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4
The Skeletal System
Lesson 4.1: Bone as a Living Tissue
Lesson 4.2: The Axial Skeleton
Lesson 4.3: The Appendicular Skeleton
Lesson 4.4: Joints
Lesson 4.5: Common Injuries and
Disorders of the Skeletal System
Chapter 4: The Skeletal System
Lesson 4.1
Bone as a Living Tissue
Bone as a Living Tissue
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functions of the skeletal system
structures and classifications of bones
growth and development of bones
remodeling of bones
15% BW
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Functions of the Skeletal System
• support
– body framework
• protection
– surround organs
• movement
– muscles pull bones
• storage
– Minerals ( Ca, P)
• blood cell formation = Hematopoiesis
– red bone marrow in medullary cavity ( flat and short bones,
vertebrae and long bone ends)
– Yellow cavity stores fat
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Structures and Classifications of Bones
• composition of bones
– osteocytes–mature bone cells
– Minerals
• 60-70% Ca (carbonate and phosphate)
• 30-40% Collagen and water (higher in kids- more flexible)
• organization of bones
– Cortical= dense
– Trabecular=honeycomb
• Adds lightness
• Birds?
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Shape Categories of Bones
• Long
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Cylindrical with bulbs
trabecular bone inside
Cortical outside
Hollow medullary canal
• Arms and legs
• Short
– Cube shaped
– Mostly trabecular
• wrists and ankles
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Shape Categories of Bones
• Flat
– Thin, elongated
– Curved
– Two thin layers of cortical
• Small amount of trabecular
– Protection and attachment
• Skull, ribs, sternum
• Irregular
– Don’t fit in a category
– Shape based on function
• Vertebrae and pelvis
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Anatomical Structure of Long Bones
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Anatomical Structure of Long Bones
• Made of three parts
• Periosteum
• Fibrous CT
• Contains vessels, lymph and nerves
• Involved in growth, repair and nutrition
• Diaphysis- cortical bone shaft
• Surrounded by periosteum
• Contains hollow medullary canal
• All begins as yellow marrow
• Lined by CT called endosteum
• Epiphysis- ends of long bones
• Mostly trabecular bone and red marrow
• Hematopoiesis =blood cell formation
• Covered by articular cartilage
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Anatomical Structure of Long Bones
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Anatomical Structure of Bones
• Bone nourishment
• Passageways through the mineralized bone
• Canaliculi
• Across
• Haversian Canals
• Lengthwise
• Connected by Volkmann’s or perforating canals
• Contain Lacunae
• Cavities in the bone
• In Lamella (“tree trunks”)
• Where the osteocytes are located
• Osteons
• Each Canal and parts
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Growth and Development of Bones
• osteoblasts
– build bone tissue
• osteoclasts
– break down bone tissue
• bone formation
– Modeling- Building new bone tissue
• Usually from hyaline cartilage (in vitro)
– Ossification
• Matrix covers cartilage, clasts resorb to form medullary
cavities
• Balanced in healthy adults
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Growth and Development of Bones
• longitudinal growth
– epiphyseal plate- location of growth during childhood
– Ends when plates dissolve and bone fuses
• circumferential growth
– change in diameter- all throughout life
• Blasts build from the periosteum
• Clasts resorb from the endosteum
• Lifelong process= SLOW
• adult bone development
– aging causes loss of bone mass, collagen (elasticity)
– Increased risk of fractures
– 25-28W, 30-35M smaller bones=more density issues
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Remodeling of Bones
• Remodeling
– Blast/clast activity
– Result of forces
– Converts forces into changes in density, size or shape
• hypertrophy of bones
– stronger bones + increased density
– Large forces, usually at attachment sites
– Active lifestyles or heavier/ High impact
• atrophy of bones
– weaker bones
– Reduced forces (swimmers and astronauts?)
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Chapter 4: The Skeletal System
Lesson 4.2
The Axial Skeleton
The Axial Skeleton
• the skull
• the vertebral column
• Thoracic cage
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The Axial Skeleton
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The Skull
• the cranium
– surround the brain
– Protects (mostly)
• the facial bones
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protect the front of the head
Produce face shape
Protect and orient eyes
Mastication
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The Cranium
• Joined by interlocking, immovable joints (Sutures)
• Sutures allow tiny amounts of movement
• Babies are different. Why?
– Big heads (1/8 v 1/4)
– Fontanels
– Soft sutures
• Birth trauma and brain development
• 22-24M
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The Cranial Bones and Facial Bones
• frontal bone
• Forehead
• parietal bones (2)
• Top/sides of skull
• Temporal bones (2)
• Surround ears
• occipital bones (2)
• Back of head
• ethmoid bone
• Nasal septum
• sphenoid bone
• Base of brain/eyes
• maxillary bones (2)
– Upper jaw
• palatine bones (2)
– Hard palate
• zygomatic bones (2)
– Cheeks/eye sockets
• lacrimal bones (2)
– Eyes and tears
• nasal bones (2)
– nose
• vomer
– Nasal septum
• inferior concha bones (2)
– Sides of nasal cavity
• mandible
– Lower jaw. Only mover
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The Cranial and Facial Bones
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The Vertebral Column
• 33 bones
• regions of the spine
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Cervical (7) Atlas and axis, yes and no
Thoracic (12)
Lumbar (5)
Sacrum (5) Fused. Form posterior p girdle
Coccyx (4) Fused. “Tailbone”
• curves of the spine= stronger and resists
injuries. Present at birth or with development.
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cervical curve – concave secondary
thoracic curve convex primary
lumbar curve- concave primary
sacral curve convex secondary
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Structures of the Vertebrae
• the vertebral body
– Thick and disc shaped
• Bears weight and forms anterior vertebra
• the vertebral arch
– Round projection surrounding the foramen
• Where the spinal cord passes
• the transverse processes
– Projections on either side of the arch
• the spinous process
– Extends posteriorly
• the superior and inferior articular processes
– Facets of articulation
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Structures of the Vertebrae
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Abnormal Spinal Curvatures
• Due to genetic or congenital abnormalities
• Lordosis
– Exaggerated lumbar curve
• Kyphosis
– Exaggerated thoracic curve
• Scoliosis
– Lateral deviation
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The Intervertebral Discs
• located between vertebrae
• shock absorbers
– Made of fibrocartilage
– cushioning
• allow flexibility
• Change in height
– Nutrients
– Sleep vs waking
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The Thoracic Cage
• sternum
– Manubrium
• Clavicle and upper 2p ribs
– body of the sternum
– xiphoid process
• projection
• ribs
– true ribs (7p)
• Attached to sternum
– false ribs (3p)
• Cartilage connections
– floating ribs (2p)
• No connection but spine
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Chapter 4: The Skeletal System
Lesson 4.3
The Appendicular
Skeleton
2 Divisions
Upper Extremity= arms
Lower Extremity= Legs
The Upper Extremity
• the shoulder complex/pectoral girdle
– Mobility vs stability
• Attachment sites for the arm
– Scapula - posterior
• Acromion- superior and posterior
• Coracoid – inferior and anterior
• Meets humerus at the glenoid fossa (shoulder joint)
– Clavicle anterior
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Attaches to scapula and sternum
Acromioclavicular joint – arm raises
Sternoclavicular joint –shrugging
Positions shoulder away from trunk
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The Upper Extremity
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The Upper Extremity
• Humerus
– Second largest bone in the body. Attaches to radius and
ulna
• Radius
– Rotational ( thumb and wrist)
– radiocarpal joint with wrist
• Ulna
– Larger and stronger than radius
– Olecranon process of ulna=elbow
• Connections
– Interosseus membrane, styloid processes
– Proximal and distal radioulnar joints
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The Upper Extremity
• the wrist and hand (54 bones) – precision and
grasp
– carpals (8)
• Two rows connected by ligaments. Base of hands.
– metacarpals (5)
• Articulate with carpals, “hands”
– phalanges (14)
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Fingers and thumb
3-3-3-3-2
Numbering system
Opposable thumb = more motion
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The Upper Extremity
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The Lower Extremity (weight bearing
and gait)
• the pelvic girdle
• Reproductive organs, bladder, colon
– Two coxal bones
• M Vs F
– Childhood 3 separate bones that fuse
• Ilium- superior and posterior, sacroilliac joint, “wings”, illiac
crest
• Ischium- inferior portion, supports upper body weight,
acetabular joint
• Pubis- anterior, pubic symphysis ( hyaline)
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The Lower Extremity (weight bearing
and gait)
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The Leg
– Femur
• Longest and largest
• Head to acetabulum=stability
• Neck vulnerability
– Tibia
• Strong- shin, bears weight
– Fibula
• Muscle attachment only, not part of knee
– Lateral malleolus=ankle outside
– I.O. membrane
– patella
• Small flat and triangular, protects the front of the knee
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The Lower Extremity
• the ankle and foot : walking and balance
– tarsals (7)
• Calcaneus
• talus
– metatarsals (5)
• “Foot”
– Phalanges (14)
• 33332
• Stability
• Weight area
• 2 arches
– Longitudinal and transverse
• Spring
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Chapter 4: The Skeletal System
Lesson 4.4
Joints
Categories of Joints
• immovable joints–synarthroses
– Fibrous joints. Little to no movement
• slightly movable joints–amphiarthroses
– Cartilage. Absorb shock
• freely movable joints–diarthroses
– Synovial joints(encapsulated)
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Immovable Joints
• TWO types
• Sutures
– Ossified fibrous tissues
– Skull only
• Syndesmoses (held by bands)
– Fibrous tissue bands prevent movement
– coracoacromial joint
– distal tibiofibular joint
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Slightly Movable Joints
• Synchondroses (held by cartilage)
– hyaline
– sternocostal joint
– epiphyseal plates
• Symphyses
– Hyaline cartilage plates and fibrocartilage disc
– vertebral joints
– pubic symphysis
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Freely Movable Joints
• Gliding
• Condyloid
– Articulating surfaces flat.
• Hinge
– Multidirectional
movement
– planar movement (door) • Saddle
– > ROM than condyloid
• Pivot
• Ball and Socket
– Around 1 axis
– Mobility vs stability
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Freely Movable Joints
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Freely Movable Joint Structures
• Bursae
– Cushioning structures filled with synovial fluid
• tendon sheaths
– Surround tendons subject to friction. Secrete synovial
fluid (wrists and fingers)
• articular tissues
– articular fibrocartilage
• meniscus
– Tendons
• Muscle to bone
– Ligaments
• Bone to bone
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Chapter 4: The Skeletal System
Lesson 4.5
Common Injuries and
Disorders of the
Skeletal System
Common Injuries and Disorders of the
Skeletal System
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common bone injuries
osteoporosis
common joint injuries
arthritis
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Fractures= a break or crack in the bone
• Force
– Size, Direction, duration
– Bone health and maturity
• Types
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Simple (closed)
Compound (open)
Communited (splinter)
Avulsion (tendon or ligament)
• Bone chip
– Spiral (twisting)
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Fractures= a break or crack in the bone
• Greenstick
– Incomplete break
– Found in children
– Higher collagen
• Stress
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Tiny cracks
Overuse
Repetitive motion injuries
“playing injured”
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Epiphyseal Injuries
• epiphyseal plate
– Premature closure
• articular cartilage
– Osteochondrosis (Osgood-schlatter)
• Young athletes, usually male
• Quadriceps to tibia attachment
• Pain and swelling at attachment site
• Apophysis
– Tendon attachment site
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Osteoporosis- demineralized bones
• low strength bones easily break
• Trabecular bone mostly
• age-related osteoporosis
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Women, most elderly
Osteopenia first- reduced mass without fracture
Type 1- postmenopausal:15 yr. femur, vertebrae, wrist
Type 2- age related: 60-70 yrs femoral neck
Common sign back pain
• Vertebral crush injuries
• kyphosis
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Osteoporosis- demineralized bones
• the female athlete triad
– disordered eating
• Anorexia nervosa
• Bulimia nervosa
– amenorrhea
– Osteoporosis
• irreversible
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Common Joint Injuries- usually to freely
moveable joints
• sprains
– Torn/overstretched ligament or tendon
– Ankle most common
– Pain and swelling = ice and elevation
• dislocations
– bone displaced from socket
– Falls or collisions
– Joint deformity, pain and swelling= replace and splint
• bursitis
– inflammation of bursae
– overuse
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Arthritis >100 types
• rheumatoid arthritis
– immune system attacks joints
– Usually adults
– Thickening of synovial membranes, breakdown of
cartilage
– Loss of motion, fusing of bones
• osteoarthritis
– degeneration of articular cartilage
– Pain swelling and stiffness
– Pain improved by rest and stiffness by use.
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