Muscular and Nervous Systems: Structured Study Guide for Anatomy & Physiology

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Muscular System

Overview of Muscular System

The muscular system is responsible for movement, posture, and heat production in the human body. It consists of different types of muscle tissues, each with specialized functions and structures.

Muscle Tissue Types: Skeletal, cardiac, and smooth muscle.
Functions: Movement, stability, heat generation, and control of body openings.
Connective Tissue Components: Epimysium, perimysium, endomysium, fascia, tendon, aponeurosis.

Muscle Structure and Function

Epimysium: Surrounds entire muscle.
Perimysium: Surrounds muscle fascicles.
Endomysium: Surrounds individual muscle fibers.
Fascia: Connective tissue separating muscles from each other.
Tendon: Connects muscle to bone.
Aponeurosis: Broad, flat tendon.

Muscle Properties

Excitability: Ability to respond to stimuli.
Contractility: Ability to shorten forcefully.
Elasticity: Ability to return to original length.
Extensibility: Ability to stretch.
Conductivity: Ability to conduct electrical impulses.

Types of Body Movements

Muscles produce various movements at joints, classified by the direction and nature of the movement.

Angular Movements: Flexion, extension, hyperextension, abduction, adduction.
Rotational Movements: Rotation, medial/lateral rotation.
Special Movements: Pronation, supination, dorsiflexion, plantarflexion, inversion, eversion, opposition, reposition, protraction, retraction, elevation, depression.

Muscle Attachments and Actions

Origin: Fixed attachment point.
Insertion: Movable attachment point.
Prime Mover (Agonist): Main muscle responsible for movement.
Antagonist: Opposes the prime mover.
Synergist: Assists the prime mover.
Fixator: Stabilizes the origin.

Major Muscles and Their Functions

Biceps brachii: Flexes the forearm.
Gluteus maximus: Extends and rotates the thigh.
Adductor longus: Adducts the thigh.
Rectus femoris: Extends the leg at the knee.
Gastrocnemius: Plantarflexes the foot.

Mechanical Advantage and Disadvantage

Muscles act as levers, and their efficiency depends on the position of the fulcrum, effort, and load.

Mechanical Advantage: When the effort arm is longer than the load arm, less force is needed.
Mechanical Disadvantage: When the load arm is longer, more force is required.
Example: The biceps brachii typically operates at a mechanical disadvantage.

Muscle Classification by Function

Voluntary Muscles: Skeletal muscles under conscious control.
Involuntary Muscles: Cardiac and smooth muscles, not under conscious control.

Nervous System

Introduction to Nervous Tissue

The nervous system is responsible for communication, control, and integration of body functions. It consists of neurons and supporting cells (neuroglia).

Neuron: Functional unit of the nervous system; transmits electrical impulses.
Neuroglia: Support, protect, and nourish neurons.

Neuron Structure

Cell Body (Soma): Contains nucleus and organelles.
Dendrites: Receive signals.
Axon: Transmits signals away from the cell body.
Axon Hillock: Initiates action potentials (trigger zone).
Terminal: Releases neurotransmitters.

Types of Neurons

Multipolar: Many dendrites, one axon (most common).
Bipolar: One dendrite, one axon (retina, olfactory).
Pseudounipolar: Single process splits into two branches (sensory neurons).

Neuroglial Cells

Astrocytes: Support and maintain the blood-brain barrier.
Oligodendrocytes: Form myelin in CNS.
Schwann Cells: Form myelin in PNS.
Microglia: Immune defense in CNS.
Ependymal Cells: Line ventricles, produce cerebrospinal fluid (CSF).

Divisions of the Nervous System

Central Nervous System (CNS): Brain and spinal cord.
Peripheral Nervous System (PNS): Cranial and spinal nerves.
Somatic Division: Voluntary control of skeletal muscles.
Autonomic Division: Involuntary control of smooth muscle, cardiac muscle, and glands (sympathetic and parasympathetic).

Functional Organization

Sensory (Afferent): Transmits impulses toward CNS.
Motor (Efferent): Transmits impulses away from CNS.
Interneurons: Connect sensory and motor pathways within CNS.

Major Brain Regions and Functions

Cerebrum: Higher cognitive functions, voluntary movement.
Cerebellum: Coordination, balance.
Brainstem: Autonomic functions, relay center.
Basal Nuclei: Motor control, habit learning.
Limbic System: Emotion, memory.

Spinal Cord Structure and Function

Gray Matter: Neuron cell bodies, processing center.
White Matter: Myelinated axons, transmission of signals.
Ascending Tracts: Sensory information to brain.
Descending Tracts: Motor commands from brain.

Motor Control and Coordination

Motor Program: Sequence of muscle activation for movement.
Proprioception: Sense of body position and movement.
Role of Cerebellum: Fine-tunes motor activity, maintains balance.
Basal Nuclei: Initiate and regulate voluntary movement.

Memory Types

Declarative Memory: Facts and events.
Procedural Memory: Skills and tasks.
Short-term Memory: Temporary storage.
Long-term Memory: Permanent storage.

Brain Lateralization

Left Hemisphere: Language, logic, analytical tasks.
Right Hemisphere: Spatial abilities, face recognition, creativity.

Sample Table: Major Brain Divisions and Functions

Division	Structures	Substructures	Main Functions	Example when playing a musical instrument
Cerebrum	Frontal, parietal, temporal, occipital lobes	Precentral gyrus, postcentral gyrus	Voluntary movement, sensory perception, cognition	Planning and executing finger movements
Cerebellum	Anterior, posterior, flocculonodular lobes	Vermis, hemispheres	Coordination, balance	Fine-tuning hand movements
Basal Nuclei	Caudate nucleus, putamen, globus pallidus	Substantia nigra	Motor control, habit learning	Learning repetitive finger patterns
All regions	Integration	-	Complex behaviors	Coordinated performance

Key Equations

Resting Membrane Potential: (approximate for neurons)
Ohm's Law (for neurons):
Action Potential Threshold:

Additional info:

Some content inferred from standard Anatomy & Physiology curriculum to fill gaps in the original notes and questions.