Brain Anatomy: Cerebrum and Lobes (stud notes pt 2)

• The cerebrum, longitudinal sulcus, central sulcus, lateral sulcus, the four lobes of the brain, cerebellum, and brainstem can be identified on the external surface of the brain

Cerebrum

• The cerebrum constitutes the largest part of the brain
• The cerebrum is divided into right and left hemispheres by the longitudinal fissure
• The cerebrum is separated from the cerebellum by the transverse fissure
• The surface of the cerebrum features ridges (gyri) and grooves (sulci), increasing its surface area
• The interior of the brain consists of white and gray matter, as well as hollow cavities filled with cerebrospinal fluid (CSF)
• Gray matter surrounds the white matter of the brain
• The cortex is the layer of gray matter surrounding the white matter
• In the cerebrum the cortex is known as the cerebral cortex
• In the cerebellum the cortex is known as the cerebellar cortex
• Gray matter is made up of neuron cell bodies
• White matter is made up of axons covered with myelin
• Most information processing in the brain is contralateral, meaning the right side of the body is controlled by the left side of the cerebral cortex, and vice versa

Cerebellum

• Located posterior to the cerebrum, the cerebellum, like the cerebrum, is divided into hemispheres and has a convoluted surface
• The cerebellum is involved in sensory and motor coordination and balance
• The cerebellum receives information regarding planned and actual movement, comparing the two to adjust movements as needed
• The precise function of the cerebellum is not fully understood, but it is essential for accurate movements

Brain Stem

• Positioned inferior to and partially covered by the cerebrum, the brain stem is a stalk-like structure
• The brain stem is divided into three sections: the medulla oblongata, the pons, and the midbrain
• The medulla oblongata constitutes the inferior part, which comes right from the spinal cord
• The pons is superior to the medulla oblongata
• The midbrain is superior to the pons
• The medulla oblongata is responsible for controlling heartbeat, respiration, and blood vessel diameter
• The pons is responsible for respiration
• The midbrain is a pathway for relaying visual and auditory impulses and other information to the cerebrum

Diencephalon

• The diencephalon is located inside the brain, inferior to the cerebrum
• The diencephalon plays a role in controlling hormone levels, hunger and thirst, body temperature, sleep-wake cycles, and sending information around the brain
• The diencephalon consists of the thalamus, hypothalamus, pineal body, and pituitary gland
• Most parts of the diencephalon work with the endocrine system to release hormones and maintain homeostasis

Corpus Callosum

• The corpus callosum is a thick, white band of nerve fibers
• Allows the two hemispheres (right and left) of the cerebrum connect and coordinate their activities