Human Physiology & Musculoskeletal System: Anatomy, Function, and Muscle Mechanics

What is the primary function of the muscular system?

To produce movement by contraction.

How many skeletal muscles are in the human body?

640 skeletal muscles.

What does the name of a muscle often indicate?

Descriptive information about location, muscle fiber organization, relative position, structural characteristics, and action.

What is the origin of a muscle?

The point of attachment of a muscle that does not change position when the muscle contracts.

What is the insertion of a muscle?

The point of attachment of a muscle at the end which is easily movable.

What is an agonist muscle?

The muscle that contracts to produce a specific movement.

What is an antagonist muscle?

The muscle that can slow down or stop the action of the prime mover.

What role does a synergist muscle play?

It assists indirectly in a movement.

What is the function of a stabilizer or fixator muscle?

To immobilize the bone of the agonist's origin.

What are the actions of the biceps brachii?

Elbow and shoulder flexion, and supination of the forearm.

What muscle is the prime mover for elbow flexion?

Biceps brachii.

What muscle acts as the antagonist during elbow flexion?

Triceps brachii.

What are the two main types of muscle actions?

Concentric (shortening) and eccentric (lengthening) contractions.

What is the role of tendons in muscle movement?

Tendons attach muscles to bones and transmit force to cause joint movement.

Name one muscle that is part of the anterior skeletal muscles.

Biceps brachii.

Name one muscle that is part of the posterior skeletal muscles.

Biceps femoris.

What is the purpose of learning skeletal muscle anatomy?

To understand the locations, origins, insertions, and actions of muscles.

What is the sliding filament mechanism?

The process by which muscles contract through the sliding of actin and myosin filaments past each other.

What is the role of the nervous system in muscle control?

It coordinates and controls muscle contractions for movement.

What is the significance of muscle fiber type?

Different muscle fiber types (e.g., slow-twitch vs fast-twitch) affect endurance and strength capabilities.

What is the function of the gluteus maximus?

It is primarily responsible for hip extension and external rotation.

What is the role of the rectus abdominis?

It flexes the vertebral column and helps stabilize the pelvis.

What is the origin of the biceps brachii?

Scapula

What is the insertion point of the triceps brachii?

Ulna

What actions are performed by the biceps brachii?

Shoulder flexion, elbow flexion, and supination of the forearm

What is the origin of the pectoralis major?

Sternum, clavicle, and ribs

What actions does the pectoralis major perform?

Flexion, adduction, and medial rotation of the shoulder

What is the origin of the latissimus dorsi?

Sacrum, lumbar vertebrae, and lower thoracic vertebrae T7-T12

What is the action of the gluteus maximus?

Hip extension, lateral rotation, and thigh abduction

What is the insertion of the biceps femoris?

Lateral condyle of tibia and fibula head

What actions does the rectus femoris perform?

Hip flexion and knee extension

What is the origin of the gastrocnemius?

Femur

What is the action of the soleus muscle?

Plantar flexion of foot at ankle

What are the three types of muscle tissue?

Skeletal, cardiac, and smooth muscle

Where is cardiac muscle found?

In the walls of the heart

What are the characteristics of smooth muscle?

Spindle-shaped cells with a single central nucleus, found in walls of internal organs

What distinguishes skeletal muscle from other muscle types?

It is multinucleated, heavily striated, and voluntary

What surrounds the entire muscle?

Epimysium

What is the function of the perimysium?

Surrounds bundles of muscle fibers (fasciculi)

What is the role of the endomysium?

Surrounds individual muscle fibers

What is the plasmalemma/sarcolemma?

The membrane of a muscle cell that aids in action potential transmission

What are transverse tubules (T-tubules)?

Interconnected network of tubules that transmit nerve impulses to myofibrils

What is the function of the sarcoplasmic reticulum?

Storage site of calcium and controls the muscle contraction-relaxation cycle

What is the sarcoplasm?

Cytoplasm of muscle fiber containing proteins, fats, and minerals

What are myofibrils?

Contractile elements of muscle, appearing as long strands of sarcomeres

What is the crossbridge cycle?

The process of muscle contraction involving the interaction between actin and myosin

What is the role of calcium in muscle contraction?

Calcium is released to initiate contraction and is stored in the sarcoplasmic reticulum