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Acetabulum: The large cup-like socket that holds the head of the femur.

Acromion: A bony extension from the scapula that forms the highest superior point or “tip” of the shoulder.

Anterior fontanelle: The largest fontanelle, located on the top of the head at the junction of the frontal and parietal bones.

Appendicular skeleton: All bones of the upper and lower limbs, plus the bones that attach each limb to the axial skeleton.

Appositional growth: The is the process by which bones grow in width or diameter.

Articular cartilage: A thin layer of hyaline cartilage that reduces friction in joints and acts as a shock absorber.

Arthritis: A general term related to inflammation of a joint.

Amphiarthrosis: A joint that has limited mobility.

Anterior cruciate ligament: A key ligament within the knee joint that connects the thigh bone (femur) to the shin bone (tibia).

Articular discs: Small, oval-shaped fibrocartilage structure located between the bones.

Atlas (C1): The first cervical vertebrae which supports the skull on top of the vertebral column.

Axial skeleton: Serves to protect the brain, spinal cord, heart, and lungs and also serves as the attachment site for muscles that move the head, neck, and back.

Axis: The second cervical vertebrae which serves as the axis for rotation when turning the head toward the right or left.

Ball and socket: Synovial joint formed between the spherical end (ball) of one bone that fits into a cuplike depression (socket) of a second bone.

Body: The middle portion of the sternum

Bone density: The total amount of bone tissue a person has.

Bone remodeling: The resorption of old or damaged bone while osteoblasts lay new bone to replace it.

Bursa: A thin connective tissue sac filled with fluid.

Bursitis: The inflammation of a bursa near a joint.

Canaliculi: These are tiny, hair-like canals that connect the lacunae (spaces housing osteocytes) to the central canal in compact bone.

Cancellous bone: A light, porous type of bone tissue found primarily at the ends of long bones and within the vertebrae, also known as spongy bone.

Cartilage: A strong, flexible connective tissue that protects your joints and bones.

Cartilaginous joint: Bones are joined by cartilage.

Carpals: Eight bones making up the wrist.

Central canal: Located at the center of each osteon in compact bone, this channel houses blood vessels, nerves, and lymphatic vessels.

Chondroblasts: Cartilage-forming cells.

Coccyx: Commonly referred to as the tailbone, area formed by the fusion of four very small coccygeal vertebrae.

Comminuted fracture: Several breaks result in many small pieces between two large segments.

Compact bone: The dense, strong type of bone tissue that provides structural support and protection.

Condyloid: Synovial joint formed by the shallow depression at the end of one bone receiving a rounded end from an adjacent bone or bones

Clavicle: The bone connecting the sternum to the scapula, also known as the collarbone

Closed fracture: A fracture that does not break the skin.

Coronal suture: Suture which runs from side to side across the top of the skull and joins the frontal bone to the parietal bones.

Dens: A bony projection that extends upward from the vertebral body, also known as the odontoid process.

Diaphysis: The shaft that runs between the proximal and distal ends of the bone.

Diarthrosis: A freely mobile joint.

Dislocation: An injury that forces the bones in a joint out of position.

Endochondral Ossification: This is the process of bone development in which hyaline cartilage is gradually replaced by bone tissue.

Endosteum: A delicate, membranous lining of the medullary cavity, where bone growth, repair, and remodeling occur.

Epiphysis: The wider end of the bone and is made of spongy or cancellous bone tissue.

Epiphyseal line: The remnant of the epiphyseal plate (growth plate) found in adult bones.

Ethmoid Bone: A single, irregularly shaped bone forming part of the nose, medial side of the eye orbits, and base of the skull.

Ethmoid air cells: Small spaces separated by very thin bony walls located in the ethmoid bone.

External Auditory Canal (or External Auditory Meatus): Paired openings (left and right) in the temporal bones, the “ear canal”.

Facets: Areas on the transverse processes of the thoracic vertebrae where the ribs attach.

False ribs: Ribs 8, 9, and 10 are attached to the costal cartilage of the seventh rib.

Femoral head: The rounded, proximal end is the head of the femur.

Femoral neck: The narrowed region below the head of the femur.

Flat bones: Typically thin and often curved bones.

Floating ribs: Ribs 11 and 12 are not attached to the sternum at all.

Fontanelles: Soft spots on a baby’s skull.

Fracture: A broken bone.

Fracture hematoma: This is the mass of clotted blood that forms at the site of a bone fracture.

Fibrous joint: Bones held together by fibrous connective tissue.

Foramen Magnum: A large hole in the base of the occipital bone.

Functional classification: The degree of movement between the bones.

Frontal Bone: A single bone superior to the eyes.

Frontal sinus: Sinus located just above the eyebrows in the frontal bone.

Fuse: To grow together.

Gomphosis: A narrow fibrous joint between the roots of a tooth and the bony socket.

Gout: A form of arthritis caused when uric acid crystals are deposited in a body joint.

Greater trochanter: The large, upward, bony projection on the femur.

Greenstick fracture: A partial fracture common in children.

Hallux: The great toe.

Hemopoiesis: The production of blood cells.

Herniated disc: A condition in which an intervertebral disc protrudes.

Hinge: Synovial joint formed by the convex surface of one bone meeting the concave surface of another.

Holes: An opening or groove in the bone.

Humerus: The upper arm bone.

Hyoid bone: An independent bone not connected to any other bone.

Iliac crest: Superior margin of the ilium.

Ilium: The superior region forming the largest part of the hip bone.

Inferior articular process: Pair of downward-facing processes on vertebrae.

Inferior nasal conchae (Turbinates): Bones forming the lower lateral walls of the nasal cavity.

Impacted fracture: One fragment is driven into the other.

Interstitial growth: Refers to longitudinal bone growth.

Intervertebral discs: The soft, cushion-like pads between the vertebrae.

Intervertebral foramen: The gap between two vertebrae where spinal nerves exit.

Intramembranous Ossification: Bone formation from mesenchymal tissue.

Irregular bones: Bones with complex shapes.

Ischium: The inferior region of each hip bone.

Joint cavity: A fluid-filled space.

Joints: Where two bones or other skeletal elements meet.

Kyphosis: Excessive posterior curvature of the upper thoracic spine.

Lacunae: Spaces that hold the osteocytes.

Lacrimal bones: Bones forming the walls of the medial orbit.

Lambdoid suture: Suture joining the occipital bone to parietal and temporal bones.

Lateral collateral ligament (LCL): Ligament on the outside of the knee.

Lamellae: Circular/concentric rings of calcified matrix.

Lateral condyle: Smooth surface forming part of the distal femur.

Lateral epicondyle: Rough area on the outer side of the lateral condyle.

Lateral malleolus: Distal end of the fibula.

Lesser trochanter: A small bony prominence on the femur.

Ligaments: Strong connective tissue bands that connect bones.

Long bones: Cylindrical bones longer than they are wide.

Lordosis: An excessive anterior curvature of the lumbar region.

Mandible: Bone forming the lower jawbone.

Manubrium: The upper portion of the sternum.

Mastoid Process(es): Protrusions on the temporal bone.

Maxillae: Pair of bones forming the upper jaw and hard palate.

Maxillary sinus: The largest sinus, located in the maxillary bones.

Medial collateral ligament: Ligament on the inner side of the knee.

Medial condyle: Smooth, articulating surface of the medial distal femur.

Medial epicondyle: Roughened area of the medial distal femur.

Medial malleolus: The distal end of the tibia.

Medullary cavity: Hollow region in the diaphysis.

Meniscus: C-shaped fibrocartilage in the knee.

Metacarpals: Five bones making up the palm of the hand.

Metatarsals: Five bones in the front part of the foot.

Metaphysis: The region where the epiphysis meets the diaphysis.

Modeling: The process in which old bone is eroded from the inner surface (along the medullary cavity) while new bone is deposited beneath the periosteum.

Nasal bones: Pair of fused bones on the right and left side of the face that form the bridge of the nose.

Oblique fracture: Fracture that occurs at an angle that is not 90 degrees.

Occipital Bone: A single bone forming the posterior side and base of the skull.

Open or compound fracture: A fracture in which at least one end of the broken bone tears through the skin; carries a high risk of infection.

Orthopedists: Medical doctors who complete specialized training in the prevention, diagnosis, treatment, and surgery of disorders and diseases related to the musculoskeletal system.

Ossification: Process of actual bone development.

Osteoid: An uncalcified bone matrix.

Osteoarthritis: Most common type of arthritis is osteoarthritis, which is associated with aging and “wear and tear” of the articular cartilage.

Osteoblasts: These are bone-forming cells found mainly in the periosteum and endosteum.

Osteoclasts: These are large, bone-breaking cells responsible for the breakdown and resorption of bone tissue.

Osteocytes: A mature bone cell responsible for maintaining bone tissue.

Osteogenic cells: These are bone stem cells with the unique ability to divide through mitosis. Found in the deep layers of the periosteum and within the bone marrow, they serve as the origin for other bone cells by developing into osteoblasts, which are responsible for forming new bone tissue.

Osteomalacia: Softening of the bones due to a lack of mineralization with calcium and phosphate, most often caused by a lack of vitamin D.

Osteomyelitis: Infection in a bone.

Osteon: Basic structural unit of compact bone.

Osteonecrosis: The death of bone tissue due to a lack of blood supply.

Osteopenia: Loss of bone mass that may lead to osteoporosis.

Osteoporosis: A disease characterized by a decrease in bone mass, a common occurrence as the body ages.

Osteosarcoma: A cancer that begins in the cells that form bones.

Pagat’s disease: A chronic condition where the body’s natural process of bone remodeling is disrupted, leading to bones becoming larger, weaker, and more brittle than normal.

Palatine bones: Pair of fused L-shaped bones on the right and left side of the face that form part of the hard palate, walls of the nasal cavity, and the orbital floor of the eye.

Paranasal sinuses: Hollow, air-filled spaces located within certain bones of the skull.

Parietal Bones: A pair of bones (left and right) on the upper sides of the skull, above the ears.

Patella: A small, sesamoid bone located in the anterior knee, commonly referred to as the kneecap.

Patellar surface: A smooth groove located on the anterior side of the distal femur, between the medial and lateral condyles that is the site of articulation for the patella.

Patellofemoral pain syndrome (PFPS): Also known as runner’s knee or anterior knee pain, is a condition characterized by pain around the kneecap (patella) and front of the knee.

Pectoral girdle: Area which serves to attach the upper limb to the sternum of the axial skeleton, consisting of the clavicle and the scapula.

Pelvis: The entire structure formed by the hip bones, the sacrum, and the coccyx.

Perichondrium: A membrane that surrounds the cartilage model.

Periosteum: The fibrous membrane layer covering the outer surface of the bone.

Perforating Canal: These are channels that run perpendicular to the central canals (Haversian canals) in compact bone. They allow blood vessels, nerves, and lymphatic vessels to extend from the central canals to the periosteum and endosteum, ensuring the bone tissue receives adequate nutrients and communication. Also known as the Volmann’s canal.

Phalanges: The 14 bones that make up the fingers (and toes).

Phalanx: Single finger bone.

Pivot: Synovial joint where the rounded portion of a bone rotates within a ring formed by a ligament and a bone.

Posterior cruciate ligament (PCL): One of the four major ligaments in the knee joint, located at the back of the knee.

Posterior fontanelle: A smaller fontanelle and is located on the posterior side of the skull between the parietal and occipital bones.

Primary ossification center: This is the region in a developing long bone where bone formation begins during endochondral ossification.

Proliferative zone: This is the second layer of the epiphyseal plate, located just below the zone of reserve cartilage. It contains stacks of slightly larger chondrocytes that actively divide through mitosis.

Projection: An area of a bone that projects above the surface of the bone.

Pterion: A small, capital-H-shaped region that unites the frontal bone, parietal bone, temporal bone, and sphenoid bone.

Pubis (or pubic bone): The pubis forms the anterior (front) portion of the hip.

Pubic symphysis: A cartilaginous joint in the pelvis that connects the two pubic bones.

Radius: The bone on the lateral or thumb side of the forearm.

Radiologic Technologist (X-ray Technician): Medical personnel who perform diagnostic imaging examinations and administer radiation therapy treatments.

Radiologist: A medical doctor that specializes in diagnosing and treating injuries and diseases using medical imaging and procedures, such as x-rays, computed tomography (CT scans), magnetic resonance imaging (MRI), nuclear medicine, positron emission tomography (PET scan), and ultrasound.

Radiology: A branch of medicine that uses imaging technology to diagnose and treat disease.

Red bone marrow: A type of bone marrow that produces blood cells.

Reserve zone: The region closest to the epiphyseal end of the plate and contains small chondrocytes (cartilage cells) within the matrix.

Rheumatoid arthritis: An autoimmune disease where the immune system attacks the joints.

Rickets: Osteomalacia in children.

Sacrum: A triangular-shaped bone that is thick and wide across the top where it is weight bearing and then tapers down to the inferior, non-weight bearing apex.

Saddle: Synovial joint in which the ends of the bones have a saddle shape, which is concave in one direction and convex in the other.

Sagittal suture: A suture which extends posteriorly from the coronal suture, along the midline at the top of the skull uniting the right and left parietal bones.

Scapula: The bone commonly known as the shoulder blade.

Sciatica: A painful condition resulting from inflammation or compression of the sciatic nerve causing widespread pain that radiates from the lower back down the thigh and into the leg.

Scoliosis: An abnormal lateral curvature of the spine accompanied by twisting of the vertebral column.

Secondary ossification centers: This is the area in a developing long bone where bone formation begins after the primary ossification center. It typically appears in the epiphyses (ends) of the bone, where cartilage remains in the form of articular cartilage and the epiphyseal plate (growth plate).

Sella Turcica: A bony landmark in the sphenoid bone, also known as “Turkish saddle” due to its resemblance to a horse’s saddle.

Sesamoid bone: A small, round bone shaped like a sesame seed. These bones develop within tendons and serve to protect the tendon and increase its mechanical efficiency.

Short bones: Cube-like in shape, with nearly equal length, width, and thickness. In the human body, the only short bones are found in the wrists (carpals) and ankles (tarsals). These bones are designed to provide stability and support while allowing for limited motion.

Sphenoid sinus: Single sinus located within the body of the sphenoid bone near the sella turcica.

Spinal column: A flexible column of bones that support the head, neck, and body and protects the spinal cord, also known as the vertebral column.

Spiral fracture: Fracture in which bone segments are pulled apart as a result of a twisting motion.

Spinous process: A single process that projects posteriorly at the midline. These processes can easily be felt as a series of bumps just under the skin down the middle of the back.

Spondylosis: A painful condition of the spine caused by the breakdown of the intervertebral discs (cartilage found between the vertebrae).

Spongy bone: Also known as trabecular or cancellous bone, this type of bone tissue is less dense than compact bone and has a porous, honeycomb-like structure. It is typically found in the interior of bones, such as the ends of long bones and in the vertebrae, where it helps reduce the weight of the bone while providing support and housing bone marrow.

Sprain: The stretching or tearing of ligaments in a joint.

Squamous suture: Suture located on each side of the skull. It unites the temporal bone with the parietal bone.

Sternum: A flat T-shaped bone located in the center of the chest, commonly called the breastbone.

Structural classification: Classification which considers how the bones are connected together.

Styloid Process(es): A long, slender protrusion off of the temporal bone below the ear on the left and right side of the skull.

Subluxation: A partial dislocation of a bone.

Superior articular process: Pair of processes that extend or face upward.

Suture: A fixed (immobile) joint between bones of the skull.

Syndesmosis: A joint held together by a ligament, a type of connective tissue that connects bones together.

Synarthrosis: An immobile or nearly immobile joint.

Synovial fluid: Lubricating fluid within the joint cavity.

Synovial joint: The bones are not directly connected, but instead come together within a joint cavity filled with a lubricating fluid called synovial fluid.

Synovial membrane: Secretes synovial fluid.

Tarsals: A group of seven bones in the posterior half of the foot.

Temporal Bones: Two bones (left and right) on the lower sides of the skull, surrounding the ears.

Temporomandibular joint (TMJ): A hingelike joint between the temporal bone and the mandible that allows for the opening, closing, protrusion, retraction, and lateral movement of the lower jaw.

Tendons: A fibrous connective tissue that attaches muscle to bone.

Transverse foramen: The opening within the transverse process.

Transverse fracture: Fracture that occurs straight across the long axis of the bone.

Transverse process: A pair of processes projecting laterally on each side serving as important muscle attachment sites.

True ribs: Ribs 1–7 are attached directly to the anterior sternum by costal (rib) cartilage.

Ulna: The bone on the medial or pinky finger side of the forearm.

Vertebra: One of the individual bones that make up the vertebral column (or spine) in vertebrate animals, including humans.

Vertebral arch: The part of a vertebra that forms the back portion of the vertebral foramen, which is the opening through which the spinal cord passes.

Vertebrae: Bones in the head, neck, and body that protect the spinal cord.

Vertebral column: A flexible column of bones that support the head, neck, and body and protects the spinal cord, also known as the spinal column.

Vertebral (spinal) canal: The tunnel-like passage that runs through the vertebral column and houses the spinal cord and its protective coverings (meninges), along with blood vessels and spinal nerves.

Vomer: Thin bone that forms the nasal septum which separates the left and right nostrils.

Xiphoid process: The lower portion of the sternum made of cartilage early in life but which gradually ossifies starting in middle age.

Yellow bone marrow: A type of bone marrow which contains adipose tissue and stores triglycerides that can be used for energy.

Zone of calcified matrix: This layer of the epiphyseal plate contains chondrocytes that are dying or already dead, as the surrounding matrix becomes calcified. Calcium salts are deposited in the matrix, hardening it and preparing it for the arrival of bone-forming cells. This zone acts as the transition between cartilage and new bone tissue.

Zone of maturation and hypertrophy: This layer of the epiphyseal plate contains older chondrocytes that have stopped dividing and begin to enlarge (hypertrophy). The lacunae surrounding them also expand, creating spaces that will later become part of the bone’s structure. This zone contributes to the lengthening of the bone as the cells grow in size.

Zygomatic bones: Pair of bones on the right and left side of the anterior face, the “cheekbones.”

Zygomatic Process(es): A long, slender protrusion off of the temporal bone that forms part of the cheek.