Objectives

1. Identify the axial and appendicular subdivisions of the skeleton
2. Describe the functions of the skeletal system
3. Identify and classify different types of bones
4. Distinguish between osteoblast, osteoclast, and osteocyte function and describe the mechanism of bone remodeling
5. Relate the structure of long bone to its function
6. Identify and describe various types of bone fractures
7. Describe the stages of bone healing
8. Explain the differences between the male and female pelvis

Link to video about bone strength:
http://www.youtube.com/watch?v=Sb-SZXtGbb0

Bone Song
http://www.youtube.com/watch?v=BdGxOB9J2t0

Website of Skeletal System:
http://www.innerbody.com/image/skelfov.html

1. Identify the axial and appendicular subdivisions of the skeleton

Axial Skeleton (green) and Appendicular Skeleton (purple)
external image skeletal-system.jpg
The axial skeleton consists of 80 bones throughout the head and trunk of the human body which form the center axis of the body. The five main parts of the axial skeleton include:

  • Bones of the skull
  • The vertebral column
  • The thoracic cage (This includes the sternum and ribs.)
  • The hyoid bone (a U-shaped bone that and hangs below the skull, suspended by ligaments. The hyoid serves as a base for muscles within the tongue and larynx.)
  • The ossicles (The three small bones in the middle ear. The ossicle bones help carry sound from the eardrum to the inner ear.)


The appendicular skeleton consists of 126 bones throughout the body which make motion possible and protects the organs of digestion, excretion, and reproduction. The eight main parts of the appendicular skeleton include:
  • The shoulder girdle (This includes the clavicle and scapula. The shoulder girdle is a set of bones which connect the upper limbs, like the arms, forearms, and hands, to the axial skeleton on each side.)
Arms
Forearms
  • Hands
The pelvic girdle (This includes the two hip bones. The pelvic girdle supports the weight of the body from the vertebral column; it also protects and supports the lower organs.)
Thighs
Legs
  • Feet




Cervical Spine Anatomy
http://www.spineuniverse.com/videos/cervical-spine-anatomy/

2. Describe the functions of the skeletal system

There are 5 functions of the skeletal system
1. Protection: Protection for soft body organs like lungs and heart, as well as protection for the spinal cord and brain.
Ex. sternum, cranium (fused skulls provides snug enclosement of the brain), vertebrae, rib cage (protects vital organs of the thorax), pelvis, etc.
2. Support: Framework for the body. The skeletal system gives the body its shape and structure.
: They form the internal framework that supports and anchors all soft organs.
: Rib cage supports the thoracic wall
: Bones of the leg acts as pillars to support the body
Ex. femur, tibia, vertebrae, etc.
3. Movement: Pulls bones towards each other. The bones are used as levers to create movement, whether its a hinge, ball-in-socket, or saddle joint.
Ex. humerus and ulna, femur and pelvis, philanges, etc.
4. Storage: Calcium, phosphorous salts, and lipids are stored in the Medullary Cavity of bone.
Ex. vertebrae, femur
5. Blood Cell Production: Red blood cells are produced in the marrow of the bone (hematopoiesis).
Ex. body of vertebrae

3. Identify and classify different types of bones

The adult skeleton is made of 206 bones. There are two basic types of osseous (bone) tissue which make up compact and some spongy bone. There are also hybrid variations such as spongy bone sandwich, which is a combination of both.
Compact Bone: is composed of strong cylinders called Haversian systems or osteons, which contains lots of ECM (storage of Ca and P), is very dense, and appears smooth.
Spongy Bone: is a lightweight bone that consists of an interwoven network of trabeculae. Spongy bone is composed of small needle-like pieces of bone and lots of open space.
Spongy Bone Sandwich: can be found in flat bones, (Ex. The skull), and can be found in places that need to be very strong but also very light.
external image compact_spongy_bone.jpgOsteon.jpg


Classifications of Bones
Bones come in many sizes and shapes. The unique shape of each bone fulfills a particular need and they are classified according to shape into four groups...
Long bones
Short bones
Flat Bones
Irregular bones
Longer than they are wide.
Composed of a shaft with heads at both ends.

Are mostly compact bone (the head is composed mostly of spongy bone and the shaft is compact bone).
All bones of the limbs except wrist and ankle bones.

Cube-shaped.
Mostly spongy bone.
Ex. ankle and wrist bones. Sesamoid bones are a special type of short bone.

They form within tendons.
Ex. patella.
Thin, flattened, usually curved.
Two thin layers of compact bone sandwiching a layer of spongy bone between them.
Ex. most of the bones of skull, ribs, and sternum.

Bones that do not fit into the other categories.
Ex. vertebrae and hip bone.

Link to bone structure video (compact, spongy, etc)
http://www.youtube.com/watch?v=4qTiw8lyYbs&feature=related

4. Distinguish between osteoblast, osteoclast and osteocyte function and describe the mechanism of bone remodeling




Function
How it Helps with Bone Remodeling
Osteoblast
Osteoblasts are small bone cells which synthesize and secrete EMC (composed of calcium, phosphorus and collagen fibers.)
When a bone is constantly being used it needs to become stronger in order to support bone. Osteoblasts, located in the periosteum (the nutrient sheath of the bone) it helps to increase bone mass
Osteoclast
Osteoclasts work at the opposite end of homeostasis of calcium levels, because when activated by the parathyroid hormone osteoclasts release calcium back into the blood taking it away from the bone.
When a bone is not being used the bone is remodeled so it smaller, since the extra strength is not needed. Osteroclast breaks down the ECM of the bone (this is known as bone resorption.)
Osteocyte
Osteocytes are the most common cells found in the human bone. They are mature bone cells which keep the bone metabolically active.
Osteocytes are created by osteoblasts and are found in clusters known as osteons. Osteocytes are connected by cannaliculi, which help transfer materials such as minerals and waste


external image SPR_20070625155114_Fig1_Osteoclasts.jpg&usg=AFQjCNFGnF1hAUC6H1kuv418D_nuy6AYaQ

Bone Remodeling Video
Link to website with animations of bone remodeling and bone growth

5. Relate the structure of long bone to its function

Long bones have an epiphysis, or head, on each end of the shaft. These consist of spongy bone and are surrounded by a thin layer of compact bone. Since spongy bone weighs less than compact bone, it makes it easier to move. Even though the spongy bone is lighter, it is still able to provide a lot of support since it has many small beams, called trabeculae, distributed throughout it. These trabeculae contain a strong ECM which is essential for the bone.The shape of the epiphysis, with its articular cartilage that has a smooth and slippery texture, facilitates movement, articulation with other bones, and muscle and ligament attachment. It also acts as cushioning so that the bones do not grind against each other, and this provides protection from the bones wearing down. Significantly, articular cartilage is also avascular so that you will not bleed internally everytime you move and your bones rub against it.
The diaphysis, commonly referred to as the shaft, is mostly made up of compact bone. There are long columns (the Haversian system) that together form a very strong bone. The ECM, extra cellular matrix, is contained in here and with it are collagen fibers, calcium, and phosphorous salts, making the bone very strong. This helps the body have a strong structural framework, as well as with protection.
In the diaphysis, there is something known as the medullary cavity. This cavity contains red bone marrow, most common when we are young, and yellow bone marrow, most common when we are old. Blood cells are made in the bone marrow, which means that this cavity allows blood cell production (hematoesis) to take place which is needed by the skeletal system. The yellow bone marrow, which is fatty connective tissue, stores lipids, and it is for this reason the long bone performs the function of storage. The ECM in the bone also works as a storage center since it stores calcium and phosphorous salts.

6. Identify and describe the various types of bone fractures

Closed (simple) fracture: bone breaks cleanly but does not penetrate the skin.
Open (compound) fracture: broken bones ends penetrate through the skin.

Fracture Type

Description
Comment
Comminuted
Bone breaks into many fragments.
Particularly common in the aged, whose bones are more brittle.
Compression
Bone is crushed (ex. osteoporotic bones)
Common in porous bones
Depressed
Broken bone portion is pressed inward.
Typical of skull fracture
Impacted
Broken bone ends are forced into each other.
Commonly occurs when one attempts to break a fall with outstretched arms.
Spiral
Ragged break occurs when excessive twisting forces are applied to a bone.
Common sports fracture.
Greenstick
Bone breaks incompletely, much in the way a green twig breaks.
Common in children, whose bones are more flexible than those of adults

Complex fractures

In long bones, such as the thighbone (femur) an injury is more likely to cause a more complex, spiral fracture. This leaves surfaces that are less likely to re-unite easily.

Stress fractures

Bones can break due to small repeated stresses and strains. This is known as a stress or fatigue fracture, and is most often seen in the lower leg or foot bones of athletes.

Avulsion fractures

Muscle or ligament that supports or is attached to bone can also cause a fracture called an avulsion fracture. This happens when the ligament or muscle pulls on the bone causing it to fracture.

Hairline fractures

Hairline fractures may occur after a trip or a fall. The bone is only partially fractured. They can be difficult to detect.

Depressed fractures

A depressed fracture is when part of the bone is pushed out of line with the rest of the bone. This is usually in the skull.

Pathological fractures

If a tumour or other disease causing factor is weakening the bone, it's called a pathological fracture.

Complicated fractures

A fracture is described as complicated if there is damage to major structures near the fractured bone, such as an artery.

Compound fractures

The broken end of a bone can break the skin, or protrude through the skin. This is known as an open or compound fracture and it can lead to infection and blood loss.

Closed fractures

If the bone doesn't damage the skin it's called a closed fracture.

Comminuted fractures

Sometimes, particularly in more serious accidents, the bone can fracture in a way that produces several fragments. This is called a comminuted fracture.

Impacted fractures

After a fracture, the broken fragments of bone usually separate to some degree. Sometimes one fragment of bone is driven into another. This is called an impacted fracture.

Fragility fractures

From middle-age onwards, your bones lose density and fractures are more likely. Osteoporosis is a bone disease that speeds up this process and weakens the bones. This makes people with osteoporosis more likely to have fragility fractures, which can occur after a minor fall, such as falling from standing height or less. For further information see Related topics.

Broken bones in children

Fractures in children tend to be different to those in adults because bone is softer and more able to bend. When fractures occur, the bone is not always broken completely. The bone can buckle and split and result in what is known as a greenstick fracture.
Another type of fracture common in children is a growth plate fracture, called an epiphyseal plate fracture. Bone grows in length from the growth plates near the ends of long bones. These fractures can affect bone growth.

Animation about common fractures
http://hcd2.bupa.co.uk/fact_sheets/html/Fractures.html

The severity of a fracture depends upon its location and the damage done to the bone and tissue near it. Serious fractures can have dangerous complications if not treated promptly; possible complications include damage to blood vessels or nerves and infection of the bone ( osteomyelitis) or surrounding tissue. Recuperation time varies depending on the age and health of the patient and the type of fracture. A minor fracture in a child may heal within a few weeks; a serious fracture in an older person may take months to heal.


external image MMPE_21PHY_309_02_eps.gif

Types of Fractures Video- http://video.about.com/orthopedics/Fractures-1.htm
Spiral fracture of the femur
Spiral fracture of the femur

transverse fracture of the Humerus
transverse fracture of the Humerus
Oblique fracture of meta tarsal
Oblique fracture of meta tarsal
Comminuted fracture in the femur
Comminuted fracture in the femur
segmental fracture and repair of the humerus
segmental fracture and repair of the humerus
Compression.jpg

basic information on female sexual problems
basic information on female sexual problems
Gunshot to the Vertebrae
Gunshot to the Vertebrae


7. Describe the stages of bone healing


Inorder for a bone to heal reduction (realignment of bone ends) must occur. There are two types of reduction...
Closed Reduction- the bone ends are coaxed back into their normal position by the physician's hands
Open Reduction- surgery is performed and the bone ends are secured together with pins and wires
After the broken bone is reduced, it is immobilized by a cast or traction to allow the followinghealing process to begin...

Phases of fracture healing
There are three major phases of fracture healing, two of which can be further sub-divided to make a total of five phases;
  • 1. Reactive Phase
    • i. Fracture and inflammatory phase
    • ii. Granulation tissue formation
  • 2. Reparative Phase
    • iii. Callus formation
    • iv. Lamellar bone deposition
  • 3. Remodeling Phase
    • v. Remodeling to original bone contour

When a person fractures a bone, there are several steps and procedures that are implemented so that the healing process is quick and efficient. Once the fracture occurs, blood cells begin to rush to the site of the fracture. The cells then clot, causing a hematoma. Furthermore, the tissue cells around the clot begin to die off. Next, chrondroblasts rush to the area to create cartilage, which serves as the basis for the bone to be formed. Then, osteoblasts release an ECM containing calcium and phosphorus. Finally, once the healing process is finished, the osteoblasts turn into mature osteoclasts.
Despite their remarkable strength, bones are susceptible to fractures or breaks. During youth, most fractures result from exceptional trauma that twists or smashes the bones. In old age, most fractures occur as bones thin and weaken. A fracture is treated by reduction, the realignment of the broken bone ends. In closed reduction, the bone ends are coaxed into position by the physician's hands. In open reduction, the bone ends are secured together surgically with pins or wires. For a simple fracture the healing time is six to eight weeks for small or medium-sized bones in young adults, but it is much longer for large, weight-bearing bones and for bones of elderly people because of their poorer circulation. Repair in a simple fracture involves four major stages:

1. Hematoma formation: When a bone breaks, blood vessels in the bone and periosteum are torn and hemorrhage. As a result, a hematoma, a mass of clotted blood, forms at the fracture sight. Soon, bone cells deprived of nutrition die and the tissue at the site becomes swollen and painful and inflamed.

2. Fibrocartilaginous callus formation. Within a few days, several events lead to the formation of soft granulation tissue. Capillaries grow into the hematoma and phagocytic cells invade the area and begin cleaning up the debris. Meanwhile, fibroblasts (and osteoblasts) invade the fracture site from the nearby periosteum and endosteum and begin reconstructing the bone. The fibroblasts produce collagen fibers that span the break and connect the broken bone ends and some differentiate into chondroblasts that secrete cartilage matrix. This entire mass of repair tissue, now called fibrocartilaginous callus, splints the broken bone.

3. Bony callus formation. Within a week, osteoblasts begin forming spongy bone and new bone trabeculae begin to appear in the fibrocartilaginous callus and gradually convert it to a bony or hard callus of spongy bone. Bony callus formation continues until a firm union is formed about two months later.

4. Bone Remodeling. Beginning during bony callus formation and continuing for several months after, the bony callus is remodeled. The excess material on the diaphysis exterior and within the medullary cavity is removed, and compact bone is laid down to reconstruct the shaft walls. The final structure of the remodeled area resembles that of the original unbroken bony region because it responds to the same set of mechanical stressors.

Slideshow: Components of Bone Healing - http://anthropology.uvic.ca/451/fractures.PDF

Fracture healing process
Fracture healing process


A Video of Bone Repair -



8. Explain the differences between the male and female pelvis

Document used in class - Pelvis differences.doc
The pelvis is a basin-shaped structure that supports the spinal column and protects the abdominal organs. It contains the following:





  • sacrum - a spade-shaped bone that is formed by the fusion of five originally separate sacral vertebrae.
  • coccyx ( tail bone.) - formed by the fusion of four originally separated coccygeal bones.
  • three hip bones, including the following:
    • ilium - the broad, flaring portion of the hip bone (the crest of the pelvis).
    • pubis - the lower, posterior part of the hip bone.
    • ischium - one of the bones that helps form the hip.

-A male pelvis has a pelvic girdle optimised for walking/running.
-A female pelvis has a wider pelvic opening to assist childbirth.
- The female pelvis ….
· The bones are more delicate – thin and light

· The pelvis is less massive

· The pelvis is more shallow

· The ilia are less sloped

· The anterior iliac spines are more widely separated – thus the greater
prominence of the hips laterally


· The superior aperture of the lesser pelvis (pelvic inlet) is larger, more nearly
circular and has greater obliquity


· The cavity of the pelvis is shallower and wider

· Sacrum is shorter, wider and the upper part is less curved, so the sacral
promontory is less imposing into the pelvic cavity


· The obturator foramina are triangular – oval in shape and smaller in size than
the male circular foramina


· The inferior aperture of the lesser pelvis (pelvic outlet) is larger and the
coccyx is more moveable


· The sciatic notches are wider and shallower

· The spines of the ischia project less inward – hence not protruding as much
into the pelvic cavity


· The acetabula are smaller and look more distinctly forward

· The superior pubic ramus is longer than the width of the acetabulum

· Ischial tuberosities and the acetabula are more wider apart

· The pubic symphysis is less deep

· The muscle attachments are more poorly marked

· The pubic arch is wider an more rounded than in the male where it is an angle
rather than an arch. (~ 90o c.f ~ 60o)
The pelvis is divided by an oblique line passing through the prominence of the
sacrum, the arcuate and pectineal lines, and the upper margin of the pubic symphysis,
into the greater and lesser pelvis.
The greater pelvis is:


· Superior to the pelvic inlet

· Bounded by the abdominal wall anteriorly, the iliac fossae posterolaterally and
the L5 and S1 vertebrae posteriorly


· The location of some of the abdominal viscera like the sigmoid colon and
ileum


· It supports the intestines and transmits some of their weight to the anterior
wall of the abdomen.
The lesser pelvis is:


· Between the pelvic inlet and outlet

· Known as the true pelvic cavity

· Bounded by the pelvic surfaces of the hip bones, sacrum and coccyx

· Limited inferiorly by the musculofascial pelvic diaphragm

· The location of the pelvic viscera – the urinary bladder and reproductive
organs such as the uterus and ovaries

Pelvic inlet


The size and shape of the pelvic inlet is important because it is through this opening
that the fetal head enters the lesser pelvis during labour. The size of the lesser pelvis is
particularly important in obstetrics because it is the bony pelvic canal through which
the fetus passes during vaginal birth. To determine the capacity of the female pelvis
for childbearing, the diameters of the lesser pelvis are noted radiologically or during a
pelvic examination.
The pelvic inlet is variable in contour. The shape can be affected by sexual, racial and
nutritional differences in the population. It is heart shaped in males and some females,
although in most females the opening is larger and is more rounded or oval in contour.
The periphery of the pelvic inlet is formed by the pelvic brim which is indicated by
the linea terminalis. This is an oblique ridge on the internal surface of the ilium (also
known as the arcuate line) and is continued onto the superior pubic ramus as the
pectineal line. The inlet is completed anteriorly by the pubic crests and posteriorly by
the anterior margin of the base of the sacrum and the sacrovertebral angle (sacral
promontory).
The inlet has three principal diameters which can be measured:


· The anteroposterior. Extends from the sacral promontory to the pubic
symphysis and is measured on average about 110mm in the female


· The transverse diameter. Extends across the width from the midpoint of the
pelvic brim on one side to the other on the opposite side. About 135mm on
average in females


· Oblique diameter. From the iliopectineal eminence on one side to the
sacroiliac articulation on the opposite. Average measurement is 125mm in
female


Pelvic outlet

The pelvic outlet has a more irregular contour. It is bounded posteriorly by the point
of the coccyx, and laterally by the ischial tuberosities. These eminences are separated
by three notches: one in front, the pubic arch, formed by the convergence of the
inferior rami of the ischium and pubis on either side. The other notches, one on either
side, are formed by the sacrum and coccyx behind, the ischium in front, and the ilium
above; they are called the sciatic notches; in the natural state they are converted into
foramina by the sacrotuberous and sacrospinous ligaments. When the ligaments are in
situ, the inferior aperture of the pelvis is lozenge-shaped or diamond shaped, bounded,
in front, by the pubic arcuate ligament and the inferior rami of the pubes and ischia;
laterally, by the ischial tuberosities; and behind, by the sacrotuberous ligaments and
the tip of the coccyx.
There are two diameters of the pelvic outlet:


· Anteroposterior diameter. Extends from the tip of the coccyx to the lower part
of the pubic symphysis. In the female average diameter is 90 – 115mm. It
varies with the length of the coccyx, and is capable of increase or diminution,
on account of the mobility of the coccyx.


· Transverse diameter. Measured between the posterior parts of the ischial
tuberosities about 115mm in the female.
Types of pelvis


There are four main types of pelvis, the prevalence dependent on sex and race. For
example the relative frequencies in white females is:


· Gynaecoid – round with enlarged transverse diameter – normal female type –
41.4%


· Of major obstetrical and gynaecological significance
Android – heart shaped – in a woman may present hazards to normal delivery

of a baby – 32.5%


· Anthropoid – long AP diameter – 23.5%

· Platypelloid – long transverse diameter – 2.6%
·


Ways to tell male pelvis from female:
  1. Spread of ilium:
    FEMALE--
    more flared and cradle-like with anterior iliac spines farther apart
    MALE--more straight or “up-and-down” in shape
  2. Shape of hole in ischium:
    FEMALE--
    smaller and triangular in female
    MALE-- larger and rounded in shape
  3. Angle across pubic symphysis = pubic arch:
    FEMALE-- greater than 90° (obtuse angle) and more rounded
    MALE-- less than 90° (acute angle) and more sharply angled
  4. Inner diameter and distance between ischia:
    FEMALE
    --larger--big enough for head of baby to pass through
        1. The coccyx:
          FEMALE-- it is straighter and has a movable joint. Can sometimes be pointed in and the mother will have to have a c-section in order to accomodate the baby.
          MALE-- turned forwards and as a rule firmly joined to the sacrum.



external image MaleFemale_Pelvis1.jpgexternal image 63.jpg
Left: Modern Female Pelvis Right: Modern Male Pelvis