Untitled Flashcards Set

Functions of Muscles

• Movement: Muscles contract to produce movement of the skeleton, allowing for physical activities such as walking, running, and swimming.

• Stabilization: Muscles help to maintain posture and stabilize joints, providing support against gravity and coordinating body position.

• Heat production: Muscle contractions generate heat, which is essential for maintaining body temperature during physical activity.

Types of Muscle

• Skeletal Muscle: Voluntary muscles attached to bones, they enable conscious movement. They are striated in appearance due to their organized fiber arrangement.

• Smooth Muscle: Involuntary muscles found in the walls of internal organs (e.g., intestines, blood vessels). They control functions such as digestion and blood flow.

• Cardiac Muscle: Found exclusively in the heart, this involuntary muscle has unique properties that enable rhythmic contractions.

Major Muscles & Actions

• Biceps Brachii: Flexes the elbow and rotates the forearm.

• Triceps Brachii: Extends the elbow.

• Quadriceps: Extends the knee and stabilizes the patella.

• Hamstrings: Flexes the knee.

• Pectoralis Major: Responsible for shoulder flexion and adduction.

Muscle Fibre Arrangement

• Parallel Fibres: Muscle fibers run parallel to the length of the muscle and are typically able to contract more than pennate muscles.

• Pennate Fibres: Fibers are arranged at an angle to the muscle's attachment, optimizing force production but reducing range of motion.

Structure of Skeletal Muscles

• Skeletal muscles consist of bundles of muscle fibers wrapped in connective tissue. Each muscle fiber is a single cell containing many nuclei and myofibrils, which facilitate contraction.

Nervous Control

• Nervous system signals initiate muscle contractions. Motor neurons transmit impulses that trigger the release of calcium ions, which start the contraction process in the muscle fibers.

All or None Principle

• The all-or-none principle states that a muscle fiber will fully contract when stimulated by a threshold stimulus; it does not contract partially.

Skeletal Muscle Action & Control

• Concentric Contraction: Muscle shortens while generating force.

• Eccentric Contraction: Muscle lengthens while still generating force, often during the lowering phase of a movement.

• Isometric Contraction: Muscle generates force without changing length, ideal for stabilization.

Reciprocal Inhibition, Agonists, Antagonists & Stabilisers

• Reciprocal Inhibition: When one muscle (the agonist) contracts, the opposing muscle (the antagonist) relaxes to allow movement.

• Agonists: Primary movers responsible for a specific movement.

• Antagonists: Muscles that oppose the action of agonists.

• Stabilisers: Muscles that stabilize a joint to allow for smooth movement of the agonist.

Muscle Fibre Types

• Type I Fibers (Slow-twitch): Endurance-oriented, resist fatigue, suited for aerobic activities.

• Type II Fibers (Fast-twitch): Quick and powerful bursts of movements, more suited for anaerobic activities.

Types of Muscular Contraction

• Muscles can contract in varying ways based on the type of activity. Understanding these types is essential for training and rehabilitation, as they dictate how muscles respond and adapt to different loads and movements.