Neuroanatomy II lecture

Welcome and Announcements

  • Course Information: Neurology 2051/2052

  • Practical Submission:

    • Submission site on Blackboard is now open for practical write-ups.

  • Timetable Issues:

    • Students enrolled late may still have unresolved practical allocations.

    • Email if no practical session appears on the timetable by Wednesday.

Lecture Overview - Neuroanatomy Two

  • Recap from previous lecture on comparative neuroanatomy and cerebral hemispheres.

  • Objectives for Today:

    • Describe common neuroanatomical terminology.

    • Discuss functions of seven parts of the central nervous system (CNS).

    • Review spinal nerve structure, spinal reflexes, and introduce the autonomic nervous system.

  • Recommended Reading:

    • Previous chapter and lectures from last year for overlap and revision.

Major Parts of the Central Nervous System

Cerebrum (Cerebral Hemispheres)

  • Involved in higher cognitive functions.

Diencephalon

  • Contains the thalamus (sensory relay) and hypothalamus (autonomic control center).

Brainstem

  • Composed of:

    • Midbrain: Topmost part.

    • Pons: Middle section connecting to the cerebellum.

    • Medulla Oblongata: Vital functions (heart rate, respiration) and non-vital reflexes (coughing, sneezing).

Cerebellum

  • Coordinates movement, balance, and posture; integrates information from spinal cord and cortex.

Spinal Cord

  • The final part of CNS; serves as a reflex center and conduit for impulses.

Gray Matter and White Matter

  • Gray Matter: Neuronal cell bodies, primarily in the cerebral cortex and subcortical areas (e.g., basal ganglia).

  • White Matter: Myelinated axons that connect different gray matter areas.

    • Provides white appearance due to lipid-rich myelin.

Neuroanatomical Terminology

Orientation in the CNS

  • Coronal Plane: Divides front and back.

  • Sagittal Plane: Divides left and right; can be mid-sagittal.

  • Horizontal (Axial) Plane: Divides top and bottom.

Anatomical Terms of Location

  • Anterior vs. Posterior: Front vs. back.

  • Rostral vs. Caudal: Toward the head vs. toward the tail (or tailbone).

  • Dorsal vs. Ventral: Back vs. front (on four-legged animals).

  • Superior vs. Inferior: Toward the top vs. toward the bottom.

Protection of the Brain

  • Bone: Skull and vertebral column provide initial protection.

  • Meninges: Three layers surrounding the brain:

    • Dura Mater: Tough outer layer.

    • Arachnoid Mater: Delicate, web-like structure.

    • Pia Mater: Innermost layer in contact with CNS tissue.

  • Cerebrospinal Fluid (CSF): Provides cushioning and buoyancy; produced in ventricles, circulates around brain and spinal cord.

Functions of Cerebral Hemispheres

  • Afferent Input to the Cortex: Mainly sensory information from thalamus and brainstem.

  • Efferent Output from the Cortex:

    • Excitatory neurotransmitter (primarily glutamate) induces motor functions; feedback to modulate responses.

  • Common Fibers: Connect left and right hemispheres (e.g., corpus callosum).

  • Interactions with Spinal Cord: Motor commands descend through brainstem.

Brainstem Functions

  • Connects CNS to peripheral systems; carries ascending/descending fibers.

  • Cranial Nerve Nuclei: Origins of cranial nerves specialized for senses and motor functions of head and neck.

Cerebellum Functions

  • Movement Coordination: Integrates spinal and cortical information for refined motor control.

  • Maintains posture and balance through muscle tone regulation.

  • Receives input from vestibular system for balance monitoring.

The Spinal Cord

  • Regions: Cervical, thoracic, lumbar, sacral, and coxal; reflex center for sensory input and motor output.

  • Spinal Nerves: 31 pairs serving as origins for peripheral nerves; mixed sensory/motor fibers.

Reflexes

  • Definition: Unlearned, rapid, involuntary responses (e.g., knee-jerk reflex).

  • Reflex Arc Components:

    • Monosynaptic Reflex: Simple, with one synapse (e.g., knee-jerk).

    • Polysynaptic Reflex: More complex, involving multiple synapses, contributing to quicker reflexive actions.

Peripheral Nervous System (PNS)

  • Divisions: Afferent (sensory) and efferent (motor).

  • Autonomic Nervous System: Regulates involuntary functions; divided into sympathetic (fight or flight) and parasympathetic (rest and digest).

  • Enteric Nervous System: Specialized for gut function; interacts with autonomic nervous system for homeostasis.

Conclusion

  • Prepare for upcoming lectures and practicals; reinforce understanding of neuroanatomy and linked functions.