Skeletal System

Learning Objectives Define terms relating to the skeletal system Describe the five functions of the skeletal system Identify at least 10 structures of the skeletal system Identify methods of assessment of the skeletal system Describe disorders of the skeletal system

Bones Inorganic salts (calcium phosphate) Water Organic material Bone tissue is composed of: Inorganic salts (calcium phosphate) Water Organic material (bone cells, blood vessels, nerves, and collagen) Bone cells must continually receive food and oxygen Bones continue to grow for the first 18 to 20 years of life Bone cells die and are replaced by new ones

Bones (Cont.) Bones may have cartilage - fibrous connective tissue / prevents friction Bones are attached to other bones by ligaments Bones are joined to muscles by tendons Two major types of bone tissue: Compact – dense Cancellous – spongy / loosely packed

Common Skeletal Bones

Types of Bones Two major groups of bones: Axial skeleton Includes 80 bones of the head & trunk Appendicular skeleton Includes 126 bones of the pelvis, shoulders, arms, and legs

Bones by Shapes Bones are also classified by shape: Long bones – longer than wide Short bones – have similar length and width Flat bones – have two layers with space between them Irregular bones – all bones that do not fit in the other categories

Skull Cranium Eight bones Includes bones of the: Cranium Eight bones At birth, bones of the cranium have two openings (fontanels) which close by age 2 Face 14 bones Ear The mandible (lower jaw) is the only movable bone of the skull

Teeth Adult has 32 teeth Each tooth has parts: Crown is the white section above the gum Root is below the gum Enamel, the hardest substance in the body, covers the crown Cementum is the hard, bonelike substance covering the root Dentin is located between the enamel and the pulp Pulp is the soft living portion of the tooth, containing the nerves and blood vessels

Parts of a Tooth

Types of Teeth Four major types of teeth (each have different shape and function): Incisor Cuspid Bicuspid Molar

Table 13-3 Teeth Types

Tooth Development

Thorax Thorax protects the heart & lungs and includes: Ribs 7 pair of “true” ribs – attached to sternum 5 pair of “false” ribs – not attached directly to sternum, costal cartilage of each false rib attaches to the rib above it 2 pair of “floating” ribs – attach only to spine Sternum Vertebral bones

Vertebral Column * Consists of five parts (total of 26 vertebrae): Cervical vertebrae (7 vertebrae) Thoracic vertebrae (12 vertebrae) Lumbar vertebrae (5 vertebrae) Sacrum Coccyx * Curvature gives it strength and flexibility * Cartilage between vertebrae cushions bones and allows movement

Vertebral Column

Long Bones of the Extremities Long bones of the arms and legs contain marrow Makes blood cells for the body Long bones grow and lengthen from a layer of cartilage (epiphyseal plate) Shaft of the long bone (diaphysis) contains fatty tissue and yellow marrow Fatty tissue provides stored energy

Long Bones of the Extremities (Cont) End of the long bone (epiphysis) contains red marrow that produces red blood cells Red marrow destroys old red blood cells, forms white blood cells, and produces platelets Periosteum (membrane) Covers the bone Contains osteoblasts Medullary cavity Contains osteoclasts which enlarge the diameter of the cavity by removing bone cells

Anatomy of a Long Bone

Bone Markings Four major types of bone markings: Projections bulge from a bone and attach to muscles, ligaments, and tendons Openings are holes or spaces in bones Depressions include openings and cavities in bone Ridges are lines on a bone surface

Joints Articulation Two or more bones join together at a joint Joints are named by the bones that are joined

Types of Joints Three types of joints: Immovable (synarthrosis) Example: sutures of the cranium Slightly movable (amphiarthrosis) Bones of the pelvis Freely movable (diarthrosis)

Types of Diarthrosis Joints Ball and socket joints of the shoulders and hips Hinge joints of the elbow and knee Gliding joints of the wrists Pivot joint at the base of the skull Saddle joint of the thumb Gomphosis, such as the attachment of a tooth in its socket in the jaw

Types of Joints (Cont.) A. Ball & Socket (shoulder/Hips) B. Hinge (elbow/knee) C. Gliding (wrist) D. Pivot (base of skull) E. Saddle (thumb) F. Gomphosis (tooth in socket)

Assessment Techniques of the Skeletal System

Assessment Techniques Bone x-rays Bone marrow aspiration Bone marrow biopsy Radionuclide bone scan Computed axial tomography (CAT) Magnetic resonance imaging (MRI) Bone densitometry

X-Ray Use electromagnetic energy that is absorbed by the body’s tissues to produce images on photographic film X-ray machines may be portable or stationary Can determine fractures, tumors, infection, arthritis, deformities, and bone age Painless Minimal risk Less sensitive than a bone scan in detecting bone destruction

Bone Marrow Aspiration Insertion of a long needle into the bone to remove marrow Used to determine cause of blood disorders, some Cancers, chromosome abnormalities May be performed in hospital or outpatient setting Local anesthesia is used to ease discomfort

Bone Marrow Biopsy Used to obtain a piece of bone with intact marrow to identify abnormalities Similar to Aspiration except that a core of the bone is removed for examination

Radionuclide Bone Scan Also known as bone scintigraphy Used to detect bone cancer when X-rays do not show abnormalities but malignancy is suspected May also be used to locate bone infections Stress fx that do not show on X-rays may be seen Involves injection of the radionuclide, which spreads through the bone Increased concentration of the material indicates a diseased area

Computerized Tomography CAT scan or CT scan Several beams of X-rays are sent simultaneously from different angles A computer determines relative density of the tissue examined by the strength of the beams May be used to picture every part of the body

Magnetic Resonance Imaging MRI Uses magnetic and radio waves to show computerized images of the body No exposure to x-rays or other damaging forms of radiation Very detailed – best technique to identify tumors in the brain Also used to examine heart, blood vessels, joints, spine, and sometimes soft parts of the body such as the liver, kidneys, and spleen

Bone Densitometry Measures bone mass density to determine the extent of osteoporosis and fracture risk