Health Occupations Skeletal System – Unit 1

Skeletal System Organs – BONES Functions 206 in adult human Framework Supports muscles, fat, skin Protection Surrounds vital organs (skull, ribs) Lever Muscles attach to bones to provide movement Production of blood cells Produce RBC, WBC, platelets (hemopoiesis or hematopoesis) Storage Stores most of calcium supply of body (bone activity)

Bone Tissue Composition Inorganic salts (calcium phosphate) Water Bone cells Blood vessels Nerves Collagen (elastic material)

Bone Tissue Must continually receive food & oxygen Has fever nerves & blood vessels than other tissues Grows for the first 18 – 20 years of life After growth stops, bone cells die & are replaced by new cells Osteoblasts – cells that MAKE bones Osteoclasts – cells that BREAK DOWN bones & reabsorb them

May contain 2 types of tissue Ligaments – attach bone to bone Tendons – attach muscle to bone 2 types of tissue Compact tissue – dense Cancellous – spongy & loosely packed

Four types of bones Long bones – longer than they are wide Humerus – upper arm Ulna – lower arm Radius - lower arm Femur – upper leg Tibia – lower leg Fibula – lower leg

Short bones Length & width are nearly equal Wrist Hand Ankles Feet

Flat bones Two layers of bone divided by a narrow span Skull Sternum – breast bone Ribs Scapula – shoulder blade

Irregular bones Bones that do not fit in any other group Face Spine Hip

Long Bone Parts Diaphysis Epiphysis Long shaft of bone Ends of the long bone Proximal distal

Proximal epiphysis Diaphysis Distal epiphysis

Medullary canal Cavity in diaphysis Contains yellow marrow Fat cells

Proximal epiphysis Diaphysis Medullary canal Distal epiphysis

Endosteum Membrane lining medullary canal Keeps yellow marrow intact Promotes bone growth

Proximal epiphysis Diaphysis Medullary canal Endosteum Yellow marrow Distal epiphysis

Red Marrow Found in bones like vertebrae, ribs, sternum, cranium, proximal ends of humerus & femur Produces – RBCs, WBCs, platelets Diagnostic tool to identify bone diseases Can be transplanted in people with defective immune systems

Proximal epiphysis Red marrow Diaphysis Medullary canal Endosteum Yellow marrow Distal epiphysis

Periosteum Membrane covering the outside of bone Tough Contains blood vessels, lymph, & osteoblasts Necessary for bone growth, repair, & nutrition

Proximal epiphysis Red marrow Diaphysis Medullary canal Endosteum Yellow marrow Periosteum Distal epiphysis

Articular cartilage Thin layer Covers epiphysis to work as a shock absorber in joints (hollow strength activity)

Articular cartilage Proximal epiphysis Red marrow Diaphysis Medullary canal Endosteum Yellow marrow Periosteum Distal epiphysis

Groups of Bones Axial skeleton – 80 bones Main trunk of body Skull Spinal column Ribs Sternum Appendicular skeleton – 126 bones Extremities – arms & legs Shoulder girdle Pelvic girdle

Joints Place where two bones meet Grouped by how much movement is allowed Synarthrosis joints – immoveable Cranium, suture joints Amphiartrosis joints – slightly moveable Vertebral discs, symphysis pubis, sacroiliac Diarthrosis joints – freely moveable Shoulder, elbow, wrist, fingers, knees, ankles, toes Ligaments – connect bone to bone Hold bones together

Skull Composed of cranium & facial bones Cranium – spherical structure surrounding & protecting brain – 8 Frontal – 1 Parietal – 2 Temporal – 2 Occipital – 1 Ethmoid – 1 Sphenoid – 1 At birth, NOT solid bone Fontanels – soft spots or spaces between bones allows for enlargement of skull as brain growth occurs Membrane & cartilage that turn to bone by 18 months of age

Frontal bone Parietal bone Sphenoid bone Ethmoid bone Occipital bone Temporal bone

Skull Facial bones – 14 Mandible – 1 lower jaw Maxilla – 2 upper jaw Zygomatic – 2 cheek Lacrimal – 2 inner aspect of eye Nasal – 5 Palatine – 2 hard palate or roof of mouth

Frontal bone Parietal bone Sphenoid bone Ethmoid bone Nasal bones Lacrimal bone Occipital bone Maxilla Zygomatic bone Temporal bone Mandible Palatine – not pictured, roof of mouth

Skull also contains Sinuses Foramina Sutures Air spaces in bones of skull Act as resonating chambers for voice Lined with mucus membranes Foramina Openings in bone allowing nerves & blood vessels to enter & leave Sutures Areas where cranial bones have joined together

Coronal suture Frontal bone Parietal bone Sphenoid bone Squamous suture Ethmoid bone Nasal bones Lamboidal suture Lacrimal bone Occipital bone Maxilla Zygomatic bone Temporal bone Mandible External auditory meatus Mastoid process Styloid process Mental foramina Palatine – not pictured, roof of mouth