Skeletal system notes (ch. 6)
http://www.youtube.com/watch?v=Ns2dkT2sIug&feature=related
Skeletal Function (131):
1. Support and shape for body and muscles.
2. Protection of delicate vital organs (brain, spinal cord, heart, lungs)
3. Movement in conjunction with joints and muscles. Bones are levers; joints are fulcrums, muscles are effectors doing the work.
4. Storage: Calcium, phosphate, and other minerals stored in bone matrix.
5. Hemopoiesis: blood cells are manufactured from marrow (red, white and platelets)
http://www.youtube.com/watch?v=7G-LsaLzUcA&feature=related
 Red marrow—in spongy bone, manufactures red and white blood cells.
 Yellow marrow—hollow cavities (medullary cavity) of long bones. Produces RBC’s in times of need.
Bone morphological (shape) classification: (131)
1. Short bones: cube shaped, provide elasticity and shock absorption: carpals(wrist), tarsals(ankle).
2. Long bones—movement, support: humerus, femur.
3. Flat bones: (protection) cranial (frontal, parietal) ilium (of pelvis), ribs, scapula
4. Irregular bones: Vertebrae, sphenoid, ethmoid, mandible (muscle attachment, distribution of loads, protection)
5. Sesamoid: nodular bone embedded in tendon or joint capsule—alters angle of muscle pull (patella, between carpals and
metacarpals)
6. Structure of Long bones:
(Leave about 1/3 page here for drawing/labeling (use pg. 132 fig. 6-1)
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Diaphysis-round shaft; made of compact bone
Medullary cavity—hollow of diaphysis; contains soft fatty yellow marrow
Epiphyses—ends of bone—red marrow fills spaces of spongy bone ends
Articular cartilage—lubricates and cushions epiphyses ends.
Periosteum—membrane covering bone exterior
Endosteum— membrane lining medullary cavity.
Epiphyseal plate—cartilage growth plate—growth ceases when growth plates turn to bone.
Dense connective tissue: Tendons (muscle to bone) and ligaments (bone to bone) sink (Sharpy’s) fibers into periosteum and
bone.
Types of bone: (observe human skeleton)
1. Spongy bone (Cancellous)—webbed texture from needle like threads called trabeculae in red marrow (hemopoietic). Found in
epiphyses of long bone and center of flat bone. Lightens bone.
2. Compact bone—strength. structural unit is osteon or Haversian system.
http://www.youtube.com/watch?v=4qTiw8lyYbs&feature=related
Central canal—blood and lymphatic vessels.
Concentric rings (lamella)
Osteocytes: “bone” cells 2 types:
o osteoblast—build calcium;
o osteoclast—crumbles calcium) (each week, we recycle 5-7% of bone mass spongy bone completely replaced every
5-7 years; compact bone replaced every 10 years.)
Lacunae—cavities containing osteocytes.
Canaliculi—little canals side passages for vessels and nutrient flow.
Matrix— inorganic matrix of Phosphorus and Calcium. (hydroxyapatite)
Bones have two components—organic (proteins)(1/3) that give flexibility, and inorganic (2/3)—strength.
Minerals—metallic elements
Vitamins—organic (Carbon chain based) molecules, usually have an enzymatic function. (enzymes are proteins that increase the
speed of a chemical reaction—they are catalysts)
Your body’s absorption of calcium increases dramatically in the presence of Vitamin D: produced in the skin with UV—or ingested.
Vitamin D also helps regulate Calcium and Phosphate levels in the blood.
Cartilage: Avascular (no nerves or vessels), mostly water and protein.
 Surrounded by perichondrium membrane>>holds shape, has vessels which feed cartilage cells by diffusion.
 Cells: Chondrocytes in lacunae rely on diffusion==> cartilage rebuilds slowly.
 Matrix: Collagen and elastin fibers embedded in gel:
 3 types:
o hyaline—articular (joint) cartilages, costal (rib to sternum), only collagen.
o elastic—contain elastin (and collagen) for resilience; ear, epiglottis.
o fibrocartilage—compressible with strength—between vertebrae, knee (meniscus).
Bone formation and growth: (pg. 135) (osteogenesis)
Osteocytes stimulated by hormones.
Calcitonin lowers blood Ca (stimulates osteoblasts)
PTH (parathyroid hormone) raises blood Ca (stimulates osteoclasts)
 Embryonic: Cartilage models “ossify” to become bones.
http://www.youtube.com/watch?v=R09Ub0quiT4&feature=related
 Growth (ossification) can occur in two ways.
1.
From a membrane surface (intramembranous ossification) (forms flat bones of skull and clavicles—this is an embryonic
process)
2.
long bone lengthening by replacement of cartilage. (endochondral ossification)>>occurs at epiphyseal plates at end of
bones.
Describe the difference in appearance of the Epiphyseal plate for youths and adults.
Divisions of Skeleton: (axial and Appendicular)
A.
Axial Skeleton: attached to spine (except pelvis)
80 bones= skull, ribs, vertebrae, sternum, hyoid
B.
Appendicular Skeleton
1. 126 bones attached to trunk as appendages.
2. Includes shoulder and pelvic girdles and upper and lower extremities.
Differences between ♀ and ♂ pelvic girdles:
♂
Attribute
General size
Pelvic shape
Pelvic
inlet:
Pubic angle (arch at symphysis)
Smaller, heavier
Deep, narrow
Small—males don’t need to bend their pelvis’ around a
baby’s head.
<90 degree
♀
Bigger, lighter
Broader, shallow
Generally wider, allowing baby’s
head through
Angle wider
>90 deg.
List and describe the major types of joints & give examples of each.
Articulations (joints): Greater range of motion means less strength and less range of motion means more strength.
Types of joints
NAME
DEGREE OF
CHARACTERISTICS
EXAMPLES
MOVEMENT
Synarthroses
immovable
No joint cavity. Fibrous cartilage or bone
Skull suture, facial
(fibrous joints)
tissue grows between articulating surfaces.
bones except mandible.
Sutures
Distal tibiofibular joint.
Amphiarthroses
(cartilaginous joints)
all at midline
(Gomphoses—tooth in socket)
Diarthroses
(synovial joints)
Thibedeau--156
Slightly movable
Freely movable
Cartilage connects articulating bones:
(2 types)
1)symphysis: growing together at body
midline
2) Synchondroses—held together by
cartilage

Have joint cavity enclosed by
articular capsule.

Have ligaments that cover and
connect ends of opposing bones.

Synovial fluid

6 classes
1) Pubic symphysis
2) between ribs and
sternum (costal
cartilage)
Hip and femur
Knee
Elbow
shoulder
fetal/newborn skull (become synarthroses/sutures
amphiarthroses (synchondroses) of vertebrae
A-GLIDING—TARSALS/CARPALS/VERTEBRAE (NOT INTERVERTEBRAL DISCS) LEAST MOVABLE.
B-HINGE—LIKE DOOR: EXTENSION (STRAIGHTENING) AND FLEXION (BENDING) KNEE, ELBOW, PHALANGES
C-PIVOT—ROTATIONAL AXIS BELOW WITH KNOB, ATLAS RING—HEAD ON ATLAS
D- CONDYLOID OVAL PROJECTION IN ELLIPTICAL SOCKET. WRISTS, SKULL ON ATLAS
E- SADDLE FREELY MOVABLE—WEAK, THUMB
F- BALL AND SOCKET—HIPS/SHOULDERS
Ball And socket joints—hip/femur & Scapula&clavicle/humerus
Saddle joint—Thumb (weakest in body)
Joint disorders
1.
Non-inflammatory
a. osteoarthritis—degenerative joint disease (DJD) involving degeneration of articular cartilage.
b. traumatic injury—dislocation of articular surfaces
 generally have longer repair times than a break.
 Sprain—stretching or tearing of ligaments (bone to bone)
 Strain—stretching or tearing of muscle and tendon. (muscle to bone)
2.
Spine(four curves) and Spinal disorders
 Babies are born with a concavely curve spine.
 As baby holds up head a convex cervical (Neck)curve forms
 As baby walks a convex lumbar (Lower back) curve forms
SPINAL DISORDERS
IN Mr. Wertz’s opinion many lower back problems, can be alleviated by stronger abdominal muscles. Crunches, sit-ups etc. now can save
you from many MANY problems later.
 Lordosis— exaggerated lumbar curvature gives “big butt or sway back”
 Kyphosis—exaggerated thoracic curvature give “hump back”
 Scoliosis sideways spinal curvature
This is a bit macabre
3.
Inflammatory (histone reactions—swelling) disorders
(Histones are proteins that accumulate in/around an inflammation. Inflammation results in fluid accumulation (swelling or edema)
increased heat/redness and soreness. Involved in allergic reactions also. Analgesics (aspirin, ibuprofen, tylenol), or antihistamines
(Benadryl, Claritin, Seldane, and Celebrex) decrease effects of inflammatory responses.)
a.
rheumatoid arthritis—autoimmune (body attacks itself) inflammation of synovial membrane (pg 163) joints swell, fingers
deflected—Inflammation can spread.
b.
Gouty arthritis—uric acid (nitrogenous waste) increases—sodium urate crystals accumulate in distal joints (avoid organ
meats, beans, anchovies) alcohol exacerbates (worsens) this condition)
c.
Infectious arthritis—EX. Lyme disease from deer ticks: spiral bacteria cause heart, nerve and joint problems.
I. Bone homeostasis (remodeling and repair)
A. Bone remodeling:
1. basic processes
a. bone deposition by osteoblasts occurs for injury or stress. Bones are thicker for laborers, muscle builders.
b. bone reabsorption—osteoclasts—parent cells same as white blood cells (lysosome enzymes and acids remove
Calcium).
2. control of remodeling
a.
negative hormonal feedback—controls Ca++ in blood.
b. Low Ca in blood=>, parathyroid hormone (PTH) stimulates osteoclasts for Ca removal (from bone).
c. High Ca=>Calcitonin causes osteoblasts to deposit Ca ions (in bone).
d. mechanical stress—Bones increases in mass when used, body builders have larger processes (sticky-outy parts)
where muscles attach.
B. Types of fractures
Youth have trauma fractures; elderly have thin weak bones.
Epiphesial plate fractures common in youth.
1. types of fractures:
Oblique Fracture:
The break occurs diagonally across the bone.
Comminuted Fracture:
A fracture in which bone is broken, splintered or crushed into 3 + pieces.
Spiral Fracture:
A fracture in which the break travels around the bone.
Compound Fracture:
A fracture in which the bone breaks through the skin, also called an open fracture.
Greenstick or incomplete Fracture:
The bone cracks one side only, not all the way through (like when trying to bend a living stick on a tree), usually only seen in
children due to the softness of their bones.
Transverse Fracture:
A complete fracture in which the break is straight (Perpendicular) across the bone.
Simple or hairline Fracture: A fracture in which the bone is only partially fractured.
2. 4 phases of bone repair
http://www.youtube.com/watch?v=qVougiCEgH8
a.
hematoma formation—blood clotting, swelling, then fibrous periosteum encapsulates formation.
b. Cartilage callus (swelling) formation (cartilage modeling)—fibrocartilage and spongy bone form fed by new vessels)
c.
bony callus: spongy bone callus replaces fibrocartilage.
d. Remodeling—bone returns to normal...tends to be overbuilt at the break point for a while.
A bad sprain involves stretched or torn ligaments (bone to bone) This takes longer to repair, or may never heal right Therefore a bad sprain
may take a lot longer to heal than a broken bone.
A strain involves injury to muscles—severely ruptured muscles can release myoglobins (muscle proteins) into the body, which can cause
liver shutdown, (and death).
II. homeostatic imbalance of bone
a. osteoporosis (holey bones)
 Calcium reabsorption outpaces Ca deposition>>Less matrix
 Low estrogen in postmenopausal women implicated.
 HRT (hormone replacement Therapy) slows, does not reverse. HRT also seems to increase the risk of breast cancer, heart
attack, and increased blood clotting. However, new studies indicate that HRT can also decrease the risk of dementia in older
women if started when younger (though it increases it if started later).
 Best: make sure you get plenty of Ca but it’s best to work out to increase bone density.
b. osteomalacia--soft bones
 Volume of matrix remains constant, but mineral content decreases. (more protein, less Ca crystals)
 Usually caused by lack of Vitamin D (adult “rickets”—advanced Vit. D deficiency).
c. Paget’s disease (osteitis deformans)
 Normal spongy bone is replaced with disorganized new bone (abnormal bone remodeling)
 Effects 3% of elderly in US.
d. Osteomyelitis: Bone inflammation caused by bacterial (or other) infection.