10/4/18. Skeletal System. 1 Copyright 2016 by Elsevier Inc. All rights reserved. Introduction. Physiology. Anatomy. Bone Cells.

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1 Introduction Skeletal System Chapter bones in the body Bones are living tissue Mammals have remarkably similar bone structure - Humans, elephants, giraffes, bats, and whales all have 7 cervical vertebra 1 2 Bones Joints Cartilage Ligaments Anatomy Support Protection Movement Physiology Blood cell production (hemopoiesis) Fat storage Mineral storage 3 4 Bone Cells Osteoclasts are bone-destroying cells - Help dissolve bone and minerals Osteoblasts are bone-forming cells - Fill the small cavities left by osteoclasts Osteocytes are mature bone cells Bone Remodeling Process of bone destruction by osteoclasts and bone formation by osteoblasts Begins after bone growth is complete and continues throughout life Factors that affect bone remodeling: - Age, gender, physical activity, nutrition, medication use 5 6 1

2 Bone Remodeling Hormones play role in bone remodeling - Blood calcium levels affect parathyroid release - Estrogens and testosterone stimulate osteoblast activity Osteoporosis can result with low estrogen Bone Tissues Compact - Hard outer shell - Contains mature bone cells called osteocytes Spongy (cancellous) - Lattice-work of thin beams within bone (trabeculae) - Looks spongy 7 8 Classification of Bones Long: Humerus, ulna and radius, femur, and tibia and fibula Short: Tarsals and carpals Irregular: Vertebrae Flat: Sternum, scapula, ribcage, pelvis, and skull Sesamoid: Patella, hands, and feet Anatomy of a Long Bone Epiphyses: Two ends, where growth occurs - Articular cartilage pads the surfaces of bone where it articulates with another bone Diaphysis: Long cylindrical shaft of the bone - Periosteum: Dense, fibrous sheath around diaphysis Medullary cavity: Hollow space within the diaphysis - Filled with red and yellow bone marrow 9 10 Ossification Ossification or osteogenesis: Process of bone development by osteoblasts - Intramembranous ossification: Bone development occurs from membranes and is found within flat bones - Endochondral ossification: Bone development occurs from cartilage Two Regions of the Skeletal System Axial skeleton - Bones of the central axis Appendicular skeleton - Bones of the extremities

3 Axial Skeleton Skull (29 bones) - 8 cranial bones (1 frontal, 2 parietal, 2 temporal, 1 occipital, 1 sphenoid, 1 ethmoid) - 14 facial bones (2 maxilla, 2 zygomatic, 2 palatine, 1 mandible, 2 lacrimal, 2 nasal, 2 inferior conch, 1 vomer) - 6 ear ossicles (2 malleus, 2 incus, 2 stapes) - 1 hyoid bone Axial Skeleton Vertebral column (26 bones) - 7 cervical vertebrae - 12 thoracic vertebrae - 5 lumbar vertebrae - 1 sacrum (5 fused vertebrae) - 1 coccyx (3 to 5 fused vertebrae) Axial Skeleton Sternum (1 bone) Ribs (24 bones 12 pairs) - 14 true ribs (7 pairs) - 6 false ribs (3 pairs) - 4 floating (2 pairs) Appendicular Skeleton (126 Bones) Shoulder girdle (4 bones) - 2 scapulae - 2 clavicles Appendicular Skeleton Upper extremities (60 bones; 30 per side) - 2 humeri - 2 ulni - 2 radii - 16 carpals - 10 metacarpals - 28 phalanges Appendicular Skeleton Pelvic girdle (6 fused bones) - Ilium (2) - Ischium (2) - Pubic (2)

4 Appendicular Skeleton Lower extremities - 2 femurs - 2 patellae - 2 tibias - 2 fibulas - 14 tarsals - 10 metatarsals - 28 phalanges Bony Markings Where muscles, tendons, and ligaments attach to bones Where nerve and blood vessels pass Sometimes called surface markings Types of Bony Markings Condyle: Knuckle-shaped projection Fossa: Shallow depression in a bone Head: Rounded end of a bone Process: A prominence of a bone Tuberosity: Large, rough projection Joints Joints (articulations): Where bones come together or join - Also called an arthrosis Functions of joints: - Enable the body to move - Bear the weight of the body - Provide stability Structural Classification Fibrous: Connected by dense fibrous connective tissue (synarthroses) Cartilaginous: Connected by cartilage (amphiarthroses) Synovial: Contains joint capsule with lubricating (synovial) fluid (diarthroses) - Most common joint type - Most movable type of joint Functional Classification Synarthrotic joints: Extremely limited movement - Example: Joints between the bones of the skull Amphiarthrotic joints: Slightly movable joints - Example: Joints of the ribs Diarthrotic joints: Freely movable joints (also known as synovial joints) - Possess a joint cavity and allow movement in one, two, or three planes - Example: Knees and shoulders

5 Articular cartilage: Smooth hyaline cartilage covering the surfaces of synovial joints - Decreases friction - Helps absorb shock Joint capsule: Double-layered structure surrounding joint - Outer layer forms ligaments that connect the bones together Joint cavity: Inner region of the capsule - Lined with a synovial membrane - Filled with synovial fluid Synovial fluid (synovia): Viscous fluid of freely moving joints - Provides nutrition and lubrication - Allows free movement and reducing friction Bursae: Saclike flattened structure with an interior lining of synovial membrane containing synovial fluid - Usually found between ligaments and joint capsules - Provides a cushion protecting tendons from rubbing against bone - Example: Knees and shoulders Synovial sheaths: Tubular structures surrounding long tendons that increase gliding capacity - Lined with synovial membranes (similar to bursae) - Found mainly in tendons of the wrists, hands, ankles, and feet Menisci: Fibrocartilage pads found in select joints - Help joint move smoothly - Serve as a shock absorber Example: Knees and jaw Joint Movements Flexion: Bending of a joint to that angle of joint decreases - Examples: Fingers, toes, elbows, hips, and so on Extension: Opposite of flexion; extending a joint so that angle increases - Hyperextension: Continuation of extension beyond anatomic position Example: Bending head backward

6 Abduction Movement of a joint so that a body part moves away from the midline of the body Horizontal Abduction Occurs as the shoulder or hip moves the upper or lower extremity away from the midline Occurs as the hand moves away from the midline of the body in the anatomic position Radial Deviation Adduction Movement of a joint so that a body part moves toward the midline of the body Applies also to movements across the body Horizontal Adduction, Ulnar Deviation, and Rotation Horizontal adduction: Occurs as the shoulder or hip moves the upper or lower extremity toward the midline Ulnar deviation: Occurs as hand moves toward midline of body Rotation: Occurs when a bone pivots or rotates around its own central axis Upward and Downward Rotation Upward rotation: Glenoid cavity rotates to orient superiorly Downward rotation: Glenoid cavity rotates to orient inferiorly

7 Supination and Pronation Supination: A type of lateral or outward rotation (assuming a lying face up position) - Supination of the forearm - Supination of the foot Pronation: A type of medial or inward rotation - Pronation of the forearm is medial rotation - Pronation of the foot is combined actions of eversion, dorsiflexion, and lateral rotation of foot so that inner edge of foot bears body's weight Plantar Flexion and Dorsiflexion Movement of ankle so that the foot moves inferiorly toward the plantar surface or bottom of foot Dorsiflexion is movement of ankle as foot moves superiorly Inversion and Eversion Inversion - Elevation of medial edge of the foot so that it turns inward or toward the midline of body - When both feet are inverted, the soles of the feet face each other Eversion - Elevation of lateral edge of foot so that it turns outward, away from midline of body Circumduction Conical movement in which the distal end of a structure moves in a circle and the proximal end remains relatively fixed Elevation and Depression Elevation - Movement at a joint in a superior of upward direction Depression - Movement at a joint in an inferior or downward direction Protraction (Protrusion) Movement at a joint in an anterior direction

8 Retraction (Retrusion) Movement at a joint in a posterior direction Opposition Movement in which the pad of the thumb comes into contact with the pad of any finger on the same hand Side-to-side action Lateral Deviation One way to classify joints is by their shape and available movement Hinge (uniaxial): - Limited to flexion and extension - Example: Elbow, ankle, and joints within fingers and toes (interphalangeal joints) Pivot (uniaxial): - Allow rotation only - Example: Joints within the elbow and wrist (radioulnar joints) and between the first and second cervical vertebrae (atlantoaxial joint) Saddle (biaxial): - Resemble a rider in a saddle - Allow movements of flexion, extension, abduction, adduction, opposition, reposition, and circumduction, but not rotation - Example: Thumb joint between carpal bone and metacarpal bone (carpometacarpal joint of the thumb) Ellipsoidal (biaxial): - Slightly altered ball-and-socket joints - Allows flexion, extension, abduction, adduction, and circumduction, but not rotation - Example: Wrists (radiocarpal joints) and the knuckle (metatarsophalangeal and metacarpophalangeal joints)

9 Ball and socket (multiaxial/triaxial): - Permit all movements except gliding - Offer the greatest range of motion - Example: Hips (iliofemoral joints) and shoulders (glenohumeral joints) Gliding (nonaxial): - Limited to gliding movement - Moves in all planes - Example: Wrists (intercarpal joints), feet (intertarsal joints), and the joints between vertebrae (facet or zygapophyseal joints) Joints Classified by Movement Joints can be classified: - By dominate plane of space - By axis of movement permitted by joint Joints movements take place in a plane and around an axis Classification by Planes Three cardinal planes: - Sagittal plane (median) bisects body from front to back and divides into right and left portions - Frontal plane (coronal) bisects body side-to-side and divides into anterior and posterior positions - Transverse plane (horizontal) bisects body horizontally and divides body into superior and inferior Classification by Planes Nonplanar: Provide only a slight back and forth or sliding movement, like gliding joints Uniplanar: Provide movement in one plane, like hinge joints Biplanar: Provide movement in two planes, like saddle joints Multiplanar: Provide movement in all three cardinal planes, like ball and socket joints Classification by Axes Movements can occur along a joint's axis - Nonaxial joints: Provide slight back-and-forth or sliding movement - Uniaxial joints: Provide movement in one axis - Biaxial joints: Provide movement in two axes - Triaxial joints: Provide movement in all three axes