2/28/18 skeletal system · and divisions of the skeleton 1. list the anatomy and physiology of the...

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Copyright © 2016 by Elsevier Inc. All rights reserved.

Skeletal System

Chapter 19

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Function and Classification of Bones and Divisions of the Skeleton

1. List the anatomy and physiology of the skeletal system and discuss bone cells and tissues.

2. Classify bones according to their shape, discuss the anatomy of a long bone and bone ossification.

3. Divide bones into either the axial or appendicular skeleton and describe various bony markings.

Lesson 19.1

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Introduction

• 206 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

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Anatomy

• Bones• Joints• Cartilage• Ligaments

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Physiology

• Support• Protection• Movement• Blood cell production (hemopoiesis)• Fat storage• Mineral storage

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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

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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

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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

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Bone Tissues

• Compact- Hard outer shell- Contains mature bone cells called osteocytes

• Spongy (cancellous)- Lattice-work of thin beams within bone

(trabeculae)- Looks spongy

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Bone

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From Herlihy B: The human body in health and illness, ed 4, St. Louis, 2011, Mosby.


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

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Examples of Bones

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From Patton KT, Thibodeau GA: Anatomy & physiology, ed 8, St. Louis, 2013, Mosby.

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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

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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

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Regions of the Skeletal System

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Regions of the Skeletal System

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Two Regions of the Skeletal System

• Axial skeleton- Bones of the central axis

• Appendicular skeleton - Bones of the extremities

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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

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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)

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Axial Skeleton

• Sternum (1 bone)• Ribs (24 bones – 12 pairs)

- 14 true ribs (7 pairs)- 6 false ribs (3 pairs)- 4 floating (2 pairs)

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Appendicular Skeleton (126 Bones)

• Shoulder girdle (4 bones)- 2 scapulae- 2 clavicles

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Appendicular Skeleton

• Upper extremities (60 bones; 30 per side)- 2 humeri- 2 ulni- 2 radii- 16 carpals- 10 metacarpals- 28 phalanges

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• Pelvic girdle (6 fused bones)- Ilium (2)- Ischium (2) - Pubic (2)

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• Lower extremities - 2 femurs- 2 patellae- 2 tibias- 2 fibulas- 14 tarsals - 10 metatarsals- 28 phalanges

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Bony Markings

• Where muscles, tendons, and ligaments attach to bones

• Where nerve and blood vessels pass• Sometimes called surface markings

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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

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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

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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

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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

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Synovial Joints

• 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

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Synovial Joints

• Synovial fluid (synovia): Viscous fluid of freely moving joints- Provides nutrition and lubrication - Allows free movement and reducing friction

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Synovial Joint Structures

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Synovial Joints

• 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

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Synovial Joints

• 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

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Synovial Joints

• Menisci: Fibrocartilage pads found in select joints- Help joint move smoothly- Serve as a shock absorber

• Example: Knees and jaw

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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

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Abduction

• Movement of a joint so that a body part moves away from the midline of the body

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Horizontal Abduction

• Occurs as the shoulder or hip moves the upper or lower extremity away from the midline

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Radial Deviation

• Occurs as the hand moves away from the midline of the body in the anatomic position

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Adduction

• Movement of a joint so that a body part moves toward the midline of the body

• Applies also to movements across the body

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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

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Upward and Downward Rotation

• Upward rotation: Glenoid cavity rotates to orient superiorly

• Downward rotation: Glenoid cavity rotates to orient inferiorly

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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

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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

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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

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Circumduction

• Conical movement in which the distal end of a structure moves in a circle and the proximal end remains relatively fixed

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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

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Protraction (Protrusion)

• Movement at a joint in an anterior direction

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Retraction (Retrusion)

• Movement at a joint in a posterior direction

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Opposition

• Movement in which the pad of the thumb comes into contact with the pad of any finger on the same hand

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Lateral Deviation

• Side-to-side action

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Joints Classified by Shape

• 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)

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• 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)

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• 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)

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• Ball and socket (multiaxial/triaxial):- Permit all movements except gliding- Offer the greatest range of motion - Example: Hips (iliofemoral joints) and shoulders

(glenohumeral joints)

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• 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)

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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

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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

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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

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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

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