The Muscular System

Muscular System Overview

  • Approx. 600 muscles in human body assist in movement.

  • Muscle Classification:

  • Involuntary Muscles: Function automatically

    Heart beating (heart)

Food moving through the digestive system (stomach, intestine)

Voluntary Muscles: Controlled consciously (e.g., walking).

Types of Muscles

  1. Skeletal/Striated Muscles: Voluntary, connected to bones.

  2. Cardiac Muscles: Involuntary, found only in the heart. (Thick and strong)

  3. Smooth Muscles: Involuntary, found in internal organs (e.g., digestive system and blood vessels)

Muscle Movement

  • Muscles contract and relax to produce movement.

  • Controlled by nerves; brain sends signals to muscles via nerve cells.

How Skeletal Muscles Work

  • Skeletal muscles are attached to bones by tendons.

  • They work in pairs (antagonistic muscles); one contracts (gets smaller) while the other relaxes (gets larger)

    • Example: Bicep contracts, Tricep relaxes to bend the arm.

    • Your biceps and tricep muscles were together to bend the arm. When the biceps contract, the triceps relax and the arms band.

    • The opposite motion is required when straightening the arm to straighten the arm, the bicep muscles relax, and the triceps muscles contract.

Flexors and Extensors

  • Muscles are grouped as flexors and extensors

  • Flexors: Muscles that cause joints to bend.

  • Extensors: Muscles that cause joints to straighten.

Major Muscles

  • Chest: Pectoralis

  • Back: Trapezius

  • Shoulders: Deltoids

  • Biceps: Biceps brachii

  • Triceps: Triceps brachii

  • Abs: Rectus abdominis

  • Glutes: Gluteus maximus/medius

  • Quads: Quadriceps

  • Hamstrings: Biceps femoris

  • Calves: Gastrocnemius

Healthy Muscles

  • Maintain through movement and a balanced diet (high in protein).

  • Exercise strengthens muscles and prevents excess body weight.

  • A balanced diet high in protein helps to build and repair muscle cells

  • Rest and relaxation helped to relieve muscle tension and fatigue.

  • Posture is crucial for muscle health; good posture reduces muscle strain.

  • Good posture puts little strain on muscles and uses little energy as possible to maintain its position.

  • Bad posture puts the muscles out of balance and puts added pressure on them overtime. The muscles, ligaments and tendons begin to tire an ache.

Muscular Injuries

  • Strain: Muscle or tendon stretched/torn.

  • Cramp: Sudden, involuntary contraction of muscles.

  • Spasm: Continuous muscle contraction.