The Skeletal System

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

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

Bones of the Human Body The adult skeleton has 206 bones Two basic types of bone tissue Compact bone Spongy bone Figure 5.2b

Classifications of Bones Page 144 Figure 5.1

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

Long Bone Anatomy Diaphysis Epiphysis Shaft Composed mostly of compact bone Epiphysis Ends of the bone Composed mostly of spongy bone Page 145 Figure 5.2a

Long Bone Anatomy Periosteum Outside covering of the diaphysis Fibrous connective tissue membrane Endosteum Lines the inner marrow cavity Red marrow Yellow marrow Figure 5.2c

Classification of Bones Short bones Generally cube-shaped Contain mostly spongy bone Examples: Carpals, tarsals

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

Classification of Bones Irregular bones Irregular shape Do not fit into other bone classification categories Example: Vertebrae and hip

Skeletal Divisions Axial Skeleton Appendicular Skeleton Bones of the skull and cranium Bones of the Vertebral Column Bones of the ribs and sturnum Appendicular Skeleton Bones of the appendages and pectoral and pelvic girdles

The Axial Skeleton Forms the longitudinal part of the body Skull: 8 cranial bones, 14 facial Vertebral column Thorax

The Cranium Frontal Bone Forms the forehead and superior surface of each eye socket (orbital) Frontal sinuses are air filled pockets that produce mucus that cleans and moistens the nasal cavities

The Cranium Parietal Bones Posterior to the frontal bones, located on each side Forms the roof and superior walls of the cranium

The Cranium Occipital Bone Posterior and inferior portions of the cranium Surrounds the foramen magnum (opening that connects the cranial cavity with the spinal cavity)

The Cranium Temporal Bones Lie below the parietal bones and contribute to the sides and base of the cranium

The Cranium Sphenoid Bone Forms part of the floor of the cranium Unites the cranial and facial bones “Bat” shaped Contains sphenoidal sinuses

The Cranium Ethmoid Bone Consists of two “honeycombed” masses of bone Forms part of the cranial floor Two projections Superior conchae Middle conchae

The Skull Zygomatic Bones Found on both sides of the face Bone curves laterally to form the cheek bone Forms lateral walls of the orbits Figure 6-14

The Skull Mandible Bone of the lower jaw Articulates with the temporal bone at the mandibular fossa Mobile

The Skull Maxillary Bone Articulates will all bones of the face, except the mandible Forms: The floor and medial portions of the rims of the orbits The walls of the nasal cavity The anterior roof of the mouth Figure 6-14

The Skull Nasal Articulate with the frontal bone and maxillary bone Form a bridge midway between the orbits Figure 6-14

The Skull Lacrimal Bones Located within the orbits, on the medial surfaces Articulate with the frontal, ethmoid, and maxillary bones Provide a passageway for the lacrimal (tear) ducts Figure 6-14

The Skull Palatine Bone Paired bones of the bony (hard) palate Roof of the mouth Contribute to the floor of the nasal cavity Figure 6-14

The Skull Foramen Magnum Connects the cranial cavity with the spinal cavity The spinal cord passes through this opening and connects to the inferior portion of the brain Figure 6-14

Review… Figure 5.7

Review… Figure 5.11

Review… Figure 5.9