Musculoskeletal System Structure, Function, and Diagnostics

Vocabulary terms and definitions covering the structure, function, bone types, skeletal divisions, joints, and diagnostic procedures of the musculoskeletal system.

Musculoskeletal system

The body system that forms the framework holding the body together, enables movement, and protects and supports internal organs; includes bones, joints, and muscles.

Osseous tissue

The dense network of connective tissue that makes up bones.

Osteocytes

Bone cells surrounded by calcium salts that are part of a dense network of connective tissue.

Cartilage

Softer, flexible connective tissue that composes bones during fetal development before ossification occurs.

Osteoblasts

Bone-forming cells that add new mineral matter to repair breaks and build bone tissue.

Osteoclasts

Cells that reabsorb bone tissue and remove bone debris during break repair.

Ossification

The hardening process and development of osteocytes, which is largely dependent on calcium, phosphorus, and vitamin D.

Skeleton

The body framework made up of bones and joints, consisting of 206 bones in a mature adult.

Long bones

Bones that form the extremities of the body, such as the arms and legs.

Compact bone

The dense, solid outer portion of bone that does not bend easily.

Diaphysis

The shaft, or longest portion, of a long bone.

Epiphysis

Each end of the shaft of a long bone (proximal and distal) shaped to connect to other bones via ligaments and muscle.

Epiphyseal plate

Cartilaginous tissue between the diaphysis and epiphyses that allows growth and calcifies when growth stops.

Short bones

Small, cube-shaped bones of the wrists, ankles, and toes.

Flat bones

Bones with large, somewhat flat surfaces that cover organs or provide attachment area for large muscles (e.g., shoulder blades, pelvis, skull).

Irregular bones

Specialized bones with specific shapes, including bones of the ears, vertebrae, and face.

Sesamoid bones

Bones formed in a tendon near joints, such as the patella (kneecap), hands, and feet.

Marrow

Soft connective tissue inside bones; functions in blood cell production as red marrow in infants/children and is replaced by fat-filled yellow marrow as people age.

Sutures

Points where skull or cranial bones join.

Fontanelles

Soft spots on a newborn's skull where cranial bones are not yet completely joined.

Frontal bone

The cranial bone forming the forehead and roof of the eye sockets.

Ethmoid bone

The cranial bone forming the nasal cavity and orbits of the eyes.

Parietal bone

The cranial bone forming the top and upper parts of the sides of the skull.

Temporal bone

The cranial bone forming the lower part and lower sides of the skull, including ear openings.

Occipital bone

The cranial bone covering the back and base of the skull.

Foramen magnum

An opening in the occipital bone through which the spinal cord passes.

Nasal bones

Facial bones that form the bridge of the nose.

Lacrimal bones

Facial bones that hold the lacrimal gland and canals for the tear ducts.

Mandible

The lower jawbone; contains sockets for lower teeth and is the only movable bone in the face.

Maxillary bones

Facial bones forming the upper jawbone and containing sockets for upper teeth.

Vertebrae

Bone segments that form the spinal or vertebral column.

Disk

A thick cartilage segment separating vertebrae that cushions them and aids in spinal flexibility and movement.

Cervical vertebrae

The seven vertebrae located in the neck.

Thoracic vertebrae

The 12 vertebrae that connect to the ribs.

Lumbar vertebrae

The five bones of the middle back.

Sacrum

Curved bone of the lower back consisting of five separate bones at birth that fuse together in early childhood.

Coccyx

The tailbone, formed from four bones fused together.

Thorax

The chest cavity.

Clavicle

The anterior collarbone.

Scapula

The posterior shoulder bone.

Sternum

The breastbone extending down the middle of the chest.

True ribs

The first seven pairs of ribs, which join both to the vertebral column and to the sternum by costal cartilage.

Pelvic girdle

A large bone forming the hips and supporting the trunk; composed of three fused bones (ilium, ischium, pubis).

Pubis

The anteroinferior portion of the hip bone.

Pelvic cavity

Space inside the pelvic girdle containing female reproductive organs, sigmoid colon, bladder, and rectum.

Pubic symphysis

The area where the two pubic bones join.

Humerus

The upper arm bone that attaches to the scapula and clavicle.

Radius

One of the two lower arm bones attaching to the wrist.

Ulna

One of the two lower arm bones attaching to the wrist.

Carpal bones

The eight bones of the wrist.

Metacarpals

The five bones of the palm that radiate out to the finger bones.

Phalanges

The finger or toe bones.

Femur

The thigh bone; the longest bone in the body.

Tibia

The shin bone; one of two bones in the lower leg.

Fibula

One of the two lower leg bones.

Patella

The kneecap.

Articulations

Points where bones connect; also called joints.

Ligaments

Bands of fibrous tissue that connect bones to other bones.

Tendons

Bands of fibrous tissue that connect muscles to bones.

Synovial joints

Joints covered with a synovial membrane secreting fluid that helps the joint move easily.

Synovial fluid

A joint lubricant secreted by a synovial membrane.

Bursa

A sac lined with a synovial membrane located between tendons and joints to decrease friction.

Orthopedists

Physicians who treat disorders of the musculoskeletal system.

Osteopaths

Physicians who combine manipulative procedures with conventional treatment.

Rheumatologists

Physicians who treat disorders of the joints specifically, and of the musculoskeletal system generally.

Podiatrists

Medical specialists who treat disorders of the foot.

Chiropractors

Health care professionals who manipulate the spine to treat certain ailments.

Arthrography

The examination of joints using radiography (x-rays).

Arthroscopy

Internal examination of a joint using a lighted instrument capable of directly viewing, cutting, irrigating, or obtaining biopsy material through a small incision.

Diskography

Examination of intervertebral disks by injecting a contrast medium into the spine and using radiography.

Myelography

The use of radiography of the spinal cord to identify spinal cord conditions.

Electromyogram

A graphic image of the electrical activity of muscles.

Bone scan

A diagnostic procedure used to detect tumors in bones.

Rheumatoid factor test

A laboratory test used to confirm rheumatoid arthritis.

Serum creatine phosphokinase (CPK)

A substance whose high blood levels appear in disorders such as skeletal injury.

Serum calcium

Measurement of calcium in the blood indicating the body's incorporation of calcium into the bones.

Serum phosphorus

Measurement of phosphorus in the blood indicating the body's incorporation of phosphorus into the bones.

Uric acid test

A laboratory test that can detect gout.

Goniometer

An instrument used to measure motion in the joints during range of motion (ROM) tests.

Densitometer

A device that uses light and x-ray images to measure bone density for osteoporosis.