chapter 5 notes

VI. Bones and Skeletal Tissue

1)    Parts of the skeletal system

a)    Bones (skeleton)

b)   Joints

c)    Cartilage

d)   Ligaments

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: femur, humerus-Typically longer than they are wide, have a shaft with heads(“knobs”) at both ends, contain mostly compact bone.

b)   Short bones: carpals, tarsals-Generally cube shaped, contain mostly spongy bone.

c)    Flat bones: skull, ribs, sternum-Thin, flattened, and usually curved, two think layers of compact bone surround a layer of spongy bone.

d)   Irregular: vertebrae, hip bones- Irregular shape, do not fit into other bone classification categories.

5)   Anatomy of long bones

a)    Diaphysis – shaft, composed of compact bone.

b)   Epiphysis – knobby ends, ends of the bone, 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 cell 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 adults.

6)   Bone markings

a)    Surface features- Sites of attachments for muscles, tendons, and ligaments, 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 5.1A

7)   Microscopic anatomy of bones

a)    Osteon = Haversian system-A unit of bone containing central canal and matrix rings.

b)   Central = Haversian canal- Opening in the center of an osteon, carries blood vessels and nerves.

c)    Perforating = Volkman’s canal- Canal perpendicular to the central canal, carries blood vessels and nerves.

d)   Lacunae: concentric rings- Cavities containing bone cells (osteocytes), arranged in concentric rings.

e)    Lamellae: sites of lacunae- Rings around the central canal, sites of lacunae.

f)    Canaliculi: tiny canals from central canal from lacunae- Tiny canals, radiate from the central canal to lacunae, 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- During development, much of this cartilage is replaced by bone.

c)    Cartilage remaining in isolated areas:- Bridge of nose, parts of ribs, joints.

9)   Bone growth

a)    Lengthwise growth from epiphyseal plates- Allow for lengthwise growth of long bones during childhood.

i)     New cartilage- Is continuously formed.

ii)    Old cartilage- Older cartilage become ossified: 1.) cartilage is broken down, 2.) enclosed cartilage is digested away, opening up a medullary cavity (middle canal), 3.) bones replaces cartilage through the action of osteoblasts.

b)   Bone remodeling- Bones are remodeled and lengthened until growth stops, bones are remodeled in response to two factors: blood calcium levels & pull of gravity and muscles on the skeleton.

c)    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.

Break down bone matrix for remodeling and release of calcium in response to parathyroid hormone.

11)  Bone fractures

a)    Types

i)     Closed(simple fracture)- Break that does not penetrate the skin.

ii)    Open(compound fracture)- Broken bone penetrates through the skin.

b)   Treatment-Bone fractures by reduction and immobilization.

c)    Table 5.2

d)   Repair

i)     Hematoma- Blood filled swelling is formed.

ii)    Fibrocartilage- Break is splinted by fibrocartilage to form a callus.

iii)  Bony callus- Fibrocartilage callus is replaced by a bony callus. Bony callus is remodeled to form a permanent patch.

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

(1)  Functions

vii) Hyoid bone- Only bone that does not articulate with any other bone, serves as a moveable base for the tongue, aids in swallowing speech.

b)   Fetal skeleton

c)    Skull proportions- The fetal skull is large compared to the infant’s total body length.

d)   Fontanel – Fibrous membranes connecting the cranial bones, allow brain to grow, convert to bone within 24 months after birth, allow skull to “squeeze” during birth

13) Vertebral column: Each vertebrae is given a name according to its location

a)    Typical vertebrae structures-24 single vertebrae bones separated by intervertebral discs.

b)   Cervical = neck- Seven cervical vertebrae are in the neck.(C1-C7)

i)     Atlas

ii)    Axis

c)    Thoracic = chest- Twelve thoracic vertebrae are in the chest region.(T1-T12)

d)   Lumbar = lower back- Five lumbar vertebrae are associated with the lower back.(L1- L5)

e)    Composite vertebrae- Formed by nine vertebrae fused together.

i)     Sacrum

ii)    Coccyx(tail bone)

f)    Curvatures-Spine has a normal curvature:

i)     Primary- Are the spinal curvatures of the thoracic and sacral regions, present form birth.

ii)    Secondary- Are the spinal curvature of the cervical and lumbar regions, develops after birth.

iii)  Abnormalities

(1)  Scoliosis

(2) Lordosis

(3) Kyphosis

g)    Bony thorax

i)     Sternum

ii)    Costal cartilage

iii)  Ribs

(1)  True

(2) False

(3) Floating

iv)   Vertebrae – facets for ribs

14) Appendicular skeleton – 126 bones

a)    Pectoral (shoulder) girdle

i)     Clavicle-Collarbone

ii)    Scapula-Shoulder blade.

iii)  Freedom of movement- These bones allow the upper limb to have exceptionally free movement, but somewhat less support.

b)   Upper limbs

i)     Humerus-Forms the arm. Single bone

ii)    Ulna- Medial bone in anatomical position.

iii)  Radius- Lateral bone in anatomical position.

(1)  Hand

(a)  Carpals- Wrist: eight bones.

(b) Metacarpals-Palm, long bones

(c)  Phalanges (phalanyx)- Fingers (digits). #1=thumb- #5= pinky.

c)    Pelvic girdle = two coxal bones

i)     Total weight

ii)    Protects several organs

iii)  Each coxal bone made of three fused bones:

(1)  Illium

(2) Ischium

(3) Pelvis- The total weights of the upper body rests on the pelvis, it protects several organs, reproductive organs, urinary bladder, parts of large intestine.

iv)   Gender differences:  Compared to the male, the female pelvis:

(1)  Inlet- Female inlet is larger and more circular.

(2) Pelvis as a whole- The female pelvis as a whole is shallower, and the bones are lighter and thinner.

(3) Ilia- The female ilia flare more laterally.

(4) Sacrum- The female sacrum is shorter and less curved.

(5) Ischial spines- Female ischial spines are shorter and farther apart; thus the outlet is larger.

(6) Pubic arch- The female pubis arch is more rounded because the angle of the pubic arch is greater.

d)   Lower limbs

i)     Upper leg- Thigh bone has one bone.

(1)  Femur- Heaviest, strongest bone in the body.

ii)    Lower leg- Has two bones.

(1)  Tibia- Shinbone, larger and medially oriented.

(2) Fibula- Thin and sticklike, lateral to the tibia.

iii)  Foot

(1)  Tarsals- Two largest tarsals= calcaneus(heelbone), talus.

(2) Metatarsals- Sole.

(3) Phalanges- Toes, #1= big toe, #5= pinky.

(4) Three arches of the foot- Bones of the foot are arranged to form three strong arches. Two longitudinal, one transverse.

15) 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- Functionally, structurally.

(1)  Synarthroses- Immovable joints.

(2) Amphiarthroses- Slightly moveable joints.

(3) Diarthroses- Freely moveable joints.

ii)    Structural classifications

(1)  Fibrous- Generally moveable.

(a)  Sutures, syndesmoses- Allows more movement than sutures.

(2) Cartilagaenous- Immovable or slightly moveable. Pubic symphysis, intervertebral joints.

(a)  Pubic symphysis, intervertebral joints

(3) Synovial- Freely moveable. separated by joint cavity.

(a)  Joint cavity with fluid- Synovial fluid.

(b) Features- Articular cartilage(hyaline cartilage) covers the ends of bones, a fibrous articular capsule encloses joint surface, a joint cavity is filled with synovial fluid, ligaments reinforce the joint.

(c)  Structures

(i)   Bursae- Flattened sacs: lined with synovial membranes, filled with synovial fluid, not actually part of joint.

(ii)  Tendon sheath- Elongated bursa that wraps around a tendon.

(d) 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 a tendon sheath

iii)  Arthritis- Inflammatory or degenerative diseases of joints: over 100 different types, the most widespread crippling disease in the united states.

(1)  Osteoarthritis- Most common chronic arthritis, probably related to normal aging processes.

(2) Rheumatoid arthritis- An autoimmune disease= the immune system attacks the joints, symptoms begin with bilateral inflammation of certain joints, often leads to deformities.

(3) Gouty- Inflammation of joints is caused by a deposition of uric acid crystals from the blood, can usually be controlled with diet.

d)   Skeletal changes throughout life- Fetus= long bones are formed of hyaline cartilage, flat bones begin as fibrous membranes, flat and long bone models are converted to bone

i)     Osteoporosis

ii)    Posture