Skeletal System Textbook: Chapter 7

Functions Support – frame on which everything else builds Protection – skull and thorax Movement – connections with muscles Storage – storage of Ca and other ions Hematopoiesis – in red marrow

Types of Bones Long Bones - humerus Short Bones - carpals Flat Bones - frontal Irregular Bones - vertebrae

Long Bones Main Parts Diaphysis (shaft) Medullary Cavity Epiphyses Articular Cartilage Periosteum Endosteum Epiphyseal plate/disk

A. Structure of Bone The skeletal system is composed of two major types of tissue – bone and cartilage Bone cells = osteocytes Cartilage cells = chondrocytes

B. Types of bone Compact Bone Covered by periosteum Appears solid Composed of osteons Lamella - rings Lacunae – b/w lamella, contain osteocytes Calaliculi – canals that reach osteocytes Central canal – blood vessel

B. Types of bone 2. Spongy Bone Appears porous Found in epiphyses Spaces contain red bone marrow Needle threads that create “sponge” = trabeculae

C. Cartilage Chondrocytes found in lacunae Matrix is flexible and contains collagen No blood vessels Slow to heal

Bone Formation and Growth New bone cells = osteoblasts; Resorbing cells = osteoclasts Ability of bone to grow and change is dependent on the osteoblasts and osteoclasts Bone Growth = ossification Endochondral Ossification –formed from cartilage Intramembranous Ossification Hematopoietic Ossification

Endochondral Ossification Bone formation begins from cartilage Blood vessel invades at diaphysis Osteoblasts/clasts result – center of ossification appears in diaphysis Centers of ossification appear in epiphyses Ephyseal Plate appears Bone grows

Endochondral Ossification Bone continues to grow while the cartilaginous cells of the epiphyseal plate are active –once ossification center meet growth stops Osteoblasts deposit bone material under periosteum – bone grows Osteoclasts erode medullary cavity

Skeleton Organization Axial Skeleton Skull 8 Cranial Bones Frontal Parietal (2) Occipital Temporal (2) Sphenoid Ethmoid ii. 14 Facial Bones 1. maxilla (2) 2. zygomatic (2) 3. palatine (2) 4. Inferior nasal concha (2) 5. Mandible 6. Lacrimal (2) 7. Nasal (2) 8. Vomer

Skeletal Organization b. Middle ear bones 1. malleus (2) 2. incus (2) 3. stapes (2)

Skeletal Organization c. Hyoid bone

Skeletal Organization d. Vertebral Column 1. Cervical Vertebrae (7) -atlas supports head 2. Thoracic Vertebrae (12) -larger than cervical -facets on sides articulate with ribs 3. Lumbar Vertebrae (5) -large and strong 4. Sacrum -five fused vertebrae 5. Coccyx -four fused vertebrae -shock absorber

Skeletal Organization e. Thoracic Cage 1. Ribs a. 7 True Ribs b. 5 False Ribs c. 2 Floating Ribs 2. Sternum -consists of manubrium, body, and xiphoid process -articulates with clavicles

Skeleton Organization 2. Appendicular Skeleton -connected to axial skeleton by pectoral girdle and pelvic girdle Upper extremities Pectoral Girdle -clavicles – hold muscles and shoulders in place -scapula – broad triangular bones that articulate with the humerus

Skeletal Organization 2. Upper Limb - Humerus – scapula to elbow, articulates with radius and ulna - Radius – thumb side of forearm, articulates with humerus, ulna, and wrist - Ulna – overlapes radius posteriorly, articulates with radius laterally - Hand - 8 carpal bones (carpus) - 5 metacarpal bones and 14 phalanges

Skeletal Organization b. Lower extremities 1. Pelvic Girdle - sacrum, coccyx, and pelvic girdle = pelvis - coxal bones -ilium – joins sacrum -ischium – lowest part, supports weight when sitting -pubis – anterior portion, fused anteriorly

Skeletal Organization 2. Lower Limb - Femur – hip to knee, articulates with patella - Tibia – medial side of leg, articulates with talus - Fibula – lateral side of tibia, articulates with ankle - Foot -tarsus - 5 metatarsals -14 phalanges