Chapter 6: The Skeletal System

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The Skeletal System Functions of bone and the skeletal system Types of bones Bone formation Exercise and bone tissue Divisions of the skeletal system Skull and hyoid bone Vertebral column Thorax Pectoral (shoulder) girdle Upper limb Pelvic (hip) girdle Lower limb Comparison of female and male skeletons Aging and the skeletal system

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Functions of Bone and the Skeletal System

Support Provides a structural framework for the body

Protection Protects many internal organs from injury

Assistance in movement Provides skeletal muscle attachments

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Functions of Bone and the Skeletal System Mineral homeostasis

Bone tissue stores several minerals, especially calcium and phosphorus

Blood cell production Within certain bones a connective tissue called

red bone marrow produces red blood cells Triglyceride storage

Yellow bone marrow consists mainly of adipose cells, which store triglycerides

Types of Bones Long bones have greater length than width and consist of a shaft and a

variable number of ends. They are usually somewhat curved for strength. Long bones include those in the thigh (femur), leg (tibia and fibula), arm (humerus), forearm (ulna and radius), and fingers and toes (phalanges).

Short bones are somewhat cube-shaped and nearly equal in length and width. Examples of short bones include most wrist and ankle bones.

Flat bones are generally thin, afford considerable protection, and provide extensive surfaces for muscle attachment. Bones classified as flat bones include the cranial bones, which protect the brain; the sternum (breastbone) and ribs, which protect organs in the thorax; and the scapulae (shoulder blades).

Irregular bones have complex shapes and cannot be grouped into any of the previous categories. Such bones include the vertebrae and some facial bones.

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Structureof Bones

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Structure of Bones

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Anatomy Overview:

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• Bone Structure and Tissues

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Animation:

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• Bone Growth and Remodeling

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Bone Formation

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Bone Formation

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Animation:

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• Bone Formation

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Bone Formation – Fractures

A fracture (FRAK-choor) is any break in a bone. Types of fractures include the following: Partial: an incomplete break across the bone, such as

a crack. Complete: a complete break across the bone; that is,

the bone is broken into two or more pieces. Closed (simple): the fractured bone does not break

through the skin. Open (compound): the broken ends of the bone

protrude through the skin.

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Bone Formation – Fractures Repair of a fracture involves several steps

First, phagocytes begin to remove any dead bone tissue

Then, chondroblasts form fibrocartilage at the fracture site that bridges the broken ends of the bone

Next, the fibrocartilage is converted to spongy bone tissue by osteoblasts

Finally, bone remodeling occurs, in which dead portions of bone are absorbed by osteoclasts and spongy bone is converted to compact bone

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Bone Formation

Bone’s role in calcium homeostasis

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Animation:

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• Regulation of Bone Growth & Blood Calcium

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Exercise and Bone Tissue Within limits, bone tissue has the ability to alter its

strength in response to mechanical stress When placed under stress, bone tissue becomes

stronger through increased deposition of mineral salts and production of collagen fibers

Without mechanical stress, bone does not remodel normally because resorption outpaces bone formation

The absence of mechanical stress weakens bone through decreased numbers of collagen fibers and demineralization, loss of bone minerals

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Exercise and Bone Tissue

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Exercise and Bone Tissue

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Animation:

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• Bone Dynamics and Tissue

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Divisions of the Skeletal System

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Divisions of the Skeletal System

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Anatomy Overview:

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• The Skeletal System

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Skull and Hyoid Bone

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Skull and Hyoid Bone

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Skull and Hyoid Bone

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Skull and Hyoid Bone

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Skull and Hyoid Bone

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Skull and Hyoid Bone

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Skull and Hyoid Bone

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Skull and Hyoid Bone

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Skull and Hyoid Bone

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Vertebral Column

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Vertebral Column Cervical

vertebrae

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Thoracic Vertebrae

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Lumbar Vertebrae

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Sacrum and Coccyx

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Vertebral Column Identify the vertebrae

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Thorax

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Pectoral (Shoulder) Girdle

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UpperLimb

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UpperLimb

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UpperLimb

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Pelvic (Hip) Girdle

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Pelvic (Hip) Girdle

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Pelvic (Hip) Girdle

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Lower Limb

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LowerLimb

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LowerLimb

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Lower Limb

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Comparison of Female and Male Skeletons

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Aging and the Skeletal System

End of Chapter 6

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