Term | Definition |
Ossification | The formation of bone from fibrous tissue. |
Osteoblasts | Immature bone cells that produce bony tissue. |
Osteoclasts | Phagocytic cells that eat away bony tissue from the medullary cavity of long bone. |
Osteocytes | Mature osteoblasts. |
Hematopoietic | Red bone marrow is this, meaning that it forms RBC's, WBC's, and clotting cells. |
Medullary cavity | Inner space of bone, containing yellow marrow. |
Cartilage | Connective tissue that is more elastic than bone. |
Articular cartilage | Covers the joint surfaces of bone. |
Meniscus | A curved fibrous cartilage found in some joints that cushions forces applied to that joint. |
Articulations | Joints. Connections between bones. |
Synarthroses | Immovable joints. |
Amphiarthroses | Semimovable joints. |
Diarthroses | Freely movable joints. |
Suture | A type of synarthrosis. A jagged line where bones join and form a nonmovable joint. (In the skull.) |
Fontanelle | Soft spot remaining at the junction of sutures that usually closes after birth. |
Symphysis | A type of amphiarthrosis. A joint where two bones join and are held firmly together so that they function as one bone. AKA cartilagious joint. |
Synovial joints | Classified as ball-and-socket joints (enarthrosis or spherioid joints), condyloid joints, trochoid or pivot joints, ginglymus or hinge joints, and gliding joints. |
Cortical bone | Hard, dense, strong bone that forms the outer layer of bone. AKA compact bone. |
Cancellous bone | Lighter, less strong bone that is found in the ends and inner portions of long bones. AKA spongy bone. |
Epiphysis | Wide end of a long bone, composed of cancellous bone and covered with articular cartilage. |
Diaphysis | Shaft of a long bone, composed mainly of compact bone. |
Physis | Cartilage segment of lone bone that involves growth of the bone. AKA growth plate or epiphyseal cartilage. |
Metaphysis | Wider part of long bone shaft located adjacent to the physis. Considered part of epiphysis in adults. |
Periosteum | Tough, fibrous tissue that forms the outer covering of bone. |
Endosteum | Tough, fibrous tissue that forms the lining of the medullary cavity. |
Long bones | Bones consisting of a shaft, two ends, and a marrow cavity. |
Short bones | Cube shaped bones with no marrow cavity. |
Flat bones | Thin, flat bones. |
Pneumatic bones | Sinus-containing bones. |
Irregular bones | Unpaired bones. |
Sesamoid bones | Small bones embedded in a tendon. |
Ball-and-socket joints | Allow a wide range of motion in many directions. |
Arthrodial or condyloid joints | Joints with oval projections that fit into a socket. |
Trochoid joints | Pulley-shaped joints. |
Hinge joints | Allow motion in one plane or direction. |
Gliding joints | Joints that move or glide over each other. |
Saddle joint | Allows primates to flex, extend, abduct, adduct, and circumduct the thumb. |
Ligament | A band of fibrous connective tissue that connects one bone to another to help stabilize joints. |
Tendon | A band of fibrous connective tissue that connects muscle to bone to help the animal move. |
Bursa | A fibrous sac that acts as a cushion to ease movement in areas of friction. |
Synovial membrane | Inner lining of bursae and synovial joints which secretes synovial fluid as a lubricant to make joint movement smooth. |
Axial skeleton | The framework of the body. Includes skull, auditory ossicles, hyoid bones, vertebral column, ribs, and sternum. |
Appendicular skeleton | The framework of the body that consists of the extremeties, shoulder, and pelvic girdles. (Appendages.) |
Cranium | The portion of the skull that encloses the brain. |
Frontal | Forms the roof of the cranial cavity, or "front" or cranial portion of the skull. |
Parietal | Paired bones that form the roof of the caudal cranial cavity. |
Occipital | Forms the caudal aspect of the cranial cavity where the foramen magnum (opening of the spinal cord) is located. |
Temporal | Paired bones that form the sides and base of the cranium. |
Sphenoid | Paired bones that form part of the base of the skull and parts of the floor and sides of the bony eye socket. |
Ethmoid | Forms the rostral part of the cranial cavity. |
Incisive | Forms the rostral part of the hard palate and lower edges of nares. |
Pterygoid | Forms the lateral wall of the nasopharynx. |
Sinuses | Air or fluid filled spaces in the skull. |
Zygomatic | The orbit and cheekbone. |
Maxilla | Upper jaw. |
Mandible | Lower jaw. |
Palatine | Part of the hard palate. |
Lacrimal | Medial part of the orbit. |
Incisive | Rostral part of the hard palate and lower edge of nares. |
Nasal | Bridge of the nose. |
Vomer | Base of the nasal septum (cartilanogous structure that divides the two nasal cavities). |
Hyoid | Bone suspended between the mandible and the laryngopharynx. |
Cervical region (vertebral) | Neck area. "C" |
Thoracic region (vertebral) | Chest area. "T" |
Lumbar region (vertebral) | Loin area. "L" |
Sacral region (vertebral) | Sacrum area. "S" |
Coccygeal/caudal region (vertebral) | Tail area. "Cy" or "Cd" |
Vertebral foramen | Opening in the middle of the vertebra where the spinal cord passes through. |
Intervertebral discs | Cartilage discs that separate and cushion vertebrae. |
Body of vertebra | Solid portion ventral to the spinal cord. |
Arch of vertebra | Dorsal part that surrounds the spinal cord. |
Lamina of vertebra | Left or right dorsal half of the arch. |
Spinous process | A single projection from the dorsal part of the vertebral arch. |
Articular processes | Paired cranial and caudal projections on the dorsum of the vertebral arch. |
Atlas | "C1" Cervical vertebra one. |
Axis | "C2" Cervical vertebra two. |
Costals | Ribs. Paired bones that attach to thoracic vertebrae. |
Sternum | Breastbone. Forms the midline ventral portion of the rib cage. Divided into 3 parts- manubrium, body, and xyphoid process. |
Manubrium | The cranial portion of the sternum. |
Body (sternum) | The middle portion of the sternum. |
Xyphoid process | The caudal portion of the sternum. |
Thoracic cavity | Rib cage. |
Scapula | Shoulder blade. |
Clavicle | Collar bone. |
Humerus | The long bone of the proximal front limb. Sometimes called brachium. |
Antebrachium | Region of the forearm of the radius and ulna. |
Radius | Cranial bone of the front limb. |
Ulna | Caudal bone of the front limb. |
Olecranon | Proximal projection of the ulna that forms the point of the elbow. |
Carpal bones | Irregularly shaped bones, the wrist in humans. In small animals it's the carpus. In large, it's the knee. |
Metacarpals | Bones found distal to the carpus. |
Splint bones | Metacarpals and metatarsals II and IV (in horses) which do not articulate with the phalanges. |
Cannon bone | The large third metacarpal or metatarsal bone, which is attached to the splint bones by an interosseous ligament. |
Phalanges | Bones of the digits. One is a phalanx. |
Digits | (Like fingers) |
Dewclaw | Digit I of dogs. In cloven-hoofed animals it's called a vestigial digit. |
Claw | Phalanx 3 (P3) in non-hooved animals. |
Sesamoid bones | Small nodular bones embedded in a tendon or joint capsule. |
Pelvis | Hip. Consists of three pairs of bones- ilium, ischium, and pubis. |
Ilium | Largest pair of bones in the pelvis, blade-shaped. |
Ischium | Caudal pair of bones in the pelvis. |
Pubis | Ventral pair of bones that are fused on midline by a cartilaginous joint called the pubis symphysis. |
Acetabulum | Large socket of the pelvic bone, where the three bones meet. Forms the ball-and-socket joint with the femur. |
Femur | Thigh bone. |
Patella | Large sesamoid bone in the rear limb. The kneecap in people. |
Stifle joint | Joint that houses the patella. Knee in humans. |
Tibia | Larger and more weight-bearing bone of the two distal long bones in the rear limb. |
Fibula | Long, slender bone (smaller of the two) in the rear limb. |
Tarsus/Hock | Irregularly shaped bones in the ankle area of people. Tarsus-small animals. Hock-large animals. |