RUMINANTIA. 



527 



many of the avian and piscine families, traces 

 of it also appearing in Solipeda and other 

 quadrupeds ; it is remarkably large in the 

 Bear. In Camelidae the basi-hyal presents no 

 anterior protuberance. The fourth pair or 

 thyro-hyals hypo-branchials of fishes and 

 amphibia (5, 5) represent the greater cornua 

 of the anthropotomist, but in certain mam- 

 mifers, as in the family under consideration, 

 their extent of development is subordinate to 

 that of the lesser horns. In birds, on the 

 other hand, the length of the thyro-hyals is 

 extreme, the lesser cornua being either rudi- 

 mentary, or altogether absent.* 



The muscles proper to the hyoid chain of 

 bones present many interesting modifications. 

 The sterno-hyoids and sterno-thyroids (which in 

 Man and mammifera generally, remain distinct 

 throughout their entire extent), are united 

 below in the majority of ruminants, their com- 

 mon band of origin dividing near the middle of 

 the neck, the larger division being connected 

 to the hyoid bone. Meckel states that the 

 sterno-hyoid is entirely absent in the Camel, 

 and Duvernoy remarks the same peculiarity 

 in the Sheep ; but Gurlt figures the upper part 

 of it in the latter animal and in the Ox. A 

 muscle analogous to the omo-hyoid presents a 

 remarkable difference of origin, relatively, in 

 the typical ruminants, the Camel and the 

 Giraffe. In the Sheep it originates, according 

 to Meckel, in the form of a muscular band of 

 considerable dimensions, which is given off 

 by the rectus capitis anticus major, and leaves 

 that muscle at a point corresponding to the 

 third cervical vertebra to be inserted into the 

 hyoid immediately behind the attachment of 

 the thyro-hyoid muscle. Its relation in the 

 Giraffe will be reverted to presently. In the 

 Camel the disposition of this structure is ex- 

 tremely complicated. From the researches 

 of Meckel we learn that it arises from the 

 anterior division of the transverse process of 

 the fourth cervical vertebra, and is confounded 

 near its commencement with the lowermost 

 bundle of the straight anterior muscle of the 

 head ; it subsequently divides into three por- 

 tions, the first becoming inserted into the 

 lower lip, the second going to the posterior 

 cornua of the hyoid, and the third attaching 

 itself to the lower jaw, upon which it acts as a 

 powerful depressor. Professor Goodsir has 

 remarked to us that an anomaly analogous to 

 this latter distribution is sometimes seen in 

 the human subject. The stylo-hyoid, which is 

 absent in certain Carnivora, its place being sup- 

 plied by a narrow muscle termed the ceratoido- 

 lateralis, is present in the Ruminantia, where 

 the latter muscle appears as a prolongation of 

 the stylo-hyoid rather than as a'distinct muscle. 

 The first of these two muscles regarding 

 them as such proceeds by a long tendon 

 from the posterior and inferior apophysis of 

 the styloid bone, to be attached below to the 

 base of the thyroid cornua ; the ceratoido- 

 lateralis also descends obliquely from the 

 lesser horn to the greater. In both the above- 



* Sea art. TONGUE. 



named families and in the Pachydermata there 

 is likewise a special muscle termed the maslo- 

 styloid ; it is short and triangular, and, arising 

 from the mastoid process of the temporal 

 bone, becomes inserted into the inferior apo- 

 physis of the hammer-shaped extremity of the 

 stylo-hyal element or styloid bone, immediately 

 above the origin of the tendon of the stylo- 

 hyoid muscle. The mylo-hyoid is distinctly 

 double, the anterior bundle having an extended 

 longitudinal development, while the posterior 

 division is short, and has its fibres directed 

 transversely outward. The genio-hyoids of 

 either side are incorporated at the middle line. 

 In the foregoing description of the muscles 

 connected with the hyoid apparatus we have 

 intentionally omitted those of the Giraffe, pre- 

 ferring, on account of the peculiar interest 

 which the muscular arrangements of this ani- 

 mal present, to treat of them separately. We 

 quote at length, therefore, from the accurate 

 researches of Professor Owen.* " The mylo- 

 hyoideus is a thick and strong muscle , it 

 arises from the whole of the internal surface 

 of the lower jaw, and is inserted principally 

 into the raphe, or longitudinal commissure, 

 dividing it from its fellow of the opposite 

 side. It adheres firmly to the genio-hyoideus : 

 this arises by a well marked tendon from the 

 posterior rugous surface of the symphysis 

 menti, and has the usual insertion. The 

 genio-glossus arises by a tendon close to the 

 inner side of the tendon of the genio-hyoidew ; 

 its fleshy belly has a considerable antero- 

 posterior extent, and diminishes to a very 

 thin edge at its anterior margin. The digas- 

 tricus has the usual origin, and is inserted, 

 broad and thick, into the under side of the 

 lower jaw. The stylo-hyoid is external to the 

 digasiricus, and is remarkable for the slender- 

 ness and length of its carneous part. The 

 most interesting modifications in the muscles 

 of the os hyoides were found in those which 

 retract that bone. The muscle which, as in 

 some other ruminants, combines the offices of 

 the sterno-thyroideus and sterno-hyoideus, arises 

 in the Giraffe by a single long and slender 

 carneous portion from the anterior extremity 

 of the sternum ; this single fleshy origin is 

 nine inches long, and terminates in a single 

 round tendon, which is six inches long ; the 

 tendon then divides into two, and each di- 

 vision soon becomes fleshy, and so continues 

 for about sixteen inches ; then each division 

 again becomes tendinous for the extent of 

 two inches, and ultimately carneous again, 

 when it is inserted into the side of the thy- 

 roid cartilage, and is thence continued in the 

 form of a fascia into the os hyoides. We have 

 in this alternation of a contractile with a non- 

 contractile tissue a striking example of the use 

 of tendon in limiting the length of the car- 

 neous or contractile part of a muscle to the 

 extent of motion required to be produced in 

 the part to which the muscle is attached. 

 Had the sterno-thyroideus .been continued 

 fleshy as usual from its origin through the 



* Memoir, I. c. p. 232. 



