Michael Paulus' Cartoon Skeletons
**The adult human skeleton usually consists of 206 named
bones.
Femur (say: fee-mur) Largest bone in the body. More commonly
known as the thigh bone. The femur is the longest, strongest, and
heaviest bone in the body. The femur supports much of our body
weight. The smallest are the ear ossicles. All 3 would find on a
dime.
The human skeleton consists of more than 200 bones of varying
size, shape, and composition. In addition to their supporting
function, bones, by virtue of their articulations with each other
and their attachments to muscles, are responsible for the mobility
of the head, trunk, and limbs. They also protect the skull,
vertebral column, sensory organs, brain, and spinal cord. In their
interior they accommodate the bone marrow. As a reservoir of
phosphate and calcium, bone tissue plays an important role in
mineral metabolism. Bone undergoes constant restructuring
(remodelling) and is thereby adapted to changes in static forces.
Coordination of the processes involved in the breakdown, formation,
and remodelling of bone, including the deposition and removal of
bone substance and the formation of new bone during the healing of
fractures, is undertaken mostly by cellular messenger substances,
hormones produced by the parathyroid gland, enzymes, and vitamin D.
The kidneys, liver, and gastrointestinal tract influence bone
tissue via their effects on protein and mineral metabolism. One
factor that has an important influence on bone in both men and
women is estrogen. Bones possess high compressive and tensile
strength. Cortical (compact) bone consists of a layer of varying
thickness that is bounded externally by periosteum and internally
by a unicellular endosteal layer. Spongy (trabecular, cancellous)
bone is the spongiform, porous bone that lies internal to the
cortical bone and itself accommodates the bone marrow. *These bones
can be grouped in two divisions: axial skeleton and appendicular
skeleton. The 80 bones of the axial skeleton form the vertical axis
of the body. They include the bones of the head, vertebral column,
ribs and breastbone or sternum.
The appendicular skeleton consists of 126 bones and includes
what is called the free appendages and their attachements to the
axial skeleton. The free appendages are the upper and lower
extremities, or limbs, and their attachments which are called
girdles. These 4 parts are the pectoral girdle, upper extremities,
the pelvic girdle and the lower extremities. and their attachments
to the axial skeleton. *Parietal (2) Temporal (2) bone where middle
and inner ear embededFrontal (1) Occipital (1) Ethmoid (1) - inside
orbital (eye) and nose eth moidSphenoid (1) spfee noid
Sutures places where these bones are fused together by fibers, a
little elasticisty; at birth not fused soft membranous areas
between plates called fontanelle by age 2 these are ossified (hard,
bone)*Maxilla (2) max cilaZygomatic (2) zy go maticMandible (1)
Nasal (2) Vomer (1) inside nose, middle behind cartilageLacrimal
(2) inside, btw eye & nose, next to ethnoid
*Malleus (2) mal lee usIncus (2) Stapes (2) stay peas
The inner and middle ear are embedded in the temporal bone*Our
gift of the gab is all due to a small horseshoe-shaped bone
suspended in the muscles of our neck, like a piece of fruit trapped
in Jell-O. The hyoid bone, which is the only bone in the body not
connected to any other, is the foundation of speech and is found
only in humans and Neanderthals. Other animals have versions of the
hyoid, but only the human variety is in the right position to work
in unison with the larynx and tongue and make us the chatterboxes
of the animal world.
This image shows the human hyoid bone, which helps to support
the tongue and serves as an attachment point for several muscles
that help to elevate the larynx during swallowing and speech. The
hyoid bone is unique in that it is the only bone of the body that
does not articulate with any other bone. Instead, it is suspended
above the larynx where it is anchored by ligaments to the styloid
processes of the temporal bones of the skull.
Hi oid*This bone is not on the list for your to
memorize*Cervical vertebrae (7) Thoracic vertebrae (12) Lumbar
vertebrae (5) Sacrum (1) 5 fused vertebrae say crumCoccyx (1) - 4
fused vertebrae cock sis
*Sternum (1) Ribs (24)
The ribs are connected to it by the costal cartilage. Without
the sternum, there would be a hole in the bone structure in the
middle of your chest, right above your heart and lungs. The sternum
protects this vital area and completes the circle of the rib
cage.
1). True Ribs: (1-7)Superior 7 pairs of ribs attach to the
sternum with costal cartilage.2). False Ribs (8-10)3 pairs of ribs
lack the sternal attachment, but connect to the costal cartilage of
the rib 7.3). Floating Ribs (11-12)no anterior attachment
*Clavicle (2) collar boneScapula (2) shoulder blade scap u
la
*Humerus (2) Radius (2) Ulna (2) ul naCarpals (16) Metacarpals
(10) Phalanges (28) fa lange
*Pelvic girdle
Coxal, innominate, or hip bones (2)
ring of bone forming the skeleton of the pelvis, supporting the
vertebral column*Femur (2) - thigh boneTibia (2) Fibula (2) Patella
(2) - kneecap - front of kneeTarsals (14) connection between leg
& foot tarsusMetatarsals (10) Phalanges (28) *Osteoblasts are
bone-forming cells. They are connective tissue cells found at the
surface of bone. They can be stimulated to proliferate and
differentiate as osteocytes.Osteocytes are bone cells. Osteocytes
manufacture type I collagen and other substances that make up the
bone extracellular matrix. Osteocytes will be found enclosed in
bone.Osteoclasts are bone-resorbing cells ("-clast" means to break;
osteoclasts break down bone). They are large, multinucleate cells
that form through the fusion of precursor cells. Unlike
osteoblasts, which are related to fibroblasts and other connective
tissue cells, osteoclasts are derived from stem cells in the bone
marrow that also give rise to monocytes.
Osteoclasts resorb bone tissueNew bone substance is produced by
osteoblasts, which tend to refill resorption lacunae as they arise.
The new bone material, or osteoid, formed in this way is rendered
hard by deposition of calcium phosphate crystals. Once the original
bone-forming cell has been incorporated into this bone matrix, it
stops dividing and (now known as an osteocyte) comes to occupy a
small cavity (bone lacuna) in the matrix. From this lacuna radiate
slender channels containing extensions of the osteocyte. These
communicate with the osteocytes of neighbouring lacunae.
Osteoclasts, by contrast, break down bone matrix. These large
cells, which have become multinucleate by a process of cell fusion,
are derived from hemopoietic stem cells of the bone marrow. They
erode bone substance by forming resorption lacunae. In the middle
of such a lacuna grows a blood capillary that supplies nutrients to
the bone cells. Once the lacuna acquires a certain depth,
osteoblasts respond by filling it with osteoid. While some tunnels
are closed with bone material, osteoclasts construct others, in the
process cutting older concentric rings of osteocytes. The more
osteoclasts are activated, the more bone material is resorbed. Each
osteoclast leaves behind a resorption lacuna with an average size
of 30 (width) x 70 (length) x 30 (depth) microns. As the number and
depth of resorption lacunae increases and as the diameter of the
remaining trabeculae (lamellae) decreases, the trabecular bone
becomes increasingly brittle. Only 5 to 20 percent of the bone
surface undergoes remodelling at any given time, the rest remaining
in the quiescent phase. The local remodelling process, which begins
with activation of osteoclasts and ends with osteoblastic new bone
formation, takes three to four months. In a healthy person between
five and ten percent of bone substance is replaced annually.
*Compact bone consists of closely packed osteons or haversian
systems. The osteon consists of a central canal called the osteonic
(haversian) canal, which is surrounded by concentric rings
(lamellae) of matrix. Between the rings of matrix, the bone cells
(osteocytes) are located in spaces called lacunae. Small channels
(canaliculi) radiate from the lacunae to the osteonic (haversian)
canal to provide passageways through the hard matrix. In compact
bone, the haversian systems are packed tightly together to form
what appears to be a solid mass. The osteonic canals contain blood
vessels that are parallel to the long axis of the bone. These blood
vessels interconnect, by way of perforating canals, with vessels on
the surface of the bone.
Spongy (cancellous) bone is lighter and less dense than compact
bone. Spongy bone consists of plates (trabeculae) and bars of bone
adjacent to small, irregular cavities that contain red bone marrow.
The canaliculi connect to the adjacent cavities, instead of a
central haversian canal, to receive their blood supply. It may
appear that the trabeculae are arranged in a haphazard manner, but
they are organized to provide maximum strength similar to braces
that are used to support a building. The trabeculae of spongy bone
follow the lines of stress and can realign if the direction of
stress changes.*Periosteum: thin membrane that covers a bone
What is bone marrow?The bone marrow is a soft, spongy tissue
found inside the bones. The bone marrow in the hips, breast bone,
spine, ribs, and skull contain stem cells that produce the body's
blood cells. The bone marrow is responsible for the development and
storage of about 95 percent of the body's blood cells. The three
main types of blood cells produced in the bone marrow include:red
blood cells (erythrocytes) - carry oxygen to the tissues in the
body. white blood cells (leukocytes) - help fight infections and to
aid in the immune system. platelets - help with blood clotting.
Each of these cells carries a life-maintaining function. The bone
marrow is a vital part of the human body.The soft tissue filling
the cavities of bones. Bone marrow exists in two types, yellow and
red. Yellow marrow is found in the large cavities of large bones
and consists mostly of fat cells and a few primitive blood cells.
Red marrow is a hematopoietic tissue and is the site of production
of erythrocytes and granular leukocytes. Bone marrow is made up of
a framework of connective tissue containing branching fibers with
the frame being filled with marrow cells.
red blood cells (erythrocytes) - carry oxygen to the tissues in
the body. white blood cells (leukocytes) - help fight infections
and to aid in the immune system. platelets - help with blood
clotting. Each of these cells carries a life-maintaining function.
The bone marrow is a vital part of the human body.
**The bones of the body come in a variety of sizes and shapes.
The four principal types of bones are long, short, flat and
irregular.
Long bones - Bones that are longer than they are wide are called
long bones. They consist of a long shaft with two bulky ends or
extremities. They are primarily compact bone but may have a large
amount of spongy bone at the ends or extremities. Long bones
include bones of the thigh, leg, arm, and forearm.
Short Bones - Short bones are roughly cube shaped with vertical
and horizontal dimensions approximately equal. They consist
primarily of spongy bone, which is covered by a thin layer of
compact bone. Short bones include the bones of the wrist and
ankle.
Flat Bones - Flat bones are thin, flattened, and usually curved.
Most of the bones of the cranium are flat bones. They protect
organs
Irregular Bones - Bones that are not in any of the above three
categories are classified as irregular bones. They are primarily
spongy bone that is covered with a thin layer of compact bone. The
vertebrae and some of the bones in the skull are irregular bones.
Ex is vertebrae
All bones have surface markings and characteristics that make a
specific bone unique. There are holes, depressions, smooth facets,
lines, projections and other markings. These usually represent
passageways for vessels and nerves, points of articulation with
other bones or points of attachment for tendons and
ligaments.**Computer color-enhanced X ray depicting the hand
development of a two, six, and nineteen year old male.
DEVELOPMENT OF BONE - 2 CATEGORIES: 1. Intramembranous (Direct)
- forms spongy bone and eventually may form compact boneBone forms
directly from mesenchyme *2. Endochondral - bone forms replacing
cartilage "model (long bones)
1. Formation of Primary Center of Ossificationa) hyaline
cartilage model is formed b) Osteoblasts invade cartilage and start
to fill with trecular
2. Expansion of Primary Center of Ossificationa) as bone
increases in size by appositional growth (laying down of layers),
primary center of ossification expands toward ends of bone b)
epiphyses at each end continue interstitial production of
cartilage, but epiphyseal regions don't expand because cartilage is
replaced on diaphyseal side by bone at same rate as it is produced
c) epiphyseal plate extends horizontally across bone and is the
region where cartilage replacement during expansion occurs. AT
adulthood this plate gets calcified and forms the Epiphyseal line,
a visual line but no growth.The growth plate, also known as the
epiphyseal plate or physis, is the area of growing tissue near the
ends of the long bones in children and adolescents. Each long bone
has at least two growth plates: one at each end. The growth plate
determines the future length and shape of the mature bone. When
growth is completesometime during adolescencethe growth plates
close and are replaced by solid bone.
Because the growth plates are the weakest areas of the growing
skeletoneven weaker than the nearby ligaments and tendons that
connect bones to other bones and musclesthey are vulnerable to
injury. Injuries to the growth plate are called fractures.**A
joint, or articulation, is where two or more bones meet and also
often where movement occurs.
There are over 100 different types of joints but they are
generally linked together by the amount of movement which they
allow. The moveable joints in the body permit different kinds of
movement. The type, direction and amount of movement is governed by
the limitations (structure) of the joint.
Muscles move our joints. If we have weak muscles the joints
don't move so well. It is important we keep using our muscles even
if we have arthritis. Ligaments hold the bones together at the
joints and look like thick white bands of tissue Tendons attach the
muscles to the bones so that the bones can be moved Cartilage coats
the end of the bones to stop the bones rubbing together.
*There are three main different types of joint. Immovable or
Fibrous joints These are very stable and allow no observable
movement. Bones are often joined by strong fibres called sutures;
eg, the sutures of the cranium.
Slightly movable joints or Cartilaginous A cartilaginous joint
allows some slight movement. The ends of bones, which are covered
in articular or hyaline cartilage, are separated by pads of white
fibrocartilage and slight movement is made possible only because
the pads of cartilage compress. In addition, the pads of cartilage
act as shock absorbers. The intervertebral discs are examples of
this type of joint. Freely movable joints or Synovial joints A
synovial joint is a freely moving joint, and is the most common
type of joint in the body, and the most important in terms of
physical activity, since they allow a wide range of movement. These
types of joint are divided up according to the movement that they
make possible. Surrounding the joint is a membrane called the
Synovial Membrane which is where Synovial fluid is formed. This
fluid acts as a lubricator and is formed within the joint AND
allows friction free movement. A good example of this is the knee
joint.
*Synovial joints permit the greatest degree of flexibility and
have the ends of bones covered with a connective tissue filled with
synovial fluid; example: hip.
The outer surface of the synovial joints contains ligaments that
strengthen joints and hold bones in position. The inner surface
(the synovial membrane) has cells producing synovial fluid that
lubricates the joint and prevents the two cartilage caps on the
bones from rubbing together. Some joints also have tendons
(connective tissue linking muscles to bones). Bursae are small sacs
filled with synovial fluid that reduce friction in the joint. The
knee joint contains 13 bursaeYOUR JOB
find out how this is done. Textbook chp 6
***Michael Paulus' Cartoon Skeletons
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