Skeletal and Muscular Systems Quiz

The Musculoskeletal System

• This chapter provides a wider perspective on the functions and importance of the skeletal system, examining growth, remodeling, and repair mechanisms.
• Bones support the weight of the body and work with muscles to control precise movements.
• The 206 bones in the adult human body are dynamic living tissue, constantly breaking down and rebuilding.
• Bone interaction with other body systems is crucial for life, not just movement.

Learning Objectives

• Describe the skeletal system's primary functions.
• Classify bones by shape and internal organization, including examples and functional significance.
• Identify bone cell types and their functions.
• Compare the structures and functions of compact and spongy bone.
• Discuss the effects of exercise, hormones, and nutrition on bone development and skeletal system.
• Describe fracture types and healing processes (summarize aging effects).
• Identify bones of the axial and appendicular skeleton, plus their functions.
• Identify upper and lower limb bones, their functions, and superficial features.

Primary Functions

• Support: Bones provide a framework for soft tissue attachment.
• Mineral and Lipid Storage: Bone stores minerals like calcium for osmotic balance and physiological processes. Also stores energy as lipids in yellow marrow.
• Blood Cell Production: Red and white blood cells are produced in red bone marrow in many bones.
• Protection: Bones like ribs, skull, vertebrae, and pelvis, protect internal organs.
• Leverage: Skeletal muscles act on bones as levers, with significant movements from precise to full-body changes.

Bone Shapes

• Sutural (Wormian): Small, irregularly-shaped bones within the skull sutures.
• Irregular: Complex shapes, like vertebrae and pelvic bones.
• Short: Box-like in appearance, like carpal and tarsal bones.
• Flat: Thin, parallel surfaces; protect underlying tissues and provide large muscle attachment areas, like skull, sternum, ribs, and scapulae.
• Long: Relatively long and slender; found in arms, legs, fingers, and toes; example: femur.
• Sesamoid: Small, round, and flat; develop within tendons; example: patella.

Bone Markings

• Elevations and projections are sites for tendon and ligament attachment.
• Depressions, grooves, and tunnels are sites where blood vessels and nerves run.
• Detailed examination can determine age, sex, and general appearance from incomplete skeletons.

Bone Structure

• A typical long bone has a shaft (diaphysis) with an expanded end (epiphysis).
• The diaphysis' wall is composed of compact bone, which surrounds a medullary cavity.
• Spongy bone (cancellous bone) fills the epiphyses, arranged in trabeculae (oriented along stress lines).

Bone Cells

• Osteocytes: Mature bone cells (main part of bone cell population).
• Osteoblasts: Produce bone matrix in the process of ossification, releasing proteins and other organic components (responsible for bone matrix formation).
• Osteogenic cells: Mesenchymal stem cells; produce osteoblasts.
• Osteoclasts: Large cells that absorb and remove bone matrix (break down bone tissue).

Compact and Spongy Bone

• Compact bone, dense, supports and protects. Thinnest where stresses arrive from limited directions.
• Spongy bone, supports less heavily stressed areas and provides marrow storage (trabeculae are oriented along stress lines).

Bone Development

• The skeleton's growth dictates the body's size and proportions, beginning around six weeks after fertilization.
• Bone growth continues through adolescence and some bones do not stop growing until approximately age 25, with ossification (bone development) driving this process.

Bone Fracture

• Fractures have specific names based on shape, location, or type of break.
• Most fractures, if given appropriate conditions, heal through a process of blood clotting, callus formation, and bone remodeling.

Axial Skeleton

• The axial skeleton forms the body's longitudinal axis, comprising 80 bones, supporting and protecting essential structures (skull, vertebral column, thoracic cage).

Appendicular Skeleton

• The appendicular skeleton includes limbs and the girdles connecting them to the axial skeleton. These bones are responsible for movement and support related to the limbs. The bones of the pectoral and pelvic girdles connect the appendicular skeleton to the axial skeleton.

Joints

• Functional joints classify according to movement freedom: immovable (synarthroses), slightly movable (amphiarthroses), and freely movable(diarthroses).
• Based on structure, joints are classified as fibrous, cartilaginous, bony, and synovial. Synovial joints are freely movable and permit a wide range of movements. They are located between long bones of the limbs.
• The structure of a synovial joint includes a joint capsule, synovial fluid, and articular cartilage, assisting movement and preventing bone contact.

Movements

• Angular: (flexion, extension), (abduction, adduction), and (circumduction) are common movements that change the angle between articulating bones.
• Rotational: Movement around a central axis (e.g., rotation of the head, forearm, or hip)
• Special Movements: (like elevation, depression, protraction, retraction, opposition, and reposition) occur in specific joints.

Shoulder and Elbow Joints

• The shoulder joint (glenohumeral joint) is a highly mobile ball-and-socket joint, sacrificing stability for a greater range of motion.
• The elbow is a hinge joint, permitting flexion and extension primarily between the humerus, radius, and ulna.

Hip and Knee Joints

• The hip joint is a stable ball-and-socket joint permitting flexion, extension, abduction, adduction, circumduction, and rotation. The knee joint functions as a hinge joint, with flexion and extension as the primary movements.

Skeletal Muscle

• The muscular system is responsible for several critical functions including skeletal movement, maintaining posture, supporting tissues, guarding body openings, and regulating body temperature.
• Skeletal muscle tissue is made up of highly specialized muscle fibers for contraction. These cells contain specialized structures like sarcolemma, sarcoplasm, myofibrils, sarcomeres, and more, allowing for efficient interactions between the muscle and other systems .
• Muscles are arranged in layers of connective tissue; the epimysium, perimysium, and endomysium.
• The nervous system communicates with skeletal muscles at the neuromuscular junction (NMJ).

Muscle Contractions

• Isotonic: Muscle length changes during contraction. Concentric shortens, eccentric lengthens.
• Isometric: Muscle length does not change, tension is generated but does not exceed the load.
• ATP: Energy needed for muscle contraction.

Muscle Classification

• Parallel: Fascicles are parallel to the long axis; example: biceps.
• Convergent: Fascicles converge on a common attachment site; example: pectoralis muscles.
• Pennate: Fascicles form an angle with the tendon (unipennate, bipennate, and multipennate); example: deltoid.
• Circular: Fascicles are arranged around an opening; example: orbicularis oris.

Classes of Levers

• Levers in the body can change the direction and strength of an applied force.
• First-class levers: Fulcrum is between load and force.
• Second-class levers: Load is between the force and the fulcrum.
• Third-class levers: Force is between the load and the fulcrum.

Origin, Insertion, and Actions

• Origin: The fixed attachment point of a muscle.
• Insertion: The point of attachment that moves when the muscle contracts.
• Action: The specific movement produced when the muscles contract.

Muscle Names

• Muscle names often describe the muscle's location, origin or insertion, fascicle arrangement or position, shape or characteristic features, and/or action.

Axial and Appendicular Muscles

• Axial muscles: Position the head, spine, and rib cage.
• Appendicular muscles: Stabilize or move components of the limbs.

Effects of Aging on Muscle

• Muscle fibers shrink. Muscle tissue loses elasticity.
• Less tolerance to exercise.
• Reduced ability to recover from injuries.

Exercise and Body Systems Interaction

• Exercise triggers various physiological responses in the cardiovascular, respiratory, and integumentary systems to maximize body function while exercising.

Test your knowledge on the functions and interactions of the skeletal and muscular systems. This quiz covers essential concepts such as bone tissue characteristics, muscle groups, and the effects of aging and exercise on the skeletal system. Perfect for biology students and enthusiasts alike!