Chapter 5 Outline

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 – has 206 bones
b) Two basic types of bone tissue
i) Compact bone
• Homogeneous
ii) Spongy bone
• Small needle-like pieces of bone
• Many open spaces
4) Classification of bones by shape
a) Long bones:
i) Typically longer than they are wide
ii) Have a shaft with heads at both ends
iii) Contain mostly compact bone
iv) Examples:
• Femur
• Humerous
b) Short bones:
i) Generally cube-shaped
ii) Contain mostly spongy bone
iii) Examples:
• Carpals
• Tarsals
c) Flat bones:
i) Thin, flattened, and usually curved
ii) Two thin layers of compact bone surround a layer of spongy bone
iii) Examples:
• Skull
• Ribs
• Sternum
d) Irregular bones:
i) Irregular shape
ii) Do not fit into other bone classification categories
iii) Examples:
• Vertebrae
• Hip Bones
5) Anatomy of long bones
a) Diaphysis – shaft
i) Composed of compact bone
b) Epiphysis – knobby ends
i) Ends of the bone
ii) Composed mostly of spongy bone
c) Diaphysis features:
i) Periosteum
• Outside covering of the diaphysis
• Fibrous connective tissue membrane
ii) Sharpey’s fibers
• Secure periosteum to underlying bone
iii) Arteries & veins
• Supply bone cells with nutrients
iv) Medullary cavity
• Cavity inside of the shaft
• Contains yellow marrow (mostly fat) in adults
• Contains red marrow (for blood cells formation) in infants
d) Epiphysis features
i) Articular cartilage
• Covers the external surface of the epiphyses
• Made of hyaline cartilage
• Decreases friction at joint surfaces
ii) Epiphyseal plate
• Flat plate of hyaline cartilage seen in young, growing bone
iii) Epiphyseal line
• Remnant of the epiphyseal plate
• Seen in adult bones
6) Bone markings
a) Surface features
i) Sites of attachments for muscles, tendons, and ligaments
ii) Passages 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 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) Cavities containing bone cells (osteocytes)
ii) Arranged in concentric rings
e) Lamellae: sites of lacunae
i) Rings around the central canal
f) Canaliculi: tiny canals from central canal from lacunae
i) Tiny canals
ii) Radiate from the central canal to lacunae
iii) Form a transport system connecting 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 replace by bone
c) Cartilage remaining in isolated areas:
i) Bridge of the nose
ii) Parts of the ribs
iii) Joints
9) Bone growth (Ossification)
a) Epiphyseal plates allow for lengthwise growth of long bones during childhood
b) Lengthwise growth from epiphyseal plates
i) New cartilage is continuously formed
ii) Older cartilage becomes ossified:
• Cartilage is broken down
• Enclosed cartilage is digested away, opening up a medullary cavity.
• Bone replaces cartilage through the action of osteoblasts
c) Bone remodeling
i) Bones are remodeled and lengthened until growth stops
ii) Bones are remodeled in response to two factors:
• Blood calcium levels
• Pull of gravity and muscles on the skeleton
d) Appositional growth = growth in width
10) Types of bone cells
a) Osteocytes
b) Osteoblasts
c) Osteoclasts
11) Bone fractures
a) Types
i) Closed
ii) Open
b) Treatment
c) Table 5.2
d) Repair
i) Hematoma
ii) Fibrocartilage
iii) Bony callus
12) Axial skeleton – longitudinal axis of body
a) Skull
i) Cranium
ii) Facial bones
iii) Sutures
iv) Mandible
v) Bones of the skull
vi) Paranasal sinuses
• Functions
vii) Hyoid bone
13) Fetal skeleton
a) Skull proportions
i) Fetal skull is large compared to the infant’s total body length
b) Fontanel – cartilage between cranial bones
c) Allows the brain to grow
d) Convert to bone within 24 months after birth
e) Allow skull to “squeeze” during birth
14) Vertebral column: 24 vertebrae separated by discs
a) Each vertebrae is given a name according to it’s location
b) There are 24 single vertebral bones separated by intervertebral discs
c) Typical vertebrae structures
d) Cervical = neck
i) Atlas
ii) Axis
iii) Seven cervical vertebrae are in neck
• C2 – C7
e) Thoracic = chest
i) Twelve thoracic vertebrae are in the chest region
f) Lumbar = lower back
i) Five lumbar vertebrae are associated with the lower back
g) Composite vertebrae
i) Nine vertebrae fuse to form two composite bones:
• Sacrum
• Coccyx
h) Curvatures
The spine has a normal curvature:
i) Primary curvatures are the spinal curvatures of the thoracic and sacral regions
• Present from birth
ii) Secondary curvatures are the spinal curvatures of the cervical and lumbar regions
• Develop after birth
iii) Abnormalities
• Scoliosis
• Lordosis
• Kyphosis
i) Bony thorax
i) Sternum
ii) Costal cartilage
iii) Ribs
• True
• False
• Floating
iv) Vertebrae – facets for ribs
15) Appendicular skeleton – 126 bones
a) Limbs (appendages)
i) Pectoral (shoulder) girdle
• Composed of two bones:
(a) Clavicle (collarbone)
(b) Scapula (shoulder blade)
(c) These bones allow the upper limb to have exceptionally free movement, but somewhat less support
• Freedom of movement
ii) Upper limbs
• Humerus
(a) Forms the arm (upper arm)
(b) Single bone
• The forearm has two bones:
(a) Ulna- medial bone in anatomical position
(b) Radius – lateral bone in anatomical position
(i) Hand
1. Carpals-little bones in wrist (8)
a. Proximal  distal then medial  lateral: Some Lefties Try Positions ThatThey Can’t Handle
2. Metacarpals – palm (long bones)
3. Phalanges (phalanyx)- fingers (digits):
a. #1 (thumb) to #5 (pinky)
b. Bones: proximal, medial, distal
b) Pelvic (hips) girdle =formed by 2 coxal (ossa, coxae) bones
i) Total weight of upper body rests on the belvis
ii) Protects several organs:
• Reproducative organs
• Urinary bladder
• Part of the large intestine
iii) Each coxal bone made of three fused bones:
• Illium
• Ischium
• Pubis
iv) Gender differences: Compared to the male, the female pelvis:
• Inlet
(a) Female inlet is larger and more circular
• Pelvis as a whole
(a) Female pelvis (as a whole) is shallower, and the bones are lighter and thinner
• Ilia
(a) Female ilia flare more laterally
• Sacrum
(a) Female sacrum is shorter and less curved
• Ischial spines
(a) Female ischial spines are shorter and farther apart; thus the outlet is larger
• Pubic arch
(a) The female pubic arch is more rounded because the angle of the pubic arch is greater
c) Lower limbs
i) Upper leg
• The thigh has one bone: Femur
• The heaviest, strongest bone in the body
ii) Lower leg
• Has two bones:
(a) Tibia
(i) Shinbone
(ii) Larger and medially oriented
(b) Fibula
(i) Thin and sticklike
(ii) Lateral to the tibia
iii) Foot
• Tarsals
(a) Two largest tarsals
(i) Calcaneus (heelbone)
(ii) Talus
• Metatarsals-sole
• Phalanges-toes
(a) #1-5
(b) Bones: proximal, medial, distal
• Three arches of the foot
(a) Two longitudinal
(b) One transverse
16) Joints = articulations of bones
a) Functions of joints :
i) Hold bones together
ii) Allow for mobility
b) Ways they are classified – Table 5.3
i) Functional classifications
• Synarthroses
(a) Immovable joints
• Amphiarthroses
(a) Slightly moveable joints
• Diarthroses
(a) Freely moveable joints
ii) Structural classifications
• Fibrous joints
(a) Generally immovable
(b) Bones united by fibrous tissue
(c) Example:
(i) Sutures in skull
(ii) Syndesmoses
1. Allows more movement that sutures
2. Example: Distal end of tibia and fibula
• Cartilagaenous joints
(a) Immovable or slightly moveable
(b) Bones connected by cartilage
(c) Example:
(i) Pubic symphysis
(ii) Intervertebral joints
(d) Pubic symphysis, intervertebral joints
• Synovial
(a) Freely moveable
(b) Articulating bones are separated by a joint cavity
(c) Synovial fluid is found in the joint cavity
(d) Features
(i) Articular cartilage (hyaline cartilage) covers the ends of bones
(ii) A fibrous articular capsule encloses joint surfaces
(iii) A joint cavity is filled with synovial fluid
(iv) Ligaments reinforce the joint
(e) Structures
(i) Bursae—flattened fibrous sacs:
1. Lined with synovial membranes
2. Filled with synovial fluid
3. Not actually part of the joint
(ii) Tendon sheath
1. Elongated bursa that wraps around a tendon
(f) Types – depend on type of movement allowed
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 diseases of joints:
• Over 100 different types
• The most widespread crippling disease in the United States
• Clinical Forms of Arthritis:
(a) Osteoarthritis
(i) Most common chronic arthritis
(ii) Probably related to normal aging processes
• 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
• Gouty:
(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:
• Long bones are formed of hyaline cartilage
ii) Osteoporosis
iii) Posture