Health Occupations

Skeletal System – Unit 1

Skeletal System Organs – BONES

– 206 in adult human Functions

– 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– 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 – Long shaft of bone

Epiphysis– Ends of the long bone

• Proximal• distal

Diaphysis

Proximalepiphysis

Distal epiphysis

Medullary canal

Cavity in diaphysis Contains yellow marrow

– Fat cells

Diaphysis

Proximalepiphysis

Distal epiphysis

Medullary canal

Endosteum

Membrane lining medullary canal Keeps yellow marrow intact Promotes bone growth

Diaphysis

Proximalepiphysis

Distal epiphysis

Medullary canal

EndosteumYellow marrow

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

Diaphysis

Proximalepiphysis

Distal epiphysis

Medullary canal

EndosteumYellow marrow

Red marrow

Periosteum

Membrane covering the outside of bone Tough Contains blood vessels, lymph, &

osteoblasts Necessary for bone growth, repair, &

nutrition

Diaphysis

Proximalepiphysis

Distal epiphysis

Medullary canal

EndosteumYellow marrow

Red marrow

Periosteum

Articular cartilage

Thin layer Covers epiphysis to work as a shock

absorber in joints (hollow strength activity)

Diaphysis

Proximalepiphysis

Distal epiphysis

Medullary canal

EndosteumYellow marrow

Red marrow

Periosteum

Articular cartilage

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 boneParietal bone

Temporal bone

Occipital bone

Sphenoid bone

Ethmoid 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 boneParietal bone

Temporal bone

Occipital bone

Sphenoid bone

Ethmoid bone

Mandible

Maxilla

Zygomatic bone

Lacrimal bone

Nasal bones

Palatine – not pictured, roof of mouth

Skull also contains

Sinuses – 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

Frontal boneParietal bone

Temporal bone

Occipital bone

Sphenoid bone

Ethmoid bone

Mandible

Maxilla

Zygomatic bone

Lacrimal bone

Nasal bones

Palatine – not pictured, roof of mouth

Coronal suture

Squamous suture

Lamboidal suture

External auditory meatusMastoid process Styloid

processMental foramina