Skeletal System 300 baby bones 206 adult bones >1/2 in hands & feet Humans & giraffes have same # neck bones Longest bone= femur Smallest bone= inner ear (hammer, anvil, stirrup)

Functions of Skeletal System Support Protection Movement Hematopoiesis Reservoir for minerals and adipose tissue

80 bones 126 bones Skull – 22 bones Vertebral Cranium – 8 Column - 32 Facial - 14 Vertebral Column - 32 Inner ear - 3 Thorax - 27 Iliac crest 80 bones Upper limb – 30 Shoulder girdle - 2 Lower limb – 29 Pelvic girdle – 6 126 bones

Thoracic Cage 27 bones

Vertebral Column 32 bones

Abnormal Spinal Curvatures Lordosis Kyphosis Scoliosis

The Hand 27 bones

The Foot 26 bones

Arches of the Foot

The Skull 22 bones Foramen – For nerves “keystone of cranium” and vessels Ethmoid Ethmoid

Suture - Fibrous joint Process - projection that contacts adjacent bone

Infant Skull closes at 8 wks closes at 9-18 mths Fontanel – space between infant skull bones

Sinus Cavities Sinus: air-filled space

Compact & Spongy Bone

Compact Bone canaliculi

Bone Classification Flat Long Short Irregular Scapula Arms Sternum Ribs Skull Arms Legs Phalanges Short Irregular Wrist Ankle Vertebrate Hip Patella

Anatomy of Long Bones

Anatomy of Short, Flat & Irregular Bones

Osteon Structural and functional unit of bone Haversion Canal Allows passage of blood vessels, lymphatic vessels, and nerve fibers Lamella Concentric rings of collagen fibers around haversion canal Allows bone to withstand force Lacunae Small cavities occupied by osteocytes that join lamella Canaliculi Hairlike canals that join lacunae to each other and the central canal Allow osteocytes to exchange nutrients, wastes, and chemical signals via gap junctions

Type of Cells in Bone Osteoblast Osteocytes Osteoclasts Build bone cells Synthesize and secrete organic components of bone matrix Initiate calcification Found in periosteum and endosteum Osteocytes Mature bone cells Formed when osteoblasts get trapped in matrix Do not secrete matrix Maintain bone tissue Osteoclasts Bone resorption (digest/break down matrix): part of normal bone growth, development, maintenance and repair Found in endosteum

Bone Matrix Organic components (1/3) Inorganic components (2/3) Collagen fibers Provide resilience against stretching and twisting Inorganic components (2/3) Mg, F, Na Salts that interact to form hydroxyapatite Calcium phosphate Calcium hydroxide Provide hardness and resist compression

Types of Tissue in Bone Connective Nervous Osseous Dense fibrous Adipose Vascular Lymphatic Nervous

Hyoid Bone A single bone in the neck. It is U shaped and can be felt just above the larynx. The tongue muscle & certain muscles on the floor of the mouth attach to the hyoid bone. This is the only bone in the body that doesn’t attach to any other bones.

Appendicular Skeleton Pelvic Girdle- Stable, circular base that supports the trunk and the lower extremities are connected to it. Early in life it is made up of three separate bones. Later they fuse into a single, massive irregular bone that is broader than any other bone in the body. Ilium Ischium Pubis

Appendicular Skeleton Pelvic Outlet- The digestive tract empties. The female reproductive tract passes here. During delivery the baby will pass through the pelvic outlet so the baby’s head must be positioned correctly. Prior to delivery the symphysis pubis softens to expand for the baby’s head. Sometimes the coccyx bone breaks during labor.

Appendicular Skeleton Femur- Thigh bone. Longest and heaviest bones in the body. Patella- kneecap. When the knee joint is extended, you can see the patella through the skin, but as the knee flexes, it sinks and can’t be distinguished. Tibia- larger, stronger bone in front Fibula- smaller and deeper into leg

Appendicular Skeleton Foot-Bones form springy lengthwise & crosswise arches that give it more strength. Strong ligaments and tendons hold the arches in position. If they weaken, the arches can flatten causing fallen arches or flat feet. High heels are bad for these arches.

Skeletal Differences in Men & Women Male skeletons are larger & heavier. The pelvic bones are shaped differently. It is wider in women.

Bone Fractures Open Fracture- (compound) broken bone projects through the surrounding tissue and skin. Closed Fracture- (simple) doesn’t break the skin & no immediate danger of infection.

Bone Fractures Incomplete Fracture- partial break in which bone fragments are still partially joined. Complete Fracture- breaks across the entire section of bone.

Bone Fractures Greenstick fracture- bone is bent on one side and the other side is broken. Usually seen in kids because their bones are less brittle. Denate fracture- fragmented ends of the bone being jagged, fitting together like teeth on a gear.

Bone Fractures Linear fracture- fracture line is parallel to the bone’s long axis. Transverse fracture- fracture is at a right angle to the bones axis. Oblique- fracture is slanted, or diagonal

Skeletal Disorders Osteomalacia “soft bones” Lacking minerals (ie. Calcium, vit D) Rickets Child form of osteomalacia More detrimental since bones are still growing Signs: bowed legs; deformities of pelvis, ribs and skull Osteomyelitis “bone marrow inflammation” Caused by pus-forming bacteria that enter via wound or nearby infection Osteoporosis Bone degradation occurs faster than bone can be deposited Decrease in bone mass Porous bones Fractures in the vertebrate and femur are common Most common postmenopause: rapid decline in estrogen (stimulates osteoblasts and inhibits osteoclasts

Skeletal Disorders Giantism Acromegaly Pituitary Dwarfism Childhood hypersecretion of GH Excessive growth Acromegaly Adult hypersecretion of GH Overgrowth of face, feet, hands Pituitary Dwarfism Childhood deficiency of GH Short long bones; max height is 4 ft. Paget’s Neoplasms Bone remodeling process disturbed Bones are abnormal, enlarged, not as dense, brittle, and prone to fracture Affects older adults