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Skeletal System Ch 3Structures
Skeletal system is the bony framework of the body
206 bones in an adult Functions
◦ Support of the body and shape & structure◦ Protection of the vital organs◦ Movement & anchorage of the muscles (levers for
muscular action)⚫Tendons – attach muscle to bone⚫Ligaments – attach bone to bone
◦ Mineral storage – calcium and phosphorus◦ Blood cell formation - hematopoiesis
Introduction
Collagen – a chief organic constituent (protein)
Inorganic calcium salts (Vit D is essential for the absorption of minerals, i.e. calcium)
Bone Composition
Cells◦ Osteoblasts-bone building, bone-repairing cells in
the periosteum◦ Osteocytes-mature bone cells within the bone
matrix◦ Osteoclast-causes the reabsorption of bone
Periosteum◦ A dense, fibrous membrane covering bone◦ Contains blood vessels◦ Essential for bone cell survival and bone
formation
Bone Composition
Grow in length at the epiphyseal line Grow in width by the addition of bone to the
surface Controlled by the anterior pituitary (growth
hormone)◦ Dwarfism-hypofunction◦ Gigantism-hyperfunction◦ Acromegaly-hyperfunction after puberty; enlarges
bones of the hands, feet, and face
Bone Growth
Bone Structures
Epiphyseal plate◦ Growth plate, found towards ends of bones
Diaphysis◦ The long shaft, major part of the bone
Condyle◦ A rounded, knuckle-like prominence usually at a point
of articulation Foramen
◦ Opening in bone through which blood vessels, nerves, and ligaments pass
Tubercles◦ A small, rounded process
Landmarks
Bone marrow◦ Red marrow
⚫hematopoietic tissue⚫Forms red blood cells, platelets, some white blood
cells, destroys old RBCs and some foreign materials◦ Yellow marrow
⚫Fat storage
Bone tissues
Pg 39
Axial◦ Central bones along your center axis◦ Protects the major organs of the nervous,
respiratory, and circulatory systems Appendicular
◦ Appendages◦ Extremities◦ Protects the organs of digestion, excretion, and
reproduction
Skeletal descriptive divisions
Skull◦ Cranium-major bones
⚫Frontal⚫Parietal-Right & Left⚫Temporal-Right & Left⚫Occipital
◦ Fontanelles-fusion of the cranial bones is not complete at birth so babies have a “soft spot”
◦ Facial
Axial skeleton-80 bones
Thoracic ◦ Ribs◦ Sternum
Spinal column-26 bones separated by intervertebral disks to cushion◦ Cervical-7, smallest vertebrae◦ Thoracic-12, progressively increase in size◦ Lumbar-5, largest and strongest◦ Sacral-five fused bones with the pelvis◦ Coccyx-3-4 fused bones, tailbone, slightly
movable to assist in childbirth
Axial skeleton
Sternum◦ Manubrium-top part◦ Body ◦ Xiphoid process-end tip
Ribs Shoulder girdle
◦ Clavicles (2)-the collarbones◦ Scapulas (2)-the shoulder blades
Appendicular skeleton-126 bones
Upper extremities◦ Humerus-upper arm◦ Radius-thumb side of forearm◦ Ulna-little finger side of forearm◦ Carpals (8)-wrist bones◦ Metacarpals (5)-hand bones◦ Phalanges (14)-finger bones
Appendicular skeleton
Pelvic Girdle◦ Os coxae (2)-contains the acetabulum (hip socket)
⚫Ilium⚫Ischium⚫Pubis
◦ Sacrum
Appendicular skeleton
Lower Extremities◦ Femur-thigh bone◦ Patella-kneecap◦ Tibia-shin bone◦ Fibula-lateral bone of the lower leg◦ Tarsals (7)-ankle bones
⚫Talus⚫calcaneus
◦ Metatarsals (5)-foot bones◦ Phalanges (14)-toe bones
Appendicular skeleton
Joints Synarthrotic-immovable
joints◦ Sutures in skull◦ Pg 39
amphiarthrotic-flexible, but not movable◦ Symphysis pubis◦ Pg 46
Diarthrotic-freely movable◦ Synovial-movable joints of
the body
Ligaments-band of fibrous connective tissue that connects one bone to another
Bursa-a fibrous sac that contains synovial fluid
Synovial fluid-a lubricant to make smooth movement of the joint possible
Joints