Comprehensive Veterinary Skeletal System Study Guide

Structural Support and Bone Features

Bones are not structurally smooth; they frequently feature bumps, grooves, ridges, depressions, and extensions that serve specific anatomical functions. Knowing descriptive medical terms makes learning bone structures easier.

Categorization of Bone Features

• Bone Extensions: Enlargements, usually located at the ends of bones, where muscles, tendons, and other bones attach.

• Bone Depressions: Depressions in bone that allow bones to attach to each other or serve as passageways for blood vessels and nerves.

Alphabetical List of Bone Terminology

• aperture (ahp-ər-chər) = opening. (Bone Depression)

• canal (kahn-ahl) = tunnel. (Bone Depression)

• condyle (kohn-dil) = rounded projection (that articulates with another bone). (Bone Extension)

• crest (krehst) = high projection or border projection. (Bone Extension)

• crista (krihs-tah) = ridge. (Bone Extension)

• dens (dehnz) = toothlike structure. (Bone Extension)

• eminence (ehm-ih-nehns) = surface projection. (Bone Extension)

• facet (fahs-eht) = smooth area. (Bone Extension)

• fissure (fihz-uhr) = deep cleft. (Bone Depression)

• foramen (fō-rä-mehn) = hole. (Bone Depression)

• fossa (fohs-ah) = trench or hollow depressed area. (Bone Depression)

• fovea (fō-vě-ah) = small pit. (Bone Depression)

• head = major protrusion. (Bone Extension)

• lamina (lahm-ih-nah) = thin, flat plate. (Bone Extension)

• line = low projection or ridge. (Bone Extension)

• malleolus (mah-lē-ō-luhs) = rounded projection (distal end of tibia and fibula). (Bone Extension)

• meatus (mē-ā-tuhs) = passage or opening. (Bone Depression)

• process (proh-sehs) = projection. (Bone Extension)

• protuberance (prō-too-bər-ahns) = projecting part. (Bone Extension)

• ramus (rā-muhs) = branch or smaller structure given off by a larger structure. (Bone Extension)

• sinus (sīn-uhs) = space or cavity. (Bone Depression)

• spine (spīn) = sharp projection. (Bone Extension)

• sulcus (suhl-kuhs) = groove. (Bone Depression)

• suture (soo-chuhr) = seam. (Bone Extension)

• trochanter (trō-kahn-tehr) = broad, flat projection (on femur). (Bone Extension)

• trochlea (trōck-lē-ah) = pulley-shaped structure in which other structures pass or articulate. (Bone Extension)

• tubercle (too-behr-kuhl) = small, rounded surface projection. (Bone Extension)

• tuberosity (too-beh-rohs-ih-tē) = projecting part. (Bone Extension)

Specific Anatomical Examples: Humerus Surface Features

• Humerus - Cranial View Landmarks:

  • Lesser tubercle

  • Teres minor tuberosity

  • Crest of the greater

  • Greater tubercle

• Humerus - Caudal View Landmarks:

  • Greater tubercle

  • Lesser tubercle

  • Head

Diagnostic Procedures for the Skeletal System

• arthrocentesis (ahr-thrō-sehn-tē-sihs) = surgical puncture of a joint to remove fluid for analysis.

• arthrography (ahr-throhg-rah-fē) = injection of a joint with contrast material for radiographic examination.

• arthroscopy (ahr-throhs-kō-pē) = visual examination of the joint using a fiberoptic scope (called an arthroscope when used in the joint).

• densitometer (dehn-sih-tohm-eh-ər) = device that measures bone density using light and X-rays.

• goniometer (gō-nē-ohm-eh-ər) = instrument that measures angles or range of motion in a joint (goni/o means angle or seed).

• radiology (rā-dē-ohl-ō-jē) = study of internal body structures after exposure to ionizing radiation; used to detect fractures and diseases of bones.

Pathologic Conditions of the Skeletal System

• ankylosis (ahng-kih-lō-sihs) = loss of joint mobility caused by disease, injury, or surgery (ankyl/o means bent or stiff).

• arthralgia (ahr-thrahl-jē-ah) = joint pain.

• arthritis (ahr-thrī-tihs) = inflammatory condition of joints.

• arthrodynia (ahr-thrō-dihn-ē-ah) = joint pain.

• arthropathy (ahr-throhp-ah-thē) = joint disease.

• bursitis (bər-sī-tihs) = inflammation of the bursa.

• chondromalacia (kohn-drō-mah-lā-shē-ah) = abnormal cartilage softening.

• chondropathy (kohn-drohp-ah-thē) = cartilage disease.

• discospondylitis (dihs-kō-spohn-dih-lī-tihs) = inflammation of the intervertebral disc and vertebrae.

• epiphysitis (eh-pihf-ih-sī-tihs) = inflammation of the growth plate.

• exostosis (ehck-sohs-tō-sihs) = benign growth on the bone surface.

• gouty arthritis (gow-tē ahr-thrī-tihs) or gout = joint inflammation associated with the formation of uric acid crystals in the joint (seen more commonly in birds).

• hip dysplasia (dihs-plā-zhē-ah) = abnormal development of the pelvic joint causing the head of the femur and the acetabulum not to be aligned properly; most commonly seen in large breed dogs.

• intervertebral disc disease (ihn-tər-vər-tē-brahl dihk dih-zēz) = rupture or protrusion of the cushioning disc found between the vertebrae that results in pressure on the spinal cord or spinal nerve roots; also called herniated disc, ruptured disc, or IVDD.

• kyphosis (kī-fō-sihs) = dorsal curvature of the spine; also called hunchback.

• Legg-Calvé-Perthes disease (lehg cah-veh pər-thehz dih-zēz) = idiopathic necrosis of the femoral head and neck of small breed dogs; also called avascular necrosis of the femoral head and neck.

• lordosis (lōr-dō-sihs) = position in which the vertebral column is abnormally curved ventrally; seen in cats in heat; commonly called swayback.

• luxation (luhck-sā-shuhn) = dislocation or displacement of a bone from its joint.

• myeloma (mī-eh-lō-mah) = tumor composed of cells derived from hematopoietic tissues of bone marrow.

• ostealgia (ohs-tē-ahl-jē-ah) = bone pain.

• osteitis (ohs-tē-ī-tihs) = inflammation of bone.

• osteoarthritis (ohs-tē-ō-ahr-thrī-tihs) = degenerative joint disease commonly associated with aging or wear and tear on the joints; also called degenerative joint disease, or DJD.

• osteochondrosis (ohs-tē-ō-kohn-drō-sihs) = degeneration or necrosis of bone and cartilage followed by regeneration or recalcification.

• osteochondrosis dissecans (ohs-tē-ō-kohn-drō-sihs dehs-ih-kahns) = degeneration or necrosis of bone and cartilage followed by regeneration or recalcification with dissecting flap of articular cartilage and some inflammatory joint changes; detached pieces of articular cartilage are called joint mice or osteophytes (ohs-tē-ō-fītz).

• osteomalacia (ohs-tē-ō-mah-lā-shē-ah) = abnormal softening of bone.

• osteomyelitis (ohs-tē-ō-mī-eh-lī-tihs) = inflammation of bone and bone marrow.

• osteonecrosis (ohs-tē-ō-neh-krō-sihs) = death of bone tissue.

• osteoporosis (ohs-tē-ō-neh-krō-sihs) = abnormal condition of marked loss of bone density and an increase in bone porosity.

• osteosclerosis (ohs-tē-ō-skleh-rō-sihs) = abnormal hardening of bone.

• periostitis (pehr-ē-ohs-tī-tihs) = inflammation of the fibrous tissue that forms the outermost covering of bone.

• rheumatoid arthritis (roo-mah-toyd ahr-thrī-tihs) = autoimmune disorder of the connective tissues and joints; abbreviated RA.

• sequestrum (sē-kwehs-truhm) = piece of dead bone that is partially or fully detached from the adjacent healthy bone.

• spondylitis (spohn-dih-lī-tihs) = inflammation of the vertebrae.

• spondylosis (spohn-dih-lō-sihs) = any degenerative disorder of the vertebrae.

• spondylosis deformans (spohn-dih-lō-sihs dē-fōr-mahnz) = chronic degeneration of the articular processes and the development of bony outgrowths around the ventral edge of the vertebrae; an age-related change in dogs where bone spurs form that can eventually bridge between vertebrae.

• spur (spuhr) = bony projection growing out of a bone.

• subluxation (suhb-luhck-sā-shuhn) = partial dislocation or displacement of a bone from its joint.

• synovitis (sihn-ō-vī-tihs) = inflammation of the synovial membrane of joints.

Fracture Terminology, Interventions, and Bone Healing

Types of Fractures and Related Terms

• avulsion (ā-vuhl-shuhn) fracture = broken bone in which the site of muscle, tendon, or ligament insertion is detached by a forceful pull.

• callus (kahl-uhs) = bulging deposit around the area of a bone fracture that may eventually become bone.

• closed fracture = broken bone in which there is no open wound in the skin; also known as a simple fracture.

• comminuted (kohm-ih-noot-ehd) fracture = broken bone that is splintered or crushed into multiple pieces.

• compression (kohm-prehs-shuhn) fracture = broken bone produced when the bones are pressed together.

• crepitation (krehp-ih-tā-shuhn) = cracking sensation that is felt and heard when broken bones move together; also referred to as crepitus (krehp-ih-tuhs).

• displaced (dihs-plāsd) fracture = bone fracture parts are out of line.

• fracture (frahck-shər) = broken bone.

• greenstick fracture = bone that is broken only on one side and the other side is bent; also called incomplete fracture.

• oblique (ō-blēck) fracture = broken bone that has an angular break diagonal to the long axis.

• open fracture = broken bone in which there is an open wound in the skin; also known as a compound fracture.

• pathologic fracture = broken bone in an area of bone weakened by disease.

Fracture Realignment and Medical Interventions

• immobilization (ihm-mō-bihl-ih-zā-shuhn) = act of holding, suturing, or fastening a bone in a fixed position, usually with a bandage or cast.

• manipulation (mahn-ihp-yoo-lā-shuhn) = attempted realignment of the bone involved in a fracture or dislocation; also known as reduction.

Physiological Mechanism of Bone Repair

1. Hematoma Formation: When a bone is fractured, blood vessels bleed into the fracture site and form a hematoma.

2. Cellular Invasion and Matrix Production: After a few days, osteoblasts move into the area and start to produce new bone matrix.

3. Osteocyte Maturation: As the new matrix is synthesized, osteoblasts develop into osteocytes.

4. Bony Fusion: The new bone eventually fuses together the segments of the fracture.

Fracture Healing Complications

• malunion (mahl-yoon-uhn) = condition in which two bony ends of the fracture fail to heal together correctly.

• nonunion = condition in which there is total failure of fracture healing.