Skeletal System

The skeletal system is made up of 206 bones. When you were born you had over 300 bones. As you grew, some of these bones began to fuse together.

4 Function of Bones Gives structure - your body without bones would just be a beanbag Protections - bones protect the brain, heart, lungs and other major organs Supply important minerals, such as calcium and phosphorus Blood cell production

Structure of Bones Periosteum- is a strong outside layer of the bone. Compact Bone- is under the periosteum, it is a hard layer of tissue, as bones grow larger, the compact bone gets thicker.

Structure of Bones Haversian system- the network of blood vessels that runs through canals in the compact bone Spongy bone- forms many cavities, the cavities provide strength for bearing weight, cushioning, and works as shock absorbers for the rest of the bone. Red bone marrow- is contained inside the spongy bone, and is a tissue that makes red blood cells and some white blood cells.

Parts of The Skeleton The skeleton is divided into two major divisions: 1.The Axial Skeleton 2. The Appendicular Skeleton

The Axial Skeleton The Axial Skeleton- Bones of the skull, the chest, and the spine, protects the body’s vital organs: the brain, spinal cord, heart, and lungs. The Skull: Contains 28 bones (A)Cranium- part of the skull that protects your brain, 8 bones fit together to make the cranium. Suture- connects the bones together. In babies the sutures are not fully formed to allow birth and we call them soft spots.

The Axial Skeleton 4 Major Bones of the head: Frontal Bone- forehead Parietal Bone- upper side of the head Temporal Bone- side of head (temple and ears) Occipital Bone- Back of the head

The Axial Skeleton Spine (back): (1)Vertebrae- 33 small bones along your back, protects the spinal cord. Between each vertebrae is cartilage disks that acts a cushion to absorb shock. Divides into 5 different parts: Cervical- 7 vertebrae, neck, holds up head. Thoracic- 12 vertebrae, upper back, support the chest. Lumbar- 5 vertebrae, lower back, most weight bearing area of the body. (6)Sacrum- 5 vertebrae, hip area, joined to the hip on either side. (7)Coccyx- 3-5 fused vertebrae, (4), also called the tailbone.

The Axial Skeleton Chest: (10)Sternum- Flat bone in the middle of the chest, is an anchor for the ribs, and protects the heart. (11)Ribs- 12 pair of ribs True ribs-1-7 False ribs Floating ribs

The Appendicular Skeleton The appendages, or limbs, that connect to the axial skeleton, made up of 126 bones include the hips, legs, feet, shoulders, arms, and hands.

The Appendicular Skeleton Pectoral girdle (9)clavicle: collar bone; keeps shoulders apart. (2)scapula: shoulder blade; flat bone.

The Appendicular Skeleton Arms (3)Humerus- a long bone in the arm that runs from the shoulder to the elbow. On a skeleton, it fits between the scapula and the radius and ulna. (5)Ulna- a long bone, placed at the medial side of the forearm, parallel with the radius. (4)Radius- the bone of the forearm that extends from the inside of the elbow to the thumb side of the wrist.

The Appendicular Skeleton Hands (13)Carpals- 8 bones, in two rows make up the carpals or the wrist. (14)Metacarpals(5 bones) - palm (15)Phalanges(14 bones) - fingers

The Appendicular Skeleton (12)Pelvis- is the bony structure located at the base of the spine. The pelvis incorporates the socket portion of the hip joint for each leg. Female: is broad and shallow, with a large opening to allow a baby to pass through during birth. Male: is narrow and deep, with a small opening.

The Appendicular Skeleton Leg (16)Femur- is the biggest, strongest, and heaviest bone in your body (because it supports the weight of the upper body). (18)Tibia- the larger of the two bones in the leg below the knee. (19)Fibula- is the bone placed on the lateral side of the tibia, with which it is connected above and below. It is the smaller of the two bones. (17)Patella- knee cap

The Appendicular Skeleton Foot (8)Tarsals (7 bones that make up the ankle) (20)Metatarsals (5 bones that make up foot) (21)Phalanges(14 bones) - toes

Connections Ligaments- thick cords of white fiber that binds bones to one another. Tendons- are bands of white fibers that connect muscles to bone. Joints- place at which two bones meet, about 400 in body.

Types of Joints (3) 1. Fibrous (Immovable)- does not move (skull-sutures, sacrum, coccyx, pelvis) 2. Cartilaginous (Partially Moveable)- vertebrae, ribs to vertebrae

3. Synovial (Freely Movable) 6 (22)Ball and Socket- (hip/shoulder) (23)Hinge- swings back and forth (elbows/knees) (24)Pivot- one bone rotates around another (ulna-radius) (25)Gliding- allows bones to slide over one another (intertarsal/intercarpal) (26)Condyloid or Ellipsoid- are similar to a ball and socket joint. They allow the same type of movement to a lesser magnitude. (wrist) (27)Saddle- A saddle joint allows movement back and forth and up and down, but does not allow for rotation like a ball and socket joint. (thumb)