TC

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.