Musculoskeletal Flashcards
How many bones are in the human body?
206
What is the axial skeleton comprised of?
Skull, vertebral column, and thorax
What is the appendicular skeleton comprised of?
Upper and lower extremities, shoulder girdle, pelvic girdle
Looking at an X-ray of a patient’s femur, what would the absence of a space between the epiphysis and metaphysis indicate?
The patient has stopped growing (post puberty)
What happens to the growth plate as children go through puberty?
Growth plate ossifies and becomes bone, also known as the epiphyseal plate.
What are the 3 components of the bone matrix?
1- Organic matrix/osteoid (25%)- mostly collagen fibers and proteoglycan which bind between collagen fibers. Glycoprotiens. Osteoblasts, osteoclasts, and osteocytes.
2- Inorganic mineral content (70%)- mineral salts; Ca and phosphorous called hydroxyapatite. They given bone its hard, rigid structure while serving as the body’s main reservoir for Ca and Phos.
3- Water (5%)
What is the basic unit of compact bone?
Osteon or the harversion system
What is the harversian canal?
The haversian canal lies at the center of each osteon. It contains blood vessels, lymph vessels, and nerve fibers.
Outline the function of an osteoblast.
-Derived from the mesenchymal cells.
-Produce type I collagen
-Respond to PTH
-Produce osteocalcin
-Synthesize osteoid (non-mineralized bone matrix)
BONE BUILDING
Outline the function of an osteoclast.
- The major RESORPTIVE cells of the bone
- Large, multi-nucleated cells
- Contain lysosomes filled with hydrolytic enzymes
Outline the function of an osteocyte.
- Transformed osteoblast surrounded in osteoid as it hardened from deposited minerals
- The housekeeper- maintains bone
Explain the process of bone remodeling?
Bone remodeling is a lifelong process that can be thought of as ‘bone metabolism’. It is a three step process: Activation, Resorption, and Formation.
Explain the RANK/RANKL relationship.
RANKL is produced by the osteoblasts to activate the RANK receptors on osteoclasts telling them to break down and resorb bone. Osteoblasts usually follow behind this process and build new bone.
What is RANKL expression increased by?
IL-1, IL-11, IL-17 TNF alpha PTH Prostaglandin E2 Glucocorticoids
What is RANKL decreased by?
IL-4
TGF beta
Estrogen (17beta-estradiol)
What is OPG’s role?
OPG is a glycoprotein also produced by the osteoblast that acts as a decoy or receptor antagonist for RANKL. OPG will fill the RANK receptor site so that RANKL cannot. This is how the body ‘turns off’ osteoclast bone resorption.
What is OPG production increased by?
IL-1, IL-12, IL-18 TNF alpha TGF beta, BMP-2 Estrogen (17beta-estradiol) Leptin Mechanical Strain
What is OPG production decreased by?
PTH
Prostaglandin E2
Glucocorticoids
Cyclosporine A
What type of bone makes up the majority of the skeleton?
Compact bone (85%)
Spongy bone is 15%)
What is the dense, double layered connective tissue covering bones?
Periosteum
What is a fracture?
A break in continuity of bone, an epiphyseal plate, or a cartilaginous joint surface.
Describe bone remodeling after a fracture.
1- Inflammation at the site of injury causes a hematoma to form around the bone. This creates an increase in blood supply
2-Soft Callous formation; cartilaginous (2-3wks)
3- Hard Callous (seen on Xray of newly healed bone-thicker)
4- Bone remodeling to normal
Adults casted for 8-12wks, children 4-6wks
What is a joint?
An articulation; point of contact between two bones
Why are the 3 types of joints?
1- Synarthrosis- Immovable
2- Amphiarthrosis- Slightly movable
3- Diarthrosis- Freely movable
Describe the Synarthrosis Fibrous joints.
Bones united by fibrous tissue.
Ex:
-Sutures
-Syndesmoses- two bony surfaces that are united by ligament or membrane; permits very limited amount of movement
-Gomphoses- projection that fits into a complimentary socket and are held there by a ligament (our teeth in mandible/maxilla)
Describe the Synarthrosis Cartilaginous joints.
Symphysis- Bone are united by a a pad or disk of fibrocartliage. Ex- symphysis pubis, intervertebral disks
Synchondrosis- Bones are united by hyaline cartilage. Ex- joints between the ribs and the sternum.
What type of joints are Synovial Joints?
Diarthosis- allow for the most movement.
Synovial joints are designed to allow mobility. They are cover with a joint capsule, or synovial sheath. Movements happens due to contraction of the muscle-tendon unit and control is dependent on joint capsule and ligaments.
Synovial fluid is produced by fibroblast-like cells lining the joint capsule and is secreted into mobile joints to provide the lubrication necessary to reduce friction at articulating surfaces.
What is the synovial structure? (5)
1-Fibrous joint capsule
2-Joint cavity enclosed by a joint capsule
3-Synovial membrane that lines the inner surfaces of the capsule
4-Lubricating synovial fluid that coats joint surfaces
5-Hyaline cartilage that covers joint surfaces.
What is a Oblique Fracture?
Fracture resulting from rotational forces, the break is along an oblique course (45-degree angle) and does not rotate around the entire bone.
What is an Occult Fracture?
A fracture in which there are clinical signs of a fracture but no radiographic evidence
What is an Open Fracture?
A broken bone that is in communication through the skin with the environment
What is a Pathologic Fracture?
A fracture that develops secondary to an underlying issues. Ex- Osteoporosis, osteopenia, or tumor growth.
What is a Segmented Fracture?
Also called comminuted fractures; consist of more than one fracture line and more than two bone fragments. May be shattered or crush. Treatment issues arise from soft tissue damage and multiple bone fragments.
What is a Spiral Fracture?
Fractures that result from rotational force and cause bone to separate in the form of an S around the bone.
What is a Transverse Fracture?
Fracture that occurs in a straight line at approximately a 90-degree angle to the longitudinal axis of the bone
What is a Greenstick Fracture?
An incomplete break in the bone with the intact side of the cortex flex. Most often seen in peds.
What is an Impacted Fracture?
Caused by excessive force that telescopes or drives one fragment into another.