Infant skull has more bones than the adult skull Skull bones such as the mandible and frontal bones are unfused At birth skull bones are connected by fontanelles Fontanelles Unossified remnants of fibrous membranes between fetal skull bones ID: 777241
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Slide1
Slide2Developmental Aspects: Fetal Skull
Infant skull has more bones than the adult skull
Skull bones such as the mandible and frontal bones are unfused
At birth, skull bones are connected by fontanelles
Fontanelles
Unossified remnants of fibrous membranes between fetal skull bones
Four fontanelles
Anterior, posterior, mastoid, and sphenoid
Slide3Figure 7.35
Frontal bone
Ossification
center
Occipital bone
(a) Superior view
Posterior fontanelle
Parietal bone
Anterior
fontanelle
Frontal suture
(b) Lateral view
Posterior
fontanelle
Mastoid
fontanelle
Parietal bone
Ossification
center
Occipital bone
Temporal bone
(squamous portion)
Frontal bone
Sphenoidal
fontanelle
Slide4Developmental Aspects: Growth Rates
At birth, the cranium is huge relative to the face
At 9 months of age, cranium is ½ adult size
Mandible and maxilla are foreshortened but lengthen with age
The arms and legs grow at a faster rate than the head and trunk, leading to adult proportions
Slide5Developmental Aspects: Spinal Curvature
Thoracic and sacral curvatures are obvious at birth
These primary curvatures give the spine a C shape
Convex posteriorly
Slide6Figure 7.37
Slide7Developmental Aspects: Spinal Curvature
Secondary curvatures
Cervical and lumbar—convex anteriorly
Appear as child develops (e.g., lifts head, learns to walk)
Slide8Developmental Aspects: Old Age
Intervertebral discs become thin, less hydrated, and less elastic
Risk of disc herniation increases
Loss of stature by several centimeters is common by age 55
Costal cartilages ossify, causing the thorax to become rigidAll bones lose mass
Slide9Ankylosing spondylitis
The cause of ankylosing spondylitis is unknown, but genes seem to play a role.
The disease most often begins between ages 20 and 40, but it may begin before age 10. It affects more males than females.
Slide10Slide11Slide12Slide13Medial
tibial
stress syndrome (MTSS),
tibial
periostitis or shin splintspain associated with MTSS is caused from a disruption of Sharpey's fibers that connect the medial soleus fascia through the periosteum of the tibia where it inserts into the bone
Slide14Slide15Stress Fractures
Stress
fractures
are tiny
cracks in a bone. Stress fractures are caused by the repetitive application of force, often by overuse — such as repeatedly jumping up and down or running long distances.
Slide16Slide17Slide18Slide19*Disorders associated with Homeostatic Imbalances
Osteomalacia
and rickets
Calcium salts not deposited
Rickets (childhood disease) causes bowed legs and other bone deformitiesCause: vitamin D deficiency or insufficient dietary calcium
Slide20Rickets
Slide21*Disorders associated with Homeostatic Imbalances
Osteoporosis
Loss of bone mass—bone resorption outpaces deposit
Spongy bone of spine and neck of femur become most susceptible to fracture
Risk factorsLack of estrogen, calcium or vitamin D; petite body form; immobility; low levels of TSH; diabetes mellitus
Slide22Figure 6.16
Slide23*Osteoporosis: Treatment and Prevention
Calcium, vitamin D, and fluoride supplements
Weight-bearing exercise throughout life
Hormone (estrogen) replacement therapy (HRT) slows bone loss Some drugs (Fosamax, SERMs, statins) increase bone mineral density
Slide24*Paget’s Disease
Excessive and haphazard bone formation and breakdown, usually in spine, pelvis, femur, or skull
Pagetic bone has very high ratio of spongy to compact bone and reduced mineralization
Unknown cause (possibly viral)
Treatment includes calcitonin and biphosphonates
Slide25Slide26Slide27Slide28Slide29Rheumatoid Arthritis (RA
)
Chronic
, inflammatory, autoimmune disease of unknown cause
Usually arises between age 40 and 50, but may occur at any age; affects 3 times as many women as menSigns and symptoms include joint pain and swelling (usually bilateral), anemia, osteoporosis, muscle weakness, and cardiovascular problems; RA begins with synovitis of the affected jointInflammatory blood cells migrate to the joint, release inflammatory chemicals Inflamed synovial membrane thickens into a pannus Pannus erodes cartilage, scar tissue forms, articulating bone ends connect (ankylosis)Conservative therapy: aspirin, long-term use of antibiotics, and physical therapyProgressive treatment: anti-inflammatory drugs or immunosuppressants
Slide30Slide31Slide32Osteoarthritis
(OA
)
Common
, irreversible, degenerative (“wear-and-tear”) arthritis85% of all Americans develop OA, more women than menProbably related to the normal aging processMore cartilage is destroyed than replaced in badly aligned or overworked jointsExposed bone ends thicken, enlarge, form bone spurs, and restrict movementTreatment: moderate activity, mild pain relievers, capsaicin creams, glucosamine and chondroitin sulfateCommon, irreversible, degenerative (“wear-and-tear”) arthritis85% of all Americans develop OA, more women than menProbably related to the normal aging process
Slide33Slide34Slide35Slide36Slide37Developmental Aspects of Bones
Embryonic skeleton ossifies predictably so fetal age easily determined from X rays or sonograms
At birth, most long bones are well ossified (except epiphyses)
Slide38Figure 6.17
Parietal bone
Radius
Ulna
Humerus
Femur
Occipital bone
Clavicle
Scapula
Ribs
Vertebra
Ilium
Tibia
Frontal bone
of skull
Mandible