The Skeletal System pt 2

The Skeleton

• The skeleton has two main sections: the axial skeleton and the appendicular skeleton.
• The axial skeleton consists of bones of the bony thorax, spinal column, hyoid bone, bones of the middle ear, and skull.
• The bones of the axial skeleton, totaling 80, protect the body organs.
• The appendicular skeleton is made up of bones of the arms, legs, hips, and shoulders, totaling 126 bones.
• Half of all bones can be found in the hands and feet.

The Human Skull

• The skull protects and houses the brain.
• It contains openings to serve sensory organs like the eyes, nose, and ears.
• Fibrous connective tissue allows some flexibility of the bones surrounding the brain.

The Thorax

• Bones of the chest form the thoracic cage.
• It provides support and protection for the heart, lungs, and great blood vessels
• The rib cage is flexible due to cartilaginous connections. These connections allow for movement during breathing.
• The ribs are attached by cartilage to allow their movement during breathing.
• Pairs 1 to 7 of the ribs are called vertebrosternal (true ribs), connecting anteriorly to the sternum and posteriorly to the thoracic vertebrae.
• Rib pairs 8 to 10 are called vertebrocostal (false ribs), connecting to the costal cartilage of the superior rib and to the thoracic vertebrae.
• Rib pairs 11 and 12 are the floating ribs, with no anterior attachment.
• There are a total of 12 pairs of ribs.

The Spinal Column

• The spinal or vertebral column protects the spinal cord.
• The spinal cord acts as a superhighway for information traveling to and from the central nervous system.
• Vertebrae are numbered and classified according to the body region.
• There are 7 cervical vertebrae.
• There are 12 thoracic vertebrae.
• There are 5 lumbar vertebrae.
• There are 5 sacral vertebrae that are located mid-buttocks.
• There are 3 to 5 coccygeal vertebrae that are located in the tailbone.

Upper and Lower Extremities

• The appendicular skeleton (126 bones) consists of pectoral girdles, upper limbs, pelvic girdle (or pelvis), and lower limbs.
• The function of the upper and lower extremities are to enable movement and to protect the major organs of digestion, excretion, and reproduction.
• The arms and legs are similar in construction.

Common Disorders

• Arthritis occurs when joints suffer from inflammation.
• "Arthr/" means "joint," and "itis" indicates "inflammation of."
• There can be many different causes of arthritis.
• Cartilage hardens with age. As a result, joints become less mobile.
• Cartilage hardening can cause a considerable amount of pain in the joint.
• Osteoporosis occurs when, with increasing age, bone starts to break down and becomes more porous.
• Osteoclasts tear down the bone faster than osteoblasts can form bone tissue, leading to decreased bone mass.
• The decrease in bone mass correlates to osteoporosis
• Osteoporosis occurs more in women.
• People with osteoporosis are more at risk for fractures, vertebral column issues, rib/hip issues and wrist issues.

Changes Related to Aging

• Both men and women experience loss of bone density.
• The loss of bone density makes people more prone to fractures and can cause them to develop postural changes.