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The Human Skeletal System
The human skeletal system consists of all the bones and supportive tissues (tissues such as cartilage, tendons and ligaments) of the body. The skeleton acts as a support frame of the body. It protects internal organs from damage and act as a base for attachment for muscles.
The sections below explore how bones come together to make up the human skeletal system.
The Cranium is the supportive structure of the face. Together with the mandible it makes up the skull. The cranium protects the eyes and brain. The Maxilla forms the upper jaw and teeth. The mandible forms the lower jaw.
The clavicle also known as the collarbone connects the arms to the trunk. The scapula also called the shoulder blade connects the upper arm to the clavicle. Humerus is the long bone of the forearm that connects the scapula to the elbow. This forms the upper arm. The ulna is a long bone of the lower arm which runs parallel to the radius. The radius is a long bone of the lower arm which runs parallel to the ulna.
Carpals are 8 short bones that form the wrist. Metacarpals consist of 5 bones located between the carpals and phalanges. Phalanges are bones that form the fingers and toes.
The Sternum is a flat bone of the chest connected to the rib bones. It is also known as the breastbone. Ribs are long curved bones that make up the rib cage. The rib cage protects internal organs of chest. The vertebral Column also known as the spine protects the spinal cord and also acts as a structural support for the body frame.
The pelvis is the bone that connects the spine to the femur. The femur is the thigh bone. The Patella is the kneecap. The Tibia is the larger of two bones of the lower leg. The Fibula is the smaller of two bones of the lower leg.
Tarsals are short bones of the foot that connects the tibia and fibula to the metatarsals. Metatarsals are bones that contact the tarsals and the phalanges.
What are Joints?
In the human skeletal system, joints are where two bones meet and are connected by series of skeletal tissues (muscles, ligaments, tendons and cartilage).
Your bones will all be loose if they were not connected together by tissues and you would have no stability.
Types of Joints in the Body
Skeletal joints can be divided into Immovable joints and Movable joints.
There is only one type of immovable joint called the fixed joint. This type of joint allows for little or no movement. Places in the body where you can find this are the skull and the pelvis. Let’s take a closer look at the skull. Bones of the skull meet at joints which look like cracks. These cracks are known as fissures and these joints show no movement whatsoever. These are just places where bones meet.
Movables joints allow movements. Most joints in the human skeletal system are free movable joints. These joints allow different type of motions that we need to carry out our day to day activities.
- Pivot Joint
The first type of movable joint we are going to look at is the Pivot joint. This occurs where one bone rotates in a ring of a bone that does not move. You can find this in the neck and your forearm. Let’s take a closer look at the pivot joint in the forearm. In the forearm, the radius connects to the humerus through a pivot joint. When you wave at somebody, it is the radius bone that would spin inside a little ring that connects to the humerus.
- Ball and Socket Joint
The next is the ball and socket joint. This joint allows for a wide range of motion. It allows for up and down, left and right, round and round motions. In the ball and socket joint, one bone has a rounded end (ball) that fits into a cup-like cavity (socket) of the other bone. A ball and socket joint can be found in your shoulders and hips. If you take a look at the shoulder, there is the rounded end of the humerus that connects to your shoulder blade (scapula). If you take a closer look, you will see the cup-like indentation of the scapula where the humerus fits into.
- Hinge Joint
The third type is the hinge joint. This allows for back and forth motion or ‘extend and bend’ motion like a door (like the hinges attached to doors which allow doors to open and close). You have hinge joints in your elbows, fingers, jaw and knee. Let’s take a look at the elbow to see how this type of joint work. The base of the humerus sits on the groove at the top of the ulna bone which allows the arm to move up and down for example when bouncing a basketball.
- Gliding Joint
The last joint is called the gliding joint. This is when one part of a bone sides over another bone. This can be found in the wrist, ankle and spine. The wrist is made up of multiple bones and these bones have to slide on one another to enable movement in the wrist area. Gliding joint can also be found between the small bones of your foot and this allows your foot to flex when you walk.
In the Human Skeletal System, some bones allow motion only in a few direction, some allow for a wide range of motion and some do not allow for any type of motion.