Lecture on the Frontal Lobe of the Cerebral Cortex

Introduction

• Focus on the frontal lobe's functional anatomy and areas.
• Key lobes involved: temporal, parietal, and frontal.

Anatomical Boundaries of the Frontal Lobe

• Central Sulcus: Separates the frontal lobe from the parietal lobe.
• Lateral Sulcus (Sylvian Fissure): Separates the frontal lobe from the temporal lobe.

Functional Areas within the Frontal Lobe

Primary Motor Cortex

• Located just anterior to the central sulcus (pre-central gyrus).
• Function: Involved in voluntary movement, particularly of skeletal muscles.
• Corticospinal Tract: Carries motor commands to the spinal cord.
  • Supplies muscles of limbs, trunk, and head/neck.
• Corticobulbar Tract: Connects motor cortex to cranial nerve nuclei.
  • Supplies muscles of mastication, facial expression, pharynx, larynx, and tongue.

Motor Homunculus

• Somatotopic arrangement of body parts on the motor cortex.
• Larger representation for hands, face, and tongue due to fine motor control.
• Clinical Correlation: Stroke effects depend on affected cerebral artery:
  • Anterior Cerebral Artery: Affects lower limb movement.
  • Middle Cerebral Artery: Affects upper extremity and facial movements.

Motor Association Cortex

• Composed of the pre-motor cortex and supplementary motor area.
• Functions: Planning, sequencing, and execution of movement.
• Interacts with:
  • Basal Ganglia: Initiates and modulates movements.
  • Cerebellum: Modifies and coordinates motor plans.

Frontal Eye Fields

• Controls voluntary rapid eye movements (saccades).
• Pathway involves cranial nerves III and VI, and the paramedian pontine reticular formation.
• Lesion Effect: Causes ipsilateral conjugate gaze deviation (eyes deviate towards the lesion).

Prefrontal Cortex

• Involved in personality, behavior, memory, cognition, decision making, and motor planning.
• Communicates with:
  • Hippocampus: Memory processing.
  • Limbic System: Regulates emotions and behavior.
  • Ventral Tegmental Area: Reward and addiction.
  • Posterior Association Area: Integrates sensory information for motor planning.
• Clinical Condition: Frontotemporal dementia impacts memory, behavior, and decision-making.

Broca’s Area

• Located in the dominant hemisphere (usually left for right-handed individuals).
• Involved in speech production, coordinating muscles like:
  • Orbicularis oris (facial), muscles of the larynx, pharynx, and tongue.
• Broca’s Aphasia: Non-fluent, grammatically incorrect speech, but comprehension remains intact.

Conclusion

• The lecture provided a comprehensive overview of the frontal lobe's functional areas and their clinical significance.
• Additional resources and contact information were mentioned for further study and engagement.