Carpals in the hand and tarsals in the feet are examples of short bones. The outside of a long bone consists of a layer of compact bone surrounding spongy bone. Inside a long bone is a medullary cavity filled with yellow bone marrow. Red bone marrow is soft tissue located in networks of spongy bone tissue inside some bones.
In adults the red marrow in bones of the cranium, vertebrae, scapulae, sternum, ribs, pelvis, and at the epiphyseal ends of the large long bones produce blood cells. One way to classify joints is by range of motion. Immovable joints include the sutures of the skull, the articulations between teeth and the mandible, and the joint located between the first pair of ribs and the sternum.
Some joints have slight movement; an example is the distal joint between the tibia and fibula. Joints that allow a lot of motion think of the shoulder, wrist, hip, and ankle are located in the upper and lower limbs.
An infant skeleton has almost a hundred more bones than the skeleton of an adult. Bone formation begins at about three months gestation and continues after birth into adulthood.
An example of several bones that fuse over time into one bone is the sacrum. At birth the sacrum is five vertebrae with discs in between them. The sacrum is fully fused into one bone usually by the fourth decade of life.
See more from our free eBook library. It opens and closes to let you talk and chew food. Your skull is pretty cool, but it's changed since you were a baby. All babies are born with spaces between the bones in their skulls. This allows the bones to move, close up, and even overlap as the baby goes through the birth canal. As the baby grows, the space between the bones slowly closes up and disappears, and special joints called sutures say: SOO-churs connect the bones. As you sit and type at the keyboard, while you swing on a swing, even when you pick up your lunch, you're using the bones in your fingers, hand, wrist, and arm.
Each arm is attached to a shoulder blade or scapula say: SKA-pyuh-luh , a large triangular bone on the upper back corner of each side of the ribcage. The arm is made up of three bones: the humerus say: HYOO-muh-rus , which is above your elbow, and the radius say: RAY-dee-us and ulna say: UL-nuh , which are below the elbow. Each of these bones is wider at the ends and skinnier in the middle, to help give it strength where it meets another bone.
At the end of the radius and ulna are eight smaller bones that make up your wrist. Although these bones are small, they can really move! Twist your wrist around or wave and you'll see how the wrist can move. The center part of your hand is made up of five separate bones. Each finger on your hand has three bones, except for your thumb, which has two. So between your wrists, hands, and all your fingers, you've got a grand total of 54 bones — all ready to help you grasp things, write your name, pick up the phone, or throw a softball!
Sure, your arm, wrist, hand, and finger bones are great for picking up the phone, but how are you supposed to run to answer it? Well, with the bones of the legs and feet! Your legs are attached to a circular group of bones called your pelvis. The pelvis is a bowl-shaped structure that supports the spine. It is made up of the two large hip bones in front, and behind are the sacrum and the coccyx. The pelvis acts as a tough ring of protection around parts of the digestive system, parts of the urinary system, and parts of the reproductive system.
Your leg bones are very large and strong to help support the weight of your body. The bone that goes from your pelvis to your knee is called the femur say: FEE-mur , and it's the longest bone in your body.
At the knee, there's a triangular-shaped bone called the patella say: puh-TEL-luh , or kneecap, that protects the knee joint.
Just like the three bones in the arm, the three bones in the leg are wider at the ends than in the middle to give them strength. The ankle is a bit different from the wrist; it is where the lower leg bones connect to a large bone in the foot called the talus say: TAL-iss. Next to the talus are six other bones. But the main part of the foot is similar to the hand, with five bones.
Each toe has three tiny bones, except for your big toe, which has just two. This brings the bone total in both feet and ankles to 52! Most people don't use their toes and feet for grabbing stuff or writing, but they do use them for two very important things: standing and walking. Without all the bones of the foot working together, it would be impossible to balance properly.
The bones in the feet are arranged so the foot is almost flat and a bit wide, to help you stay upright. So the next time you're walking, be sure to look down and thank those toes! Fixed joints are fixed in place and don't move at all. Your skull has some of these joints called sutures, remember? The carpals in the wrist scaphoid, lunate, triquetral, hamate, pisiform, capitate, trapezoid, and trapezium and the tarsals in the ankles calcaneus, talus, navicular, cuboid, lateral cuneiform, intermediate cuneiform, and medial cuneiform are examples of short bones.
Irregular bones vary in shape and structure and therefore do not fit into any other category flat, short, long, or sesamoid. They often have a fairly complex shape, which helps protect internal organs. For example, the vertebrae, irregular bones of the vertebral column, protect the spinal cord. The irregular bones of the pelvis pubis, ilium, and ischium protect organs in the pelvic cavity. Sesamoid bones are bones embedded in tendons.
These small, round bones are commonly found in the tendons of the hands, knees, and feet. Sesamoid bones function to protect tendons from stress and wear. The patella, commonly referred to as the kneecap, is an example of a sesamoid bone. See more from our free eBook library. A description of types of bones from the edition of Gray's Anatomy of the Human Body.
Actions for this page Listen Print. Summary Read the full fact sheet. On this page. The skeleton The human skeleton is made up of bones, including bones of the: Skull — including the jaw bone Spine — cervical, thoracic and lumbar vertebrae, sacrum and tailbone coccyx Chest — ribs and breastbone sternum Arms — shoulder blade scapula , collar bone clavicle , humerus, radius and ulna Hands — wrist bones carpals , metacarpals and phalanges Pelvis — hip bones Legs — thigh bone femur , kneecap patella , shin bone tibia and fibula Feet — tarsals, metatarsals and phalanges.
Bone types There are four different types of bone in the human body: Long bone — has a long, thin shape. Examples include the bones of the arms and legs excluding the wrists, ankles and kneecaps. With the help of muscles, long bones work as levers to permit movement. Short bone — has a squat, cubed shape. Examples include the bones that make up the wrists and the ankles. Flat bone — has a flattened, broad surface.
Examples include ribs, shoulder blades, breast bone and skull bones. Irregular bone — has a shape that does not conform to the above three types. Examples include the bones of the spine vertebrae. Bone tissue The different layers of bone tissue include: Periosteum — the dense, tough outer shell that contains blood vessels and nerves Compact or dense tissue — the hard, smooth layer that protects the tissue within Spongy or cancellous tissue — the porous, honeycombed material found inside most bones, which allows the bone to be strong yet lightweight Bone marrow — the jelly-like substance found inside the cavities of some bones including the pelvis that produces blood cells.
Bone marrow Bone marrow is where blood cells are made.
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