CNS - BRAIN

CENTRAL NERVOUS SYSTEM 

BRAIN 

A. Describe the location and function of each major area of the brain (cerebrum,  diencephalon, cerebellum, brainstem). 

​​Cerebrum: Largest part, controls thinking, learning, and voluntary movements.

Diencephalon: Located between the spinal cord and cerebrum; acts as a relay for sensory information.

Cerebellum: At the back of the brain; controls balance and coordination.

Brainstem: Connects brain to spinal cord; manages vital functions like breathing and heartbeat.

B. Distinguish between gray matter (basal nuclei and cortex) and white matter  (corpus callosum, projection fibers and association fibers) in relation to their  composition and distribution in the brain. 

Gray Matter:

• Composition: Made of unmyelinated axons, dendrites, synapses, and neuron cell bodies.

• Distribution:

  • Found on the outer layer of the brain (cortex).

  • Also present in clusters deep inside the brain (basal nuclei), surrounded by white matter.

White Matter:

• Composition: Made of myelinated axons, which allow for faster signal transmission.

• Distribution:

  • Located beneath the gray matter in the cerebrum.

  • Organized into tracts:

    • Commissural Tracts: Connect the left and right hemispheres (e.g., corpus callosum).

    • Projection Tracts: Connect the cerebrum with lower brain and spinal cord areas.

    • Association Fibers: Connect regions within the same hemisphere.

C. Describe the following anatomical features of the brain: sulcus (central), gyrus (precentral and postcentral) and fissure (longitudinal and lateral). 

Sulcus: Indentations (e.g., central sulcus divides motor and sensory areas).

Gyrus: Ridges (e.g., precentral for movement; postcentral for touch).

Fissure: Deep grooves (e.g., longitudinal fissure separates hemispheres).

D. Explain the physical boundaries and functions of each of the five cerebral lobes. 

Frontal: Thinking, movement, personality (not fully developed until 25).

Parietal: Processes sensory information. – forms general senses such as written and spoken languages 

Temporal: Hearing, smell, and memory integration.

Occipital: Vision processing.

Insula: Deep; processes taste.

Frontal = Foresight & Movement.

Parietal = Perception (Sensory).

Temporal = Tone (Hearing) & Smell.

Occipital = Optics (Vision).

E. List and describe the three cranial meninges (dura mater, arachnoid mater,  pia mater) and the associated spaces created between these membranes  (subdural space, subarachnoid space, epidural space). 

Dura Mater: Tough outer layer (creates the epidural and subdural spaces).

Arachnoid Mater: Middle web-like layer (forms the subarachnoid space with cerebrospinal fluid).

Pia Mater: Thin inner layer following brain contours

F. Describe the composition and functions of cerebrospinal fluid (CSF). 

Composition: Clear fluid with nutrients (glucose, oxygen).  Functions: Buoyancy, protection, and nutrient delivery.

G. Describe the formation of CSF, its circulation and its reabsorption back into the  blood stream

Formation:

• CSF is made by the choroid plexuses (capillaries surrounded by ependymal cells) in all four ventricles.

Circulation:

• CSF flows through the ventricles:

  1. Lateral ventricles 

  2. Interventicular foramina

  3. Third ventricle →

  4. Cerebral aqueduct

  5. Fourth ventricle →

  6. Into the subarachnoid space via small openings (apertures).

  7. Superior sagittal sinus

• From the subarachnoid space, CSF surrounds the brain and spinal cord.

Reabsorption:

• CSF is absorbed back into the blood through arachnoid granulations (tiny projections) into the sagittal sinus, a large vein in the brain.

• From there, it drains into veins like the jugular vein and exits the head.

H. Describe the formation and importance of the blood-brain barrier and the  substances that can cross the barrier. 

Formed by astrocytes and tight junctions; blocks harmful substances but allows oxygen, glucose, and certain drugs.

I. Identify the location and function of the primary motor area

Location: Precentral gyrus in the frontal lobe.

Function: Initiates voluntary movements.

J. Identify the location and function of the following sensory cortices: primary  somatosensory cortex (S1), primary visual cortex, primary auditory cortex,  gustatory cortex, olfactory cortex). 

Primary Somatosensory Cortex: Parietal; receives body sensation signals.

Primary Visual Cortex: Occipital; processes visual input.

Primary Auditory Cortex: Temporal; processes sound.

Gustatory Cortex: Insula; processes taste.

Olfactory Cortex: Temporal; processes smell.

K. Identify the location and function of the following association areas: premotor  cortex, somatosensory association cortex (S2), Broca’s area, Wernicke’s  area, prefrontal cortex and visual association areas. 

1. Premotor Cortex: Frontal; movement planning.

2. Somatosensory Association Cortex: Parietal; interprets sensory data.

3. Broca’s Area: Frontal; speech production.

4. Wernicke’s Area: Temporal; language comprehension.

5. Prefrontal Cortex: Frontal; decision-making and personality.

L. Explain the main functions of the structures of the limbic system (fornix, limbic  lobe, hippocampus, amygdala). 

Fornix: Connects limbic parts.

Limbic Lobe: Memory formation.

Hippocampus: Learning and memory.

Amygdala: Fear and emotion.

M. Identify and explain the function(s) of the anatomical structures of the  diencephalon (thalamus, hypothalamus, and epithalamus).

Thalamus: Relays sensory info to cerebrum.

Hypothalamus: Controls hormones, temperature, and hunger.

Epithalamus: Contains the pineal gland (regulates sleep).

N. Explain the anatomical and functional relationship between the pituitary gland and the hypothalamus.

The hypothalamus regulates the pituitary through hormones, controlling growth and metabolism.

O. Explain primary function of the cerebellum and the anatomical structures arbor  vitae and folia. 

Coordinates movement and balance.

Arbor Vitae: Tree-like white matter for signal conduction.

Folia: Outer gray ridges for surface area.

P. Identify and explain the function of the following structures associated with the  brainstem: midbrain (superior and inferior colliculi), pons, and medulla  oblongata (pyramids). 

Midbrain: Visual and auditory reflexes (superior and inferior colliculi).

Pons: Bridges brain parts; aids breathing.

Medulla Oblongata: Controls heart rate, breathing, and reflexes.

Q. Identify the cranial nerves by name and number. 

Olfactory (I) – Smell

Optic (II) – Vision

Oculomotor (III) – Eye movement

Trochlear (IV) – Eye movement

Trigeminal (V) – Facial sensation