Section 1.
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CAKTILAOKS. P
These bodies are divided into the temporary and permanent. The former, which supply the place of bones exist only in the fetus and in young persons; they constantly and regularly disappear in proportion as ossification advances. The latter, which are met with in all periods of life, cover or incrust the extremities of the bones in the moveable joints; and in the instant of the ribs, they assist in the formation of the thoracic cavity. The temporary cartilages will be described with the osseous system.
Those of the joints are named articular or diarthrodial cartilages; each of them consists of a layer which corresponds in shape with the process it covers. The thickness of this plate, varying from one or two lines to the fraction of a line, is generally proportioned to its size; but it usually happens that the elastic substance is accumulated on the center of convex surfaces and on the circumference of those which are concave.
The adherent surface of these cartilages is intimately connected to the bone, that it is impossible to effect a complete separation without the assistance of maceration. The exact means by which this union is accomplished, are not known, but it is certain that in the adult, the cartilage is not a prolongation of the bone although in the early periods of life there is only a cartilaginous mass in the place of the latter. It has been justly observed by Fichat, that if there were such a continuity, it ought to be perceived when the bone is deprived of its earthy part by diluted acids; but instead of this, it is seen that the cartilage is constantly detached by the action of the acid, either in one entire piece or in fragments.
The free surface owes its polished appearance to the synovial membrane by which it is covered; the connexion between the two structures is so very close, that it is almost impossible to separate one from the other. This circumstance has induced some anatomists to deny the reflection of the strous membrane of the joint on the cartilage. The incorrectness of this opinion has been pointed out in a preceding chapter.
The cartilages of the second dose, which are called the costal, are the largest and thickest of the body; they form cartilaginous prolongations to the osseous ribs. The cartilage of the first rib is immovably fixed by the insertion of its fibrus into the side of the sternum; those of the six following are joined to the latter by diarthrodial articulations; the three next are connected in a similar manner to each other, and the two inferior are attached to muscular structure.
The costal cartilages are covered by a dense membrane, which is called the perichondrium; it adheres very firmly to their surface, but not so closely as the peritoneum to the bone. It serves to convey the small blood-vessels which penetrate into these bodies.
<Callout type="important" title="Key Observation">Fichat noted that if there were a continuity between cartilage and bone, it would be visible when the bone is treated with acids.</Callout>
The costal cartilages of the second dose are the largest and thickest in the body; they form cartilaginous prolongations to the osseous ribs. The cartilage of the first rib is immovably fixed by its insertion into the side of the sternum, while those of the six following are joined to the latter by diarthrodial articulations.
<Callout type="risk" title="Risk of Misdiagnosis">Incorrectly assuming a continuity between cartilage and bone can lead to misdiagnosing joint injuries.</Callout>
The costal cartilages are covered by a dense membrane, the perichondrium; it adheres firmly but not as closely as the peritoneum. This serves to convey blood vessels into the cartilages.
<Callout type="beginner" title="Clarification for Beginners">Understanding that cartilage is separate from bone helps in diagnosing and treating joint injuries.</Callout>
Key Takeaways
- Cartilages are divided into temporary and permanent types.
- Articular cartilages assist in the formation of the thoracic cavity.
- The perichondrium is crucial for conveying blood vessels to cartilage.
Practical Tips
- Understand that cartilage and bone are separate structures, which can help in diagnosing joint injuries.
- Recognize the importance of synovial membranes in maintaining the health of joints.
- Be aware of the role of costal cartilages in supporting the ribcage.
Warnings & Risks
Risk of Misdiagnosis
Incorrectly assuming a continuity between cartilage and bone can lead to misdiagnosing joint injuries.
Injuries involving cartilages require careful treatment to avoid infection, as they lack the protective layer of bones. Ignoring the health of cartilages can lead to joint degeneration and arthritis over time.
Modern Application
While this chapter provides foundational knowledge on cartilage anatomy, modern techniques in imaging and diagnostics have greatly improved our ability to accurately assess and treat joint injuries. Understanding these historical principles remains valuable for recognizing basic issues and preparing for more advanced medical care.
Frequently Asked Questions
Q: What are the differences between temporary and permanent cartilages?
Temporary cartilages exist only in fetuses and young persons, disappearing as ossification advances. Permanent cartilages cover or incrust the extremities of bones in moveable joints and assist in forming the thoracic cavity.
Q: How does the perichondrium contribute to the health of cartilage?
The perichondrium adheres firmly to the surface of cartilages, serving to convey small blood vessels which are essential for maintaining their health and function.
Q: What is the significance of Fichat's observation about cartilage-bone continuity?
Fichat noted that if there were a continuity between cartilage and bone, it would be visible when the bone is treated with acids. This observation highlights the importance of understanding the distinct nature of these structures in diagnosing joint injuries.