Medical Terminology AHS 115 Skeletal System

Functions Support: body structure and shapeSupport: body structure and shape Protection for vital organs (brain, heart, etc.)Protection for vital organs (brain, heart, etc.) Movement for attached skeletal musclesMovement for attached skeletal muscles –Tendons: attach muscle to bone –Ligaments: attach bone to bone Mineral storage: calcium and phosphorusMineral storage: calcium and phosphorus Blood cell formation - hematopoiesisBlood cell formation - hematopoiesis

Types of Bone

Compact Bone Very dense, stress bearingVery dense, stress bearing Haversian systems –basic unitHaversian systems –basic unit of compact bone of compact bone Lamellae: concentric cylinderLamellae: concentric cylinder shaped calcified structure shaped calcified structure Lacunae: small spaces containing tissue fluidLacunae: small spaces containing tissue fluid Osteocytes: facilitate exchange of calcium between blood and boneOsteocytes: facilitate exchange of calcium between blood and bone Canaliculi: canals connecting the lacunae together and to the haversian canal which carries nutrients and wastes to and from the osteocytesCanaliculi: canals connecting the lacunae together and to the haversian canal which carries nutrients and wastes to and from the osteocytes

Cancellous Bone Light, spongyLight, spongy Found at ends of long bones, ribs, sternum, hips, vertebrae, craniumFound at ends of long bones, ribs, sternum, hips, vertebrae, cranium No haversian systemsNo haversian systems Web-like arrangementWeb-like arrangement Highly vascularHighly vascular

Classification of Bones

Long bones Found in the extremitiesFound in the extremities Act as leversAct as levers Includes:Includes: –Epiphysis End of long bonesEnd of long bones Covered with hyaline cartilage for articulationCovered with hyaline cartilage for articulation Filled with cancellous boneFilled with cancellous bone –Diaphysis –Shaft –Covered with periosteum –Medullary canal –Compact bone Examples: femur, tibia, fibula, humerus,Examples: femur, tibia, fibula, humerus, radius, clavicle, metacarpals, phalanges radius, clavicle, metacarpals, phalanges

Short Bones Cube shapedCube shaped Allows flexible movementAllows flexible movement Cancellous bone covered by compact boneCancellous bone covered by compact bone Examples:Examples: –Carpals –Tarsals

Flat Bones Protect vital organs and provide broad surface area for muscle attachmentProtect vital organs and provide broad surface area for muscle attachment Examples:Examples: –Cranial bones –Scapula –Sternum –Ribs

Irregular Bones Peculiarly shaped to provide support and protection, yet allow flexibilityPeculiarly shaped to provide support and protection, yet allow flexibility Examples:Examples: –Vertebrae –Ear –Hyoid –Mandible

Sesamoid Bones Extra bones found in certain tendonsExtra bones found in certain tendons Example:Example: –Patella

Composition Collagen: chief organic constituent (protein)Collagen: chief organic constituent (protein) Inorganic calcium salts (Vitamin D essential for absorption of minerals i.e. calcium)Inorganic calcium salts (Vitamin D essential for absorption of minerals i.e. calcium) Deposition favored byDeposition favored by –a. Estrogen, testosterone –b. Alkaline phosphatase –c. Thyrocalcitonin –d. Mechanical stress i.e. traction Withdrawal favored byWithdrawal favored by –a. Alkaline phosphatase –b. Parathormone –c. Inactivity

Composition Cells Osteoblasts: bone building, bone repairing cells in the periosteumOsteoblasts: bone building, bone repairing cells in the periosteum Osteocytes: mature bone cells within the bone matrixOsteocytes: mature bone cells within the bone matrix Osteoclast: causes reabsorption of boneOsteoclast: causes reabsorption of bonePeriosteum 1. Dense, fibrous membrane covering bone1. Dense, fibrous membrane covering bone 2. Contains blood vessels2. Contains blood vessels 3. Essential for bone cell survival and bone formation3. Essential for bone cell survival and bone formation

Osteoblast Osteocyte Osteoclast Eats bone Builds new bone Mature bone cell Cells that Aid in Bone Formation

Bone Formation Initially collagen fibers secreted by fibroblastsInitially collagen fibers secreted by fibroblasts Cartilage deposited between fibersCartilage deposited between fibers Skeleton fully formed by 2nd month of fetal development (all cartilage)Skeleton fully formed by 2nd month of fetal development (all cartilage) After 8th week of fetal development ossification (mineral matter deposited and replaces cartilage) beginsAfter 8th week of fetal development ossification (mineral matter deposited and replaces cartilage) begins Childhood and adolescence:Childhood and adolescence: –ossification exceeds bone loss Early adulthood thru middle age:Early adulthood thru middle age: –ossification equals bone loss After age 35:After age 35: –bone loss exceed ossification

275 bones 12 weeks (6-9 inches long) Fetal Skeleton

Anatomy of Long Bone DiaphysisDiaphysis –Shaft –Composed of compact bone EpiphysisEpiphysis –Ends of bone composed mostly of spongy bone of spongy bone PeriosteumPeriosteum –outside covering of diaphysis EndosteumEndosteum –Lines medullary cavity ArteriesArteries Articular cartilageArticular cartilage Medullary cavityMedullary cavity –Cavity inside the shaft –Contains yellow marrow (mostly fat) in adults

Bone Marrow Red bone marrowRed bone marrow –Found in vertebrae, ribs, sternum, cranium, ends of humerus and femur –Produces: Erythrocytes – red blood cellsErythrocytes – red blood cells Plateletes - thrombocytes – clotting cellsPlateletes - thrombocytes – clotting cells Some leukocytes – white blood cellsSome leukocytes – white blood cells Yellow bone marrowYellow bone marrow –Found in medullary cavity of long bones –Fat storage

Bone Marrow Yellow marrow Medullary cavity of long bonesMedullary cavity of long bones Fat storageFat storage Red marrow Hematopoietic tissueHematopoietic tissue In all cancellous bone in childrenIn all cancellous bone in children In adults: cancellous bone of vertebrae, hips, sternum, ribs, cranial bones, proximal ends of femur and humerusIn adults: cancellous bone of vertebrae, hips, sternum, ribs, cranial bones, proximal ends of femur and humerus Forms RBCs, platelets, some WBCs, and destroys old RBCs and some foreign materialsForms RBCs, platelets, some WBCs, and destroys old RBCs and some foreign materials

Divisions of the Skeletal System

Axial Skeleton Forms the longitudinal axis of the body Divided into three parts: SkullSkull Vertebral ColumnVertebral Column ThoraxThorax

Appendicular Skeleton Composed of 126 bonesComposed of 126 bones Includes bones of the:Includes bones of the: –Limbs (appendages) –Pectoral (shoulder) girdle –Pelvic (hip) girdle

Joints

Classification Synarthrotic: immovable - craniumSynarthrotic: immovable - cranium Amphiarthrotic: limited movement i.e. pubic symphysis, vertebral joints, sacroiliac jointAmphiarthrotic: limited movement i.e. pubic symphysis, vertebral joints, sacroiliac joint Diarthrotic: freely movableDiarthrotic: freely movable –Gliding: bones of the wrist –Pivot: between radius and ulna –Ball and socket: hip –Hinge: elbow

Immovable Joints Synarthrosis

Slightly Movable Joint Ampharthrosis

Freely Movable Diarthrosis

Abduction Extension Rotation Flexion Adduction Synovial Joint Movement