Chapter 3 The Skeletal System PDF

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Chapter 3 of EHS 115...

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● Structures And Functions Of The Skeletal System ○ Consist of bones, bone marrow, cartilage, joints, ligaments, synovial membranes, synovial fluid, and bursae. ○ Ossification = natural process of bone formation. ■ Osteoclasts → break down old or damaged bone ■ Osteoblasts → help rebuild the bone ● The Structure Of Bones

○ Periosteum = tough, fibrous tissue that forms the outermost covering of bone (peri- → surrounding; oste- → bone) ○ Compact bone (cortical bone) = dense, hard, and very strong bone that forms the protective outer layer of bones. ○ Spongy bone (cancellous bone) = porous (“sponge-like”); red bone marrow is found here. ○ Medullary cavity = central cavity located in the shaft of long bones, where it is surrounded by compact bone; red and yellow bone marrow are stored here (medullary → pertaining to the inner section) ○ Endosteum = tissue that lines the medullary cavity (end- → within)

○ Bone Marrow ■ Red bone marrow → located with spongy bone; hemopoietic tissue that manufactures red blood cells, hemoglobin, white blood cells, and thrombocytes. ■ Hemopoietic = pertaining to the formation of blood cells (-poietic → pertaining to formation) ■ Yellow bone marrow → fat storage area; composed of fat cells and located in medullary cavity of long bones. ○ Cartilage ■ Cartilage = smooth, rubbery, blue-white connective tissue that acts as a shock absorber between bones. ■ Articular cartilage = covers surfaces of bones where they articulate, or come together, to form joints. ■ Meniscus = curved, fibrous cartilage found in some joints, such as the knee and the temporomandibular joint of the jaw. ○ Anatomic Landmarks of Bones ■ Diaphysis = shaft of a long bone ■ Epiphyses = wider ends of long bones such as the femurs of the legs (singular epiphysis); each epiphysis is covered with articular cartilage to protect it. ● Proximal epiphysis = end of the bone located nearest the midline ● Distal epiphysis = end of bone located farthest away from midline ■ Foramen = opening in a bone through which blood vessels, nerves, and ligaments pass. ■ Process = normal projection on the surface of a bone that most commonly serves as an attachment for a muscle or tendon. ● Mastoid process = bony projection located on the temporal bones just behind the ears.

○ Joints ■ Joints (articulations) = place of union between two or more bones. ■ Fibrous joints = consist of inflexible layers of dense connective tissue, hold the bones tightly together. ■ Fontanelles (soft spots) = flexible soft spots facilitate passage of the infant through the birth canal; normally present on the skull of a newborn. ■ Cartilaginous Joints = allow only slight movement and consist of bones connected entirely by cartilage. ■ Pubic symphysis = allows some movement to facilitate childbirth. ■ Synovial joint = created where two bones articulate to permit a variety of motions. ● Ball-and-socket joints → allow wide range of movement in many directions; ex: hips and shoulders ● Hinge joints → allow movement primarily in one direction or plane; ex: elbows and knees ■ Synovial capsule = outermost layer of strong fibrous tissue that resembles a sleeve as it surrounds the joint. ■ Synovial membrane = lines the capsule and secretes synovial fluid. ■ Synovial fluid = flows within the synovial cavity, acts as a lubricant to make the smooth movement of the joint possible. ■ Ligaments = bonds of fibrous tissue that forms joints by connecting bone to another bone or by joining a bone to cartilage. ■ Bursa = fibrous sac that acts as a cushion to ease movement in areas that are subject to friction, such as in the shoulder, elbow, and knee joints where a tendon passes over a bone (plural, bursae) ○ The Skeleton ■ Axial skeleton = protects the major organs of the nervous, respiratory, and circulatory systems.

■ Appendicular skeleton = makes body movement possible and also protects the organs of digestion, excretion, and reproduction. ● Upper extremities → shoulders, arms, forearms, wrists, and hands ● Lower extremities → hips, thighs, legs, ankles, and feet ● Appendage → anything that is attached to a major part of the body ● Extremity → terminal end of a body part such as an arm or leg ■ Skull = has 8 bones to form cranium, 14 bones form face, and 6 bones in the middle ear. ■ Cranium = portion of skull that encloses and protects the brain (crani → skull) ■ Frontal bone = anterior portion of cranium that forms the forehead; houses frontal sinuses and forms the roof of the ethmoid sinuses, the nose, and part of the socket that protects the eyeball. ■ Parietal bone = form most of the roof and upper sides of the cranium ■ Occipital bone = forms back part of the skull and base of the cranium ■ Temporal bones = form the sides and base of the cranium ■ External auditory meatus = opening of external auditory canal of the outer ear; located within the temporal bone on each side of the skull. ● Meatus → external opening of a canal ■ Sphenoid bone = irregular, wedge-shaped bone at the base of the skull; it makes contact with all other cranial bone and helps form the base of the cranium, sides of the skull, and floors and sides of eye sockets. ■ Ethmoid bone = light, spongy bone located at the roof and sides of the nose.

■ Auditory ossicles = three tiny bones located in the middle ear; malleus, incus, and stapes. ■ Nasal bones = form upper part of the bridge of the nose ■ Zygomatic bones (cheekbones) = articulate with the frontal bone that makes up the forehead ■ Maxillary bone = form most of the upper jaw ■ Palatine bone = form anterior (front) part of the hard palate of the mouth and floor of the nose. ■ Lacrimal bone = makes up part of the orbit (eye socket) at the inner angle. ■ Inferior conchae = thin, scroll-like bones that form part of the interior of the nose. ■ Vomer bone = forms base for the nasal septum. ● Nasal septum = cartilage wall that divides the two nasal cavities. ■ Mandible (jawbone) = only moveable bone of skull; attached to the skull at the temporomandibular joint (TMJ) ○ Thoracic Cavity ■ Thoracic Cavity (a.k.a. rib cage) = bony structure that protects the heart and lungs. ■ Ribs (costals) = attach posteriorly to the thoracic vertebrae (cost- → rib) ● First 7 pairs of ribs → true ribs → attach anteriorly to sternum ● Next 3 pairs of ribs → false ribs → attach anteriorly to cartilage that connects them to the sternum ● Last 2 pairs of ribs → floating ribs → only attached posteriorly to the vertebrae but are not attached anteriorly

■ Sternum (breast bone) = flat, dagger-shaped bone located in middle of chest; forms 3 parts ● Manubrium = bony structure that forms upper portion of sternum ● Body of sternum (gladiolus) = bony structure that forms middle portion of sternum ● Xiphoid process = structure made of cartilage that forms lower portion of sternum ○ The Shoulders ■ Shoulders form the pectoral girdle → supports arms and hands ■ Clavicle (collar bone) = slender bone that connects manubrium of sternum to the scapula. ■ Scapula = shoulder blade ■ Acromion = extension of the scapula that forms the high point of the shoulder. ○ The Arms ■ Humerus = bone of upper arm ■ Radius = smaller and shorter bone of forearm; runs up the thumb side of the forearm. ■ Ulna = larger and longer bone of forearm; proximal end of ulna articulates with distal end of humerus to form elbow joint. ■ Olecranon process (funny bone) = large projection on upper end of ulna; forms point of the elbow and exposes a nerve that tingles when struck. ○ The Wrists, Hands, and Fingers ■ Carpals = 8 bones that form the wrist; form a narrow bony passage known as the carpal tunnel. ■ Metacarpals = 5 bones that form the palms of the hand. ■ Phalanges = 14 bones of the fingers; bones of toes are also called this.

○ Spinal Column ■ Spinal column (vertebral column) = protects spinal cord and supports the head and body. ● Consists of 26 vertebrae ■ Lamina = posterior part of a vertebrae ■ Vertebral foramen → opening in the middle of vertebra ■ Intervertebral disks = made of cartilage, separate and cushion the vertebrae from each other; also act as shock absorbers and allows for movement of spinal column. ■ Cervical vertebrae = first set of 7 vertebrae and they form the neck ● Cervical → pertaining to the neck; C1 → C7 ■ Thoracic vertebrae = T1 → T12; 2nd set of vertebrae; each of these vertebrae has a pair of ribs attached to it, and together they form the outward curve of the spine. ■ Lumbar vertebrae = L1 → L15 make up the 3rd set of 5 vertebrae; form inward curve of lower spine; largest and strongest of vertebrae; bear most of the body’s weight ● Lumbar → relating to the part of the back and sides between the ribs and the pelvis. ■ Sacrum = slightly curved, triangular-shaped bone near the base of the spine that forms the lower portion of the back. ■ Coccyx (tailbone) = forms the end of the spine and is actually made up of four small vertebrae that are fused together. ○ The Pelvis ■ Pelvis (bony pelvis) = protects internal organs and supports the lower extremities; includes the pelvic girdle (consists of ilium, ischium, and pubis) ■ Ilium = broad, blade-shaped bone that forms the back and sides of the

pubic bone. ■ Sacroiliac = forms slightly movable articulation between the sacrum and posterior portion of the ilium (sacr/o → sacrum; ili → ilium) ■ Ischium = forms lower posterior portion of pubic bone and bears the weight of the body when sitting. ■ Pubis = forms anterior portion of pubic bone; located just below the urinary bladder. ● Symphysis = place where two bones are closely joined. ■ Pubic symphysis = cartilaginous joint that unites the left and right pubic bones. ■ Acetabulum (hip socket) = large circular cavity in each side of the pelvis that articulates with the head of the femur to form the hip joint. ○ The Legs and Knees ■ Femur ● Femurs (thigh bones) → largest bones in the body ○ Head of the femur articulates the acetabulum ○ Femoral neck → narrow area just below head of the femur ■ Knees ● Patella (kneecap) = bony anterior part of the knee ● Popliteal = describes posterior space behind the knee where the ligaments, vessels, and muscles related to this joint are located. ● Cruciate ligaments = make movement of knee possible; there are anterior and posterior cruciate ligaments because they’re shaped like a cross. ■ Lower Legs ● Tibia (shinbone) = larger anterior weight-bearing bone of lower leg. ● Fibula = smaller of two bones of lower leg.

■ The Ankles ● Ankles = joints that connect the lower leg and foot and make necessary movements possible. ● Tarsal = ankles consist of 7 of these each. ● Malleolus = rounded bony projection on the tibia and fibula on the sides of each ankle joint. ● Talus = ankle bone that articulates with tibia and fibula. ● Calcaneus (heel bone) = largest of the tarsal bones. ■ The Feet and Toes ● Metatarsals = 5 bones that form part of the foot to which the toes are attached. ● Phalanges = bones of the toes; greatest two has two phalanges; each of the other toes has three phalanges. ● Medical Specialities Related To The Skeletal System ○ Chiropractor = holds a Doctor of Chiropractic (DC) degree and specializes in the manipulative treatment of disorders originating from misalignment of the spine. ○ Orthopedic surgeon (orthopedist) = physician who specializes in diagnosing and treating diseases and disorders involving the bones, joints, and muscles. ○ Osteopath = holds Doctor of Osteopathy (DO) degree and uses traditional forms of medical treatments in addition to specializing in treating health problems by spinal manipulation. ○ Podiatrist = Doctor of Podiatry (DP) degree; diagnoses and treats disorders of the foot (pod → foot) ○ Rheumatologist = diagnoses and treats arthritis and disorders such as osteoporosis, fibromyalgia, and tendonitis that are characterized by inflammation in joints and connective tissue. ● Pathology Of The Skeletal System

○ Joints ■ Ankylosis = loss or absence of mobility in a joint due to disease/injury/surgical procedure (ankyl → crooked, bent, or stiff) ■ Adhesive capsulitis (frozen shoulder) = painful ankylosis of the shoulder (capsul → little box) ■ Atherosclerosis = stiffness of joints, especially in the elderly. ■ Baker’s cyst (popliteal cyst) = fluid-filled sac behind knee. ■ Bursitis = inflammation of bursa ■ Chondromalacia = abnormal softening of cartilage (chondr/o → cartilage) ■ Costochondritis = inflammation of cartilage that connects a rib to the sternum. ■ Hallux valgus (bunion) = abnormal enlargement of the joint at the base of the great toe. ■ Hemarthrosis = blood within a joint; due to joint injury ■ Polymyalgia rheumatica = inflammatory disorder of the muscles and joints characterized by pain and stiffness in the neck, shoulders, upper arms, and hips and thighs (poly- → many) ■ Sprain = when ligament that connects bones to a joint is wrenched or torn. ■ Synovitis = inflammation of the synovial membrane that results in swelling and pain of the affected joint. ■ Dislocation (luxation) = total displacement of a bone from its joint. ■ Subluxation = partial displacement of a bone from its joint. ○ Arthritis ■ Arthritis = inflammatory condition of one or more joints.

■ Osteoarthritis (wear-and-tear arthritis) = associated with aging. ● Degenerative joint disease → characterized by wearing away of the articular cartilage within the joints. ● Osteophytes = bone spurs ● Spondylosis (spinal osteoarthritis) = cause loss of normal spinal structure and function (spondyl → vertebrae) ■ Gout (gouty arthritis) = characterized by deposits of uric acid crystal in the joints, usually beginning with the big toe; joints affected are typically warm, red, and excruciatingly sensitive. ■ Rheumatoid arthritis (RA) = chronic autoimmune disorder in which the joints and some organs of other body systems are attacked. ■ Ankylosing spondylitis = form of rheumatoid arthritis that causes inflammation of the joints between the vertebrae. ■ Juvenile rheumatoid arthritis = an autoimmune disorder that affects children (6 years or older) with stiffness, pain, joint swelling, skin rash, fever, slowed growth, and fatigue. ○ The Spinal Column ■ Herniated disk (slipped/ruptured disk) = breaking apart of an intervertebral disk that results in pressure on spinal nerve roots. ■ Lumbago (low back pain) = pain of lumbar region of spine (-ago → diseased condition) ■ Spondylolisthesis = forward slipping movement of the body of one of the lower lumbar vertebrae on the vertebra or sacrum below it (-listhesis → slipping) ■ Spina bifida = congenital defect that occurs during early pregnancy when the spinal canal fails to close completely around the spinal cord to protect it.

■ Kyphosis = abnormal increase in the outward curvature of the thoracic spine as viewed from the side (kyph → hump); a.k.a. Humpback or dowager’s hump; associated with aging. ■ Lordosis = abnormal increase in the forward curvature of the lumbar spine (lord → bent backward); a.k.a. swayback. ■ Scoliosis = abnormal lateral (sideways) curvature of the spine (scoli → curved) ○ Bones ■ Avascular necrosis (osteonecrosis) = area of bone tissue death caused by insufficient blood flow (vascul → blood vessels; necrosis → tissue death) ■ Craniostenosis = malformation of the skull due to the premature closure of the cranial sutures (stenosis → abnormal narrowing) ■ Osteitis = inflammation of a bone (oste → bone) ■ Osteomalacia (adult rickets) = abnormal softening of bones in adults; caused by a deficiency of vitamin D, calcium, and/or phosphate. ■ Osteomyelitis = inflammation of the bone marrow and adjacent bone (myel → bone marrow) ■ Paget’s disease = chronic bone disease of unknown case; abnormal breakdown of bone, usually in pelvis, skull, spine and legs, followed by abnormal bone formation. ■ Periostitis = an inflammation of the periosteum (peri- → surrounding); associated with shin splints. ■ Rickets = deficiency disease in children; defective bone growth resulting from a lack of vitamin D necessary for the body to maintain calcium and phosphorus levels in the bones. ■ Short stature (dwarfism) = condition resulting from the failure of the bones of the limbs to grow to an inappropriate length compared to the size of the head and trunk.

■ Talipes (clubfoot) = any congenital deformity of the foot involving the talus. ■ Primary bone cancer = rare malignant tumor that originates in a bone. ■ Secondary bone cancer = tumors that have metastasized (spread) to bones from other organs such as the breasts and lungs. ■ Myeloma = type of cancer that occurs in blood-making cells found in the red bone marrow (-oma → tumor) ■ Osteochondroma = benign bony projection covered with cartilage. ○ Osteoporosis and Osteopenia Compared ■ Osteoporosis = marked loss of bone density and an increase in bone porosity that is frequently associated with aging (por → small opening) ■ Osteopenia = thinner-than-average bone density (-penia → deficiency) ■ Compression fracture (vertebral crush fracture) = occurs when bone is pressed together on itself ■ Colles’ fracture (fractured wrist) = occurs at lower end of radius when a person tries to stop a fall by landing on his/her hands. ■ Osteoporotic hip fracture (broken hip) = caused by weakening of bones due to osteoporosis and can occur spontaneously or as a result of a fall. ○ Fractures ■ Fracture = broken bone ● Closed fracture (simple/complete fracture) = bone is broken, but there is no open wound in the skin. ● Open fracture (compound fracture) = bone is broken and there is an open wound in the skin. ● Comminuted fracture = bone is splintered or crushed. ● Greenstick fracture (incomplete fracture) = bone is bent and only

partially broken; typically occurs in children. ● Oblique fracture = occurs at an angle across the bone. ● Pathologic fracture = occurs when a weakened bone breaks under normal strain. ● Spiral fracture = fracture in which the bone has been twisted apart. ● Stress fracture = overuse injury; small crack in the bone that often develops from chronic, excessive impact.

● Transverse fracture = occurs straight across the bone.

■ Fat embolus = can form when a long bone is fractured and fat cells from yellow bone marrow are released into the blood. ● Embolus = any foreign matter circulating in the blood that can become lodged and block the blood vessel. ■ Crepitation (crepitus) = grating sound heard when the ends of a broken bone move together. ■ Callus = bulging deposit around the area of the break; forms as the bone heals. It is also a thickening of the skin caused by repeated rubbing.

● Diagnostic Procedures Of The Skeletal System ○ Radiograph (x-ray) = use of x-radiation to visualize bone fractures and other abnormalities. ○ Arthroscopy = visual examination of internal structure of a joint. ○ Bone marrow biopsy = diagnostic test that may be necessary after abnormal types or numbers of red or white blood cells are found in a complete blood count test. ○ Magnetic resonance imaging (MRI) = used to image soft tissue structures such as the interior of complex joints. ○ Bone density testing → used to determine losses or changes in bone density. ■ Ultrasonic bone density testing = screening test for osteoporosis, or other conditions that cause a loss of bone mass; sound waves are used to take measurements of the calcaneus (heel) bone. ■ Dual x-ray absorptiometry = low-exposure radiographic measurement of the spine and hips to measure bone density. ● Treatment Procedures Of The Skeletal System ○ Bone marrow transplant = used to treat certain types of cancers, such as leukemia and lymphomas, which affect bone marrow. ■ First, both the cancer cells and patient’s bone marrow are destroyed with high intensity radiation and chemotherapy. Then, healthy bone marrow stem cells are transfused into the recipient’s blood. The cells migrate to the spongy bone, where they multiply to form cancer-free red bone marrow. ○ Allogenic bone marrow transplant = uses healthy bone marrow cells from a compatible donor, often a sibling (allogenic = originating within another) ○ Autologous bone marrow transplant = patient receives his or her own bone marrow cells, which have been harvested, cleansed, treated, and stored before remaining bone marrow in patient’s body is...