Chapter 08

Skeletal System

The system composed of bones, joints, cartilage, and ligaments that provides structure and support to the body.

Compact Bone

Dense and hard bone tissue primarily found in the shafts of long bones.

Spongy Bone

Less dense, cancellous bone located primarily at the ends of long bones and in the center of others.

Osteoblasts

Bone-forming cells that secrete the intercellular matrix for bone development.

Osteoclasts

Bone-destroying cells that break down bone tissue, involved in bone remodeling.

Diaphysis

The long shaft of a long bone, primarily composed of compact bone.

Epiphysis

The enlarged ends of a long bone, each articulating with another bone at a joint.

Epiphyseal Disc

Band of hyaline cartilage at the ends of long bones; site of longitudinal growth.

Haversian System

The microscopic structure of compact bone, consisting of layers of osteocytes arranged in concentric circles around blood vessels.

Articular Cartilage

Smooth, shiny cartilage covering the ends of bones at a joint, reducing friction.

Synovial Fluid

Thick fluid that nourishes and lubricates the inner surfaces of joints.

Axial Skeleton

Part of the skeleton that consists of the skull, vertebral column, and thoracic cage.

Appendicular Skeleton

Part of the skeleton composed of the bones of the limbs and girdles.

Long Bones

Bones that are longer than they are wide; found in arms and legs.

Short Bones

Cube-shaped bones primarily found in wrists and ankles.

Flat Bones

Thin, flat, and curved bones such as those in the ribs and cranium.

Irregular Bones

Bones that do not fit into the other categories due to their shape, such as vertebrae.

Ossification

The process of bone formation where cartilage is replaced by bone.

Joint

The site where two or more bones meet, allowing for movement and flexibility.

Ligaments

Fibrous connective tissue that connects bones to other bones at joints.

Tendons

Tissue that connects muscle to bone, enabling movement.

Flexion

The act of bending a joint to decrease the angle between bones.

Extension

The act of straightening a joint to increase the angle between bones.

Abduction

Movement away from the midline of the body.

Adduction

Movement towards the midline of the body.

Pronation

Turning the hand so that the palm faces downward.

Supination

Turning the hand so that the palm faces upward.

Circumduction

A circular movement that combines flexion, extension, abduction, and adduction.

Hinge Joint

A joint that allows movement in one direction, like the knee or elbow.

Ball-and-Socket Joint

A joint that allows for the greatest range of motion, such as the hip or shoulder.

Pivot Joint

A joint that allows for rotation, like the atlas and axis in the neck.

Gliding Joint

Joint with flat surfaces that allow for complex movements, found in the wrist and ankle.

Saddle Joint

Joint that allows a wide range of motion, such as the thumb joint.

Condyloid Joint

Joint where an oval protrusion fits into an oval depression, allowing movement in two directions.

Bone Marrow

The soft tissue inside bones where blood cells are produced.

Periosteum

A dense layer of vascular connective tissue that envelops the bones except at the surfaces of the joints.

Cartilage

A flexible connective tissue found in various parts of the body, including joints, ear, and nose.

Fibrous Joint

A joint where bones are connected by dense connective tissue; no movement occurs.

Cartilaginous Joint

A joint where bones are joined by cartilage; allows for limited movement.

Synovial Joint

A joint characterized by a fluid-filled joint cavity that allows for free movement.

Fracture

A break in a bone caused by stress or injury.

Articulation

The area where two or more bones meet to form a joint.

Meniscus

Crescent-shaped cartilage in the knee that absorbs shock and stabilizes the joint.

Ligament Sprain

An injury to a ligament caused by overstretching or tearing.

Tendonitis

Inflammation of a tendon, often caused by repetitive strain or injury.

Epicondyle

A bony projection on a bone where tendons or ligaments attach, commonly found around joints.

Sutures

Immovable joints where the bones of the skull are fused together.

Osteoporosis

A condition characterized by weakened bones and an increased risk of fractures.

Arthritis

Inflammation of the joints, leading to pain and stiffness.

Rheumatoid Arthritis

An autoimmune disorder that causes chronic inflammation of the joints.

Synovitis

Inflammation of the synovial membrane, often leading to joint pain and swelling.

Bone Density

A measure of the amount of minerals (mostly calcium) contained in a certain volume of bone.

Chondrocytes

Cells that produce and maintain the cartilaginous matrix.

Stress Fracture

A small crack in a bone that occurs due to repetitive force or overuse.

Biomechanics

The study of the mechanical laws relating to the movement or structure of living organisms.

Skeletal Muscle

Striated muscle tissue under voluntary control, primarily responsible for movement of the skeleton.

Function of Skeletal Muscle

Facilitates movement by contracting and relaxing in response to nervous stimulation.

Muscle Fiber Types

The two main types are fast-twitch (Type II) fibers for quick bursts of activity and slow-twitch (Type I) fibers for endurance.

Muscle Contraction Mechanism

Involves the sliding filament theory where myosin heads attach to actin filaments and pull them, shortening the muscle.

Sarcoplasmic Reticulum

A specialized endoplasmic reticulum in muscle cells that stores and releases calcium ions during contraction.

Motor Unit

Consists of a motor neuron and the skeletal muscle fibers it innervates, functioning together for muscle contraction.

Neuromuscular Junction

The synapse or connection between a motor neuron and a skeletal muscle fiber, where nerve impulses trigger muscle contraction.

Muscle Tone

The continuous and passive partial contraction of skeletal muscles, contributing to posture and readiness for action.

Tendons in Skeletal Muscle

Connective tissues that attach skeletal muscles to bones, facilitating movement.

Hypertrophy

The increase in muscle fiber size due to resistance training, leading to stronger and larger muscles.

Muscle Endurance

The ability of a muscle to sustain repeated contractions against a resistance for an extended period.

Anaerobic Exercise

High-intensity exercise that lasts for short durations, relying on energy sources stored in the muscles without using oxygen.

Aerobic Exercise

Physical activity that uses oxygen to fuel the body, typically of lower intensity and longer duration, such as running or cycling.

Isometric Contraction

A type of muscle contraction where the muscle exerts force without changing length, often used in strength training.

Isotonic Contraction

A type of muscle contraction where the muscle changes length while contracting, either shortening (concentric) or lengthening (eccentric).

Core Muscles

A group of muscles located in the center of the body that provide stability and support for the spine and pelvis.

Dynamic Stretching

An active form of stretching that involves moving parts of your body through a full range of motion to increase blood flow and flexibility.

Static Stretching

A form of stretching where you hold a position to lengthen and relax a muscle, typically used after workouts.

Resistance Training

A form of exercise that improves muscular strength and endurance by exercising a muscle against an external resistance.

Flexibility

The range of motion in a joint or series of joints, and is an important component of physical fitness.