lecture recording on 13 March 2025 at 09.10.06 AM

Central Nervous System (CNS)

• Components of CNS: Brain and spinal cord.

• Meninges: Protective layers covering the brain and spinal cord.

  • Dura mater: Outer layer, tough and protective.

  • Arachnoid mater: Middle layer.

  • Pia mater: Inner layer, adheres to the brain surface.

• Spaces:

  • Epidural space: Area above the dura mater that can cause epidural hemorrhaging.

  • Subarachnoid space: Area beneath the arachnoid where cerebrospinal fluid circulates.

• Spinal Cord Structure: Ends in medullary cone with nerves fanning out, forming the cauda equina.

  • White Matter: Myelinated, carries information up and down (ascending and descending tracts).

    • Ascending tracts: Convey sensory information (e.g., sensation of pain when stepping on a tack).

    • Descending tracts: Convey motor commands (e.g., response to drop the pencil).

  • Gray Matter: Unmyelinated, processes information in and out of the spinal cord.

    • Sensory information enters via dorsal root, motor information exits via ventral root.

Reflex Arcs

• Reflexes allow for rapid responses without involving the brain.

• Pathway: Sensory information travels to spinal cord through dorsal root, processed in gray matter, and motor response transmitted back out.

• 31 pairs of spinal nerves: Include dorsal and ventral roots, named according to their position in relation to vertebrae.

  • Cervical nerves: Control head, neck, diaphragm.

  • Thoracic nerves: Control trunk.

  • Lumbar nerves: Control legs.

  • Sacral nerves: Control urogenital system.

Brain Anatomy

• Major Regions of the Brain:

  • Cerebrum: Upper part, responsible for higher thought, learning, sensory processing.

  • Diencephalon: Includes thalamus, hypothalamus, and epithalamus (homeostasis and relay functions).

  • Brain Stem: Connects to the spinal cord, controls vital functions (heart rate, respiration).

  • Cerebellum: Regulates balance and fine motor coordination.

Cerebrum Functions

• Divided into lobes:

  • Frontal: Conscious thought, emotions, movement.

  • Parietal: Sensory perception.

  • Temporal: Memory, language processing.

  • Occipital: Visual processing.

• Motor cortex: Precentral gyrus controls skeletal muscle movements; separate from sensory cortex located in postcentral gyrus for sensory feedback.

• Association areas:

  • Wernicke's area: Comprehension of speech.

  • Broca's area: Production of speech.

Diencephalon

• Thalamus: Relay station for sensory and motor information.

• Hypothalamus: Regulates homeostasis, temperature, hunger, and links to endocrine functions.

• Pineal gland: Produces melatonin for sleep regulation.

Brain Stem Functions

• Midbrain: Involved in motor functions, produces dopamine (substantia nigra) which regulates movement.

• Pons: Controls breathing and is a relay point for cranial nerves.

• Medulla Oblongata: Controls heart rate and respiratory rate; essential for basic life functions.

Cerebellum

• Controls fine motor skills and balance.

• Ataxia: Disturbance in balance, often due to cerebellar dysfunction.

• Clinical Connection: Damage to cerebellum can lead to impaired motor skills, as illustrated by individuals born with cerebellar hypoplasia.

Review and Practice

• Recommended supplemental resources available for deeper understanding.

• Emphasis on understanding how different injuries affect specific brain regions and associated functions.

• Knowledge Check: Engage with practice materials to label brain areas and understand their functions before concluding tutorials.