Gross Anatomy of NS 2022

Gross Anatomy of the Nervous System

  • Instructor: NORHIDA RAMLI, 2022, OCT 11

Objectives of Lecture

At the end of this lecture, students should be able to:

  1. Describe the organization of the nervous system.

  2. Identify components of the central and peripheral nervous systems.

  3. List functions of the nervous system.

  4. Recognize components of the brain and spinal cord in models, specimens, or diagrams and describe their general functions.

  5. Describe the basal ganglia.

  6. Describe the anatomy of the limbic system.

What is the Nervous System?

The nervous system is a complex network of nerves that carries messages between the brain, spinal cord, and various parts of the body. The functional unit of the nervous system is the neuron.

General Functions of the Nervous System

  1. Serves as the main coordinator of all bodily activities.

  2. Enables the body to respond and adapt to internal and external changes.

Neuronal Communications in the Nervous System

  • Types of Synapses:

    • Electrical Synapse:

      • Uses gap junctions to allow current to flow passively through intercellular channels affecting postsynaptic membrane potential, thereby initiating or inhibiting action potentials.

    • Chemical Synapse:

      • Involves the secretion of neurotransmitters which bind to receptors, opening or closing postsynaptic ion channels.

      • Reference: NCBI

Structure of the Nervous System

  • Central Nervous System (CNS):

    • Comprises the brain and spinal cord.

  • Peripheral Nervous System (PNS):

    • Comprises cranial and spinal nerves.

Division of the Nervous System

Anatomical Division

  1. Central

  2. Peripheral

Functional Division of the Peripheral Nervous System

  1. Somatic Nervous System: Responsible for voluntary movements.

  2. Autonomic Nervous System: Manages involuntary functions.

    • Subdivisions:

      • Parasympathetic: Also known as 'Rest and Digest'.

      • Sympathetic: Known as the 'Fight or Flight' system.

Autonomic Nervous System Functions

Parasympathetic Division

  • Constricts pupils

  • Stimulates salivation

  • Constricts airways

  • Slows heartbeat

  • Stimulates digestion

  • Stimulates gallbladder function

Sympathetic Division

  • Dilates pupils

  • Inhibits salivation

  • Relaxes airways

  • Increases heartbeat

  • Inhibits digestion

  • Stimulates glucose release

Cranial Nerves

  • Types:

    • Sensory Fibers:

      • Example: Olfactory (I) - sensory (nose).

    • Motor Fibers:

      • Example: Oculomotor (III) - motor (eye movement).

    • Mixed Fibers:

      • Example: Trigeminal (V) - both sensory and motor functions (face).

Summary of Cranial Nerves by Type

  1. O: Olfactory (CN I) - Sensory

  2. O: Optic (CN II) - Sensory

  3. O: Oculomotor (CN III) - Motor

  4. T: Trochlear (CN IV) - Motor

  5. T: Trigeminal (CN V) - Both

  6. A: Abducens (CN VI) - Motor

  7. F: Facial (CN VII) - Both

  8. V: Vestibulocochlear (CN VIII) - Sensory

  9. G: Glossopharyngeal (CN IX) - Both

  10. V: Vagus (CN X) - Both

  11. A: Accessory (CN XI) - Motor

  12. H: Hypoglossal (CN XII) - Motor

Spinal Nerves

  1. Cervical Nerves: C1-C8

    • Innervate neck muscles, diaphragm, shoulders, and arms.

  2. Thoracic Nerves: T1-T12

    • Innervate trunk and abdominal muscles.

  3. Lumbar Nerves: L1-L5

    • Innervate hips and legs.

  4. Sacral Nerves: S1-S5

    • Innervate pelvic organs.

Central Nervous System (CNS)

The CNS integrates information and coordinates the activities of all body parts. It is enclosed within bony structures: the skull and the spine.

Functions of the CNS

  • Integrates information from the peripheral nervous system

  • Coordinates body activities

Major Parts of the Brain

  1. Cerebrum

  2. Diencephalon

  3. Brainstem

  4. Cerebellum

Brain Structure Overview

Based on Embryological Derivative

  • Forebrain:

    • Thalamus, Hypothalamus, Pituitary

  • Midbrain:

    • Pons, Medulla Oblongata

  • Hindbrain:

    • Cerebellum

Cerebral Anatomy

  • Gray Matter: Composed of neuron cell bodies.

  • White Matter: Comprised of myelinated axons.

Functional Areas of the Brain

  • Frontal Lobe: Higher cognitive functions.

  • Parietal Lobe: Somatosensory processing.

  • Temporal Lobe: Auditory and memory functions.

  • Occipital Lobe: Visual processing.

Basal Ganglia

The basal ganglia are associated with managing movement and are critical for regulating muscle tone.

  • Components:

    • Caudate nucleus, Putamen, Globus pallidus, Substantia nigra, Subthalamic nucleus

  • Functions:

    • Facilitate movement and inhibit competing movements. Produces dopamine, important for motor control.

Limbic System

The limbic system is integral for emotional responses and memory formation.

  • Structures:

    • Cingulate gyrus, Parahippocampal gyrus, Hippocampus, Amygdala

  • Functions:

    • Control behavioral and emotional responses, as well as memory.

  • Clinical Relevance: Involves emotional responses and memory, where lesions may lead to deficits in these areas.

Summary

This lecture detailed the anatomy of the nervous system, focusing on structural divisions, major functions, and critical components including the brain, spinal cord, cranial nerves, and the limbic system.uesj318sjqeiubce