Musculoskeletal system

The system of muscles, tendons, ligaments, bones, joints and associated tissues that move the body and maintain its form.

Muscular system

Humans are vertebrates, with a vertebral column also called backbone. The human skeletal system consists of bones, cartilage, ligaments and tendons and accounts for about 20 percent of the body weight.

Bony framework

• Bones provide a rigid framework, known as the skeleton, that support and protect the soft organs of the body.
• The skeleton supports the body against the pull of gravity.
• The large bones of the lower limbs support the trunk when standing.
• The skeleton also protects the soft body parts.
• The fused bones of the cranium surround the brain to make it less vulnerable to injury.
• Vertebrae surround and protect the spinal cord and bones of the rib cage help protect the heart and lungs of the thorax.
• Bones work together with muscles as simple mechanical lever systems to produce body movement.

Muscles

The muscular system is composed of specialized cells called muscle fibers. Their predominant function is contractibility. Muscles, attached to bones or internal organs and blood vessels, are responsible for movement. Nearly all movement in the body is the result of muscle contraction. Exceptions to this are the action of cilia, the flagellum on sperm cells, and amoeboid movement of some white blood cells.

Integrated movement

The integrated action of joints, bones, and skeletal muscles produces obvious movements such as walking and running. Skeletal muscles also produce more subtle movements that result in various facial expressions, eye movements, and respiration.

Muscular system

Other functions of muscles

• In addition to movement, muscle contraction also fulfills some other important functions in the body, such as posture, joint stability, and heat production.
• Posture, such as sitting and standing, is maintained as a result of muscle contraction.
• The skeletal muscles are continually making fine adjustments that hold the body in stationary positions.
• The tendons of many muscles extend over joints and in this way contribute to joint stability.
• This is particularly evident in the knee and shoulder joints, where muscle tendons are a major factor in stabilizing the joint. Heat production, to maintain body temperature, is an important by-product of muscle metabolism.

Human skeleton

Heat production

• Nearly 85 percent of the heat produced in the body is the result of muscle contraction.

Glossary

• Ambe - A term used in specific cultural or medical contexts, referring to certain muscle or musculoskeletal conditions.
• Anococcygeal body - A fibromuscular structure located between the anus and the coccyx, providing support to the pelvic floor.
• Anserine bursa - A small sac filled with synovial fluid located near the knee joint, reducing friction between the tendons and bones.
• Bicipitoradial bursa - A bursa located between the biceps tendon and the radius, facilitating smooth movement of the biceps tendon over the radius.
• Bone marrow adipose tissue - Fat tissue located within the bone marrow, playing roles in energy storage and regulation of bone metabolism.
• Cranial kinesis - Movement between the bones of the skull, found in some animals and affecting feeding, breathing, and sensory perception.
• Dacryon - The point at the junction of the frontal, lacrimal, and maxillary bones of the skull.
• Davis's law - A principle stating that soft tissue models along the lines of stress, important in the context of rehabilitation and physical therapy.
• Distal humeral fracture - A break in the lower end of the humerus, near the elbow, often requiring medical intervention for proper healing.
• Eminence (anatomy) - A projection or elevated area on a bone or soft tissue, often serving as a point of attachment for tendons or muscles.
• Endosteum - A thin layer of connective tissue lining the inner surface of bones, playing a role in bone growth and repair.
• Enostosis - A benign growth of bone tissue within the bone, often detected incidentally through imaging.
• Enthesis - The site of attachment of a tendon, ligament, joint capsule, or fascia to bone.
• External intercostal membrane - A fibrous structure that replaces the external intercostal muscles anteriorly near the sternum, contributing to the thoracic cage's mechanical properties.
• Flexor retinaculum of the hand - A fibrous band on the palmar side of the hand that holds the tendons of the long flexor muscles in place.
• Fracture of biological materials - The breaking or cracking of bones or other biological materials under stress.
• Fryette's laws - Principles that describe the movements of the spine and how spinal segments move in relation to each other.
• Human musculoskeletal system - The organ system that includes bones, muscles, tendons, ligaments, and other connective tissues, providing structure and facilitating movement.
• Iliopectineal bursa - A bursa located near the hip joint, reducing friction between the iliopsoas muscle and the pelvis.
• Intramuscular fat - Fat located within skeletal muscle, affecting muscle function and metabolism.
• Lacuna (histology) - A small space, cavity, or depression, often housing cells such as chondrocytes in cartilage or osteocytes in bone.
• Locomotive syndrome - A condition characterized by reduced mobility due to impairment of the musculoskeletal system.
• Muscle contraction - The process by which muscle fibers produce force and shorten, facilitating movement and support.
• Muscular evolution in humans - The evolutionary process that has led to the development of the unique muscular structure in humans, enabling bipedalism and dexterity.
• Musculoskeletal physiology - The study of how the musculoskeletal system functions, including muscle contraction, bone metabolism, and joint mechanics.
• Myogenic tone - The intrinsic contractility of smooth muscle, contributing to the regulation of blood flow and pressure.
• Palatovaginal canal - A passage in the skull connecting the nasopharynx to the middle nasal concha, involved in drainage and ventilation of the nasal cavities.
• Preflexes - Automatic movement responses that are not mediated by the brain, providing rapid reactions to external stimuli.
• Prolotherapy - A treatment for chronic musculoskeletal pain involving the injection of an irritant solution into the soft tissue of an injured joint to stimulate healing.
• Sharpey's fibres - Thick collagen fibers that anchor the periosteum to the bone, providing structural support and playing a role in the attachment of tendons and ligaments.
• Synovial bursa - A small fluid-filled sac located near joints, reducing friction between bones and soft tissues such as skin, muscles, or tendons.
• Tendon sheath - A protective layer of synovial membrane around a tendon, facilitating smooth movement.
• Umbilical fascia - Connective tissue in the abdominal region that covers the umbilicus (navel) and surrounding area, providing support.
• Wolff's law - A principle stating that bone in a healthy person or animal will adapt to the loads under which it is placed, leading to changes in bone density and structure.

See also

• Tendons
• Bursae
• Bones
• Ligaments
• Joints
• Skeletal muscle
• Muscular system

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