The skeletal system

The Skeletal SystemII-Aristotle

Introduction

The human skeletal system is made up of bones, the joints where bones meet, and the connective tissues that hold the bones together. The skeletal systerm is a living framework for the body.

BonesThe human skeleton is made up of 206 bones. A vertebrae skeleton can be divided into two parts: the axial and appendicular skeletons. Each bon of the skeleton is adapted for its function by its size and shape. For example, the long bones of the arms and legs support the large muscles that attach to these bones. The small, short bones of the wrists allow flexibility. The flat bones of the skull protect the brain.

Functions

The bones that make up the skeletal system have several functions. Together, the bones of the skeletal system support the body and give it shape. In addition to support, bones also serve the following functions:

Functions:• Bones serve as anchors to which muscles attach.

Without the bones, muscles could not move the body.

• Bones protect internal organs. For example, the skull protects the brain, and the ribs protect the heart, lungs and other organs.

• Bones make blood cells. Cells called stem cells in the red bone marrow develop into red blood cells and white blood cells.

• Bones store minerals, especially calcium and phosphorus, that take part in many biochemical reactions.

Bone Structure:

The outside of a bone, except at the ends where the bones meet, is covered by a membrane called the periosteum (payr-ee-OS-tee-um). Branching through the periosteum are small blood vessels. Blood moving through these vessels carries nutrients to the bone and takes away wastes.

Bone Structure:

Bone is referred to as either spongy or compact. Spongy bone has many spaces. It is found in the ends of long bones and in the middle part of short, flat bones. Compact bone is very dense and has few spaces. The density of compact bone provides support in long bones, such as in the shafts of the bones in the upper arm (humerus) and the upper leg (femur).

Bone Structure:

In the figure, find the large spaces in the spongy bone that contain red bone marrow. Red bone marrow is a material that produces blood cells. Another kind of bone marrow, yellow bone marrow, is mostly made up of fat cells. Yellow bone marrow is most often found in the cavities within the shafts of long bones.

Bone Structure:

Notice the circular channels called Haversian canals in the compact bone. These are spaces through which nerves and blood vessels pass. These canals also make compact bone lighter in mass than they would be if they were solid.

Bone Structure:

Scattered throughout the bone are cells called osteoblasts. Osteoblasts make the new bone cells needed for the growth and repair of the bones. Found in both compact and spongy bone, osteoblasts are concentrated on the inner surface of the periosteum.

Joints

The places where bones meet are called joints. Joints are classified as immovable, slightly movable, or freely movable, depending on their range of motion.

No movement takes place in immovable joints, such as those between the bones of the skull. Slightly movable joints, such as those between the vertebrae, allow a small amount of movement. Most motion takes place in freely movable joints, such as the joints of the shoulder, elbow, and knee.

Joints

Cushions of cartilage in joints keep the ends of the bones from rubbing against each other. Some freely movable joints are also protected by fluid-filled sacs called bursae (singular, bursa). In the figure, find the bursa in the shoulder joint. Bursae absorb the impact of sudded pressure on the joint. Some bursae are present at birth, but others can develop later in life in heavily used joints.

Joints

The bones and muscles of freely movable joints are bound together by bands of tough connective tissues called ligaments and tendons. Ligaments are connective tissues that connect bones to other bones. Tendons are connective tissues that attach muscles to bones.

Joints

There are several kinds of freely movable joints. These joints are classified according to how they move bones. One type is the ball-and socket joint, which is formed by a bone with a ball-shaped end that fits into a bone with a cup-shpaed end. Ball-and-socket joints, such as the hip, allow a wide range of movement.

Joints

Another joint type is the hinge. Hinge joints, such as the knee and elbow, let bones move back and forth like a door opening and closing. A gliding joint, such as that found in the wrist, allows bones to rotate around each other. To see how a pivot joint operates, watch your elbow as you hold your arm out in front of you and pretend to use a screwdriver.

Diseases, Symptoms and TreatmentOsteoarthritis - is a group of mechanical abnormalities involving degradation of joints,

including articular cartilage and subchondral bone.

Diseases, Symptoms and Treatment

Symptoms may include joint pain, tenderness, stiffness, locking, and sometimes an effusion. A variety of causes—hereditary, developmental, metabolic, and mechanical—may initiate processes leading to loss of cartilage. When bone surfaces become less well protected by cartilage, bone may be exposed and damaged. As a result of decreased movement secondary to pain, regional muscles may atrophy, and ligaments may become more lax.

Diseases, Symptoms and TreatmentTreatment generally involves a combination of exercise, lifestyle modification, and analgesics. If pain becomes debilitating, joint replacement surgery may be used to improve the quality of life.

Diseases, Symptoms and TreatmentOsteoporosis - is a disease of bones that leads to an increased risk of fracture. The disease may be classified as primary type 1, primary type 2, or secondary. The form of osteoporosis most common in women after menopause is referred to as primary type 1 or postmenopausal osteoporosis. Primary type 2 osteoporosis or senile osteoporosis occurs after age 75 and is seen in both females and males at a ratio of 2:1

Certain medications have been associated with an increase in osteoporosis risk; only steroids and anticonvulsants are classically associated, but evidence is emerging with regard to other drugs.


Bone Tumor - refers to a neoplastic growth of tissue in bone. Abnormal growths found in the bone can be either benign (noncancerous) or malignant(cancerous).


The most common symptom of bone tumors is pain, which will gradually increase over time. A person may go weeks, months, and sometimes years before they seek help; it depends on the growth of the tumor. Many patients will not experience any symptoms, except for a painless mass. Some bone tumors may weaken the structure of the bone, causing pathologic fractures.


Treatment of bone tumors is highly dependent on the type of tumor.Chemotherapy and radiotherapyChemotherapy and radiotherapy are effective in some tumors (such as Ewing's sarcoma) but less so in others (such as chondrosarcoma). There are a variety of chemotherapy treatment protocols for bone tumors. The protocol with the best reported survival in children and adults is an intra-arterial protocol where tumor response is tracked by serial arteriogram. When tumor response has reached >90% necrosis surgical intervention is planned.


MedicationOne of the major concerns is bone density and bone loss. Non-hormonal bisphosphonates increase bone strength and are available as once-a-week prescription pills. Metastron also known as strontium-89 chloride is an intravenous medication given to help with the pain and can be given in three month intervals. Generic Strontium Chloride Sr-89 Injection UPS, manufactured by Bio-Nucleonics Inc., its the generic version of Metastron.


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The skeletal system

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