Chapter 5 The Skeletal System

The Skeletal System Parts of the skeletal system  Bones (skeleton)  Joints  Cartilages  Ligaments Divided into 2 divisions  Axial skeleton  Appendicular skeleton

Functions of Bones  Support body  Protect soft organs  Movement due to attached skeletal muscles  Storage of minerals and fats  Blood cell formation

Bones of the Human Body The skeleton has 206 bones Two types of bone tissue  Compact bone - Homogeneous  Spongy bone - Small needle-like pieces of bone - Many open spaces

Classification of Bones on the Basis of Shape Figure 5.1

Classification of Bones Long bones  Typically longer than wide  Have a shaft with heads at both ends  Contain mostly compact bone - Ex: Femur, - humerus

Classification of Bones Short bones  Generally cube-shape  mostly spongy bone - Ex: Carpals, tarsals

Classification of Bones Flat bones  Thin and flattened  Usually curved  Thin layers of compact bone around a layer of spongy bone -Ex: Skull, ribs, sternum

Classification of Bones Irregular bones  Irregular shape  Don’t fit into other classification categories -Ex: Vertebrae and hip

Axial Skeleton - Axial Skeleton - longitudinal part of the body Three parts  Skull  Vertebral column  Bony thorax

The Skull  Two sets of bones - Cranium - Facial bones  Bones are joined by sutures  Only the mandible is attached by a freely movable joint

Bones of the Skull

Human Skull, Superior View

Human Skull, Inferior View

Paranasal Sinuses  Hollow parts of bones surrounding nasal cavity  Functions: -Lighten the skull -Resonate and amplify voice

The Hyoid Bone  Only bone that doesn’t articulate with another bone  Moveable base for tongue

The Bony Thorax  Forms cage to protect major organs  3 parts - Sternum - Ribs - Thoracic vertebrae

The Vertebral Column  separated by intervertebral discs  normal curvature  named based on location

Structure of a Typical Vertebrae

Characteristics of Cervical Vertebrae

Characteristics of Thoracic & Lumbar Vertebrae

Plate Test – know these structures! Atlas (C1) lamina Axis (spinous process – C2) Body of cervical vertebra Body of lumbar vertebra Body of sternum Body of thoracic vertebra Cervical vertebra Chondral end Coccyx Coronal suture (Frontal) Costal cartilage Demifacet Ethmoid bone Facet (articulating process) False rib Floating rib Foramen magnum Head (facets for vertebra) Intervertebral disc (annulus fibrosous)

Lacrimal Lamina Lamina (lumbar vert) Ligament in vertebra Lumbar Vertebra (Spinous process) Mandible Mastoid process (temporal bone) Maxilla Nasal bones Nerve in vertebra Occipital bone Occipital condyle Palatine Parietal bone Pedicle Sacrum Sagittal suture Spinous process Styloid process (temporal bone) Thoracic vertebra Transverse process True Rib Vertebral foramen Vomer Xiphoid process (sternum) Zygomatic bone