Exam 2 Review Notes PDF

Cells that break down (resorb) bone matrix Compact Bone anatomy - Osteon (Haversian system) -- Structural unit - Lamellae - Weight-bearing - Column-like matrix tubes - Central (Haversian) canal - Contains blood vessels, nerves, and lymphatic vessels - Pe...

Cells that break down (resorb) bone matrix Compact Bone anatomy - Osteon (Haversian system) -- Structural unit - Lamellae - Weight-bearing - Column-like matrix tubes - Central (Haversian) canal - Contains blood vessels, nerves, and lymphatic vessels - Perforating (Volkmann's) canals - At right angles to the central canal - Connects blood vessels and nerves of the periosteum and central canal - Lacunae - Small cavities that contain osteocytes - Canaliculi - Hair-like canals that connect lacunae to each other and the central canal Spongy Bone Anatomy - Trabeculae - Align along lines of stress - No osteons - Contain irregularly arranged lamellae, osteocytes, and canaliculi - Capillaries in endosteum supply nutrients Structures of a long bone - Diaphysis - Shaft - Epiphyses - Expanded ends of bone - Spongy bone interior - Epiphyseal line (remnant of the growth plate) - Articular (hyaline) cartilage on joint surfaces Two types of ossification - Intramembranous ossification - Membrane bone develops from fibrous membrane - Forms flat bones - Clavicles and cranial bones - Endochondral Ossification - Cartilage (endochondral) bone forms by replacing hyaline cartilage - Forms most of the skeleton Intramembranous Ossification process - An ossification center appears in the fibrous connective tissue membrane - Selected centrally located mesenchymal cells cluster and differentiate into osteoblasts, forming an ossification center - Bone matrix (osteoid) is secreted within the fibrous membrane - Osteoblasts begin to secrete osteoid, which is mineralized within a few days - Trapped osteoblasts become osteocytes - Woven bone and periosteum form - Accumulating osteoid is laid down between embryonic blood vessels, which form a random network. The result is a network of trabeculae or spongy bone - Vascularized mesenchyme condenses on the external face of the woven bone and becomes the periosteum - Bone collar of compact bone forms and red marrow appears - Trabeculae just deep to the periosteum thickens, forming a woven bone collar that is later replaced with mature lamellar bone. - Spongy bone consisting of distinct trabeculae, persists internally and its vascular tissue becomes red marrow. Endochondral Ossification process - Bone collar forms around hyaline cartilage model - Cartilage in the center of the diaphysis calcifies and develops cavities - The periosteal bud invades the internal cavities and spongy bone begins to form. - The diaphysis elongates and a medullary cavity forms as ossification continues. Secondary ossification centers appear in the epiphyses in preparation for stage 5. - The epiphyses ossify. When completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilage. The skull has two sets of bones - Cranium bones (8) - Facial bones (14) Classifications of Joints Functional Classifications - Synarthroses -- Immovable - Amphiarthroses -- Slightly movable - Diarthroses -- freely movable Structural Classifications - Fibrous - Cartilaginous - Synovial Fibrous Joints Bones joined by dense fibrous connective tissue NO joint cavity Most are synarthrosis (immovable) There are three types - Sutures - Syndesmoses - Gomphoses Suture -- Joint held together with very short interconnecting fibers, and bone edges interlock - Fibrous - Synarthroses - Found only in the skull Syndesmosis -- Joint held together by a ligament. Fibrous tissue can vary in length but is longer than is sutures - Fibrous - Synarthroses Gomphosis -- Peg in socket fibrous joint. The periodontal ligament holds teeth in their socket - Fibrous - Synarthroses Cartilaginous Joints Bones united by cartilage No joint cavity Two types - Synchondroses - Symphyses Synchondroses -- Bones used by hyaline cartilage (Epiphyseal plate, sternum, joint between first rib and sternum) - Cartilaginous - Synarthroses Symphyses -- Bones united by fibrocartilage (Pubic symphysis) - Cartilaginous - Amphiarthroses Synovial Joins - All are diarthrotic - Include all limb joints, most joints of the body - Articular cartilage: hyaline cartilage - Joint (synovial) cavity: small potential space - Articular (joint) capsule - Outer fibrous capsule - Inner synovial membrane - Synovial fluid - Viscous slippery filtrate of plasma and hyaluronic acid - Lubricates and nourishes articular cartilage - Three types of reinforcing ligaments - Capsular (intrinsic) -- part of the fibrous capsule - Extracapsular -- outside the capsule - Intracapsular- deep to capsule; covered by synovial membrane - Rich nerve and blood vessel supply - Capillary beds produce filtrate for synovial fluid Synovial Joint types Friction-Reducing Structures - Bursae - Flattened, fibrous sacs lines with synovial membranes - Tendon Sheath - Elongated bursa that wraps completely around a tendon Synovial joint movements - Gliding - One bone surface glides or slips over another similar surface - Hand gliding over the ulna and radius - Angular movement that occurs along the sagittal plane - Flexion- Decreases the angle of the joint - Extension- increases the angle of the joint - Hyperextension- excessive extension beyond the normal range of motion - Angular movement that occurs along the frontal plant - Abduction -- movement away from the midline - Adduction -- movement towards the midline - Circumduction -- flexion + abduction + extension + adduction of a limb so at to describe a cone in space - Rotation - The turning of a bone around its own long axis - Between the c1 and c2 vertebrae - Rotation of the humerus and femur - Special movements - Movement of radius around the ulna - Supination -- turning hand backward (cupping motion) - Pronation -- turning hand forward - Movements of the foot - Dorsiflexion (upward movement) - Plantar flexion (downward movement) - Inversion -- turn of the sole medially - Eversion -- turn of the sole laterally - Movements in a transverse plane - Protraction (anterior movement) - Retraction (posterior movement) - Elevation (lifting a body part superiorly) - Depression ( moving a body part inferiorly) - Opposition of the thumb -- Movement in the saddle joint so that the thumb touches the tips of the other fingers Nonaxial joints (plane joints) - Flat articular surfaces - Short gliding movements Uniaxial joints (hinge joints, pivot joints) - Hinge Joints - Motion along a single plane - Flexion and extension only - Pivot joints - The rounded end of the bone conforms to a "sleeve" or ring of another bone Biaxial Joints (condyloid ((ellipsoidal)) joints, saddle joints) - condyloid ((ellipsoidal)) joints - Both articular surfaces are oval - Permit all angular movements - Saddle Joints - Allow greater freedom of movement than condyloid joints - Each articular surface has both concave and convex areas Multiaxial joints (Ball-and-socket joints) - The most free-moving synovial joints