2. Fibrous Joint Structure
These types of joints are held together by
fibrous connective tissue, no joint cavity is
present. Either slightly mobile or immobile.
3. Synovial Joint Structure
Made up of synovial fluid, freely movable and
characterize most joints.
Subtypes-
Hyaline Cartilage- Covers the end of the bone
Synovial Membrane- Surrounds synovial cavity.
Fibrous capsule- Made up of ligaments ( dense,
irregular connective tissue)
Articulate capsule- Both synovial and fibrous
membrane.
4. Types of Movement
SYNOVIAL JOINTS- All are freely movable
(diarthrosis)
Gliding- Two sliding surfaces
Hinge- Concave surface with convex surface,
diathrosis
Pivot- Rounded end fits into ring
Condyloid- oval condyle with oval cavity
Saddle- each surface is concave or convex
Ball&Socket- Ball shaped head, and cup
shaped pocket
6. The Four Types of Bones
● Long Bones
● Short Bones
● Flat Bones
● Irregular Bones
7. Long Bones
These bones typically have an elongated shaft and two
expanded ends one on either side of the shaft. The shaft is
known as diaphysis and the ends are called epiphyses.
Normally the epiphyses are smooth and articular. The shaft
has a central medullary cavity where lies the bone marrow.
Examples include the humerus, femur, radius, ulna, tibia
and fibula
8. Short Bones
These bones are short in posture and can
be of any shape. Most of them are named
according to their shape.
Examples of this class of bones include
cuboid, cuneiform, scaphoid, trapezoid
etc. In fact all the carpal and tarsal bones
are included in this category.
9. Flat Bones
These bones are flat in appearance and
have two prominent surfaces. They
resemble shallow plates and form
boundaries of certain body cavities.
Examples include scapula, ribs, sternum
etc.
10. Irregular Bones
The shape of these bones is completely
irregular and they do not fit into any
category of shape.
Examples of this type of bones are
vertebrae, hip bone and bones in the
base of skull.
11. Major Structures of a Long
Bone
● The diaphysis, or shaft, is the long tubular portion of long bones. It is
composed of compact bone tissue.
● The epiphysis (plural, epiphyses) is the expanded end of a long bone. It
is in the epiphyses where red blood cells are formed.
● The metaphysis is the area where the diaphysis meets the epiphysis. It
includes the epiphyseal line, a remnant of cartilage from growing bones.
● The medullary cavity, or marrow cavity, is the open area within the
diaphysis. The adipose tissue inside the cavity stores lipids and forms the
yellow marrow.
● Articular cartilage covers the epiphysis where joints occur.
● The periosteum is the membrane covering the outside of the diaphysis
(and epiphyses where articular cartilage is absent). It contains
osteoblasts (bone-forming cells), osteoclasts (bone-destroying cells),
nerve fibers, and blood and lymphatic vessels. Ligaments and tendons
attach to the periosteum.
● The endosteum is the membrane that lines the marrow cavity.
13. Bone as a Tissue
There are two different kinds of bone tissue: Compact and Spongy bone.
Compact bone
● Is made up of concentric rings of matrix that surround central canals which
contain blood vessels.
● Embedded in this bone tissue are small cave-like spaces called lacunae,
which are connected to each other through small tunnels called canaliculi.
● The lacunae contain osteocytes cells. As just discussed, osteocytes help
maintain healthy bone tissue and are involved in the bone remodeling
process that will be outlined later in this lesson.
Spongy bone
● Looks like an irregular latticework (or sponge) with lots of spaces
throughout.
● These spaces are filled with red bone marrow which is the site of
hematopoiesis or formation of blood cells.
14. The Haversian System
A Haversian System consists of many cylinder-shaped
structural units. There are four types of structures that make up
each Haversian system. (1)
1. Lamellae – concentric, cylinder-shaped layers of calcified
matrix
2. Lacunae – small spaces containing tissue fluid in which
bone cells lie imprisoned between the hard layers of the lamellae
3. Canaliculi – ultrasmall canals radiating in all directions
from the lacunae and connecting them to each other and into a
larger canal, the haversian canal
4. Haversian canal – extends lengthwise through the center
of each Haversian system; contains blood vessels, lymphatic
vessels, and nerves from the Haversian canal; nutrients and
oxygen move through canaliculi to the lacunae and their bone
15. Three Major Types of Cells
Found in Bones
1. Osteoblasts – bone-forming
cells
2. Osteoclasts – bone-
resorbing cells
3. Osteocytes – mature bone
cells
19. Homeostatic Functions of
Bones
1. Support: contributes to the shape, alignment, and
positioning of the body parts
2. Protection: hard, bony “boxes” that serve to protect the
delicate structures they enclose
3. Movement: bones with their joints constitute levers,
muscles are anchored firmly to bones, as muscles contract
and shorten, they pull on bones. Making it movement in a joint
4. Mineral storage: depends on changes in the rate of
calcium movement between the blood and bones
5. Hematopoiesis: blood cell formation
(1)
20. Intramembranous and
Endochondral Bone
Intramembranous and Endochondral bone are two essential processes during
fetal development of the mammalian skeletal system by which bone tissue is
created
Intramembranous:
· Cartilage is not present during intramembranous ossification
· Intramembranous ossification is essential process during the natural
healing of bone fractures and the rudimentary formation of bones of
the head
Endochondral:
· Cartilage is present during endochondral ossification
· Essential process during the rudimentary formation of long bones,
the growth of the length of long bones, and the natural healing of bone
fractures.
21. Bone Fracture Repair
1. White blood cells move in to the area to clean up debris created by
the break, which creates inflammation, in turn triggering the growth
of new blood cells
2. New blood vessels develop to begin the healing process
3. Soft callus also known as cartilage or soft fibrous tissue, begins to
form to bridge the gap from the break.
4. A harder cartilage develops in place of the soft cartilage, forming a
more solid bond within the gap
5. Through a process called remodeling, old bone is continually
replaced by new bone, completing the process of bone fracture
healing.
22. Bone and Cartilage
A bone is a rigid organ that constitutes part of the
endoskeleton of vertebrates. It supports and protects the
various organs of the body, produces red and white blood
cells and stores minerals. Bone is made up of osteoblasts,
osteocytes, osteoclasts, and bone lining cells which
regulate the movement of calcium
· Cartilage is a flexible connective tissue found in many
areas in the bodies of humans and other animals, including
the joints between bones. Cartilage is made up of
chondroblasts, chondrocytes, and dense matrix made up of
collagen and elastic fibers
24. Elastic Cartilage
Elastic cartilage or yellow cartilage is a type of cartilage
present in the outer ear and epiglottis. It contains elastic
fiber networks and collagen fibers. The principal protein is
elastin.
Elastic cartilage is histologically similar to hyaline cartilage
but contains many yellow elastic fibers lying in a solid
matrix. These fibers form bundles that appear dark under a
microscope. These fibers give elastic cartilage great
flexibility so that it is able to withstand repeated bending.
The chondrocytes lie between the fibers. It is found in the
epiglottis (part of the larynx) and the pinnae (the external
ear flaps of many mammals including humans). Elastin
fibers stain dark purple/black with Verhoeff stain.
25. Hyaline Cartilage
: Hyaline cartilage is a type of cartilage found on many joint surfaces. It is pearly
bluish in color with firm consistency and considerable collagen. It contains no
nerves or blood vessels, and its structure is relatively simple.
Hyaline cartilage is covered externally by a fibrous membrane, called the
perichondrium, except at the articular ends of bones and also where it is found
directly under the skin. This membrane contains vessels that provide the
cartilage with nutrition.
If a thin slice is examined under the microscope, it will be found to consist of
cells of a rounded or bluntly angular form, lying in groups of two or more in a
granular or almost homogeneous matrix.
The cells, when arranged in groups of two or more, have generally straight
outlines where they are in contact with each other, and in the rest of their
circumference are rounded.
They consist of clear translucent protoplasm in which fine interlacing filaments
and minute granules are sometimes present; embedded in this are one or two
round nuclei, having the usual intranuclear network.
26. Fibrocartilage
White fibrocartilage consists of a mixture of white fibrous
tissue and cartilaginous tissue in various proportions. It
owes its flexibility and toughness to the former of these
constituents, and its elasticity to the latter. It is the only type
of cartilage that contains type I collagen in addition to the
normal type II.
Fibrocartilage is found in the pubic symphysis, the annulus
fibrosis of intervertebral discs, menisci, and the TMJ.
During labor, relaxin loosens the pubic to aid in delivery,
but this can lead to later joint problems.
27. Bone Growth
To make a bone longer just add bone tissue to the ends. The problem is, we
can't add directly to the end of a bone, it has to move at the joints. If tissue is
added at the end of the bone the skeleton could not move properly. It's like
closing both lanes on an interstate until the bridge is repaired.
For this to work, bone tissue must be added below the joint somewhere along
the length of the bone. This occurs at the epiphyseal plate, or growth plate.
Here chondrocytes first produce hyaline cartilage. The cartilage then
becomes calcified or ossified to form hard bone tissue (involves addition of Ca+
and Phosphorous ions). The chondrocytes produce cartilage on one side of the
plate and push the end of the bone up. The other side of the epiphyseal plate
gradually becomes calcified.
Once a person reached adulthood and the bones have reached maximum
length, and the whole plate gets calcified. It forms a visible line called the
epiphyseal line.
28. Cartilage Growth
In embryogenesis, the skeletal system is derived from the
mesoderm germ layer. Chondrification (also known as
chondrogenesis) is the process by which cartilage is
formed from condensed mesenchyme tissue, which
differentiates into chondroblasts and begins secreting the
molecules that form the extracellular matrix.
Following the initial chondrification that occurs during
embryogenesis, cartilage growth consists mostly of the
maturing of immature cartilage to a more mature state.
