equilibrium
Cerebral Cortex
•Outer portion (1.5mm to 5mm) of the cerebrum

•Receives and processes sensory information

•Divided into cerebral cortex lobes
Cerebral Cortex Lobes
•Frontal Lobes -involved with decision-making, problem solving, and planning
•Occipital Lobes-involved with vision and color recognition
•Parietal Lobes - receives and processes sensory information
•Temporal Lobes - involved with emotional responses, memory, and speech
Cerebrum
•Largest portion of the brain

•Consists of folded bulges called gyri that create deep furrows
Corpus Callosum
•Thick band of fibers that connects the left and right brain hemispheres
Cranial Nerves
•Twelve pairs of nerves that originate in the brain, exit the skull, and lead to the head, neck and torso
Fissure of Sylvius (Lateral Sulcus)
•Deep grove that separates the parietal and temporal lobes
Limbic System Structures
•Amygdala - involved in emotional responses, hormonal secretions, and memory
•Cingulate Gyrus - a fold in the brain involved with sensory input concerning emotions and the regulation of aggressive behavior
•Fornix - an arching, fibrous band of nerve fibers that connect the hippocampus to the hypothalamus
•Hippocampus - sends memories out to the appropriate part of the cerebral hemisphere for long-term storage and retrievs them when necessary
•Hypothalamus - directs a multitude of important functions such as body temperature, hunger, and homeostasis
•Olfactory Cortex - receives sensory information from the olfactory bulb and is involved in the identification of odors
•Thalamus - mass of grey matter cells that relay sensory signals to and from the spinal cord and the cerebrum
Medulla Oblongata
•Lower part of the brainstem that helps to control autonomic functions
Meninges
•Membranes that cover and protect the brain and spinal cord
Olfactory Bulb
•Bulb-shaped end of the olfactory lobe

•Involved in the sense of smell
Pineal Gland
•Endocrine gland involved in biological rhythms

•Secretes the hormone melatonin
Pituitary Gland
•Endocrine gland involved in homeostasis

•Regulates other endocrine glands
Pons
•Relays sensory information between the cerebrum and cerebellum
Reticular Formation
•Nerve fibers located inside the brainstem

•Regulates awareness and sleep
Substantia Nigra
•Helps to control voluntary movement and regualtes mood
Tectum
•The dorsal region of the mesencephalon (mid brain)
Tegmentum
•The ventral region of the mesencephalon (mid brain).
Ventricular System - connecting system of internal brain cavities filled with cerebrospinal fluid
•Aqueduct of Sylvius - canal that is located between the third ventricle and the fourth ventricle
•Choroid Plexus - produces cerebrospinal fluid
•Fourth Ventricle - canal that runs between the pons, medulla oblongata, and the cerebellum
•Lateral Ventricle - largest of the ventricles and located in both brain hemispheres
•Third Ventricle - provides a pathway for cerebrospinal fluid to flow
Wernicke's Area
•Region of the brain where spoken language is understood