chapter 11

🧠 1. Regions and Organization

Four Regions of the Adult Brain:

  1. Cerebrum – largest part; responsible for higher mental functions.

  2. Diencephalon – thalamus, hypothalamus, epithalamus.

  3. Brainstem – midbrain, pons, medulla oblongata.

  4. Cerebellum – coordinates movement and balance.

Gray Matter:

  • The outer layer of both cerebrum and cerebellum is gray matter.

  • Gray matter contains neuron cell bodies, dendrites, and synapses.

Cortex:

  • The gray matter outer layer is called the cortex in both cerebrum (cerebral cortex) and cerebellum (cerebellar cortex).

🧩 2. Ventricles of the Brain

What Fills Brain Ventricles:

  • Cerebrospinal fluid (CSF).

What Lines Brain Ventricles:

  • Ependymal cells, a type of neuroglia that helps circulate CSF.

Ventricles (Identification):

  1. Lateral ventricles (right and left) – one in each cerebral hemisphere.

  2. Third ventricle – in diencephalon.

  3. Fourth ventricle – between pons and cerebellum.

Connection to Subarachnoid Space:

  • Median and lateral apertures (openings in the 4th ventricle) connect the ventricles to the subarachnoid space.

🧭 3. Cerebral Hemispheres

Five Lobes of the Cerebrum:

  1. Frontal lobe

  2. Parietal lobe

  3. Temporal lobe

  4. Occipital lobe

  5. Insula (deep to temporal lobe)

Surface Markings:

  • Gyri – ridges

  • Sulci – shallow grooves

  • Fissures – deep grooves (e.g., longitudinal fissure)

Three Basic Regions:

  1. Cerebral cortex (gray matter) – outer surface

  2. White matter – internal

  3. Basal nuclei (gray matter) – deep within white matter

🧠 4. Cerebral Cortex

Mental Functions:

  • Conscious thought, sensation, voluntary movement, reasoning, memory, language, emotion.

Three Types of Functional Areas:

  1. Motor areas – control voluntary movement.

  2. Sensory areas – receive and interpret sensory information.

  3. Association areas – integrate information, involved in learning, memory, reasoning, and emotion.

Motor Areas (mostly in frontal lobe):

Area

Location

Function

Primary motor cortex

Precentral gyrus

Controls voluntary skeletal muscle movements.

Premotor cortex

Anterior to precentral gyrus

Plans and coordinates learned motor skills.

Broca’s area

Usually in left frontal lobe

Controls muscles of speech production.

Frontal eye field

Frontal cortex

Controls voluntary eye movements.

Sensory Areas:

Area

Location

Function

Primary somatosensory cortex

Postcentral gyrus, parietal lobe

Receives sensory info (touch, pressure, pain, temperature).

Somatosensory association cortex

Posterior to primary somatosensory cortex

Interprets sensory input (e.g., recognizing an object by touch).

Primary visual cortex

Occipital lobe

Receives visual info from retina.

Visual association area

Surrounds primary visual cortex

Interprets what is seen (faces, letters, etc.).

Damage comparison:

—

Damage to primary visual cortex → blindness; damage to visual association area → can see but cannot interpret (visual agnosia).

Primary auditory cortex

Superior temporal lobe

Receives sound information (pitch, loudness).

Auditory association area

Posterior to primary auditory cortex

Interprets sounds (speech, music, etc.).

Vestibular cortex

Insula and parietal cortex

Awareness of balance and spatial orientation.

Olfactory cortex

Temporal lobe (uncus)

Sense of smell.

Gustatory cortex

Insula

Taste perception.

Visceral sensory area

Insula

Sensation from internal organs (e.g., upset stomach, full bladder).

Multimodal Association Areas:

Integrate multiple types of sensory input for complex understanding and actions.

Area

Function

Anterior association area (prefrontal cortex)

Intellect, judgment, reasoning, personality, planning.

Posterior association area (includes Wernicke’s area)

Recognizing patterns and faces, understanding language.

Limbic association area

Emotional impact of experiences, memory formation.

Lateralization of Cortical Functions:

  • Left hemisphere: Language, math, logic.

  • Right hemisphere: Visual-spatial skills, emotion, artistic and musical ability.

  • Hemispheres communicate via corpus callosum.

Cerebral White Matter:

Three types of fibers:

Fiber Type

Function

Association fibers

Connect areas within the same hemisphere.

Commissural fibers

Connect right and left hemispheres (e.g., corpus callosum).

Projection fibers

Connect cerebrum with lower brain regions or spinal cord.