Brain Teaser

• A bat and a ball cost $1.10 in total.

• The bat costs $1.00 more than the ball.

• Question: How much does the ball cost?

Housekeeping

• Module 2 exam grades posted by Monday at the latest.

• Module 3 content posted on D2L this afternoon.

Learning Objectives

1. Use directional terms to navigate around the anatomy of the brain.

2. Describe the general anatomic features of the brain.

3. Name the major gyri, sulci, and fissures of the brain.

4. Describe the four major regions of the brain.

5. Describe the composition and distribution of gray and white matter in the brain.

6. Describe the concept of cerebral lateralization.

7. Describe the general functions of the 5 lobes of the Cerebrum.

8. Describe the location and function of the association areas in the brain.

9. Describe how the motor and sensory systems are mapped to the cerebrum.

10. Describe the basic anatomy and physiology of the diencephalon.

11. Describe the basic anatomy and physiology of the brain stem.

12. Describe the basic anatomy and physiology of the cerebellum.

Myth Busting: Brain Usage

• Misconception: Do we only use 10% of our brain?

  • Origin: Early 20th Century.

  • Notable Figure: William James stated that we are utilizing only a small part of our possible mental and physical resources in "The Energies of Men".

  • Popular Press: This notion was further popularized by self-help publications that suggested the figure of 10%.

Brain Size and Intelligence

• The adult human brain is about the size of a grapefruit and weighs approximately 3 pounds.

• Question of correlation between brain size and intelligence is raised.

• Associated with the myth of using only 10% of the brain.

Structural Features of the Brain

• Anatomical Elements:

  • Meninges

  • Skull

  • Brain

  • Cerebral ventricles (fluid-filled spaces)

  • Spinal cord

  • Fluid surrounding the brain and spinal cord.

Brain Activity and Blood Flow

• Increased neural activity within the brain results in increased blood flow to facilitate this enhanced activity.

• Contribution of Italian physiologist Angelo Mosso in early brain research highlighted this relationship.

Basic Anatomical Directions of the Brain

• Directional Terms:

  • Anterior

  • Medial

  • Posterior

  • Lateral

  • Superior

  • Inferior

• Importance of these terms for navigating the brain's anatomy.

Overview of Brain Anatomy

• The outer surface of the brain is highly folded.

  • Definitions:

  • Gyri: Ridges on the brain's surface.

  • Sulci: Depressions between the gyri.

  • Fissures: Deep sulci that divide large regions of the brain.

Major Gyri, Sulci, and Fissures

• Key Anatomical Structures:

  • Central Sulcus

  • Lateral Sulcus

  • Longitudinal Fissure

Major Regions of the Brain

1. Cerebrum

2. Diencephalon (includes: Epithalamus, Thalamus, Hypothalamus)

3. Brain Stem (includes: Midbrain, Pons, Medulla)

4. Cerebellum

Composition of Brain Matter

• Gray Matter:

  • Composition: Cell bodies and dendrites.

• White Matter:

  • Composition: Myelinated axons.

  • White Matter Tracts: Large bundles that span longer distances.

• Distribution in Cerebrum:

  • Gray and white matter mixed:

  • Corpus Callosum

  • Cerebral Cortex

  • Cerebral Medulla

  • Basal Nuclei

Cerebral Lateralization

• Definition: Localization of functions within the cerebral hemispheres.

• Features:

  1. Some degree of function localization is evident, but precise assignments are challenging.

  2. Sensory input and motor commands from the body are processed contralaterally (opposite side).

  3. The two hemispheres mirror each other with some level of specialization:

  • Left Hemisphere: Typically involved in analytical processes.

  • Right Hemisphere: Often associated with creativity and spatial ability.

General Functions of the Cerebral Lobes

1. Frontal Lobe:

   • Functions: Decision making, concentration, planning, personality, verbal communication, motor areas (Primary Motor Cortex, Motor Speech Area), voluntary movement.

2. Parietal Lobe:

   • Functions: Sensation (touch, pressure, pain, temperature), position awareness (proprioception), processing of sensory information via the Primary Somatosensory Cortex and Somatosensory Association Area.

3. Temporal Lobe:

   • Location: Inferior to the lateral sulcus.

   • Functions: Processing of hearing and smells, storage of auditory and visual memories (Primary Auditory Cortex, Primary Olfactory Cortex).

4. Occipital Lobe:

   • Location: Most posterior lobe.

   • Functions: Processing visual inputs and coordinating eye movements (Primary Visual Cortex, Visual Association Area).

5. Insular Lobe:

   • Location: Deep to the temporal lobe and lateral sulcus.

   • Functions: Informed sensory processing (e.g., taste) as well as visceral organ input integration.

Mapping of Motor and Sensory Information in the Brain

• Homunculus Models:

  • Primary Motor Cortex (located in the precentral gyrus): Maps motor function on the cerebrum into organized body regions.

  • Primary Somatosensory Cortex (located in the postcentral gyrus): Maps sensory input regions correspondingly.

Specific Function Questions

• Example Questions:

  • Which lobe of the brain is primarily involved in motor function?

  • Options: A. Insula B. Parietal C. Frontal D. Occipital

  • Which lobe is primarily involved in sensory functions?

  • Options: A. Insular B. Frontal C. Parietal D. Ear

Diencephalon

• Composition:

  1. Epithalamus: includes pineal gland.

  2. Thalamus: relay station for sensory information.

  3. Hypothalamus: regulates autonomic nervous system and endocrine system; involved in temperature regulation, food and water intake, emotional behavior, and sleep-wake cycles.

Brain Stem

• Sections:

  1. Midbrain: Relay center for motor and sensory pathways.

  2. Pons: Connects motor and sensory tracts between brain and spinal cord; regulates respiration.

  3. Medulla Oblongata: Contains nuclei that control cardiovascular and respiratory functions.

Cerebellum

• Function: Assists in refining movements and providing feedback on motor tasks; integrates movement data from primary motor cortex and makes corrective feedback adjustments.

Concussions

• Definition: Temporary brain injury caused by blunt force trauma or rapid head movements.

• Causes: Falls, contact sports, car accidents, violent shaking.

• Signs: Dazed appearance, slurred speech, delayed responses, forgetfulness.

• Symptoms: Headache, nausea, confusion, fatigue, blurry vision.

Woodpecker Biology

• Why Woodpeckers Don’t Get Concussions:

  • Forces experienced: ~1000x gravity versus humans who generally withstand ~100x gravity.

  • Adaptations: Thick neck muscles absorb forces, third inner eyelid protects eyes, brain is surrounded by spongy bone and trabecular structures.