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The Skeletal System image (Movement classifications: image (Flexion:…
The Skeletal System
Functions:
Framework for the human body
Produces blood cells
Provides protection for organs
Helps us to breathe
Acts as a warehouse for mineral storage
Allows for movement
Bones
Are primary components of skeleton
Although composed of non-living minerals such as calcium and phosphorous, bones are very much alive, constantly building and repairing themselves
Word ‘bone’ comes from Greek meaning “dried up body”
Four types:
Long bones: longer than they are wide and can be found in arms and legs
Short bones: fairly equal in width and length and found mostly in wrists and ankles
Flat bones: thinner and can be either flat or curved; can be plate-like in nature and would include skull, ribs, and sternum (breast bone)
Irregular bones: like parts of jigsaw puzzle, odd in shape, and include hip bone and vertebrae
Composed of:
Periosteum
Tough and fibrous connective tissue covering bone
Contains blood vessels which transport blood and nutrients to nurture bone cells
Also contains lymph vessels and nerves
Acts as anchor point for ligaments and tendons
Epiphysis and diaphysis
Epiphysis: formed by increase in size of both ends of long bone
Diaphysis: region running between two epiphyses; hollow area called medullary cavity acts as storage area for bone marrow
Bone marrow
Yellow marrow: has high fat content; can convert to red marrow in an emergency
Red marrow: produces red blood cells
Compact bone
Dense, hard tissue that composes shafts of long bones and forms outer layer of other bone types
Material forms microscopic, cylindrical shaped units called osteons, or Haversian systems
Under a microscope you can see the tightly packed material within tissue makes for dense and strong structure
Osteons (unit or Haversion systems) run parallel to each other with blood vessels literally connecting with them to ensure sufficient oxygen and nutrients for bone cell
Each units has mature bone cells (osteocytes) forming concentric circles (like a bulls-eye) around blood vessels
Area around osteocyte is filled with protein fibers, calcium, and other minerals
Spongy (cancellous) bone
Instead of having Haversion Systems it has an arrangement of bars and plates called trabeculae
Irregular holes between trabeculae make bone lighter in weight and provide space for red bone marrow, which produces red blood cells
Holes give bone spongy appearance
Surface structures
Bone is not perfectly smooth; has variety of projections, bumps, and depressions
Projections act as points of attachment for muscles, ligaments, or tendons
Grooves and depressions act as pathways for nerves and blood vessels
Projecting structures and depressions can work together as joining or articulation points to form joints such as ball and socket joint in hip
Cartilage
Special form of dense connective tissue that can withstand fair amount of flexing, tension, and pressure
Flexible part of nose and ears are cartilage
Fontanels at child birth
Also makes flexible connection between bones, as between ribs and sternum, allowing chest flexion during deep breathing
Cartilage acts as cushion between bones; articular cartilage located on ends of bones and acts as shock absorber, preventing ends from grinding together when you move
In this location, small sacs, called bursa, secrete lubricant called synovial fluid
Joints can still wear out and become inflamed despite all this protection, resulting in arthritis or osteoarthritis
Joints and Ligaments
Without joints the body could not move
When two or more bones join together they form a joint or articulation
Articulating joints held together, yet still movable; accomplished by special connective tissue called ligaments
Ligaments: tough, whitish bands that connect from bone to bone and can withstand heavy stress
Tendons: cord-like structures that attach muscle to bone
Types of synovial joints
Classified by function or structure
In terms of function joints can be immobile, move a little, or move freely
Pivot joint: turnstile movement in neck and forearm
Ball and socket joint: hip and shoulder; all forms of movement, including rotation
Hinge joint: allow opening and closing movement in knees and elbows
Gliding joint: wrists and ankles; provides sliding back and forth movement
Saddle joint: shaped like saddle, found in thumb; can rock up and down or side to side
Condyloid joint: oval shaped bone end fitting into elliptical cavity in other bone so there is movement from one plane to another but no rotation as found in fingers and toes
Ellipsoidal joint: provide two axes of movement through same bone like joint formed at wrist with radius and ulna
Growth and repair
Ossification or osteogenesis: describes formation of bone in body
Bones grow longitudinally to develop height and horizontally (wider and thicker) so they can more efficiently support body weight and any other weight we support
There are four types of cells involved in bone formation and growth
Osteoprogenitor cells
Non-specialized stem cells found in periosteum, endosteum, and central canal of compact bones; can turn into other types of cells as needed (remember they are stem cells)
Osteoblasts
Cells that actually form bones; arise from non-specialized osteoprogenitor cells and are cells that secrete a matrix of calcium with other minerals that give bone its typical characteristics
Like a builder (b) are masons laying down the brickwork to make new exterior walls
Osteocytes
Considered mature bone cells that started as osteoblasts; osteoblasts surround themselves with matrix to then become mature osteocytes
Osteoclasts
Believed to originate from type of white blood cell called monocyte found in red bone marrow; job is to tear down bone material and help move calcium and phosphate into blood
(c) As in clearing away – tearing out the inside to remodel
Bone development begins when we are embryos through intramembranous and endochondral ossification
Process starts at 8 weeks after conception when bone begins to replace cartilage
Intramembranous ossification occurs when bone develops between two sheets composed of fibrous connective tissue
Such as the development of your skull
Cells from connective tissue turn into osteoblasts and form matrix while other osteoblasts create compact bone over surface of spongy bone; once matrix surrounds osteoblasts they become osteocytes, which is how bones of skull develop
Majority of bones form through endochondral ossification
Shaped cartilage replaced by bone
Periosteum surrounds diaphysis of cartilage bone as cartilage itself begins to break down
Osteoblasts come into region and create spongy bone in area that is then referred to as primary ossification center
Other osteoblasts begin to form compact bone under periosteum; osteoclasts break down spongy bone of diaphysis to create medullary cavity
Epiphyseal plate (growth plate)
After we are born, epiphysis on long bones continues to grow
Plate is thin band of cartilage formed between primary and secondary ossification centers
Plate exists as long as bones need to lengthen and widen; controlled by hormones, plate will eventually ossify and stop growth process
Pathology Connection:
Osteoporosis
As we age (50s) breakdown of bone becomes greater than formation of new bone (causing bone mass to gradually decrease)
Bones become lighter and weaker, with holes in spongy bone becoming more prominent; weakened bones more prone to breakage; condition of decreasing density causing osteoporosis
Men appear to lose less then 25% where women can experience a 35% loss on the average
Hereditary
Hormonal changes during menopause increases the rate of bone loss
Thin white, and Asian women are at higher risk
4 million American suffer and over 6 million related doctor visits a year
Loss of bone mass can be slowed down by
Increasing calcium (forms matrix of bone), fluoride, and vitamin D (helps body absorb ingested calcium from digestive tract) in diet, particularly in formative years
Eliminating smoking and decreasing caffeine consumption (both aid in calcium depletion)
Engaging in weight-bearing exercise
Taking medications to increase bone mass (such as alendronate)
Common joint disorders
Types of Arthritis
Is a general term used to describe an inflammatory process of a joint (s)
Osteoarthritis: when a joint “wears out;” risk factors include sports injury, trauma, repetitive motion, obesity, and aging
Rheumatoid arthritis: autoimmune disease affecting joints
Septic arthritis: infection in a joint
Gout: metabolic disorder where uric acid crystals deposit in connective tissues and synovial fluid
Once thought to be a disease of royalty because of the rich food and alcohol
Inflammation can also develop in other structures near joint
Bursitis: inflammation of a bursa (due to infection or repetitive motion)
Tendonitis (tendonitis): inflammation of a tendon (usually due to repetitive movement)
Treatments: rest, analgesics, application of cold and heat, and sometimes steroid injections
Remember RICE
Rotator cuff tear
Rotator cuff is group of muscles that hold head of humerus in shoulder socket
Activities that stress shoulder can cause tendons attaching rotator cuff to tear
Tennis, baseball, and basketball
When a tear occurs a snapping sound and acute pain radiating from the area is felt. There is difficulty abducting the affected arm
Treatment often involves surgery and rehabilitation
Arthroscope– used to determine joint injuries
Spinal column abnormalities
Herniated disk: when soft central portion of intervertebral disk is forced through outer covering of disk
May cause compression on nearby nerves
Commonly occurs in low back
Symptoms may include: low back pain and radiating pain down sciatic nerve to buttock, leg, and foot on one side of body
Initial curvature of back begins in newborn period; concave, like fetal position
Curvature changes as infant learns to hold its head up, again as it begins to walk, curving in opposite direction
From about age 2 onward, vertebral column will present with secondary curvature in neck, primary in upper back, secondary in lower back, and primary in mid buttocks and tailbone region
Abnormal spinal curvature
Kyphosis: exaggerated “humpback;” usually in thoracic spine
Lordosis: exaggerated “swayback;” usually in lumbar spine
Scoliosis: abnormal sideways curve of any portion of spine
Signs and symptoms: lateral curvature of spine;may lead to backache, fatigue, dyspneal pulmonary deficient
Diagnostic tests:visual exam, radiology exam
Etiology:congenital defect, trauma, etc.
Treatment:depends on age and severity;may include exercise, bracing, surgery
Key to successful treatment is early detection; spinal corrections can be accomplished through, exercise good nutrition with weight control, bracing, corrective shoes (so legs are of equal length), or surgery
Bone fractures and healing
Fracture is a broken bone
Types of fractures
Simple (closed): break without puncture to skin
Compound (open): fracture in which bone has been pushed through skin
Fracture in which bone is pushed through skin referred to as compound or open; particularly nasty because deep tissue has potential to be exposed to bacteria once bone is set into place, and, hence, chance for infection in addition to break is increased
Hairline: fine fracture that does not completely break or displace bone (looks like hair on x-ray)
Spiral: fracture caused by severe twisting of bone
Greenstick: incomplete breaks, more common in children (like a sapling branch) (compared to a seasoned twig)
Comminuted: when bone has been fragmented or splintered
Bones take several weeks to heal; can only heal normally if ends of bones are touching; if bones are not touching (are poorly aligned), bone must be set (reduced)
If misalignment is slight, a closed reduction may be enough. (Force is exerted on the broken bone to bring the bones back into alignment
Surgical or Open Reduction- pins, screws, plates, or other hardware is necessary to fix the bones in place.
Traction- may be necessary to treat fx of long bones. Uses heavy weights to make a puling force on the injured ones which helps keep the bones in correct position
In first few hours after injury hematoma, or blood clot, forms around broken bone and inflammation sets in
For next 3-4 weeks soft callus forms, replacing hematoma and bridging gap between broken ends of bone; soft callus starts as hyaline cartilage which eventually has some bone cells within it; capillaries invade site, ready to vascularize healing bone
From week 4 to week 12 after injury, bony callus forms, replacing soft callus via endochondral ossification; usually bony callus will contain excess bone
Remodeling necessary after bony callus formation to make repaired bone match rest of bone
Common skeletal disorders
Osteomalacia-softening of bone
Signs and symptoms: bone pain;loss of height;deformity of weight bearing bones
Diagnostic tests: visual examination; bone scan
Etiology: decreased mineralization of bone due to insufficient vitamin D;can be caused by poor diet, lack of sufficient sunlight, malabsorption condition
Treatment: correct nutritional deficiency
Osteomyelitis-acute or chronic condition of inflammation of the bone
Signs and symptoms: sudden pain, swelling, heat, tenderness of affected site, high fever, chills, and sometimes nausea and malaise
Diagnostic tests: visual examination: culture for pathogen
Etiology: infection in bone, often seeded by wound in skin: staphylococcus aureus a common pathogen
Treatment: antibiotics, surgical deridement
Osteoporosis
Signs and symptoms: decreasing bone density; pain; fractures; loss of height; kyphosis; height loss of 4-5 inches
Diagnostic tests: X-ray, bone density
Etiology:decreased bone mass that can be due to aging, decreased mobility, estrogen deficient or post-menopausal women
Treatment:early prevention including adequate dietary calcium, avoiding smoking and caffeine, engaging in weight-bearing exercise, supplementary calcium, vitamin D, and/or fluoride, and, if necessary, medications that increase bone mass
Plantar fasciitus (runner's heel)
Signs and symptoms:intermittent pain, really bad pain after you have been sitting or laying in bed for a long time
Diagnostic tests:radiology exam
Etiology:repetitive impact on heel resulting in inflammation of the connective tissue on the plantar surface of foot;predisposing factors include high arches, flat feet; shoes with poor support, increased body weight, sudden increase in activity, and heel spurs
Treatment:application of ice, analgesic and anti-inflammatory medications, padding heel; and possible surgical intervention
Rickets
Signs and symptoms:weak, deformed bones
Diagnostic tests: visual exam; radiology exam and patient history
Etiology:lack of vitamin D in childhood, resulting in impaired calcium absorption and bone calcification
Treatment: dietary correction to increase vitamin D;vitamin D supplementation;sunlight exposure (which increases vitamin D production
Tendonitis (tendinitis)-inflammation of the tendon
Signs and symptoms:inflammation of involved tendon;pain on movement of involved arean
Diagnostic tests: visual exam;radiology exam, patient history
Etiology:repetitive movement, calcium deposits at the site, etc.
Treatment: rest, application of moist heat/cold, analgesics, and anti-inflammatory medications, and injection of corticosteroids
Movement classifications:
Flexion: bending a joint and decreasing angle between involved bones
Extension: straightening a joint
Plantar flexion: pointing toes down
Dorsiflexion: bending foot up toward body
Abduction: moving away from body’s midline
Adduction: moving toward midline of body
Inversion: turning foot inward toward other foot
Eversion: turning foot outward away from opposing foot
Supination: turning hand palm up
Pronation: turning hand palm down
Circumduction: circular arm movement of a pitcher
The skeleton
Two main sections
Axial skeleton: bones of bony thorax, spinal column, hyoid bone, bones of middle ear, and skull; protect body organs and total 80 bones
Appendicular skeleton: bones of arms, legs, hips, and shoulders and total 126 bones
Half of bones in body found in hands and feet
These areas perform most of body’s movement, making them more vulnerable to sports injuries
Pelvic girdle is different for women than men; women have greater pubic angle that facilitates childbirth and broad girdle to support weight of growing fetus; helps scientists identify skeletons as male or female
The human skull
Protects and houses brain; has openings needed for sensory organs such as eyes, nose, and ears
Forms mouth, common passageway for both respiratory and digestive systems
Fibrous cartilage allows for some flexibility of bones surrounding brain
The bony thorax
Bones of chest form thoracic cage that provides support and protection for heart, lungs, and great blood vessels
Cage is flexible due to cartilaginous connections that allow for movement during breathing
Sternum is location for conducting chest compressions during CPR, compressing heart between sternum and bones of vertebrae
The spinal column
Individual bones, or vertebrae, are numbered and classified according to body region where they are located
7 cervical vertebrae in neck area
12 thoracic vertebrae in chest area
5 lumbar vertebrae in waist area
5 sacral vertebrae below waist
3 - 5 small fused bones at very tail-end that form coccyx
Maintaining good bone health
Bone mass loss is a natural process of aging, can be slowed by healthy lifestyle; important to consume proper amount of dietary calcium to build strong bones
As previously discussed, exercise (especially weight-bearing forms) also plays vital role in developing and maintaining bones, so stay active
Two cups of coffee tend to show an increase of bone loss and cigarette smokers show a loss of 5%-8% bone density
While osteoporosis and arthritis are big concerns, many more potential disorders of bones and joints
Disorders generally classified by these causative agents:
Congenital
Degenerative
Nutritional
Secondary disorders
Tumors
Trauma
Inflammation
Infection
Pharmacology center
Corticosteroid injections (injected into affected site)
Pain medication: NSAIDs (ibuprofen and naproxen) treat inflammation and pain; aspirin and acetaminophen treat pain (no anti-inflammatory effect)
Analgesic creams (often contain capsacin; applied to affected site)
Methotrexate:treats rheumatoid arthritis
Calcium supplements (including calcium base antiacids) helps maintain or improve bone density
Alendronate: powerful medication that improves bone density
Estrogen replacement therapy: improves bone density, now considered controversial due to possible complications of treatment
Vitamin D: improves body's ability to absorb calcium
