Medical Terminology - The Skeletal System

Structures and Functions of the Skeletal System

• Bones:
  • Act as the framework of the body.
  • Support and protect internal organs.
• Joints:
  • Work with muscles, ligaments, and tendons.
  • Enable a wide variety of body movements.
• Calcium:
  • Essential mineral for nerve and muscle function.
  • Stored in bones.
• Red Bone Marrow:
  • Important for blood cell formation.
  • Located within spongy bone.

Formation of Bones

• Newborn's Skeleton:
  • Begins as fragile membranes and cartilage.
• Ossification:
  • Process of turning cartilage into bone.
  • Continues through adolescence.
• Post-Growth Bone Formation:
  • Osteoclast cells break down old or damaged bone.
  • Osteoblast cells rebuild bone.
  • Repairs minor damage and fractures.

Structure of Bones

• Bone as Connective Tissue:
  • Second hardest tissue in the human body.
  • Capable of growth, healing, and reshaping.
• Compact Bone (Cortical Bone):
  • Dense, hard, and strong.
  • Forms the outer layer of bones.
• Spongy Bone (Cancellous Bone):
  • Porous and lighter than compact bone.
  • More susceptible to fractures.
  • Contains red bone marrow.
  • Examples: femur and humerus.
• Medullary Cavity:
  • Central cavity in long bones, surrounded by compact bone.
  • Stores red and yellow bone marrow.
• Endosteum:
  • Tissue lining the medullary cavity.
• Bone Marrow Types:
  • Red Bone Marrow:
    • Hematopoietic tissue.
    • Located in spongy bone.
    • Manufactures red blood cells, hemoglobin, white blood cells, and thrombocytes.
  • Yellow Bone Marrow:
    • Fat storage area.
    • Replaces about half of the red bone marrow after adolescence.
• Cartilage:
  • Smooth, rubbery, blue-white connective tissue.
  • Acts as a shock absorber between bones.
  • Forms flexible parts of the skeleton (e.g., outer ear, nose tip).
• Articular Cartilage:
  • Covers bone surfaces where they articulate.
  • Enables smooth joint movement.
  • Protects bones from rubbing against each other.
• Meniscus:
  • Curved, fibrous cartilage in some joints.
  • Examples: knee and temporomandibular joint.
• Anatomic Landmarks of Bones
  • Diaphysis: shaft of a long bone.
  • Epiphyses: wider ends of long bones:
    *Proximal epiphysis: end nearest to the midline.
    *Distal epiphysis: end farthest from the midline.
  • Foramen: opening for blood vessels, nerves, and ligaments (e.g., foramen magnum).
  • Process: normal bone projection for muscle or tendon attachment (e.g., mastoid process).

Joints

• Also known as articulations.
• Union between two or more bones.
• Classified by construction or degree of movement.
• Fibrous Joints:
  • Hold bones tightly together with dense connective tissue.
  • Sutures in adults allow little or no movement.
  • Fontanelles (soft spots) in newborns allow passage through the birth canal and skull growth.
• Cartilaginous Joints:
  • Allow only slight movement.
  • Bones connected entirely by cartilage.
  • Examples: breastbone (ribs to sternum) and pubic symphysis.
• Synovial Joints:
  • Ball-and-socket joints (hips and shoulders) allow wide range of movement.
  • Hinge joints (knees and elbows) allow movement in one direction.
  • Components: synovial capsule, synovial membrane, synovial fluid, ligaments, and bursa.

The Skeleton

• Typical Adult Skeleton:
  • Approximately 206 bones.
  • Divided into axial and appendicular skeletons.
• Axial Skeleton:
  • Protects major organs of the nervous, respiratory, and circulatory systems.
  • 80 bones of the head and body, organized into:
    • Bones of the skull.
    • Ossicles of the middle ear.
    • Hyoid bone.
    • Rib cage.
    • Vertebral column.
• Appendicular Skeleton:
  • Enables body movement protects digestive, excretory, and reproductive organs.
  • 126 bones:
    *Upper and lower extremities (shoulders, arms, forearms, wrists, hands, hips, thighs, legs, ankles, feet).
  • Appendage: anything attached to a major body part.

Bones of the Skull

• Bones of the Cranium:
  • Frontal, parietal, occipital, temporal sphenoid, ethmoid enclose, and protect the brain.
• Auditory Ossicles:
  • Malleus, incus, and stapes three tiny bones located in the middle ear.
• Bones of the Face:
  • Nasal, zygomatic, maxillary, palatine, lacrimal, inferior conchae, vomer, and mandible.

Thoracic Cavity

• Also called the rib cage, consists of ribs and sternum.
• Bony structure that protects the heart and lungs.
• Ribs (12 pairs):
  • True ribs: first seven pairs attached anteriorly to the sternum.
  • False ribs: next three pairs attached anteriorly to cartilage that connects to the sternum.
  • Floating ribs: only attached posteriorly to the vertebrae, not anteriorly.
• Sternum (breast bone):
  • Manubrium: upper portion.
  • Body (gladiolus): middle portion.
  • Xiphoid process: lower cartilage portion.

Shoulders and Arms

• Shoulders:
  • Clavicle (collarbone).
  • Scapula (shoulder blade).
  • Acromion (extension of scapula).
• Arms:
  • Humerus (upper arm bone).
  • Radius (smaller, shorter forearm bone).
  • Ulna (larger, longer forearm bone).
  • Olecranon (proximal tip of the ulna; funny bone).

Wrists, Hands, and Fingers

• Carpals:
  • Eight bones forming the wrist; form the carpal tunnel.
• Metacarpals:
  • Five bones forming the palm of the hand.
• Phalanges:
  • 14 bones of the fingers; each finger has three (distal, middle, proximal), thumb has two (distal and proximal).

Spinal Column (Vertebral Column)

• Protects the spinal cord and supports the head and body.
• Consists of 26 vertebrae (each a vertebra).
• Vertebral Structures:
  • Body: anterior portion.
  • Lamina: posterior portion.
  • Vertebral foramen: opening in the middle.
• Intervertebral Disks:
  • Cartilage pads between vertebrae, cushioning and allowing movement.
• Types of Vertebrae:
  • Cervical: first seven, forming the neck.
  • Thoracic: T1-T12, with ribs attached.
  • Lumbar: L1-L5, forming an inward curve.
  • Sacrum: triangular bone near the base of the spine.
  • Coccyx: tailbone at the end of the spine.

The Pelvis

• Bony Pelvis:
  • Protects internal organs and supports the lower extremities.
  • Includes sacrum, coccyx, and pelvic girdle (ilium, ischium, and pubis).
• Sacroiliac:
  • Slightly movable articulation between the sacrum and ilium.
• Pubic Symphysis:
  • Cartilaginous joint uniting the pubic bones.
• Acetabulum:
  • Hip socket.

Legs and Knees

• Femurs: largest bones in the body.
• Knees:
  • Patella (kneecap).
  • Popliteal (space behind knee).
  • Cruciate ligaments (cross-shaped) enable knee movements.
• Lower Legs:
  • Tibia (shinbone): larger, anterior weight-bearing bone.
  • Fibula: smaller of the two bones.

Ankles, Feet, and Toes

• Ankles: joints connecting the lower leg and foot.
  • Tarsal bones: similar to wrist bones, but larger.
  • Malleolus: rounded bony projection.
  • Talus: articulates with the tibia and fibula.
  • Calcaneus: heel bone (largest tarsal bone).
• Feet and Toes:
  • Metatarsals form the part of the foot to which the toes are attached.
  • Phalanges: bones of the toes; great toe has two, other toes have three.

Medical Specialties Related to the Skeletal System

• Chiropractor:
  • Doctor of Chiropractic (DC) degree.
  • Specializes in manipulative treatment for spine misalignment disorders.
• Orthopedic Surgeon (Orthopedist):
  • Physician specializing in diagnosing and treating bone, joint, and muscle diseases and disorders.
• Osteopath:
  • Doctor of Osteopathy (DO) degree.
  • Uses traditional medicine and spinal manipulation.
• Podiatrist:
  • Doctor of Podiatry (DP) or Doctor of Podiatric Medicine (DPM) degree.
  • Specializes in diagnosing and treating foot disorders.
• Rheumatologist:
  • Physician specializing in diagnosing and treating arthritis, osteoporosis, fibromyalgia, and tendinitis.

Pathology of the Skeletal System - Joints

• Ankylosis: loss or absence of mobility.
• Adhesive Capsulitis: frozen shoulder; ankylosis caused by adhesions.
• Arthrosclerosis: stiffness of the joints.
• Baker’s Cyst: popliteal cyst; fluid-filled sac behind the knee.
• Bursitis: inflammation of the bursa.
• Chondromalacia: abnormal softening of cartilage.
• Costochondritis: inflammation of cartilage connecting the ribs to the sternum.
• Hallux Valgus: bunion; abnormal enlargement of the base joint of the great toe.
• Hemarthrosis: blood within a joint.
• Polymyalgia Rheumatica (PMR): inflammatory disorder of muscles and joints.
• Sprain: ligament connecting bones to a joint is wrenched or torn.
• Synovitis: inflammation of the synovial membrane.
• Joint Dislocation:
  • Dislocation (Luxation): total displacement of a bone from its joint.
  • Subluxation: partial displacement of a bone from its joint.

Pathology of the Skeletal System - Arthritis

• Osteoarthritis (OA): wear-and-tear arthritis; degenerative joint disease.
  • Osteophytes: formation of bone spurs.
  • Spondylosis: spinal osteoarthritis.
• Gout: gouty arthritis; deposits of urate crystals in the joints.
  • Pseudogout: buildup of calcium pyrophosphate crystals.
• Rheumatoid Arthritis (RA): chronic autoimmune disorder.
  • Joints and other body systems are attacked.
• Ankylosing Spondylitis (AS): inflammation of joints between vertebrae.
• Juvenile Idiopathic Arthritis (JIA): formerly juvenile rheumatoid arthritis.
• Psoriatic Arthritis (PsA): affects about 20% of people with psoriasis.

Pathology of the Skeletal System - Spinal Column

• Herniated Disk: slipped or ruptured disk.
• Lumbago: low back pain (LBP).
• Spondylolisthesis: forward slipping movement of lower lumbar vertebrae.
• Spina Bifida: congenital defect; spinal canal fails to close completely.
• Curvatures of the Spine:
  • Kyphosis: hunchback; outward curvature.
  • Lordosis: swayback; forward curvature.
  • Scoliosis: lateral curvature.

Pathology of the Skeletal System - Bones

• Avascular Necrosis: osteonecrosis; insufficient blood flow to bone tissue.
• Osteitis: inflammation of a bone.
• Osteomalacia: adult rickets; abnormal bone softening; vitamin D deficiency.
• Osteomyelitis: inflammation of the bone marrow and adjacent bone.
• Paget’s Disease: chronic bone disease of unknown cause.
• Periostitis: inflammation of the periosteum; often associated with shin splints.
• Radiculopathy: pinched nerve; compression of a nerve in the spine.
• Rickets: defective bone growth resulting from vitamin D deficiency in children.
• Spinal Stenosis: narrowing of the spaces within the spine.
• Short Stature: formerly known as dwarfism caused by more than 200 different conditions.
• Clubfoot: Talipes congenital deformity of the foot involving the talus.
• Bone Tumors:
  • Primary Bone Cancer: rare malignant tumor originating in the bone.
  • Secondary Bone Cancer: bone metastasis; cancer spreads to bones from other organs.
  • Multiple Myeloma: cancer that occurs in blood-making plasma cells of red bone marrow.
  • Osteochondroma: benign bony projection covered with cartilage.

Pathology of the Skeletal System - Osteoporosis and Osteopenia

• Osteoporosis (OP):
  • Marked loss of bone density.
  • Increase in bone porosity frequently associated with aging.
  • Most common in women over 50 years old; decrease in estrogen after menopause.
• Osteopenia:
  • Thinner-than-average bone density.
  • Condition of someone who does not yet have osteoporosis.

Pathology of the Skeletal System - Fractures

• Osteoporosis-Related Fractures:
  • Compression Fracture: bone is pressed together (compressed) on itself.
  • Colles Fracture: broken wrist; often occurs when a person tries to stop a fall by landing on the hand.
  • Osteoporotic Hip Fracture: broken hip usually caused by weakening of the bones due to osteoporosis.
• Fractures:
  • Broken bones described in terms of complexity.
  • Closed Fracture: simple fracture or a complete fracture no open wound in the skin.
  • Open Fracture: compound fracture open wound in the skin.
  • Comminuted Fracture: bone is splintered or crushed.
  • Incomplete Fracture: bone does not break into two separate pieces occurs primarily in children.
    • Greenstick Fracture: one side of the bone is broken and the other side is only bent.
    • Buckle Fracture (Torus Fracture): affected side of the bone is compressed and buckles but does not break.
  • Oblique Fracture: occurs at an angle across the bone.
  • Pathologic Fracture: bone weakened by osteoporosis or cancer breaks under normal strain.

Pathology of the Skeletal System - Fractures (cont.)

• Spiral Fracture:
  • Complete fracture in which the bone has been twisted apart.
  • Occurs as the result of a severe twisting motion.
• Stress Fracture (Overuse Injury):
  • Small crack in bone that develops from chronic, excessive impact.
• Transverse Fracture:
  • Occurs straight across, perpendicular to the shaft of the bone.
• Additional Terms Associated with Fractures:
  • Fat Embolus: fat cells from yellow bone marrow are released into the blood.
  • Crepitation (Crepitus): grating sound heard when ends of a broken bone move together.
  • Callus: bulging deposit around the area of the break that forms as bone heals.

Diagnostic Procedures of the Skeletal System

• X-Ray Imaging (Radiography):
  • Uses electromagnetic radiation to create x-rays.
• Arthroscopy:
  • Visual examination of the internal structure of a joint using an arthroscope.
• Bone Marrow Biopsy:
  • Necessary after abnormal types or numbers of red or white blood cells are found in a complete blood count test.
• Bone Marrow Aspiration:
  • Use of a syringe to withdraw tissue from the red bone marrow.
• Magnetic Resonance Imaging (MRI):
  • Used to image soft tissue structures such as the interior of complex joints.
• Bone Density Testing:
  • Determine losses or changes in bone density.
  • Used to diagnose osteoporosis, osteomalacia, osteopenia, and Paget’s disease.
  • Measures the amount of mineral in the bones.
    • Ultrasonic Bone Density Testing: screening test for osteoporosis. Sound waves are used to take measurements of the calcaneus (heel) bone.
    • Dual X-Ray Absorptiometry (DXA): Low-exposure radiographic measurement of the spine and hips. Produces more accurate results than ultrasonic bone density testing.

Treatment Procedures of the Skeletal System - Medications

• Bisphosphonates:
  • Class of drugs used to slow the loss of bone density due to osteoporosis.
  • Reduces the risk of broken bones.
• Low-Dose Hormone Replacement Therapy:
  • Sometimes used in the short term to maintain bone density in women at high risk for bone loss after menopause.

Treatment Procedures of the Skeletal System - Bone Marrow Transplants (BMT)

• Stem cell transplant used to treat certain types of cancers, such as leukemia and lymphomas.
• Initially, both the cancer cells and the patient’s bone marrow are destroyed with high-intensity radiation and chemotherapy.
• Next, healthy bone marrow stem cells are infused into the recipient’s blood.
• Cells migrate to the spongy bone, where they multiply to form cancer-free red bone marrow.
• Stem cells produced by the bone marrow eventually develop into blood cells.
• Types of Bone Marrow Transplants
  • Allogenic Bone Marrow Transplant (Allogenic Stem Cell Transplant):
    • Uses healthy bone marrow cells from a compatible donor, often a sibling.
    • Donor needs to be a perfect match, otherwise, the recipient’s body could reject the transplant.
  • Autologous Bone Marrow Transplant (Autologous Stem Cell Transplant):
    • Patient receives his or her own bone marrow cells.
    • Harvested (usually from the hip), cleansed, treated, and stored before the remaining bone marrow in the patient’s body undergoes treatment.
  • Peripheral Blood Stem Cell Transplant:
    • Utilizes blood-forming stem cells from the bloodstream of the patient or donor.

Treatment Procedures of the Skeletal System - Medical Devices and Joints

• Medical Devices
  • Orthotic:
    • Mechanical appliance, such as a shoe insert, leg brace, or a splint.
    • Specially designed to support, control, correct, or compensate for impaired limb function
  • Prosthesis:
    • Substitute for a diseased or missing body part, such as a leg that has been amputated
• Joints
  • ACL Reconstruction:
    • Surgery to replace a torn anterior cruciate ligament (ACL) in the knee.
  • Arthrodesis (Surgical Ankylosis):
    • Surgical fusion (joining together) of two bones to stiffen a joint
  • Arthroscopic Surgery
    • Minimally invasive procedure for the treatment of the interior of a joint.
    • Example: torn cartilage removed using an arthroscope and instruments inserted through small incisions
  • Bone Grafting:
    • Transplanting bone to rebuild bones damaged by injury or disease.
    • Uses synthetic material, allograft (donor tissue), or autograft (patient’s tissue)
  • Synovectomy:
    • Removal of a synovial membrane from a joint

Treatment Procedures of the Skeletal System - Joint Replacements

• Arthroplasty:
  • Surgical repair of a damaged joint.
  • Usually refers to resurfacing of bones or surgical placement of an artificial joint (implant).
• Total Knee Replacement (TKR):
  • All parts of the knee are replaced.
  • Also known as a total knee arthroplasty.
  • Usually necessitated by damage to the joint from arthritis.
• Total Hip Replacement (THR):
  • Total hip arthroplasty.
  • Restores a damaged hip to full function.
• Hip Resurfacing Arthroplasty:
  • Alternative to removing the head of the femur.
• Shoulder Replacement Surgery:
  • Replaces top of the humerus with a metal ball and the damaged portion of the socket with a plastic prosthesis.
• Revision Surgery:
  • Replaces a worn or failed implant.

Treatment Procedures of the Skeletal System - Spinal Column

• Phantom Limb Pain:
  • Post-amputation phenomenon; sensation of pain from a body part that is no longer there.
• Percutaneous Diskectomy:
  • Removal of a fragment of the disk that is compressing a nerve.
• Percutaneous Vertebroplasty:
  • Bone cement injected to stabilize osteoporosis-related compression fractures.
• Laminectomy (Decompression Surgery):
  • Surgical removal of lamina; relieves pressure on the spinal cord by enlarging spinal column.
• Spinal Fusion:
  • Immobilizes part of the spine by joining together (fusing) two or more vertebrae.

Treatment Procedures of the Skeletal System - Bones

• Decompressive Craniectomy:
  • Surgical removal of a portion of the skull.
  • Relieves increased intracranial pressure due to swelling from a traumatic brain injury.
• Craniotomy:
  • Surgical incision or opening into the skull.
  • Performed to gain access to the brain to remove a tumor, relieve intracranial pressure, or obtain access for other surgical procedures.
• Osteotomy:
  • Surgical cutting and reshaping of a bone.
  • Used to repair damaged joints, realign dental occlusions, correct congenital defects, and reshape arthritic knees and hips.

Treatment Procedures of the Skeletal System - Treatment of Fractures

• Closed Reduction (Manipulation):
  • Attempted non-surgical realignment of a fracture or joint dislocation.
• Open Reduction (Surgical Procedure):
  • Performed when closed reduction is not practical.
• Immobilization (Stabilization):
  • Holding, suturing, or fastening bone in a fixed position with strapping or a cast.
• Traction:
  • Pulling force exerted on a limb to return the bone or joint to normal alignment.
• External Fixation:
  • Fracture treatment with external appliance.
• Internal Fixation:
  • Also known as open reduction internal fixation (ORIF).
  • Plate or pins placed directly into the bone to hold pieces in place.
  • This form of fixation is not usually removed after the fracture has healed.

Abbreviations Related to the Skeletal System

• Bone Density Testing = BDT
• Osteoarthritis = OA
• Partial Knee Replacement = PKR
• Rheumatoid Arthritis = RA
• Total Hip Arthroplasty = THA