B R A I N

MAJOR PARTS OF THE BRAIN

CEREBRUM

• Largest part of the brain

• two cerebral hemispheres connected by a mass of white matter (corpus callosum)

• hemispheres are separated by the Longitudinal fissure

HEMISPHERES ARE SEPARATED BY: • surface layer of each

cerebral hemisphere composed of gray matter

• folds (gyri) separated by fissures (sulci)

• large sulci subdivide the surface of each hemisphere into lobe

INSULA• ka Island of Reil

• ▪folded deep within the lateral sulcus between the temporal lobe and the frontal lobe

• ▪functions– perception

• – motor control– self-awareness– cognitive functioning

PRECENTRAL GYRUS • mmediately anterior to the

central sulcus

• motor area

• – control voluntary movements on the contralateral side of the body (corticospinal tract)

• • decussation at the cervicomedullary junction

MOTOR HOMUNCULUS• body is represented in an inverted

position

• nerve cells controlling the the feet located in the upper part

• those controlling the movements of the face and hands in the lower part

Homunculus

POSTCENTRAL GYRUS

• immediately posterior to central sulcus

• sensory area

• – pain, temperature, touch, and pressure from the contralateral side of the body

BROCA’S AREA • above the lateral sulcus motor speech area

• –  dominant in the left hemisphere in right- handed persons

• –  dominant in the right hemisphere in left- handed persons

SUPERIOR TEMPORAL GYRUS • immediately below the lateral sulcus

• auditory area

• – concerned with reception and interpretation of sound

BROCA’S AREA • above the lateral sulcus motor speech area

• –  dominant in the left hemisphere in right- handed persons

• –  dominant in the right hemisphere in left- handed persons

VISUAL AREA• situated on the posterior pole in the region of the

calcarine sulcus

• ▪receiving area for visual impressions

DIENCEPHALON

FUNCTIONS OF THE DIENCEPHALON• 5 Functions of the Limbic System

• Feeding

• FlightFight

• Feelings

• Fucking (SEX)

Largest part of diencephalon Influences mood and registers unlocalized, uncomfortable perception of pain.

Thalamus

Small area located superior-posterior to the thalamus Emotional and visceral response to odors

Epithalamus

Most inferior part of the diencephalon Maintaining homeostasis Control of body temperature, hunger, and thirst

Hypothalamus

Sexual pleasure, feeling of good after a meal, rage, and fear. Infundibulum – funnel-shaped stalk Major role in controlling hormones from the pituitary gland

Brainstem

Connects spinal cord to the brain Consist of: Medulla oblongata Pons Midbrain

Functions vital functions: Control of heart rate, blood pressure and breathing

Medulla Oblongata

Most inferior part of the brainstem Contains ascending and descending Pyramids- descending tracts Conscious control of skeletal muscle

Functions as: Regulation of heart rate, blood vessel diameter, breathing, swallowing, vomiting, coughing, sneezing, balance, and coordination.

Pons

Contains ascending and descending tracts Relay information between cerebrum and cerebellum. Footbridge

Functions as: Breathing, swallowing, balance, and control. Chewing and salivation.

Midbrain

Smallest region of the brainstem Colliculi – 4 mounds posterior to the midbrain

2 inferior – major relay centers for auditory nerve pathways 2 superior – Visual reflexes; turning the head on a tap shoulder, sudden noise, bright flash of light

Coordination of eye movements and in diameter of pupil and lens shape. Substancia nigra – basal nuclei

Regulation of general body movement

Midbrain

• narrow part of brain that passes through tentorial notch

• two lateral halves called cerebral peduncles

• – anterior part is crus cerebri

• – posterior part is tegmentum

• – pigmented band of gray matter (substantia nigra)

Flow of CSF

• Choroid plexusLateral ventriclesForamen of MonroThird VentricleAqueduct of Sylvius Fourth VentricleForamina of Luschka and Magendie Subarachnoid spaceArachnoid granulations