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Muscular System Overview

• Course: BI 117 General Human Anatomy & Physiology Lab

• Instructor: Kate E. Kryger

Types of Muscle

• Skeletal Muscle:

  • Voluntary control

  • Striated appearance

  • Attached to bones for movement

• Cardiac Muscle:

  • Involuntary control

  • Striated with intercalated discs

  • Found only in the heart

• Smooth Muscle:

  • Involuntary control

  • Non-striated

Structural Organization of Skeletal Muscle

• Levels of muscle organization:

  • Whole Muscle: Combination of tendon + muscle belly

  • Fascicle: Bundle of muscle fibers

  • Muscle Fiber: Individual muscle cell

Connective Tissue Surrounding Muscle

• Each level of muscle is enclosed by connective tissue:

  • Epimysium: Surrounds the muscle belly

  • Perimysium: Surrounds each fascicle

  • Endomysium: Surrounds each muscle fiber

Tendons and Muscle Actions

• Tendons: Connect muscle to bone

• Muscle Action Rule:

  • Any muscle or tendon crossing a joint will act upon that joint.

• Key Terms:

  • Origin [O]: Fixed end of muscle

  • Insertion [I]: Moveable end of muscle

Muscle Groups and Actions

• Muscles function in groups with different roles:

  • Prime Mover: Main muscle performing the movement

  • Synergist: Assists the prime mover

  • Fixator: Stabilizes a joint

  • Antagonist: Opposes the movement

Important Muscle Actions

• Flexion: Decreases the angle between body parts

• Extension: Increases the angle between body parts

• Abduction: Movement away from the midline

• Adduction: Movement toward the midline

• Pronation: Rotation of forearm to face down

• Supination: Rotation of forearm to face up

• Inversion: Movement of the foot toward the midline

• Eversion: Movement of the foot away from the midline

• Plantarflexion: Pointing toes down

• Dorsiflexion: Lifting toes up

• Elevation: Moving structures superiorly

• Depression: Moving structures inferiorly

Anatomical Grouping of Thigh Muscles

• Anterior Group: Extends the knee

• Posterior Group: Flexes the knee

• Medial Group: Adducts the thigh

  • Sartorius: Separates anterior from medial group

  • "ThighMaster" Muscles: Refer to the medial group

Lab Expectations

• Identify muscles and connective tissues as per the SPOs

• Understand the muscle’s primary action (one action required per muscle for the lab exam)

• Use provided labels for models; instructor approval needed

• No disassembly of models permitted

Preparation for Next Lab

• Watch the introductory videos on the nervous system before the next lab to prepare for the material to be covered.