NL TO 6-7

General Overview: The brain is the central organ of the nervous system, situated within the protective environment of the skull.
Major Subdivisions: The brain is categorized into three primary anatomical and functional divisions:
- Cerebrum: The largest and most prominent portion of the brain.
- Cerebellum: Located inferior to the posterior portion of the cerebrum.
- Brain Stem: The stalk-like portion that connects the cerebrum and cerebellum to the spinal cord.

Cranial Cavity: The brain occupies the entirety of the cranial cavity.
Neuronal Composition: The brain is composed of over $1,000,000,000$ (one billion) multipolar neurons.
Meninges: The brain is covered and protected by three distinct layers of membranes known as meninges.
- Function: These membranes provide physical support and protection to the neural tissue.
- Dura Mater: Unlike the spinal cord, the brain has no epidural space. The dura mater in the cranium conforms exactly with and is fused directly to the cranial bones.

Cerebrum: Identified as the largest portion of the brain, responsible for higher brain functions, including thought and action.
Cerebellum:
- Primarily involved in the coordination of somatic motor functions (skeletal muscle contractions).
- Plays a critical role in maintaining balance and equilibrium.
- Refines and coordinates movement for precision and timing.
Brain Stem: Consists of three major parts:
- Midbrain: Contains the corpora quadrigemina.
- Pons: Acts as a relay station, directing sensory information from the brain stem to the thalamus and cerebellum.
- Medulla Oblongata: The most inferior part of the brain stem, which is continuous with the spinal cord.

Cerebral Cortex: This is the thin, outermost layer of the cerebrum, composed of gray matter.
Surface Features:
- Gyrus (Convolution): An elevated area or ridge on the surface of the cerebrum.
- Sulcus: A depressed area, groove, or shallow furrow between gyri.
- Central Sulcus: A prominent sulcus that separates the frontal lobe from the parietal lobe.
Hemispheres and Fissures:
- Right and Left Hemispheres: The cerebrum is divided into two distinct halves.
- Longitudinal Fissure: The deep groove that separates the right and left cerebral hemispheres.
- Transverse Fissure: The groove that separates the cerebrum from the cerebellum.
Cerebral Lobes: Each hemisphere is divided into specific lobes named after the cranial bones they underlie:
- Frontal Lobe: Located at the anterior of the brain.
- Parietal Lobe: Located posterior to the frontal lobe.
- Temporal Lobe: Located on the lateral sides of the brain.
- Occipital Lobe: Located at the posterior pole of the brain.
- Insula: A deeper lobe located underneath the temporal lobe, visible only when the temporal lobe is retracted.

Frontal Lobe: Responsible for reasoning, planning, speech, emotions, and problem-solving.
Parietal Lobe: Handles movement, recognition, and the perception of stimuli.
Temporal Lobe: Involved in the recognition of auditory stimuli, memory, and speech.
Occipital Lobe: Dedicated to the processing of visual stimuli.

Bridges of White Matter:
- Corpus Callosum: The upper bridge of white matter that connects the left and right hemispheres of the cerebrum.
- Fornix: The lower bridge of white matter that also connects the left and right cerebral hemispheres.
Diencephalon: A central region that includes the following structures:
- Thalamus: Functions as a major relay center for sensory information.
- Hypothalamus: Located below the thalamus, it regulates many visceral activities.
Pituitary Gland and Associated Structures:
- Pituitary Gland: Connected to the hypothalamus via a stalk-like structure called the infundibulum.
- Mamillary Bodies: Small, rounded structures located on the inferior surface of the hypothalamus.
- Pineal Gland: Part of the diencephalon structure located posteriorly.

Olfactory Nerve (Cranial Nerve I):
- Function: Sense of smell.
- Olfactory Bulb: An enlargement at the distal end of the nerve.
- Olfactory Tract: Transmits impulses from the bulb to the olfactory cortex of the cerebrum.
- Anatomy: Nerve fibers pass through the cribriform plate of the ethmoid bone to the olfactory epithelium.
Optic Nerve (Cranial Nerve II):
- Function: Vision.
- Optic Chiasm: The specific area where the optic nerves from both eyes cross to the opposite side of the brain.
- Optic Tract: The pathway continuing from the optic chiasm to the brain.
- Lateral Geniculate Nucleus: Located in the thalamus, it receives visual input from the optic tract.
- Optic Projection Fibers: Project from the thalamus to the visual cortex in the occipital lobes.
Other Cranial Nerves (Listed I-XII):
- I: Olfactory
- II: Optic
- III: Oculomotor
- IV: Trochlear
- V: Trigeminal
- VI: Abducens
- VII: Facial
- VIII: Vestibulocochlear
- IX: Glossopharyngeal
- X: Vagus
- XI: Accessory
- XII: Hypoglossal

Corpora Quadrigemina: Located in the midbrain, involved in visual and auditory reflexes.
Cerebral Aqueduct: A narrow canal within the midbrain that connects the third and fourth ventricles.
Reticular Formation: A network of neurons located throughout the brain stem that plays a role in consciousness and arousal.
Vasculature:
- Basilar Artery: Formed by the junction of the vertebral arteries, located on the ventral surface of the pons.
- Vertebral Artery: Supplies blood to the brain stem and posterior brain.

Subdivisions Identification: Ability to name and describe the Cerebrum, Cerebellum, and Brain Stem.
Cerebral Anatomy Checklist:
- Identify Cerebral cortex, Gyri, and Sulci.
- Differentiate between the Right and Left Hemispheres.
- Locate the Longitudinal and Transverse fissures.
- Identify and define the functions of the Frontal, Parietal, Temporal, and Occipital lobes.
Internal Anatomy Checklist:
- Identify the Olfactory and Optic nerves/structures (bulbs, tracts, chiasm).
- Identify the Corpus callosum and Fornix bridges.
- Locate the Pituitary gland, Infundibulum, and Mamillary bodies.
- Identify the components of the Diencephalon (Thalamus and Hypothalamus).
- Locate the Corpora quadrigemina in the midbrain.