Skeletal System PDF

THE SKELETAL SYSTEM HAP Unit 4th  THE SKELETAL SYSTEM  Parts of the skeletal system include:  Bones (skeleton)  Joints  Cartilages  Ligaments  Divided into two divisions: 1. Axial skeleton (skull, ribs and vertebra) 2. Appendicular skeleto...

THE SKELETAL SYSTEM HAP Unit 4th  THE SKELETAL SYSTEM  Parts of the skeletal system include:  Bones (skeleton)  Joints  Cartilages  Ligaments  Divided into two divisions: 1. Axial skeleton (skull, ribs and vertebra) 2. Appendicular skeleton (pelvis, extremities)  FUNCTIONS OF BONES  Support of the body  Protection of soft organs  Movement due to attached skeletal muscles  Storage of minerals and fats  Blood cell formation  BONES OF THE HUMAN BODY  The adult skeleton has 206 bones  Two basic types of bone tissue  Compact bone  Homogeneous  Spongy bone  Small needle-like pieces of bone  Many open spaces CLASSIFICATION OF BONES ON THE BASIS OF SHAPE  CLASSIFICATION OF BONES  Long bones  Typically longer than wide  Have a shaft with heads at both ends  Contain mostly compact bone  Examples: Femur, humerus  Short bones  Generally cube-shape  Contain mostly spongy bone Examples: Carpals, tarsals  CLASSIFICATION OF BONES  Flat bones  Thin and flattened, usually curved  Thin layers of compact bone around a layer of spongy bone  Examples: Skull, ribs, sternum  Irregular bones  Irregular in shape  Do not fit into other bone classification categories Example: Vertebrae and hip  GROSS ANATOMY OF A LONG BONE  Diaphysis  Shaft  Composed of compact bone  Epiphysis  Ends of the bone  Composed mostly of spongy bone Figure 5.2a  STRUCTURES OF A LONG BONE  Periosteum  Outside covering of the diaphysis  Fibrous connective tissue membrane  Sharpey’s fibers  Secure periosteum to underlying bone  Arteries  Supply bone cells with nutrients Figure 5.2c  STRUCTURES OF A LONG BONE  Articular cartilage  Covers the external surface of the epiphyses  Made of hyaline cartilage  Decreases friction at joint surfaces Figure 5.2a  STRUCTURES OF A LONG BONE  Medullary cavity  Cavity of the shaft  Contains yellow marrow (mostly fat) in adults  Contains red marrow (for blood cell formation) in infants Figure 5.2a  BONE MARKINGS  Surface features of bones  Projectionsand processes – grow out from the bone surface  Depressions or cavities – indentations  Sites of attachments for muscles, tendons, and ligaments  Passages for nerves and blood vessels  MICROSCOPIC ANATOMY OF BONE  Osteon (Haversian System)  A unit of bone  Central (Haversian) canal  Carries blood vessels and nerves  Perforating (Volkman’s) canal  Canal perpendicular to the central canal  Carries blood vessels and nerves  CHANGES IN THE HUMAN SKELETON  Inembryos, the skeleton is primarily hyaline cartilage  During development, much of this cartilage is replaced by bone  Cartilage remains in isolated areas  Bridge of the nose  Parts of ribs  Joints  BONE GROWTH  Epiphyseal plates allow for growth of long bone during childhood  New cartilage is continuously formed  Older cartilage becomes ossified  Cartilage is broken down  Bone replaces cartilage  BONE GROWTH  Bones are remodeled and lengthened until growth stops  Bones change shape somewhat  Bones grow in width LONG BONE FORMATION AND GROWTH Figure 5.4b  TYPES OF BONE CELLS  Osteocytes  Mature bone cells  Osteoblasts  Bone-forming cells  Osteoclasts  Bone-destroying cells  Break down bone matrix for remodeling and release of calcium  Boneremodeling is a process by both osteoblasts and osteoclasts THE SKELETAL SYSTEM (B)  BONE FRACTURES A break in a bone  Types of bone fractures  Closed (simple) fracture – break that does not penetrate the skin  Open (compound) fracture – broken bone penetrates through the skin  Bone fractures are treated by reduction and immobilization  Realignment of the bone COMMON TYPES OF FRACTURES Table 5.2  REPAIR OF BONE FRACTURES  Hematoma (blood-filled swelling) is formed  Break is splinted by fibrocartilage to form a callus  Fibrocartilage callus is replaced by a bony callus  Bony callus is remodeled to form a permanent patch STAGES IN THE HEALING OF A BONE FRACTURE Figure 5.5  THE AXIAL SKELETON  Forms the longitudinal part of the body  Divided into three parts  Skull  Vertebralcolumn  Bony thorax THE AXIAL SKELETON Figure 5.6  THE SKULL  Two sets of bones  Cranium  Facial bones  Bones are joined by sutures  Only the mandible is attached by a freely movable joint THE SKULL Figure 5.7 BONES OF THE SKULL Figure 5.11 HUMAN SKULL, SUPERIOR VIEW HUMAN SKULL, INFERIOR VIEW THE SKELETAL SYSTEM (C)  PARANASAL SINUSES  Hollow portions of bones surrounding the nasal cavity Figure 5.10  PARANASAL SINUSES  Functions of paranasal sinuses  Lighten the skull  Give resonance and amplification to voice  THE HYOID BONE  The only bone that does not articulate with another bone  Serves as a moveable base for the tongue  THE FETAL SKULL  Thefetal skull is large compared to the infants total body length Figure 5.13  THE FETAL SKULL  Fontanelles – fibrous membranes connecting the cranial bones  Allow the brain to grow  Convert to bone within 24 months after birth  THE VERTEBRAL COLUMN  Vertebrae separated by intervertebral discs  The spine has a normal curvature  Each vertebrae is given a name according to its location Figure 5.14 STRUCTURE OF A TYPICAL VERTEBRAE Figure 5.16 REGIONAL CHARACTERISTICS OF VERTEBRAE Figure 5.17a–b REGIONAL CHARACTERISTICS OF VERTEBRAE Figure 5.17c–d THE SKELETAL SYSTEM (D) THE BONY THORAX  Forms a cage to protect major organs  THE BONY THORAX  Made-up of three parts  Sternum  Ribs  Thoracic vertebrae  THE APPENDICULAR SKELETON  Limbs (appendages)  Pectoral girdle  Pelvic girdle  THE PECTORAL (SHOULDER) GIRDLE  Composed of two bones  Clavicle – collarbone  Scapula – shoulder blade  Thesebones allow the upper limb to have exceptionally free movement BONES OF THE SHOULDER GIRDLE BONES OF THE SHOULDER GIRDLE  BONES OF THE UPPER LIMB  The arm is formed by a single bone  Humerus  BONES OF THE UPPER LIMB  The forearm has two bones  Ulna  Radius  BONES OF THE UPPER LIMB  The hand  Carpals– wrist  Metacarpals – palm  Phalanges – fingers  BONES OF THE PELVIC GIRDLE  Hipbones  Composed of three pair of fused bones  Ilium  Ischium  Pubic bone  The total weight of the upper body rests on the pelvis  Protects several organs  Reproductive organs  Urinary bladder  Part of the large intestine THE SKELETAL SYSTEM (E) THE PELVIS THE PELVIS: RIGHT COXAL BONE GENDER DIFFERENCES OF THE PELVIS  BONES OF THE LOWER LIMBS  The thigh has one bone  Femur – thigh bone  BONES OF THE LOWER LIMBS  The leg has two bones  Tibia  Fibula Figure 5.24c  BONES OF THE LOWER LIMBS  The foot  Tarsus– ankle  Metatarsals – sole  Phalanges – toes Figure 5.25  ARCHES OF THE FOOT  Bones of the foot are arranged to form three strong arches  Two longitudinal  One transverse  JOINTS  Articulationsof bones  Functions of joints  Hold bones together  Allow for mobility  Ways joints are classified  Functionally  Structurally  FUNCTIONAL CLASSIFICATION OF JOINTS  Synarthroses – immovable joints  Amphiarthroses – slightly moveable joints  Diarthroses – freely moveable joints THE SKELETAL SYSTEM (F)  STRUCTURAL CLASSIFICATION OF JOINTS  Fibrous joints  Generally immovable  Cartilaginous joints  Immovable or slightly moveable  Synovial joints  Freely moveable  FIBROUS JOINTS  Bonesunited by fibrous tissue  Examples  Sutures  Syndesmoses  Allows more movement than sutures  Example: distal end of tibia and fibula  CARTILAGINOUS JOINTS  Bonesconnected by cartilage  Examples  Pubic symphysis  Intervertebral joints Figure 5.27d–e  SYNOVIAL JOINTS  Articulating bones are separated by a joint cavity  Synovial fluid is found in the joint cavity  FEATURES OF SYNOVIAL JOINTS  Articular cartilage (hyaline cartilage) covers the ends of bones  Joint surfaces are enclosed by a fibrous articular capsule  Have a joint cavity filled with synovial fluid  Ligaments reinforce the joint STRUCTURES ASSOCIATED WITH THE SYNOVIAL JOINT  Bursae – flattened fibrous sacs  Lined with synovial membranes  Filled with synovial fluid  Not actually part of the joint  Tendon sheath  Elongated bursa that wraps around a tendon THE SYNOVIAL JOINT TYPES OF SYNOVIAL JOINTS BASED ON SHAPE TYPES OF SYNOVIAL JOINTS BASED ON SHAPE INFLAMMATORY CONDITIONS ASSOCIATED WITH JOINTS  Bursitis – inflammation of a bursa usually caused by a blow or friction  Tendonitis – inflammation of tendon sheaths  Arthritis – inflammatory or degenerative diseases of joints  Over 100 different types  The most widespread crippling disease in the United States  CLINICAL FORMS OF ARTHRITIS  Osteoarthritis  Most common chronic arthritis  Probably related to normal aging processes  Rheumatoid arthritis  An autoimmune disease – the immune system attacks the joints  Symptoms begin with bilateral inflammation of certain joints  Often leads to deformities  CLINICAL FORMS OF ARTHRITIS  Gouty Arthritis  Inflammation of joints is caused by a deposition of urate crystals from the blood  Can usually be controlled with diet  DEVELOPMENTAL ASPECTS OF THE SKELETAL SYSTEM  At birth, the skull bones are incomplete  Bones are joined by fibrous membranes – fontanelles  Fontanelles are completely replaced with bone within two years after birth