Chapter 5 Skeletal System

Chapter 5 Bones and Skeletal Tissue

1) Parts of the skeletal system
a) Bones (skeleton)
b) Joints
c) Cartilage
d) Ligaments- connect bone to bone
e) Subdivisions of the skeleton
i) Axial – central “core”
ii) Appendicular – parts that stick out
2) Functions of the bones
a) Support the body
b) Protect soft organs
c) Allow movement due to attachment to skeletal muscles
d) Store minerals and fats
e) Blood cell formation
3) Bones of the human body
a) Adult skeleton – 206 bones
b) Two basic types of bone tissue
i) Compact bone- homogeneous
ii) Spongy bone- small needle like piece of bone, many open spaces
4) Classification of bones by shape
a) Long bones: femur, humerus
i) Longer then they are wide
b) Short bones: carpals, tarsals
i) Generally cube-shaped
ii) Contain mostly spongy bone
c) Flat bones: skull, ribs, sternum
i) Thin, flattened, and usually curved
ii) Two thin layers of compact bone surround a layer of spongy bone
d) Irregular: vertebrae, hip bones
i) Irregular shape
ii) Do not fit into other bone classification categories
5) Anatomy of long bones
a) Diaphysis - shaft
b) Epiphysis – knobby ends
c) Diaphysis features:
i) Periosteum-
(1) outside covering of the diaphysis
(2) fibrous connective tissue membrane
ii) Sharpey’s fibers
(1) Secure periosteum to underlying bone
iii) Arteries & veins
(1) Supply bone cells with nutrients
iv) Medullary cavity
(1) Cavity inside of the shaft
(2) Contains yellow marrow (mostly fat) in adults
(3) Contains red marrow (for blood cell formation) in infants
d) Epiphysis features
i) Articular cartilage
(1) Covers the external surface of the epiphyses
(2) Made of hyaline cartilage
(3) Decreases friction at joint surfaces
ii) Epiphyseal plate
(1) Flat plate of hyaline cartilage seen in young , growing bone
iii) Epiphyseal line
(1) Remnant of the epiphyseal plate
(2) Seen in adult bones
6) Bone markings
a) Surface features
i) Sites of attachments for muscles, tendons, and ligaments
ii) Passage for nerves and blood vessels
b) Categories of bone markings
i) Projections or processes- grow out from the bone surface
ii) Depressions or cavities- indentations
iii) Table 5.1
7) Microscopic anatomy of bones
a) Osteon = Haversian system
i) A unit of bone containing central canal and matrix rings
b) Central = Haversian canal
i) Opening in the center of an osteon
ii) Carries blood vessels and nerves
c) Perforating = Volkman’s canal
i) Canal perpendicular to the central canal
ii) Carries blood vessels and nerves
d) Lacunae: concentric rings
i) Cavaties containing bone cells (osteocytes)
ii) Arranged in concentric rings
e) Lamellae: sites of lacunae
i) Rings around the central conal
ii) Sites of lacunae
f) Canaliculi: tiny canals from central canal from lacunae
i) Rasiate from the central canal to lacunae
ii) Form a transport system connection all bone cells to a nutrient supply
8) Formation of human skeleton
a) In embryos, the skeleton is primarily hyaline cartilage
b) During development, much of this cartilage is replaced by bone
c) Cartilage remaining in isolated areas:
i) Bridge of the nose
ii) Parts of ribs
iii) Joints
9) Bone growth (ossification)
a) Epiphyseal plates allow for lengthwise growth of long bones during childhood
i) New cartilage is continuously formed
ii) Old cartilage becomes ossified
(1) Cartilage is broken down
(2) Encloses cartilage is digested away, opening up a medullary cavity
(3) Bone replaced cartilage through the action of osteoblasts
b) Bones are remodeled and lengthened until growth stops
c) Bones are remodeled in response to two factors:
i) Blood calcium levels
ii) Pull of gravity muscles on the skeleton
d) Appositional growth = growth in width
10) Types of bone cells
a) Osteocytes- mature bone cells
b) Osteoblasts- bone-forming cells
c) Osteoclasts- bone-destroying cells
d) Break down bone matrix for remodeling and release calcium in response to parathyroid hormone
11) Bone fractures- break in the bone
a) Types
i) Closed (simple) fracture- break that does not penetrate the skin
ii) Open (compound) fracture- broken bone penetrates through the skin
b) Treated by reduction and immobilization
c) Table 5.2
d) Repair
i) Hematoma- (blood-filled swelling)
ii) Break is splinted by fibrocartilage to form a callus
iii) Bony callus is remodeled to form a permanent patch
12) Axial skeleton – longitudinal axis of body
a) Skull
i) Cranium
ii) Facial bones
iii) Bones are joined by sutures
iv) Only the mandible is joined by a freely moveable joint
v) Bones of the skull
vi) Paranasal sinuses
(1) Hollow portions of bones surrounding the nasal cavity
(2) Functions
(a) lighten the skull
(b) give resonance and amplification to voice
vii) Hyoid bone
(1) The other bone that does not articulate with another bone
(2) Serves as a moveable base for the tongue
(3) Aids in swallowing and speech
b) Vertebral column
c) Bony thorax
13) Fetal skeleton
a) Skull proportions
b) The fetal skull is large compared to the infants total body length
c) Fontanel – cartilage between cranial bones, fibrous membranes connecting the cranial bones
d) Allow the brain to grow
e) Convert to bone within 24 months after birth
f) Allow skull to “squeeze” during birth
14) Vertebral column: 24 vertebrae separated by intervertebral discs
a) Each vertebrae is given a name according to its location
b) Seven cervical vertebrae are in the neck
c) Twelve thoracic vertebrae are in the chest region
d) Five lumbar vertebrae are associated with the lower back
e) Nine vertebrae fuse to form two composite bones:
i) Sacrum
ii) coccyx
f) the spine has a normal survature:
i) primary curvatures are the spinal curvatures of the thoracic and sacral regions
(1) present from birth
ii) secondary curvatures are the spinal curvatures of the cervical and lumber regions
(1) develop after birth
g) Typical vertebrae structures
h) Cervical = neck
i) Atlas
ii) Axis
iii) C2 – C7
i) Thoracic = chest
j) Lumbar = lower back
k) Composite vertebrae
i) Sacrum
ii) Coccyx
l) Curvatures
i) Primary
ii) Secondary
iii) Abnormalities
(1) Scoliosis
(2) Lordosis
(3) Kyphosis
m) Bony thorax
i) Sternum
ii) Costal cartilage
iii) Ribs
(1) True
(2) False
(3) Floating
iv) Vertebrae – facets for ribs
15) Appendicular skeleton – 126 bones
a) Pectoral (shoulder) girdle
i) Clavicle- collar bone
ii) Scapula- shoulder bone
iii) These bones allow the upper limb to have exceptionally free movement, but somewhat less support
b) Upper limbs
i) Humerus- forms the arm
(1) Single bone
ii) Ulna- medial bone in anatomical position
iii) Radius- lateral bone in anatomical position
(1) Hand
(a) Carpals- wrist (8 bones)
(b) Metacarpals- palm (long bones)
(c) Phalanges (phalanyx)- fingers (digits)
(d) #1 (thumb) to #5 (pinky)
(e) Bones: proximal, medical, distal
c) Pelvic girdle = two coxal (ossa coxae) bones
i) Total weight of the upper body rests on the pelvis
ii) Protects several organs-
(1) Reproductive organs
(2) Urinary bladder
(3) Part of the large intestine
iii) Each coxal bone made of three fused bones:
(1) Illium
(2) Ischium
(3) Pelvis
iv) Gender differences: Compared to the male, the female pelvis:
(1) The female inlet is larger and more circular
(2) The female pelvis as a whole is shallower and the bones are lighter and thinner
(3) The female ilia flare more laterally
(4) The female sacrum is shorter and less curved
(5) The female ischial spines are shorter and farther apart; thus the outlet is larger
(6) The pubic arch is more rounded because the angle of the pubic arch is greater
d) Lower limbs
i) Upper leg
(1) Femur (thigh bone)
(2) The heaviest, strongest bone in the body
ii) Lower leg
(1) Tibia
(a) Shinbone
(b) Larger and medial oriented
(2) Fibula
(a) Thin and sticklike
(b) Lateral to the tibia
iii) Foot
(1) Tarsals
(2) Two largest tarsals
(a) Calcaneus (heelbone)
(b) talus
(3) Metatarsals (soles)
(4) Phalanges (toes)
(5) #1-5 (#1 Big toe)
(6) Bones: proximal, medial, distal
(7) Three arches of the foot
(a) Twp longitudinal
(b) One transverse
16) Joints = articulations of bones
a) Functions of joints- hold bones together, allow for mobility
b) Ways they are classified – Table 5.3
i) Functional classifications
(1) Synarthroses- immovable joints
(2) Amphiarthroses- slightly moveable joints
(3) Diarthroses- freely moveable joints
ii) Structural classifications
(1) Fibrous- generally immovable
(a) Sutures, syndesmoses
(2) Cartilagaenous- immovabke or slightly moveable
(a) Pubic symphysis, intervertebral joints
(b) Bones connected by cartilage
(c) Intervertebral joints
(3) Synovial- freely moveable
(a) Articulating bones are separated by a joint cavity
(b) Articular cartilage (hyaline cartilage) covers the ends of bones
(c) Joint cavity with fluid
(d) A fibrous articular capsule encloses joint surfaces
(e) A joint cavity is filled with synovial fluid
(f) Features
(g) Structures
(i) Bursae- flattened fibrous sacs
(ii) Tendon sheath
(h) Types – depend on type of movement allowed
(i) Lined with synovial membranes
(j) Filled with synovial fluid
(k) Not actually part of the joint
(l) Tendon sheath: elongated bursa that wraps around a tendon
c) Inflammatory conditions
i) Bursitis- inflammation of a bursa usually caused by a blow or friction
ii) Tendonitis- inflammation of tendon sheaths
iii) Arthritis- inflammatory or degenerative disease of joints
(1) Over 100 different types
(2) The most widespread crippling disease in the United States
(3) Osteoarthritis arthritis-
(a) Most common chronic arthritis
(b) Probably related to normal aging process
(4) Rheumatoid arthritis-
(a) An autoimmune disease- the immune system attack the joints
(b) Symptoms begin with bilateral inflammation of certain joints
(c) Often leads to deformities
(5) Gouty arthritis-
(a) Inflammation of joints is caused by a deposition of uric acid crystals from the blood
(b) Can usually be controlled with diet
d) Skeletal changes throughout life
i) Fetus:
(1) Long bones are formed of hyaline cartilage
(2) Flat bones being as fibrous membranes
(3) Flat and long bone models are converted to bone
ii) Osteoporosis
iii) Posture