The Skeletal System PDF

Anatomy and Physiology Unit 3 - Principles of Support and Movement The Skeletal System Skeletal System  Introduction The skeletal system includes the bones of the skeleton The joints, cartilages, ligaments, and other connective tissues that st...

Anatomy and Physiology Unit 3 - Principles of Support and Movement The Skeletal System Skeletal System  Introduction The skeletal system includes the bones of the skeleton The joints, cartilages, ligaments, and other connective tissues that stabilize or interconnect bones. Individual bones are the organs of the skeletal system. Bone contains very active, living tissues. Bones  Main functions of bones: 1. Serve as body framework 2. Protect organs 3. Serve as levers for movement 4. Store fat, minerals, such as, phosphorous calcium salts (such as, calcium phosphate salt). 5. Form blood cells (hematopoiesis) Bones (continued)  Bone structure: 1. Long bone Diaphysis – shaft Epiphysis – end 2. Bone tissue Compact – in shaft of long bones; outside of other bones Spongy (cancellous) – in end of long bones; center of other bones 10-4 Bones (continued) 3. Bone marrow Red – in spongy bone Yellow – in central cavity of long bones 4. Bone membranes – contain bone forming cells Periosteum – covers bone Endosteum – lines marrow cavity Bones (continued) Bones (continued)  Microstructure of bones: Bones (continued) Bones (continued) Bones (continued)  Bone growth and repair 1. Bone cells Osteoblasts – bone forming cells Osteocytes – mature bone cells that maintain bone Osteoclasts – cells that break down (resorb) bone; derived from monocytes (types of white blood cells) 2. Formation of a long bone – begins in center of shaft and continues at epiphyseal plate Bones (continued)  Bone development and growth: Intramembranous ossification: Bones develop between sheets of fibrous connective tissue like the cranium (skull) and clavicles (collarbones). Endochondral ossification: Bone replaces cartilage as do most bones of the skeleton. Bones (continued)  Bone Repair: Hematoma: A mass of clotted blood. Fibrocartilaginous callus: fibrocartilage fills spaces between broken bones for about three weeks 10-9 Bones (continued)  Bone Repair: Bony callus: Fibrocartilage is replaced by bone tissue and lasts for 3 to 4 months. Remodeling: Old bone tissue is replaced by new bone tissue. Bones (continued)  Bone markings 1. Projections – head, process, condyle, crest, spine Head – a rounded, knoblike end separated from the rest of the bone by slender region, the neck. Process – a large projection of a bone, such as the upper part of the ulna in the forearm that creates the elbow. Condyle – a rounded projection; a small projection above a condyle in an epicondyle. Bones (continued)  Projections: head, process, condyle Bones (continued)  Projections: head, condyle Bones (continued) Spine – a sharp projection from the surface of a bone, such as the spine of the scapula (shoulder blade). The shoulder girdle and scapula. [A] Bones of the shoulder girdle, left anterior view. [B] Left scapula, posterior view. Bones (continued) Crest – a distinct border or ridge, often rough, such as over the top of the hip bone. Bones (continued) 1. Depressions and holes – foramen, sinus, fossa, meatus Foramen – a hole that allows a vessel or a nerve to pass through or between bones. The plural is foramina. Sinus – an air space found in some skull bones. Fossa – a depression on a bone surface. The plural is fossae. Meatus – a short channel or passageway, such as the channel in the temporal bone of the skull that leads to the inner ear.  Bones (continued)  Depressions and holes – foramen, sinus, fossa, meatus Bones (continued) Sinus – an air space found in some skull bones. Classification of the Bones  The human skeleton is divided into two major parts: Axial Skeleton Appendicular Skeleton Classification of the Bones (continued) Bones of the Axial Skeleton  Framework of the skull: 1. Cranium – frontal, parietal, temporal, ethmoid, sphenoid, occipital 2. Facial – mandible, maxilla, zygomatic, nasal, lacrimal, vomer, palatine, inferior nasal conchae Bones of the Axial Skeleton (continued) Bones of the Axial Skeleton (continued) Bones of the Axial Skeleton (continued) 3. Other – ossicles (of ear), hyoid 4. Infant skull – fontanels (soft spots) Bones of the Axial Skeleton (continued)  Framework of the trunk: 1. Vertebral column – divisions: cervical 7, thoracic 12, lumbar 5, sacral 5, coccygeal 4 Curves  Thoracic and sacral – concave, primary  Cervical and lumbar – convex, secondary Bones of the Axial Skeleton (continued) 2. Thorax Sternum – manubrium, body, xiphoid process  True – first seven pairs  False – remaining five pairs, including two floating ribs Bones of the Appendicular Skeleton  Upper division: 1. Shoulder girdle – clavicle, scapula 2. Upper extremity – humerus, ulna, radius, carpals, metacarpals, phalanges Bones of the Appendicular Skeleton  Lower division: 1. Pelvic bones – os coxae (hip bone): ilium, ischium, pubis Female pelvis lighter, wider, more rounded than male 2. Lower extremity – femur, patella, tibia, fibula, tarsals, metatarsals, phalanges Bones of the Appendicular Skeleton  Female pelvis lighter, wider, more rounded than male  Disorders of Bone For Reading  Metabolic: Osteoporosis – abnormal loss of bone tissue with tendency to fracture Osteopenia – reduction in bone density to below average levels Osteitis deformans – bones undergo periods of calcium loss followed by periods of excessive deposition of calcium salts Bone tissue Osteoporosis Disorders of Bone (continued) Disorders of Bone For Reading (continued) Osteomalacia – softening of bone tissue due to lack of formation of calcium Rickets – softening of bone (osteomalacia) in children, usually caused by a deficiency of vitamin D  Rickets: Rickets occurs when children have a deficiency of vitamin D.  Bones growth and remodeling Disorders of Bone For Reading (continued)  Tumors – abnormal growth or neoplasm Osteosarcoma - malignant tumor of bone cells Chondrosarcoma – malignant tumor arises in cartilage  Infection: Osteomyelitis – Inflammation of bone caused by pyogenic (pus-producing) bacteria, especially Staphylococcus aureus. Tuberculosis – may spread to bones (eg. Wrist and ankle; in spine is called Pott disease) caused by the bacillus bacteria (Mycobacterium tuberculosis).  Disorders of Bone (continued)  Structural Disorders: Curvature of the spine  Kyphosis (hunchback) – exaggeration of the thoracic curve  Lordosis (swayback) – excessive lumbar curve  Scoliosis – lateral curvature of the vertebral column Disorders of Bone For Reading (continued) Cleft palate: It is a congenital deformity in which there is an opening in the roof of the mouth owing to faulty union of the maxillary bones. Flatfoot: It is a common disorder in which the tendons and ligaments that support the long arch of the foot are weakened and the curve of the arch flattens. Disorders of Bone (continued)  Fractures - to break a bones Closed fracture: It is a simple fracture of the bone with no open wound. Open fracture: In which a broken bone protrudes through the skin or an external wound leads to a broken bone. Greenstick fracture: In which one side of the bone is broken and the other is bent. Impacted fracture: In which the broken ends of the bone are jammed into each other. Disorders of Bone (continued) Comminuted fracture: In which there is more than one fracture line and the bone is splintered or crushed. Spiral fracture: In which the bone has been twisted apart. Transverse fracture: In which the fracture goes straight across the bone. Oblique fracture: In which the break occurs at an angle across the bone. Disorders of Bone (continued)  Bone Repair: Skeletal changes in the Aging  Skeletal changes in the Aging The aging process includes significant changes in all connective tissue including bone. There is a loss of calcium salts and a decrease in the amount of protein formed in bone tissue. Changes in the vertebral column with age lead to a loss of height. Approximately 1.2 cm (about 0.5 inches) are lost each 20 years beginning at age 40, owing primarily to a thinning of the intervertebral disks (between the bodies of the vertebrae) Joints (Articulations)  Joints (Articulations): Joints can be classified on the basis of the amount of movement they make possible.  Fibrous - immovable joints (synarthrosis) The bones of immoveable joints are in close contact, separated by a thin layer of fibrous tissue or cartilage, as in suture. No active movements are possible at these joints.  Cartilaginous - slightly moveable joints (amphiarthrosis) The bones of slightly moveable joints are connected by disks of fibrocartilage or by ligaments, as in the vertebrae. Such a joint allows a limited amount of movement. Joints (Articulations) (continued)  Synovial - freely moveable joints (diarthrosis) The bones of a freely moveable joint are covered with hyaline cartilage and held together by a fibrous capsule. The joint capsule consists of an outer layer of ligaments and an inner lining of synovial membrane. Freely moveable joints include several types: gliding, hinge, pivot, condyloid, saddle, and ball-and-socket. Structure of a synovial joint. [A] Anterior view of the hip joint showing ligaments that reinforce and stabilize the joint. [B] Frontal section through right hip joint showing protective structures.  Joints (Articulations) (continued)  More about synovial joints: 1. Structure of synovial joints Joint cavity – contains synovial fluid Ligaments – hold joint together Joint capsule – strengthens and protects joint Articular cartilage – covers ends of bones Bursae – fluid-filled sacs near joints; cushions and protect joints and surrounding tissue Joints (Articulations) (continued)  Knee joint Joints (Articulations) (continued) 2. Types of synovial joints: Freely moveable joints include several types:  Gliding joint: Bone surfaces slide over one another. Joints in the wrist and ankles  Hinge joint: Allows movement in one direction, changing the angle of the bones at the joint. Elbow joint; joint between phalanges of fingers and toes. Joints (Articulations) (continued)  Pivot joint: Allows rotation around the length of the bone. Joints between the first and second cervical vertebrae; joint at proximal ends of the radius and ulna.  Condyloid joint: Allows movement in two directions. Joint between the metacarpal and the first phalanx of the finger (knuckle). Joint between the occipital bone of the skull and the first cervical vertebra (atlas). Joints (Articulations) (continued)  Saddle joint: Like a condyloid joint, but with deeper articulating surfaces. Joint between the wrist and the metacarpal bone of the thumb.  Ball-and-socket joint: Allows movement in many directions around a central point. Gives the greatest freedom of movement. Shoulder joint and hip joint. Movement at synovial joints 3. Movement at synovial joints: The following terms are used to describe various movements of synovial joints. Movement at synovial joints (continued)  Angular Motions: Flexion - bending a joint so that the angle between its parts is decreased and the parts come closer together, e.g. bending the leg at the knee. Extension - straightening a joint so that the angle between its parts is increased and the parts move farther apart, e.g. straightening the leg at the knee. Hyperextension - excessive extension of the parts at a joint, beyond the anatomical position, e.g. bending the head back beyond the upright position. Movement at synovial joints (continued) Abduction - moving a part away from the midline, e.g. lifting the arm horizontally to form a right angle with the side of the body. Adduction - moving a part toward the midline, e.g. returning the arm from the horizontal position to the side of the body. Movement at synovial joints (continued)  Circular Motions: Circumduction - moving a part so that its end follows a circular path, e.g. moving the finger in a circular motion without moving the hand or moving arm in a loop. Rotation - moving a part around an axis, e.g. twisting the head from side to side. Movement at synovial joints (continued)  Special movements at forearm: Pronation - turning the hand so the palm is downward. Supination - turning the hand so the palm is upward. Movement at synovial joints (continued)  Special movements at ankle: Inversion - turning the foot so the sole is inward. Eversion - turning the foot so the sole is outward. Dorsiflexion - flexing the foot at the ankle, e.g. bending the foot upward. Plantar flexion - extending the foot at the ankle, e.g. bending the foot down downward. Disorders of Joints For Reading  Disorders of joints: Dislocation – derangement of the parts of the joints. Mostly ball-and-socket and shoulder joints are dislocated in the body.  Sprain – Wrenching (to pull or twist) of a joint with rupture or tearing of the ligaments.  Herniated disk – central portion of intervertebral disk projects through outer cartilage. Disorders of Joints For Reading (continued)  Arthritis: The most common type of joint disorder is termed arthritis, which means “inflammation of the joints.” The term arthritis refers to many different diseases, most of which are characterized by inflammation of one or more joints. Inflammation, pain, and stiffness may also be present in adjacent parts of the body, such as the muscles near the joint.  Disorders of Joints For Reading (continued)  Osteoarthritis: It is a degenerative joint disease (DJD) that usually occurs in elderly persons (aging) as a result of normal wear and tear. Other factors such as obesity and trauma (injury or wound).  Osteoarthritis occurs mostly in joints used in weight bearing, such as the hips, knees, and spinal column.  It involves degeneration of the joint cartilage, with growth of new bone at the edges of the joint.  Injured joints can be examined from outside and even repaired surgically with a lighted instrument known as an arthroscope, a type of endoscope. Disorders of Joints For Reading (continued)  Rheumatoid arthritis: is a crippling condition (unable to walk or move properly) characterized by swelling of the joints of the hands, the feet, and other parts of the body as a result of inflammation and overgrowth of the synovial membranes and other joint tissues.  The articular cartilage is gradually destroyed, and the joint cavity develops adhesions (that is, the surfaces tend to stick together) so that the joints stiffness and ultimately become useless. Disorders of Joints For Reading (continued)  Septic (infectious) arthritis: It is arises when bacteria spread to involve joint tissue, usually by way of the blood stream.  A variety of organisms is commonly involved, Streptococcus, Staphylococcus, and Neisseria.  The joints and the bones may attack by tuberculosis organism, and the result may be gradual destruction of parts of the bone near the joint.  Tuberculosis of the spine is called Pott’s disease.  Disorders of Joints For Reading (continued)  Gouty arthritis: It is kind of arthritis caused by a disturbance of metabolism, which is production of uric acid excreted in urine.  The cause is overproduction of uric acid or less excretion.  The accumulated uric acid forms crystals, which are deposited as masses about the joints and other parts of the body.  As a result, the joints become inflamed and extremely painful.  Backache, dislocation and sprain and strain are common complaint of joints.