They contain active tissues that consume nutrients, require a blood supply and change shape or remodel in response to variations in mechanical stress. Bones provide a rigid framework, known as the skeleton , that support and protect the soft organs of the body. The skeleton supports the body against the pull of gravity. The large bones of the lower limbs support the trunk when standing. The skeleton also protects the soft body parts. There are four main types of cells within bones: Osteoblasts, osteocytes, osteoclasts and lining cells, according to the NCBI.
Osteoblasts are cells that create new or repair existing bone material as the bones grow or break. The cells create a flexible material called osteoid and then fortify it with minerals to harden and strengthen it. When osteoblasts successfully finish their job, they retire to become osteocytes or lining cells.
Osteocytes, found in the compact bone, are responsible for exchanging minerals and communicating with other cells in the vicinity. They are formed from old osteoblasts that have gotten stuck in the center of bones. Osteoclasts break down existing bone material and reabsorb it.
These cells often work with osteoblasts to heal and reshape bone after a break the osteoclasts break down the extra callus formed by the healing process to make room for new blood vessels and nerves and to make bones thicker and stronger. Lining cells are flat bone cells that completely cover the outside surface of bones. Their primary function is controlling the movement of minerals, cells and other materials into and out of the bones.
Muscles move body parts by contracting and then relaxing. Muscles can pull bones, but they can't push them back to the original position. So they work in pairs of flexors and extensors. The flexor contracts to bend a limb at a joint. Then, when the movement is completed, the flexor relaxes and the extensor contracts to extend or straighten the limb at the same joint. For example, the biceps muscle, in the front of the upper arm, is a flexor, and the triceps, at the back of the upper arm, is an extensor.
When you bend at your elbow, the biceps contracts. Then the biceps relaxes and the triceps contracts to straighten the elbow. Joints are where two bones meet. They make the skeleton flexible — without them, movement would be impossible. Joints allow our bodies to move in many ways.
Some joints open and close like a hinge such as knees and elbows , whereas others allow for more complicated movement — a shoulder or hip joint, for example, allows for backward, forward, sideways, and rotating movement.
Reviewed by: KidsHealth Medical Experts. Larger text size Large text size Regular text size. Bones are made up of two types of bone tissues: Compact bone is the solid, hard outside part of the bone. It looks like ivory and is extremely strong. Holes and channels run through it, carrying blood vessels and nerves. Cancellous pronounced: KAN-suh-lus bone , which looks like a sponge, is inside compact bone. It is made up of a mesh-like network of tiny pieces of bone called trabeculae pronounced: truh-BEH-kyoo-lee.
This is where bone marrow is found. How Do Bones Grow? The quadratus plantae is a muscle in the foot that extends from the anterior front of the calcaneus heel bone to the tendons of the digitorum….
The depressor labii inferioris muscle is a four-sided facial muscle located in the jaw area that draws the lower lip down and to the side. The muscles of the face give it general form and contour, help you outwardly express your feelings, and enable you to chew your food.
The quadriceps femoris is a group of muscles located in the front of the thigh. The Latin translation of 'quadriceps' is 'four headed,' as the group…. The palmaris brevis muscle lies just underneath the skin.
It is a short muscle on the flat of the hand. The muscle begins at the flexor retinaculum in…. The movement of the upper arm and shoulder is controlled by a group of four muscles that make up the rotator cuff. The largest and strongest muscle in…. The extensor pollicis longus muscle begins at the ulna and the interosseous membrane, a tough fibrous tissue that connects the ulna and the radius in….
The biceps brachii, sometimes known simply as the biceps, is a skeletal muscle that is involved in the movement of the elbow and shoulder. It is a…. The jejunum is one of three sections that make up the small intestine. Learn about its function and anatomy, as well as the conditions that can affect….
Health Conditions Discover Plan Connect. Skeletal System Overview. Medically reviewed by William Morrison, M. Axial skeleton anatomy. Skull bones The adult skull comprises 22 bones. These bones can be further classified by location: Cranial bones. The eight cranial bones form the bulk of your skull. They help to protect your brain. Facial bones. There are 14 facial bones.
Auditory ossicles The auditory ossicles are six small bones found within the inner ear canal in the skull. There are three auditory ossicles on each side of the head, known as the: malleus hammer incus anvil stapes stirrup They work together to transmit sound waves from the surrounding environment to the structures of the inner ear.
Hyoid The hyoid is a U-shaped bone found at the base of the jaw. Vertebral column The vertebral column is made up 26 bones. The 24 vertebrae can be further divided into the: Cervical vertebrae.
These seven bones are found in the head and neck. Thoracic vertebrae. These 12 bones are found in the upper back. Lumbar vertebrae.
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