exam 3

What is an isometric contraction?

A muscle contraction where muscle length stays the same while tension increases, resulting in no movement.

What is an isotonic contraction?

A muscle contraction where muscle changes length, causing movement.

What are the two types of isotonic contractions?

Concentric (muscle shortens) and eccentric (muscle lengthens).

Name two major muscles of the shoulder.

Deltoid and rotator cuff muscles (supraspinatus, infraspinatus, teres minor, subscapularis).

What is the deepest abdominal muscle?

Transversus abdominis.

What are the main muscles used in mastication?

Masseter, temporalis, medial pterygoid, and lateral pterygoid.

What is the role of the agonist muscle?

It is the main muscle responsible for causing a movement.

What are the roles of antagonists, synergists, and fixators?

Antagonists oppose the agonist, synergists assist the agonist, and fixators stabilize the origin of the agonist.

What are the origin and insertion of the biceps brachii?

Origin: scapula; Insertion: radius.

What are the components of the sliding filament model?

Actin (thin filament), myosin (thick filament), tropomyosin (blocks binding sites), troponin (binds Ca²⁺).

What causes muscle fatigue?

Ion imbalances, lack of ATP, and accumulation of lactic acid.

What are the four processes leading to muscle contraction?

NMJ Activation, Muscle Fiber Excitation, Excitation-Contraction Coupling, Cross Bridge Cycling.

Name the three types of muscle cells.

Skeletal, cardiac, and smooth muscle cells.

What are the four functions of the muscular system?

Movement, posture maintenance, joint stabilization, and heat generation.

What are the features of synovial joints?

Articular cartilage, joint cavity, articular capsule, synovial fluid, reinforcing ligaments, nerves, and blood vessels.

What are the three factors affecting joint stability?

Articular surface shape, ligament strength and number, and muscle tone.

Define flexion and extension in terms of angular movements.

Flexion: decrease angle; Extension: increase angle.

What is the 'unhappy triad' injury?

An injury that damages the ACL, MCL, and medial meniscus, often caused by a lateral blow to the knee.