Functions of Bones 1. Gives the body its shape 2. Support of the body’s weight 3. Protection of soft organs 4. Movement due to attached skeletal muscles. Joints act as levers. 5. Storage of minerals and fats. Mainly Calcium and Phosphate. 6. Blood cell formation. Red and White blood cells and Platelets are formed in the Red Marrow of Spongy Bone.

Gross Anatomy of a Long Bone A bone is and organ. It is composed of bone, cartilage, fibrous connective, blood and nervous tissue. Diaphysis –Shaft –Composed of compact bone Epiphysis –Ends of the bone. Covered with Hyaline Cartilage where it articulates with another bone. –Composed mostly of spongy bone

Structures of a Long Bone Periosteum –Outside covering of the diaphysis –Fibrous connective tissue membrane Sharpey’s fibers –Secure periosteum to underlying bone Arteries –Supply bone cells with nutrients

Medullary cavity Cavity of the shaft –Lined with epithelial cells called the Endosteum –Contains yellow marrow (mostly fat) in adults –Contains red marrow (for blood cell formation) in infants Articular cartilage –Covers the external surface of the epiphyses –Made of hyaline cartilage –Decreases friction at joint surfaces

Types of Bone Cells Osteocytes –Mature bone cells Osteoblasts –Bone-forming cells. –Stores Calcium in bones when level in blood is high Osteoclasts –Bone-destroying cells –Break down bone matrix for remodeling and release of calcium when level in blood is low. Bone remodeling is a process by both osteoblasts and osteoclasts

Human Bone Development In embryos, the skeleton is primarily Hyaline Cartilage (endochondral bones) and Fibrous Connective tissues (Intramembranous bones) During development, much of this cartilage and fibrous connective tissue is replaced by bone Cartilage remains in isolated areas –Bridge of the nose –Parts of ribs –Joints

Bone Growth Epiphyseal plates allow for growth of long bone during childhood –New cartilage is continuously formed –Older cartilage becomes ossified Cartilage is broken down Bone replaces cartilage

Long Bone Formation and Growth

Functional Classification of Joints Synarthroses – Immovable joints Amphiarthroses – Slightly movable joints Diarthroses – Freely movable joints

Immovable Joints Bones united by fibrous connective tissue Examples –Sutures of the Skull

Slightly Movable Joints Bones connected by cartilage. Movement limited Examples –Pubic symphysis –Intervertebral disks –Sacroiliac joint Figure 5.27d–e

Freely Movable Joints Articular cartilage (hyaline cartilage) covers the ends of bones Joint surfaces are enclosed by a fibrous articular capsule Have a joint cavity filled with synovial fluid Ligaments reinforce the joint

The Synovial (freely movable) Joint

Types of Synovial Joints Based on Shape

Freely Movable Joints 1. Ball and Socket. –Movement in all planes and rotation. –Examples: Hip, Shoulder 2.Condyloid. Movement in all planes except rotation Examples: Metacarpal – Phalange, Occipital - Atlas 3.Plane Sliding or twisting movements Examples: Carpal-carpal, tarsal-tarsal

4. Hinge –Movement up and down in one plane –Examples: Elbow, Knee, Phalange-Phalange 5.Pivot Movement of rotation only Examples: Proximal ends of the Ulna- Radius, Atlas Axis 6.Saddle Opposition movement Example: Trapezium-Metacarpal of the thumb

Types of Ordinary Body Movements Flexion – Decreases the angle between bones Extension – Increases the angle between bones Hyperextension – Extension beyond 180 o Rotation – Movement of a bone around an axis Abduction – Moving a limb away from the midline Adduction – Movement of a limb toward the midline Circumduction – Movement of a limb in a cone shaped pattern

Body Movements Figure 6.13a–c

Special Movements Dorsiflexion – Pointing the toes upward Plantar flexion – Pointing the toes downward Inversion – Turning the sole medially Eversion – Turning the sole laterally Supination – Rotation of the palm upward Pronation – Rotation of the palm downward Opposition – Touching the fingertips with the thumb