The Skeletal System: Structure, Function, and Diseases

The Skeletal System
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Parts of the skeletal system
Bones (skeleton)
Joints
Cartilages
Ligaments (bone to bone)(tendon=bone to muscle)
Divided into two divisions
Axial skeleton- skull, spinal column
Appendicular skeleton – limbs and girdle

Functions of Bones
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Support of the body
Protection of soft organs
Movement due to attached skeletal muscles
Storage of minerals and fats
Blood cell formation

The skeleton has 206 bones
Two basic types of bone tissue
Compact bone
Homogeneous
Spongy bone
Small needle-like
pieces of bone
Many open spaces
Bones of the Human Body
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.2b

Bones are classified by their shape:
Long- bones are longer than they are wide (arms, legs)
Short- usually square in shape, cube like (wrist, ankle)
Flat- flat , curved (skull, Sternum)
Irregular- odd shapes (vertebrae, pelvis)
Sesamoid bones

Classification of Bones on the Basis of Shape
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.1

Types of Bone Cells
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Osteocytes
Mature bone cells
Osteoblasts
Bone-forming cells
Osteoclasts
Bone-destroying cells
Break down bone matrix for remodeling and release of calcium
Bone remodeling is a process by both osteoblasts and osteoclasts

Changes in the Human Skeleton
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
In embryos, the skeleton is primarily hyaline cartilage
During development, much of this cartilage is replaced by bone
Cartilage remains in isolated areas
Bridge of the nose
Parts of ribs
Joints

The Skull
8 sutured bones in cranium
Facial bones: 13 sutured bones 1 mandible
Cranium
encases brain
attachments for muscles
sinuses

Bones of the Skull
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.11

The Vertebral Column
Slide 5.28
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Vertebrae separated by intervertebral discs made of cartilage
The spine has a normal S curvature
Each vertebrae is given a name according to its location
Figure 5.14

Thoracic cage
ribs
thoracic Vertebrae
sternum
costal cartilages
True ribs are directly attached to the sternum
(first seven pairs)
Three false ribs are joined to the 7th rib
Two pairs of floating ribs

Joints
A joint, or articulation, is the place where two bones come together.
Fibrous- Immovable:connect bones, no movement. (skull and pelvis).
Cartilaginous- slightly movable, bones are attached by cartilage, a little movement (spine or ribs).
Synovial- freely movable, much more movement than cartilaginous joints. Cavities between bones are filled with synovial fluid. This fluid helps lubricate and protect the bones.

Types of Joints
Hinge- A hinge joint allows extension and retraction of an appendage. (Elbow, Knee)

Ball and Socket- A ball and socket joint allows for radial movement in almost any direction. They are found in the hips and shoulders. (Hip, Shoulder)

Gliding- In a gliding or plane joint bones slide past each other. Mid-carpal and mid-tarsal joints are gliding joints. (Hands, Feet)

Saddle- This type of joint occurs when the touching surfaces of two bones have both concave and convex regions with the shapes of the two bones complementing one other and allowing a wide range of movement. (Thumb)

Diseases and Conditions
of the Skeletal System

Arthritis

Bursitis
Inflammation of the Bursa (fluid filled sac surrounding the joint).
A bursa can become inflamed from injury, infection (rare in the shoulder), or due to an underlying rheumatic condition.
Bursitis is typically identified by localized pain or swelling, tenderness, and pain with motion of the tissues in the affected area.

Tendonitis
Sometimes the tendons become inflamed for a variety of reasons, and the action of pulling the muscle becomes irritating. If the normal smooth gliding motion of your tendon is impaired, the tendon will become inflamed and movement will become painful. This is called tendonitis, and literally means inflammation of the tendon.
The most common cause of tendonitis is overuse.

Carpal Tunnel Syndrome
Any condition that causes swelling or a change in position of the tissue within the carpal tunnel can squeeze and irritate the median nerve. Irritation of the median nerve in this manner causes tingling and numbness of the thumb, index, and the middle fingers, a condition known as "carpal tunnel syndrome."

Osteoporosis
Osteoporosis is a term that means "porous bones." It is a skeletal disease affecting women and men. Osteoporosis is a condition in which bones have lost minerals especially calciumﾑmaking them weaker, more brittle, and susceptible to fractures (broken bones). Any bone in the body can be affected by osteoporosis, but the most common places where fractures occur are the back (spine), hips, and wrists.

Scoliosis
Scoliosis is an abnormal curvature of the spine. If your child has scoliosis, the view from behind may reveal one or more abnormal curves.Scoliosis runs in families, but doctors often don't know the cause. More girls than boys have severe scoliosis. Adult scoliosis may be a worsening of a condition that began in childhood, but wasn't diagnosed or treated. In other cases, scoliosis may result from a degenerative joint condition in the spine.

Kyphosis
With kyphosis, your spine may look normal or you may develop a hump. Kyphosis can occur as a result of developmental problems; degenerative diseases, such as arthritis of the spine; osteoporosis with compression fractures of the vertebrae; or trauma to the spine. It can affect children, adolescents and adults.

Lordosis
A normal spine, when viewed from behind appears straight. However, a spine affected by lordosis shows evidence of a curvature of the back bones (vertebrae) in the lower back area, giving the child a "swayback" appearance.

Rickets
Rickets is the softening and weakening of bones in children, usually because of an extreme and prolonged vitamin D deficiency.
Some skeletal deformities caused by rickets may need corrective surgery.

Scurvy
The human body lacks the ability to synthesize and make vitamin C and therefore depends on exogenous dietary sources to meet vitamin C needs. Consumption of fruits and vegetables or diets fortified with vitamin C are essential to avoid ascorbic acid deficiency. Even though scurvy is uncommon, it still occurs and can affect adults and children who have chronic dietary vitamin C deficiency.

Gout
Gout is a disease that results from an overload of uric acid in the body. This overload of uric acid leads to the formation of tiny crystals of urate that deposit in tissues of the body, especially the joints. When crystals form in the joints it causes recurring attacks of joint inflammation (arthritis). Chronic gout can also lead to deposits of hard lumps of uric acid in and around the joints and may cause joint destruction, decreased kidney function, and kidney stones.

Acromegaly
Acromegaly is a serious condition that occurs when the body produces too much of the hormones that control growth. ･The hormone most often affected is called growth hormone, or GH. Itﾊis produced by the pituitary gland, a tiny organ at the base of the brain.･･Growth hormoneﾊpromotes growth of bone, cartilage, muscle, organs, and other tissues.･･When there is too much growth hormone in the body, these tissues grow larger than normal. This excessive growth can cause serious disease and even premature death.