CARTILAGE. 



495 



We sometimes find the cervical portion of this 

 artery in a tortuous state, but we rarely see in 

 it those atheromatous and earthy deposits which 

 are met with in other parts of it. 



In the dead body there is no difficulty in 

 exposing the common carotid artery in any 

 part of its course, but during life much em- 

 barrassment is occasioned by the alternate di- 

 latation and collapse of the internal jugular 

 vein, corresponding with expiration and inspi- 

 ration, and sometimes by some small veins 

 which lie in front of the artery. It may be 

 cut down upon either above or below the omo- 

 hyoid muscle, but in the former situation the 

 superficial position of the vessel and the less 

 complexity of its relations render it more easy 

 to be got at. In both situations the anterior 

 margin of the sternomastoid muscle forms a 

 useful guide to the artery; but much more 

 careful dissection is required when the 

 operation is done in the region below the 

 omohyoid muscle. Here great care is de- 

 manded in dissecting back the sternomastoid 

 muscle, and in drawing the sternothyroid 

 inwards; the thyroid body and, on the left, 

 the ossophagus must be avoided, and in pas- 

 sing the ligature round the artery, the ope- 

 rator must take care to avoid not only the vein 

 and par vagum but also the inferior thyroid 

 artery, the recurrent and sympathetic nerves 

 and the cardiac branches of the latter, and on 

 the left side the thoracic duct. As anomalies 

 in the distribution of some of the arteries in 

 the neck are occasionally met with, the surgeon 

 should be on his guard against such an occur- 

 rence, especially in operating in the low region 

 where they are most likely to be met with. Two 

 arteries may be found here occupying pretty 

 nearly the situation of the carotid artery. One 

 of these will be the carotid itself, the other the 

 vertebral, which sometimes passes high up in the 

 neck in front of the rectus capitus an ticus muscle, 

 before it enters the canal in the transverse pro- 

 cesses of the cervical vertebrae. In a case related 

 by Mr. Allan Burns,* the vertebral artery en- 

 tered this canal only a few lines below the bifur- 

 cation of the carotid, and in its passage up the 

 neck, parallel to and behind the carotid, it was 

 separated from that vessel only by its sheath. 

 A low bifurcation of the carotid artery would be 

 equally likely to occasion embarrassment; and 

 the possibility of such a condition of the cer- 

 vical vessels as well as of the anomalous course 

 of the vertebral artery before alluded to are 

 strong arguments in favour of the recommenda- 

 tion of Mr. Burns, that, " when the surgeon 

 has reached the sheath of the vessels he ought 

 uniformly, before opening it, to press the carotid 

 between the finger and thumb. If the pulsa- 

 tion of the tumour be not in this way con- 

 trolled, he will do well to pause before he pass 

 a ligature round that vessel."! In fine we 

 sometimes find the inferior thyroid artery cros- 

 sing in front of the common carotid in the 

 inferior region. 







* Surgical Anatomy of the Head and Neck, 

 p. 170. 



t Loc. cit. 



It is very easy in the dead body to find the 

 primitive carotid low down in the neck by 

 cutting in the cellular interval between the 

 clavicular and sternal portions of the sterno- 

 mastoid muscle, but it is not so easy to pass 

 a ligature round it; and this difficulty is greatly 

 magnified in the living subject, in consequence 

 of the necessarily limited space in which the 

 operator has to work; the difficulty too is 

 greatly increased by the contractions of the 

 sternomastoid muscle. 



To expose the external carotid artery shortly 

 after its origin, it is only requisite to follow the 

 same steps as are necessary for cutting down 

 on the common carotid above the omohyoid 

 muscle. It is in general advisable to apply 

 the ligature below the point at which the di- 

 gastric muscle crosses the artery and below the 

 origin of the superior thyroid. Some embar- 

 rassment is likely to result from the plexus 

 of veins which in this region often lies in front 

 and on the sides of the artery. A ligature, 

 however, may be passed round this artery 

 above the digastric muscle, but it will be re- 

 quisite that the external incision shall com- 

 mence higher up. The needle must be passed 

 between the parotid gland and the digastric 

 tendon, the distances between these parts hav- 

 ing been previously increased by drawing down 

 the tendon of the muscle. 



(U. B. Todd.) 



CARTILAGE (Lat. cartilago, quasi car- 

 nilago; Gr.^oi^o?; Fr. cartilage; Germ.Knor- 

 pel ; Ital. cartilagine) is a firm elastic sub- 

 stance, of pearly whiteness, and uniform or 

 homogeneous in its appearance. It bears a 

 considerable analogy to bone, and is to be 

 found in situations where less rigidity and more 

 elasticity are required than the osseous system 

 presents. 



Several tissues, differing a good deal from 

 each other, were formerly comprehended under 

 this term. These have been variously classified 

 by modern anatomists ; but the division of them 

 into cartilages and jibro-cartilages, proposed by 

 Bichat,* is that which is now generally adopted. 

 Although Bichat was happy in the choice of 

 names for these tissues, yet, in arranging the 

 individual pieces under the two heads just 

 mentioned, he has not been found quite correct. 

 Some of the true cartilages are placed by him 

 amongst the fibro-cartilages, an error which 

 Meckel perceived and rectified.! 



Cartilages may be divided into the temporary, 

 the permanent) and the accidental. 



A. The TEMPORARY cartilages are substitutes 

 for bone in the earlier periods of life, and after 

 a certain time become ossified. We find them 

 at birth forming the extremities and larger emi- 

 nences of long bones, a great part of the short 

 bones, and the margins of the broad ones. 

 These gradually disappear, and at puberty cease 

 to exist. It is unnecessary to say more of 

 them here. (See OSTEOGENY.) 



B. PERMANENT cartilages are met with under 



* Anatomic Generale, torn. iii. Par. 1812. 

 t Manuel d'Anatomie, torn. i. Par. 1825. 



