skeletal system: day one function, bone classification, and bones of the axial & appendicular...
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Skeletal System: Day OneFunction, Bone Classification,and Bones of the Axial & Appendicular Skeleton
Function of BonesSupportProtectionMovement
◦Skeletal muscles attach to bones by tendons
Storage◦Fat and Minerals (calcium and
phosphorus)Blood Cell Formation
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•Bones give shape to the head, thorax, and limbs.•Bones such as the pelvis and lower limbs provide support for the body.•Bones of the skull protect the brain, ears, and eyes.
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Support and Protection
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Body Movement
Bones can act as levers.
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Blood Cell Formation• Blood cells begin to form through hematopoiesis in the yolk sac; they are later manufactured in bone marrow.• Two kinds of marrow occupy the medullary cavities of bone.1. Red marrow functions in the formation of
red blood cells, white blood cells, and platelets, and is found in the spongy bone of the skull, ribs, sternum, clavicles, vertebrae, and pelvis.
2. Yellow marrow, occupying the cavities of most bones, stores fat.
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Storage of Inorganic Salts• The inorganic matrix of bone stores inorganic mineral salts in the form of calcium phosphate that is important in many metabolic processes.•Calcium in bone is a reservoir for body calcium; when blood levels are low, osteoclasts release calcium from bone. •Calcium is stored in bone under the influence of calcitonin when blood levels of calcium are high.•Bone also stores magnesium, sodium, potassium, and carbonate ions.•Bones can also accumulate harmful elements, such as lead, radium, and strontium
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Classification of Bones206 bones in adult skeletonClassified by shape
◦Long◦Short◦Flat◦Irregular
Two Basic Types:◦Compact◦Spongy
Classification by ShapeLong
◦ Longer than wide◦ Shaft with head at
both ends◦ Made mostly of
compact bone◦ All of the bones of
the limbs are long bones except the wrist and ankle bones
Classification by Shape
Short◦ Cube-shaped◦ Made mostly of
spongy bone◦ Bones of the wrist
and ankles
Classification by Shape
Flat Bones◦ Thin, flattened, and
curved◦ Two thin layers of
compact bone, sandwiching a layer of spongy bone
◦ Most of the bones in the skull, the ribs, and sternum
Classification by Shape
Irregular ◦ All bones that are
not long, short, or flat
◦ Includes the vertebral and coxal (hip) bones
Two Types of Bone
Spongy Bone◦ Small, needlelike
pieces of bone with lots of open space.
Compact Bone◦ Dense; smooth and
homogenous
Axial SkeletonSkull
◦ Cranium Frontal, Parietal, Temporal, Occipital, Sphenoid, and Ethmoid
Bones◦ Facial Bones◦ Hyoid Bone
Vertebral Column (spine)◦ Cervical Vertebrae (7)◦ Throacic Vertebrae (12)◦ Lumbar Vertebrae (5)◦ Sacrum◦ Coccyx
Bony Thorax◦ Sternum◦ Ribs
12 pair ( True Ribs – 7; False Ribs – 5 (2 floating ribs) )
Fetal SkullDifferent from adult skull
◦Infant’s face is very small compared to the size of its cranium
◦Skull as a whole is large compared to the infant’s total body length Adult skull – 1/8 of total body length Fetal skull – ¼ of total body length
◦Some areas of hyaline cartilage still present Membranes connecting cranial bones are called
fontanels Soft spot Allow brain to continue to grow No longer felt after 22-24 months
Appendicular SkeletonShoulder Girdle
◦ Clavicle (long bone)
◦ Scapula (flat bone)
Upper Limb◦ Humerus◦ Radius (thumb
side)◦ Ulna (pinky side)◦ Carpals◦ Metacarpals◦ Phalanges
Pelvic Girdle◦ Coxal bones: ilium,
ischium, pubisLower Limb
◦ Femur◦ Tibia ◦ Fibula◦ Tarsal◦ Metatarsal◦ Phalanges
Male and Female Pelvis
Differences in male and female pelvis aid in childbirth◦Female inlet is larger and more circular◦Female pelvis as a whole is shallower
and the bones are lighter and thinner◦Female ilia flare more laterally◦Female sacrum is shorter and less
curved◦Female ischial spines are shorter and
further apart◦Female pubic arch is more rounded
because the angle of the pubic arch is greater