Illustrated anatomical parts with images from e-Anatomy and descriptions of anatomical structures. The costal cartilages are bars of hyaline cartilage which serve to prolong the ribs forward and contribute very materially to the elasticity of the walls of the thorax. The first seven pairs are connected with the sternum; the next three are each articulated with the lower border of the cartilage of the preceding rib; the last two have pointed extremities, which end in the wall of the abdomen.
Like the ribs, the costal cartilages vary in their length, breadth, and direction. They increase in length from the first to the seventh, then gradually decrease to the twelfth. Their breadth, as well as that of the intervals between them, diminishes from the first to the last. They are broad at their attachments to the ribs, and taper toward their sternal extremities, excepting the first two, which are of the same breadth throughout, and the sixth, seventh, and eighth, which are enlarged where their margins are in contact.
They also vary in direction: the first descends a little, the second is horizontal, the third ascends slightly, while the others are angular, following the course of the ribs for a short distance, and then ascending to the sternum or preceding cartilage.
Each costal cartilage presents two surfaces, two borders, and two extremities. The others are covered by, and give partial attachment to, some of the flat muscles of the abdomen. The posterior surface is concave, and directed backward and downward; that of the first gives attachment to the Sternothyroideus, those of the third to the sixth inclusive to the Transversus thoracis, and the six or seven inferior ones to the Transversus abdominis and the diaphragm.
The inferior borders of the sixth, seventh, eighth, and ninth cartilages present heel-like projections at the points of greatest convexity. These projections carry smooth oblong facets which articulate respectively with facets on slight projections from the upper borders of the seventh, eighth, ninth, and tenth cartilages. The medial end of the first is continuous with the sternum; the medial ends of the six succeeding ones are rounded and are received into shallow concavities on the lateral margins of the sternum.
Enable Autosuggest. You have successfully created a MyAccess Profile for alertsuccessName. Home Books Junqueira's Basic Histology, 14e. Previous Chapter. Next Chapter. AMA Citation Cartilage. In: Mescher AL. Mescher A. Anthony L. Junqueira's Basic Histology, 14e. McGraw Hill; Accessed November 12, APA Citation Cartilage. Mescher AL. McGraw Hill. MLA Citation "Cartilage. Download citation file: RIS Zotero. Reference Manager. Autosuggest Results. Subscribe: Institutional or Individual. Username Error: Please enter User Name.
Password Error: Please enter Password. The collagen fibers form arches giving it a strong structural arrangement to withstand pressure. Figure 4 shows the location of the articular hyaline cartilage in a joint.
Articular cartilage is made up of different zones. These include the superficial zone, followed by the middle transitional zone, the deep zone, and finally the calcified zone. Within each zone, there are 3 regions. These are the pericellular region, the territorial region, and the interterritorial region. The video below presents the layers found in articular cartilage. Collagen fibers II and IX can be found here. It contains a large volume of chondrocytes that have a more flattened appearance.
The superficial zone is in direct contact with the synovial fluid and protects the deeper layers from force and stresses. The middle zone follows directly from the superficial zone and provides the bridge to the deeper layers. It consists of thicker collagen fibers and proteoglycans. The chondrocytes here are spherical and found in small amounts.
The middles zone functions to protect against compacting forces. The deep zone follows on from the middles zone and provides the best resistance to compacting forces.
It contains the highest proteoglycan content and the least water content. The collagen fibers are arranged at right angles to the surface and the chondrocytes are arranged in columns.
Finally, the calcified zone attaches the cartilage to the bone. It does this by anchoring the collagen fibers in the deep zone to the subchondral bone. As mentioned above, hyaline cartilage connective tissue is made up of cells and fibers within an extracellular matrix.
Hyaline cartilage histology describes how hyaline cartilage looks when viewed under a microscope. The chondrocytes can be seen as rounded or angular in form.
In adult cartilage, the cells are present in isogenous groups, formed from a single progenitor cell. The matrix is visually homogenous and basophilic in appearance. The reason for this is because of the high concentration of sulfated GAGs in the matrix mask the collagen fibers.
Type II collagen fibers are also very small which is why the extracellular matrix appears so shiny and smooth. There is no uniform distribution within the extracellular matrix.
Therefore, the three basic zones can be seen. Figure 5. Shows these different zones. The Van Geison stain uses picric acid and acid fuchsin and stains collagen red. The cartilage is viewed as a red zone lying below the epithelium.
The staining is lighter where it becomes closer to the lacunae indicating the territorial matrix. The territorial matrix is dark, and the interterritorial matrix is a lot lighter in color. These chondrocytes are derived from the same progenitor and are therefore an isogenous group. The perichondrium surrounds the cartilage except in the articular cartilage.
There are 3 different cartilage types found in the body. Hyaline cartilage is the most common but also the weakest type of cartilage. The other two types of cartilage are fibrocartilage and elastic cartilage. How is hyaline cartilage different from elastic cartilage or fibrocartilage? See below to see descriptions of each cartilage type. The visual differences between the types of cartilage can be seen in Figure 1.
Let us look at Hyaline cartilage vs elastic cartilage. Elastic cartilage or yellow fibrocartilage provides strength and elasticity to certain parts of the body. Where is elastic cartilage found? Elastic cartilage functions to give support with additional elasticity.
It contains a dense network of elastin fibers. It does not protect from mechanical stress or compression. More details such as elastic cartilage locations and appearance are highlighted in table 1 below.
Fibrocartilage connective tissue is a dense flexible and supporting cartilage made up of fibrous tissue. Where is fibrocartilage found? Fibrocartilage locations include the intervertebral discs of the spine , in the jaw , and the knee and wrist. This fibrocartilage tissue contains large bundles of type I collagen.
It is the strongest type of cartilage. Fibrocartilage functions to give support against weight-bearing and pressure forces. Fibrocartilage vs hyaline cartilage, as well as the locations in the body where fibrocartilage is located, is described in table 1 below.
So, what is the function of hyaline cartilage? Hyaline cartilage contains relatively few fibers and provides a smooth surface for movement as well as a cushion that absorbs shock where the bones meet.
In articular cartilage, the primary function is to provide a smooth surface that can withstand friction and pressure from weight-bearing functions. In the trachea, it provides support for the softer tissues and allows them to maintain an open position. The most important role of hyaline cartilage is to provide mechanical support for the respiratory system, developing bones and articular surfaces.
As we age, problems with the quality of our hyaline cartilage can arise. With increased age, the number of chondrocytes in the superficial layer of articular cartilage drops whereas the number of chondrocytes in the deeper layers increases. Also, with an increase in age is a decrease in proteoglycans in the extracellular matrix. There is also an increase in keratin sulfate and a decrease in chondroitin sulfate. The volume of hyaluronic acid also increases. Hyaline cartilage is susceptible to wear and tear due to its role as a shock absorber and heavy use in daily activities.
All these factors can lead to hyaline cartilage becoming more susceptible to damage and disease than the other types of cartilage.
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