SKELETAL SYSTEM rev 12-12

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SKELETAL SYSTEM rev 12-12

• Bone or Osseous Tissue
• consists primarily of nonliving extracellular
  crystals of calcium minerals which make the bone
  hard
• contains several types of living bone cells,
  nerves, and blood vessels
• Is classified as a connective tissue

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• Bones perform 5 important functions
• support-provides a hard framework that supports
  the body, attaches the skeletal muscles and
  cradles the bodys organs
• movement-supports muscles to allow us to move
• protection-because they are hard and surround our
  internal organs, they protect our organs
• formation of blood cells within the marrow cavity
  
• mineral storage-bones store minerals that are
  important to body metabolism and function

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• Bones can be classified into 4 categories based
  on shape
• Long--bones of the limbs and fingers
• are longer than they are wide
• consist of a hollow, cylindrical shaft called the
  diaphysis and
• an enlarged knob at each end called the epiphysis
• An internal marrow space or cavity

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• Short--bones of the wrists
• are approximately as wide as they are long
• Flat--including the cranial bones, sternum and
  ribs
• are thin, flattened and sometimes curved, with a
  small amount of spongy bone between 2 layers of
  compact bone
• Irregular--hip bones and vertebrae
• include a variety of shapes that dont fit into
  the other categories

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• All bones contain 2 types of osseous tissue
• a solid, compact tissue which forms the external
  layer of bone
• a spongy tissue with trabeculae

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• Periosteum covers the outer surface of all bones
• is a tough connective tissue consisting of 2
  layers
• the outermost layer is dense irregular connective
  tissue
• is richly supplied with nerve fibers, lymphatic
  vessels and blood vessels which enter the bone
  through openings called nutrient foramen

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• provides insertion or anchoring points for the
  tendons and ligaments
• contains specialized bone forming cells
• if the end of a long bone forms a movable joint,
  the joint surface is covered by a thin layer of
  articular or hyaline cartilage that reduces
  friction, cushions the bone ends during joint
  movement, and absorbs mechanical stress

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• The internal part of the bone surface is covered
  by endosteum (a delicate connective tissue
  membrane)
• this covers the trabeculae in the marrow cavities
  of the spongy bone
• lines the canals that pass through compact bone
• contains osteoblasts (bone forming cells),
  osteoclasts (bone resorption cells), and
  osteocytes (bone cells)

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Long bones

• Compact bone forms the external layer
• central cavity of the shaft of long bones is
  called the medullary cavity
• this cavity is filled with red marrow in children
  (for RBC production), and with yellow bone marrow
  in adults
• yellow marrow is primarily fat which can be
  utilized for energy
• Compact bone consists of calcium phosphate laid
  in a pattern around the central cavity

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• Structural Unit of Compact bone is the
• Osteon (or Haversian system) this forms a
  pattern of hollow tubes like the growth rings of
  a tree trunk

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• Parts of the Haversian system
• each ring of bone tissue in the hollow tube is
  called a lamellae
• Haversian or Central canal middle cavity in a
  Haversian system. Contains the blood vessels
  and nerve fibers
• lacunae found at the junctions of the lamellae
  and is filled with bone cells called osteocytes

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• canaliculi thin canals in bone tissue which
  connect the lacunae to each other and to the
  central canal
• provide a path for nutrients to travel to the
  osteocytes and for wastes to be removed
• Volkmanns canals lie at right angles to the long
  axis of the bone and connect the blood and nerve
  supply of the periosteum to those in the central
  canals and the medullary cavity
• this allows all osteocytes to get nutrients even
  though they arent near a blood vessel

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Spongy bone

• Is found inside the epiphysis
• spongy bone is less dense than compact bone
  allowing the bones to be light but strong
• this helps the bone to withstand mechanical
  stress
• spongy bone is a honeycomb of hard, strong pieces
  called trabeculae
• helps the bone to resist mechanical stress
• the open spaces of the trabeculae are filled with
  red or yellow bone marrow
• blood cell formation (hemopoiesis) takes place in
  the spongy bone

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• Contains the epiphyseal plate line of cartilage
  where bone lengthening takes place in childhood
• When bone length growth is completed, the
  epiphyseal plate becomes ossified (hardened) and
  leaves an epiphyseal line

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SKELETAL SYSTEM

• Skeleton
• provides support
• protects internal organs
• produces blood cells
• stores minerals (calcium and phosphorus)
• stores energy
• Permits movement via muscle attachments
• Provides levers to make movement easier

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• Skeletal system contains 3 types of connective
  tissue
• bone--hard elements of the skeleton
• ligaments--dense fibrous connective tissue that
  binds the bones to each other
• cartilage--specialized connective tissue
  consisting primarily of fibers of collagen and
  elastic in a gel-like fluid called ground
  substance

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• Knuckle Cracking
• The snapping sound is made by the rush of
  synovial fluid from one area of the joint to
  another as the joint is forcefully pulled apart.
  Research shows that
•  this should not cause an increase in
  osteoarthritis,
• that people who crack their knuckles eventually
  have decreased grip and hand function.
• Joint damage may be caused by long term chronic
  ligament inflammation with subsequent pain
• Related research found that knuckle crackers are
  also more likely to bite their fingernails,
  smoke, and drink alcohol

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• The Skeleton is organized into the
• Axial skeleton and the Appendicular skeleton
• Axial skeleton
• forms the long axis of the body which supports
  the head, neck and trunk
• consists of the
• skull, bones of the ear
• vertebral column, hyoid bone (in the
  throat)
• ribs and
• sternum
• Appendicular skeleton
• bones which help get us from place to place
  (locomotion) and enable us to manipulate our
  environment

these bones are also parts of the axial skeleton
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• The Skull includes the bones of the face, the
  cranial bones and the jaws
• Frontal bone (forehead)
• Parietal bones (behind the frontal bone, on the
  top rear part of the skull)
• Occipital bone (forms the back of the skull)
• near the base of this bone is an opening
  called the foramen magnum. This is where the
  vertebral column connects to the skull and the
  spinal cord enters the skull to communicate with
  the brain

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• Occipital condyles--2 rounded bumps at the base
  of the skull which pivot on the 1st vertebrae (as
  in nodding the head to say yes)
• Temporal bones (on the lateral left and right
  side of the skull under the parietal bone)
• each temporal bone has an opening into the ear
  canal which allows sound to travel to the eardrum
• Sphenoid bone which forms the back of the eye
  sockets
• Ethmoid bone which helps support the nose and
  part of the eye socket

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• Facial bones and jaws-comprise the front of the
  skull
• zygomatic bones form the cheeks and the outer
  part of the eye sockets
• nasal bones (including the ethmoid) underlie only
  the upper bridge of the nose (the rest of the
  nose is made up of cartilage and other connective
  tissue)
• lacrimal bones are the inner part of the eye
  sockets
• each is pierced by a tiny opening through which
  the tear ducts drain

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• maxillary bones form part of the eye sockets,
  anchors the upper row of teeth, and forms part of
  the upper palate
• upper, immovable, jaw bone is called the maxilla
• Mandible or lower jaw anchors the lower teeth
• Hyoid bone not really part of the skull lies
  inferiorly to the mandible in the anterior neck
• is the only bone in the body which doesnt
  articulate with another bone

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• Ear bones
• present in the middle ear and move when air
  vibrations bend the eardrum inward
• called the malleus (hammer), incus (anvil) and
  stapes (stirrup)
• Several of the cranial and facial bones contain
  air spaces which form the sinuses and make the
  skull lighter
• Vertebral column or spine
• supports the head, protects the spinal cord and
  serves as the attachment for each of our arms and
  legs and the bodys muscles

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• Is a column of 33 vertebrae (irregular bones)
  which extends from the skull to the pelvis
• is classified into 5 anatomical regions
• cervical (neck)-7 vertebrae
• thoracic (chest or thorax)- 12 vertebrae
• lumbar (lower back)-5 vertebrae
• sacral (sacrum/upper pelvic region)- 5 vertebrae
  which have fused
• coccygeal (coccyx or tailbone)- 4 fused vertebrae

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• The first cervical vertebrae is called the Atlas
• it articulates with the occipital condyles
• The second cervical vertebrae is called the Axis
• you need to know these names
• vertebrae share 2 points of contact called
  articulations
• The spinal cord passes through a canal between
  the articulations
• vertebral bodies are separated from each other by
  intervertebral disks which serve as shock
  absorbers and permit a limited amount of movement
  and flexibility

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• Ribs and sternum (breastbone)
• Sternum is actually 3 fused bones
• protect the chest cavity
• we have 12 pairs of ribs
• the upper 7 pairs, called true ribs,
• False ribs
• pairs 8-10 are joined to the 7th rib by cartilage
  and are thus indirectly attached to the sternum
• Floating ribs pairs 11 and 12 dont attach to
  the sternum at all.

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• Appendicular skeleton
• bones which help get us from place to place
  (locomotion) and enable us to manipulate our
  environment
• includes the
• Pectoral or Shoulder Girdle is a supportive frame
  for the upper limbs
• consists of the clavicles and scapulas
• Arms (the humerus, ulna, radius, carpals wrist
  bones, the palm metacarpal bones, and the
  fingers the phalanges)

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• The Pelvic or Hip Girdle consists of the 2 pelvic
  (hip) bones and the sacrum and coccyx of the
  vertebral column
• they meet in front at the pubic symphysis where
  cartilage joins the 2 bones
• primary purpose is to support the weight of the
  upper body against the force of gravity
• in adult women, the pelvic girdle is
• broader and shallower than in men and
• the pelvic opening is wider/rounder--to allow for
  childbirth
• the sacrum is flatter

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• The leg bones
• Femur (thigh)
• Patella (knee cap)
• Tibia (lower leg)
• Fibula (lower leg)
• Tarsals (ankle joint)
• Metatarsals (foot)
• Phalanges (toes)

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Mature Bone Remodeling and Repair

• Changes in shape, size, strength
• Dependent on diet, exercise, age
• Bone cells regulated by hormones
• Parathyroid hormone (PTH) removes calcium from
  bone
• The thyroid hormone Calcitonin adds calcium to
  bone
• Repair hematoma and callus formation

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• Joints or Articulations
• are sites where 2 or more bones meet
• give our skeleton mobility
• hold the skeleton together
• are the weakest parts of the skeleton
• Ligaments (connective tissues) and tendons
  (muscular tissue) stabilize each joint

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• Joint types
• freely movable or synovial --bones are separated
  by a thin fluid filled synovial cavity which
  secretes synovial fluid as a lubricant
• Synovial membrane lines the interior surfaces of
  the joint.
• Hyaline cartilage lines the articulating surfaces
  of the bones
• Types of synovial joints
• Ball and socket--the ball end of one bone fits
  into the socket of another bone shoulder and
  hip joints
• Hinge joint allows movement in one plane
• Knee and elbow joints

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• Slightly Movable or Cartilaginous --has no
  synovial cavity and permit only slight movement
  (this type joint is mainly found in the axial
  skeleton)
• has a pad of fibrocartilage between 2 bones
• Pubic Symphysis (is only moveable during
  childbirth)
• intervertebral discs
• sacroiliac
• joint connecting the lower ribs to the sternum

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• Immovable or Fibrous Joints
• flat bones in a babys skull
• at birth these bones are separated by space
  filled with fibrous connective tissue. These
  soft spots are called fontanels
• allow the babys head to squeeze through the
  birth canal
• allow for brain growth and development

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Diseases and Disorders of the Skeletal System

• Sprains stretched or torn ligaments or muscular
  injury
• Partially torn ligaments will repair themselves
  but take a long time due to poor vascularization
• Completely torn ligaments require surgery to
  repair
• Cartilage injuries usually due to overuse
• Require surgery to remove damaged cartilage
• Bone dislocation occurs when bones are forced
  out of alignment
• Subluxation is a partial dislocation

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• Bursitis inflammation of the part of the joint
  which contains the synovial fluid
• Falling on your knees, repeated leaning on your
  elbows
• Inject with anti-inflammatory drugs
• Remove some excess fluid by needle aspiration to
  relieve pressure in the joint
• Tendinitis inflammation of the tendon sheath
• Typically caused by overuse
• Arthritis inflammation of joints
• Rheumatoid Arthritis
• Osteoarthritis Degenerative Joint Disease (DJD)

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• Rheumatoid Arthritis
• Thought to be an autoimmune disease that causes
  chronic joint inflammation as well as
  inflammation of tissue around the joints
• Inflammation in other body organs
• ? Genetic cause, environmental, viral, bacterial
• Exacerbations and remissions
• Chronic inflammation leads to destruction of
  cartilage, bone and ligaments?joint deformity
• Symptoms fatigue, energy loss, decreased
  appetite, low-grade fever, muscle and joint aches
  and stiffness (worse in mornings)

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• Treatment ---REST
• reduce joint inflammation and pain
• Patient education to maximize joint function
• Prevent joint destruction and deformity
• Medications
• Aspirin and corticosteroids, NSAIDs
  (non-steroidal anti-inflammatory drugs), to
  decrease pain and inflammation
• No known cure

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• Osteoarthritis
• Most common form of arthritis
• Characterized by the breakdown of cartilage and
  can also damage ligaments and muscles
• Causes changes in joint structure and joint
  capsule thickening that leads to stiffness,
  aching and pain
• Causes obesity, joint injury, repetitive stress
  to a joint

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Homeostatic Imbalances

• Rickets
• Bones of children are inadequately mineralized
  causing softened, weakened bones
• Bowed legs and deformities of the pelvis, skull,
  and rib cage are common
• Caused by insufficient calcium in the diet, or by
  vitamin D deficiency

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Homeostatic Imbalances

• Osteomalacia (in adults)
• Bones are inadequately mineralized causing
  softened, weakened bones
• Main symptom is pain when weight is put on the
  affected bone
• Caused by insufficient calcium in the diet, or by
  vitamin D deficiency

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Homeostatic Imbalances

• Osteoporosis
• Group of diseases in which bone reabsorption
  outpaces bone deposit
• Excessive loss of calcium and also collagen
  fibers from bone
• Spongy bone of the spine is most vulnerable
• Occurs most often in postmenopausal women
• Bones become so fragile that sneezing or stepping
  off a curb can cause fractures

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Osteoporosis Treatment

• Calcium and vitamin D supplements
• Increased weight-bearing exercise
• Hormone (estrogen) replacement therapy (HRT)
  slows bone loss
• Natural progesterone cream prompts new bone
  growth
• Statins increase bone mineral density

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Pagets Disease

• Characterized by excessive bone breakdown with
  new bone formation
• Initially have excessive bone resorption
  (osteoclastic phase) followed by a reactive phase
  of excessive, abnormal bone formation
  (osteoblastic phase)
• Pagetic bone is chaotic, fragile and weak and
  tends to have reduced mineralization
• Usually localized in the skull, spine, pelvis,
  femur,
• Unknown cause (possibly viral)
• Treatment includes the drugs Didronate and
  Fosamax

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Bone Fractures (Breaks)

• Bone fractures are classified by
• The position of the bone ends after fracture
• The completeness of the break
• The orientation of the bone to the long axis
• Whether or not the bones ends penetrate the skin

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Types of Bone Fractures

• Nondisplaced bone ends retain their normal
  position
• Displaced bone ends are out of normal alignment
• Complete bone is broken all the way through
• Incomplete bone is not broken all the way
  through

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Types of Bone Fractures

• Compound (open) bone ends penetrate the skin
• Simple (closed) bone ends do not penetrate the
  skin
• Comminuted bone breaks into three or more
  pieces common in the elderly
• Oblique - a fracture which goes at an angle to
  the axis

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Common Types of Fractures

• Epiphyseal epiphysis separates from diaphysis
  along epiphyseal plate occurs where cartilage
  cells are dying
• Greenstick incomplete fracture where one side
  of the bone breaks and the other side bends
  common in children

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• Spine Curvature Disorders
• Lordosis. Also called swayback, the spine
  curves significantly inward at the lower back.
• Kyphosis. characterized by an abnormally rounded
  upper back, also called humpback or hunchback
• Scoliosis. sideways curve to the spine. The curve
  is often S-shaped or C-shaped.

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• Causes
• Osteoporosis
• Obesity
• Inflammation of the disc space between the bones
  of the spine most often caused by infection
• Abnormal vertebrae development in utero
  (congenital kyphosis)
• Poor posture or slouching (postural kyphosis)
• Arthritis
• Osteoporosis
• Spina bifida the spinal column of the fetus does
  not close completely
• Spine infections
• Spine tumors
• Genetic

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• Idiopathic (80).
• Neuromuscular conditions (15) include cerebral
  palsy, spina bifida and poliomyelitis.
• Metabolic problems
• Crush fracture from trauma, osteoporosis,
  tuberculosis or malignancy.

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• Symptoms vary depending on the type and severity
  of curvature
• Appearing swayback
• Having a large gap between the lower back and the
  floor when lying on your back on a hard surface
  that doesnt change when you bend forward
• Back pain and discomfort
• Problems moving certain ways
• head appears to bend forward
• Hump or curve to the upper back

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• Fatigue in back or legs
• Uneven shoulder blades with one being higher than
  the other
• An uneven waist or hip
• Leaning toward one side
• clothing seems longer on one side than on the
  other.
• when looking in a mirror the height of the hips
  and shoulders appears uneven.

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• Treatment
• determined based on the severity and type of
  spinal curvature disorder
• Medication to relieve pain and swelling
• Exercise to increase muscle strength and
  flexibility
• Wearing a back brace
• Weight loss
• Surgery
• Observation. If there is a slight curve your
  doctor may choose to check your back every four
  to six months to see if the curve gets worse.
• Bracing. A back brace is often prescribed for
  kids and adolescents who are still growing to
  prevent the curve from getting worse.

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• Types of surgery
• Spinal instrumentation. Instruments such as
  hooks, rods, and wire are attached to the spine
  to realign the bones of the spine and keep them
  secure following spinal fusion.
• Artificial disc replacement. Degenerated discs in
  the spine are replaced with artificial ones.

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•  
• Complications
• Distortion of the spinal column may cause
  restriction of the chest with impairment of lung
  function
• Compression of abdominal contents can occur
• Severe deformity may impinge on the spinal cord
  and cause paraplegia