Section II.
ORGANIZATION OF THE ARTERIES.
The arteries, after they are emptied of their contents, are of a whitish or yellowish colour; and they present on their external surface a loose and flocculent appearance, whilst their inner surface is everywhere perfectly smooth and polished. When one of these vessels is cut across, its parietes seem to be homogeneous; but on a closer examination it is evident that they are composed of several laminae superposed on each other and intimately united by delicate cellular tissue. Each of these layers, which are three in number, possesses a peculiar textDTT and has a separate function to perform in the circulation of the blood.
The internal membrane, called also the intima, commona, &c., lines the whole extent of the arterial system; but the portion which belongs to the pulmonary artery is distinct from that connected with the aorta. If a large artery be slit open, some longitudinal folds may be observed on its internal surface, and in a vessel which is placed in the wind of a joint, as the popliteal artery, a few small transverse lines may be perceived.
The middle or muscular coat, which has also been termed mucous tunic, proper membrane of the arteries, has commanded great attention, in consequence of its importance. It is composed of yellowish and flattened fibres, all of which pass in a circular, or, strictly speaking, in rather an oblique direction around the calibre of the artery; they appear not to form complete circles, but to consist of segments which are joined so as to produce rings. These fibres form several layers, which may be easily raised by the forceps, especially in the real trunks; this circumstance has deceived many writers, by making them think that the large arteries possessed a great number of tunics.
The external, or elastic coat, consists of small whitish fibres, which are very dense and tough, and interlaced together in every direction. The outer surface of this membrane is covered by an extremely loose and flocculent cellular substance, which connects the artery to the surrounding parts, and particularly to the sheath of the vessel; the cells of this tissue are filled in the early period of life by a serous fluid, and in advanced age by an oily matter. Many writers have erroneously described this substance as a distinct cellular coat, placed externally to all the others; but it is evidently nothing more than the common connecting cellular membrane.
The external coat is proportionally thicker in the large than in the small arteries, being in this respect opposite to the fibrous membrane; its thickness is also liable to variation in particular vessels; it is, for example, very thick on the convexity of the curvature of the aorta, whilst in the branches of the internal carotid and vertebral arteries, it is almost as thin as paper.
This membrane is distinguished by its great resistance and elasticity, especially in the longitudinal direction; its firmness is so great that it is not divided by the application of the ligature. It has been shown in the preceding part of this chapter, that the arteries are provided with proper nutritious vessels, and also with nerves. The vasa vasorum of the arteries are of immense importance in a surgical point of view; and each individual part of an artery is supplied by its own appropriate vessels, which form but few communications with those above and below. It is therefore essential, in tying any arterial trunk, to disturb it as little as possible, and only to expose so much of it as is precisely required for the proper application of the ligature.
<Callout type="important" title="Proper Tying Technique">It is crucial to minimize disturbance when tying an artery to prevent complications.</Callout>
The nerves of the arteries are so very small that they are traced with difficulty; they penetrate to the intima coat, to which it appears they are principally distributed.
<Callout type="risk" title="Potential Nerve Damage">Care must be taken not to damage surrounding nerves during surgical procedures.</Callout>
Key Takeaways
- Arteries are composed of three layers: intima, media (muscular coat), and adventitia (external elastic coat).
- The muscular coat is essential for the contractile function of arteries.
- Proper surgical technique involves minimizing disturbance to the artery and its surrounding structures.
Practical Tips
- When performing arterial surgery or tying off an artery, ensure that you have a clear understanding of the layers involved to avoid damaging underlying tissues.
- Use precise and controlled movements when working with arteries to minimize tissue damage and reduce post-operative complications.
- Always check for the presence of nerves in the vicinity of the artery before proceeding with any surgical intervention.
Warnings & Risks
Nerve Damage
Improper handling can result in nerve injury, leading to long-term sensory or motor deficits.
Artery Disturbance
Excessive disturbance of the artery during surgery can lead to complications such as aneurysm formation or thrombosis.
Modern Application
While the techniques described in this chapter are rooted in historical medical practices, they provide a foundational understanding of arterial anatomy that is still relevant for modern survivalists. Knowledge of how arteries function and their structure can aid in emergency first aid, such as stopping bleeding or performing basic life-saving procedures. However, it's important to note that modern surgical techniques have advanced significantly, providing safer and more effective methods.
Frequently Asked Questions
Q: What are the three layers of an artery?
The three layers of an artery are the intima (innermost layer), media (middle muscular coat), and adventitia (outer elastic coat).
Q: Why is it important to minimize disturbance when tying off an artery during surgery?
Minimizing disturbance helps prevent complications such as damage to surrounding tissues, nerve injury, or the formation of aneurysms. Proper technique ensures that only the necessary portion of the artery is exposed and manipulated.
Q: What role do the vasa vasorum play in arterial surgery?
The vasa vasorum supply nutrients to the walls of the arteries, making them crucial for maintaining the health of the vessel. During surgery, these vessels must be carefully managed to avoid compromising the artery's integrity.