Anatomy of the Brain

Brain Activity
Human Brain Showing Neuron Activity. Science Photo Library - SCIEPRO/Getty Images

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. The brain and spinal cord are the two main structures of the central nervous system. There are three major divisions of the brain. They are the forebrain, the midbrain, and the hindbrain.

Brain Divisions

The forebrain is the division of the brain that 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 cerebrum. 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. or mesencephalon, 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.

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)

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

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)

    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 white matter axons (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 retrieves 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 gray 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

    Wernicke's Area

    • Region of the brain where spoken language is understood

    Midbrain

    Cerebral Peduncle

    • anterior portion of the midbrain consisting of large bundles of nerve fiber tracts that connect the forebrain to the hindbrain

    Reticular Formation

    • Nerve fibers located inside the brainstem and a component of the tegmentum (midbrain)
    • Regulates awareness and sleep

    Substantia Nigra

    • Helps to control voluntary movement and regulates mood (midbrain)

    Tectum

    • The dorsal region of the mesencephalon (midbrain)
    • Assists in visual and auditory reflexes

    Tegmentum

    • The ventral region of the mesencephalon (midbrain)
    • Includes the reticular formation and the red nucleus

    Brain Ventricles

    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

    More About the Brain

    For additional information about the brain, see Divisions of the Brain. Would you like to test your knowledge of the human brain? Take the Human Brain Quiz!