The Body’s Framework

 The adult skeletal system consists of: ◦ 206 bones ◦ The strong elastic tissue that forms ligaments, tendons, and cartilages  These tie the bones together  They also form the nose, larynx, trachea, bronchial tubes, and the outer ear

 1. Provides a framework for the body  2. Gives the body it’s basic shape  3. Permits us to stand upright  4. Supports, restrains, and protects soft internal organs  5. Allows coordinated movement at it’s joints  6. Provide an anchor for skeletal muscles  7. Produce red blood cells within the bone marrow (hematopoiesis)

 Bones are made up of 2 types of material ◦ Compact bone ◦ Spongy bone (cancellous bone)

 Very dense and hard  Located near the surface of bones where strength is needed

 A network of thin strands of bone and spaces  The spaces are filled with bone marrow ◦ Red bone marrow – produces blood cells ◦ Yellow bone marrow – stores fat cells

 4 Classes of Bone

◦ Strong shafts made of compact bone tissue  Called the diaphysis ◦ Large ends made of spongy tissue covered with compact tissue  Called the epiphyses  At the joint ends, the epiphyses are covered with articular cartilage ◦ Covered by a layer of connective tissue called periosteum  Produces bone cells  Allows muscle attachment

 Slightly curved to absorb shock  Examples – leg, arm, clavicle, toe, and finger bones

 Shaped like irregular cubes  Spongy with a covering of compact tissue  Examples – patella, carpal, and tarsal bones

 Broad, flat plates of spongy tissue sandwiched between 2 layers of compact tissue  Examples – Skull, ribs, sternum, hips, and scapulae

 Irregularly shaped  Proportion of spongy to compact tissue varies from bone to bone  Examples – Vertebrae and facial bones

 Axial skeleton – bones of the center (axis) of the body ◦ Skull ◦ Vertebral column ◦ Thorax ◦ Hyoid bone  Appendicular skeleton – bones of the upper and lower extremities ◦ Upper extremity ◦ Lower extremity

 2 main parts ◦ Cranium (brain case) ◦ Facial bones  Number of bones ◦ 8 bones form the cranium  The cranial bones are fused at lines called sutures ◦ 14 bones form the face ◦ 6 (tiny) bones that form the middle ear

 Bones of the cranium ◦ Frontal (1) ◦ Parietal (2) ◦ Sphenoid (1) ◦ Ethmoid (1) ◦ Temporal (2) ◦ Occipital (1)

 Bones of the face ◦ Nasal (2) ◦ Maxilla (2) ◦ Zygomatic (2) ◦ Mandible (1) ◦ Lacrimal (2) ◦ Palatine (2) ◦ Inferior concha (2)  Nasal turbinates  Part of ethmoid ◦ Vomer (1)

 Bones of the middle ear ◦ Malleus (2) ◦ Incus (2) ◦ Stapes (2)

 The “chest” bones  Includes: ◦ Ribs  True ribs (14)  thoracic vertebrae  sternum  False ribs (6)  thoracic vertebrae  cartilage of ribs above  Floating ribs (4)  thoracic vertebrae  no anterior connection ◦ Sternum  Manubrium  Body  Xiphoid process

 Stack of 33 irregular bones  Separated by discs ◦ Shock absorption  Curved at each region ◦ Helps support body weight ◦ Provides balance ◦ Shock absorption  5 regions ◦ Cervical (7) ◦ Thoracic (12) ◦ Lumbar (5) ◦ Sacrum (5 fused vertebrae) ◦ Coccyx (4)

 Top 7 vertebrae  Form the neck  Support the skull  Concave curvature  Smallest of the vertebrae  1 st cervical vertebra – atlas  2 nd cervical vertebra - axis

 Next 12 vertebrae  Convex curvature  Attach to the 12 ribs ◦ Forms the thorax  T 2

 Next 5 vertebrae  Form the lower back  Concave curvature  Largest and thickest  L 4

 5 fused vertebrae  Triangular in shape  Makes up part of the pelvis

 Bottom 4 vertebrae  Fused  Also called the tailbone

 Appendicular skeleton  Consists of: ◦ Scapula ◦ Clavicle ◦ Humerus ◦ Ulna ◦ Radius ◦ Carpals (8) ◦ Metacarpals (5) ◦ Phalanges (14)

 Appendicular skeleton  Consists of: ◦ Hip – Innominate or Coxal  Ilium  Ischium  Pubis ◦ Femur ◦ Patella ◦ Tibia ◦ Fibula ◦ Tarsals ◦ Metatarsals ◦ Phalanges

Cervical vertebrae – C1-C7 Thoracic vertebrae – T1-T12 Lumbar vertebrae – L1-L5 Sacrum – S1-S5 Coccyx Atlas – C1 Axis – C2

Ilium Pubis Ischium