Skeletal System Chapter 32.1

Exo vs Endo External Internal

5 Functions of the Skeletal System 1. Movement: Skeletal system provides points of attachment for muscles. Your legs and arms move when the muscles pull on the bones. 2. Support: The backbone is the main support center for the upper body. It holds your head up and protects your spinal cord. Muscle attached to bones!!

5 Functions of the Skeletal System 3. Protection: The bones of your skull protect your brain. Your ribs protect your lungs and heart from injury. 4. Makes Blood: Red and white blood cells are formed by tissue called marrow, which is in the center of the bone.

5 Functions of the Skeletal System ► 5. Storage: Bones store minerals, such as calcium and phosphorus, for use by the body

Parts of the Skeletal System ► Bones ► Joints ► Ligaments ► Cartilage

BONES Bone Dance Bone Dance

Types of Bone Cells ► Osteocytes  Mature bone cells ► Osteoblasts  Bone-forming cells ► Osteoclasts  Bone-destroying cells  Break down bone matrix for remodeling and release of calcium ► Bone remodeling is a process by both osteoblasts and osteoclasts

Two Major Skeletal System Parts ► Axial Skeleton: includes the skull, spine, ribs and sternum. ► Appendicular Skeleton: includes the appendages of the body, which are the shoulders, arms, hips, and legs.

Classification of Bones on the Basis of Shape Figure 5.1

Bone Structure ► Typical Four Layers:  Periosteum: Covers Bones  Compact Bone: Lies beneath the periosteum  Spongy Bone: Lies beneath the compact bone  Bone Marrow: Fills the gaps between the spongy bone

Structure of Bones Within many bones are cavities that contain a soft tissue called bone marrow.bone marrow Bone Marrow Donation Video Yellow marrow consists primarily of cells that store fat. Red marrow contains stem cells that produce most types of blood cells.

Bones of the Cranium ► Some are thicker than others!!! than others!!!

Cranium Bones Frontal Bone Occipital Bone Temporal Bone Parietal Bone

Maxilla and Mandible Maxilla Mandible ?

Clavicle or Collarbone ► The clavicle, or collar bone, holds the shoulder joint away from the rest of the upper body and is only as thick as your little finger.

Rib Cage

Scapula ► The scapula is located on the back side of the ribcage and helps provide part of the shoulder joint and movement for the arms.

Vertebral Column or Spinal Cord 1) The cervical region (neck bones) 1) The cervical region (neck bones) 2) The thorasic region (what the ribs attach to) 3) The lumbar region (the lower part of the back) 3) The lumbar region (the lower part of the back)

Coccyx and Sacrum

Humerus (Upper Arm Bone)

Radius and Ulna ► Radius on Top ► Ulna on Bottom

Carpals or (Wrist Bones)

Metacarpals (Top of Hands)

Phalanges (Little Fingers)

Sternum (Breastbone)

Pelvis

Gender Differences of the Pelvis ► Used in forensics to determine sex of an individual ► Females have a wider pubic arch ► WHY? Figure 5.23c

Femur (Largest Bone in the Body)

The Tibia and Fibula

Tarsals

Metatarsals

Phalanges

Calcaneous

Joints Functions of joints  Hold bones together  Allow for mobility

Joints A place where one or more bones meet another bone is called a joint. Joints contain connective tissues that hold bones together. Joints permit bones to move without damaging each other.

Joints of the Body ► Ball and Socket Joint: Round end of bone fitting snuggly within another bone.  Ex. Shoulder and Hip

Joints of the Body ► Hinge Joint: Movement at joint in one direction like a door.  Ex. Knee and Elbow

Joints of the Body ► Pivot Joint: Bone resting atop another bone permitting free movement.  Ex. Neck, Wrist and Ankles

Joints of the Body ► Fixed Immovable: Joint does not move  Ex. Skull ► Gliding Joint: Bones slipping over other bones with a free flowing movement.  Ex. Knuckles

Ligaments

The Connectors of the Body ► Ligaments: Connect bone to bone

The Connectors of the Body!! ► Tendon: Attaches muscles to bones

Cartilage

The Connectors of the Body ► Cartilage: It acts as a cushion between bones at a joint and protects the bones.

Problems of the Skeletal System ► Fracture: Break ► Dislocation: Out of joint

Fractures

Bone Fractures ► A break in a bone ► Types of bone fractures  Closed (simple) fracture – break that does not penetrate the skin  Open (compound) fracture – broken bone penetrates through the skin ► Bone fractures are treated by reduction and immobilization  Realignment of the bone

Common Types of Fractures Table 5.2

Stages in the Healing of a Bone Fracture Figure 5.5

Problems of the Skeletal System!! ► Scoliosis: Curvature of the spine ► Osteoporosis: Brittle bones

Problems of the Skeletal System ► Sprain: Swelling in the joint ► Arthritis: Inflamed and stiff joints

Skeletal Muscles Skeletal muscles are usually attached to bones. Most skeletal muscle movements are consciously controlled by the central nervous system (the brain and spinal cord).

Skeletal Muscles When viewed under a microscope, skeletal muscle appears to have alternating light and dark bands called “striations.” For this reason, it is said to be striated. Skeletal muscle cells are large, have many nuclei, and vary in length. The smallest skeletal muscle, which is about 1 millimeter long is found in the middle ear. The longest skeletal muscle, which may be as long as 30 centimeters, runs from the hip to the knee. Because skeletal muscle cells are long and slender, they are often called muscle fibers.

How Muscles and Bones Interact Skeletal muscles are joined to bones by tough connective tissues called tendons. Tendons pull on the bones and make them work like levers. The joint functions as a fulcrum—the fixed point around which the lever moves. The muscles provide the force to move the lever.

How Muscles and Bones Interact Most skeletal muscles work in opposing pairs—when one muscle contracts, the other relaxes.

 There are 350 bones in your body when you are a baby, but there are 206 bones in your body when you are an adult  Half of your bones are in your hands and feet  Your bones are made of bone marrow, which is where red and white blood cells come from Fun Amazing Facts

 The longest bone in your body is your femur. It is 18 1/2 inches long when you are an adult.  The smallest bone in your body is located in your ear  There are 230 joints in your body.  There are 27 bones in your hand.  Your face has 14 bones in it.  There are 6 bones in your pelvis More Amazing Facts

 Your leg is the fastest growing bone in your body  There are a total of 22 bones in your skull and 26 bones in your spine.  The hardest part of the bone is the outer part  An adult’s rib cage has 12 ribs  A giraffe has the same amount of bones in its neck as you have in your neck. Its neck is just longer. Even More Amazing Facts About the Human Body