The Skeletal System

The Skeletal System 206 bones in adult human (about 300 in babies) Functions of the skeleton Support Protection for internal organs (heart, brain, lungs, etc) Provides movement Stores minerals (calcium) Site of attachment for muscles Site of blood cell formation (from bone marrow)

Two Parts of a Skeleton Axial and appendicular skeleton Axial skeleton – supports central part of body and consists of skull, vertebral column (backbone), and rib cage Appendicular skeleton – limbs – consists of arms, legs, shoulders, and pelvis (hip)

Appendicular Skeleton The Skeleton Skull Sternum Ribs Vertebral column Axial Skeleton Appendicular Skeleton Metatarsals Metacarpals Phalanges Clavicle Scapula Humerus Radius Pelvis Ulna Carpals Femur Patella Fibula Tibia Tarsals

The Male Skeleton vs. Female Skeleton

Types of Bone Joints Place where one bone attaches to another is a joint Some joints allow extensive movement (shoulder), while others are fixed (skull) Three types of bone joints Immovable – fixed joints allowing no movement and the bones may be interlocked (skull) Slightly movable – small amount of restricted movement (backbone) Freely movable – allow movement in one or more directions and there are four types of freely movable joints

Types of Freely Movable Joints Ball and socket – circular movement (leg and arm) Hinge – back and forth movement (elbow and knee) Pivot – one bone rotates around another (lower arm) Saddle – one bone slides in two directions (thumb/hand)

Freely Movable Joints Ball-and-Socket Joint Pivot Joint Hinge Joint Clavicle Ball-and-socket joint Scapula Humerus Humerus Radius Pivot joint Ulna Hinge Joint Femur Patella Hinge joint Tibia Fibula Metacarpals Carpals Saddle joint

Structure of A Knee Joint Muscle Tendon Femur Patella Bursa Ligament Synovial fluid Cartilage Fat Fibula Tibia

Structure of Bone Joints Connective tissue called a ligament holds bones together at a joint Arthritis is an inflammation of a joint

Structure of Bones Bones are living tissue made of living cells and protein surrounded by calcium Bone is surrounded by tough layer of connective tissue called periosteum Blood vessels in bone carry oxygen and nutrients to bone

Types of Bone and Marrow Two types of bone – compact and spongy Compact bone – dense bone Spongy bone – less dense, but very strong and adds strength, but not mass Bone marrow is within cavities of bone and there are two types Yellow bone marrow – made up of fat cells Red bone marrow – produces red blood cells, some white blood cells, and platelets

The Structure of Bone Cartilage Spongy bone (contains red bone marrow) Figure 27.28 The Structure of Bone Cartilage Spongy bone (contains red bone marrow) Compact bone Central cavity Yellow bone marrow Fibrous connective tissue Blood vessels Cartilage

Development of Bone When born, most of skeleton is cartilage Cartilage is replaced by bone during bone formation, called ossification When cartilage has been completely replaced, the person “stops growing”