The Brain- Unit 4

Unit 4, Anatomy 2300

Gyrus

Elevated fold of the brain

Sulcus

Shallow groove between gyri

Fissure

Deep groove between gyri

Central Sulcus

Separates the frontal and parietal lobes- separates precentral and postcentral gyrus

Lateral fissure

Separates the frontal and parietal lobes from the temporal lobe

Longitudinal fissure

Separates the left and right hemispheres

Transverse fissure

Separates the cerebrum from the cerebellum

Parieto-occipital sulcus

Separates the parietal and occipital lobes

3 regions of each hemisphere

Cerebral cortex (higher-level thinking), internal white matter (information carrying), basal nuclei (inner gray matter)

Function of cerebral cortex

Conscious thought, speech, memory, evaluation of sensory input, personality, initiation of voluntary movement, etc.

3 main function areas of the cortex

Motor, Sensory, and Association areas

Motor areas of the cortex

Initiation of movement

Sensory areas

Reception of sensory information and perception

Association areas

Complex integrative functions

Prefrontal cortex

Frontal lobe, controls personality and character traits

Primary motor cortex

Precentral gyrus of frontal lobe, controls fine motor control

Broca’s area

Dominant hemisphere of frontal lobe, controls motor speech

Primary sensory cortex

Postcentral gyrus of parietal lobe, controls sensory

Primary auditory cortex

Temporal lobe, controls hearing

Primary visual cortex

Occipital lobe, controls vision

Cerebral white matter fibers

Commissural, association, and projection fibers

Commissural fibers

Fibers connecting gray matter areas between the two hemispheres, like corpus callosum

Association fibers

Fibers connecting parts of the same hemisphere

Projection fibers

Fibers connecting the cerebral cortex to other parts of the CNS, like spinal tracts

Basal nuclei

Collection of nerve cell bodies deep in the cerebrum

Function of basal cell bodies

Initiation and termination of motor activities. Damage can lead to diseases like parkinson’s

Types of basal cell bodies

Globus pallidus (eye), putamen (head), caudate nucleus (tail)

Central brain structures

Thalamus, hypothalamus, and epithalamus

Thalamus

major relay center for all sensation entering the cerebral cortex EXCEPT olfaction. Aids in motor activity

Hypothalamus

Major regulator of the body’s internal environment, through the autonomic, limbic, and endocrine systems. Inferior and anterior to thalamus.

Epithalamus

Helps to regulate sleep-wake cycle with the hypothalamus (main projection is the pineal body, which secretes the hormone melatonin). Inferior and posterior to thalamus.

Components of the brain stem

Midbrain, pons, and medulla oblongata

Role of brain stem

produces autonomic behaviors necessary for survival. Provides a pathway for axons ascending from the spinal cord and descending from the brain. Nuclei for CN III-XII located within

Midbrain

CN III, CN IV. Communication pathway

Pons

CN V, VI, VII, VIII. Pathway for axons between brain + spinal cord and motor cortex + cerebellum

Medulla oblongata

CN VIII, CN IX, CN X, CN XI, CN XII. Autonomic reflexes like heart rate and breathing.

Role of cerebellum

Provides timing and patterns of skeletal muscle contractions for smooth and coordinated movement. Also provides error correcting feedback for movements.