Anatomy of Major Brain Parts: Part 2

Overview

This lecture covers the anatomy and functions of major brain parts including the diencephalon, pituitary gland, cerebellum, midbrain, pons, and medulla.

Diencephalon

• Composed of the thalamus, hypothalamus, and epithalamus.
• Acts as a relay center between the cerebrum and midbrain.

Thalamus

• Two oval masses of grey matter connected by the interthalamic adhesion.
• Largest part of the diencephalon.
• Relays sensory impulses to the cerebral cortex, except for olfaction.

Hypothalamus

• Located beneath the thalamus.
• Known as the master gland controlling heart rate, temperature, blood pressure, gastrointestinal secretions, and motility.
• Connects to other brain parts via the infundibular stalk.

Epithalamus

• Composed of the pineal gland and habenula.
• Pineal gland: Secretes melatonin important for circadian rhythms and sleep cycles.
• Habenula: Part of the olfactory pathway.

Pituitary Gland (Hypophysis)

• Closely associated with the hypothalamus.
• Connected via the infundibular stalk.
• Divided into the anterior lobe (adenohypophysis) and posterior lobe (neurohypophysis).
• Located in the sella turcica of the sphenoid bone.

Cerebellum

• Second largest brain division, located dorsally to pons and medulla, caudal to occipital lobe.
• Functions as a motor reflex center coordinating skeletal muscle movements.

Cerebellum Structure

• Central part: Vermis (resembles a worm).
• Separated into caudal and rostral lobes.
• Lateral masses and folia (surface laminae).
• Arbor vitae: White matter tracks resembling a tree (tree of life).

Midbrain

• Located between the diencephalon and pons.
• Connects lower brain centers and spinal cord to higher brain centers.

Midbrain Structure

• Tectum: Dorsal part, composed of corpora quadrigemina with rostral (visual reflex centers) and caudal colliculi (auditory reflex centers).
• Tegmentum: Ventral part.

Pons

• Located between the midbrain and medulla oblongata.
• Bridges spinal cord and brain, controls motor functions.

Medulla Oblongata

• Caudal part of the brain, continues as the spinal cord.
• Houses three vital reflex centers:
  • Cardiac center: Regulates heart contraction rate and strength.
  • Vasomotor center: Regulates blood vessel diameter.
  • Respiratory center: Regulates breathing rhythm.

Conclusion

• Familiarity with the location and structures of these brain parts is crucial for understanding their functions.
• Next module will cover brain ventricles and meninges.