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 217 Part II. A N A T Q M Y. It is fixed to the anterior parts of, the tranfverfe apo- and according to the different fituation of the head and phyfis of the third, fourth, fifth, and fixth vertebrse ia trunk. a digitated manner. From thence it runs obliquely in- When we keep th? head and trunk ftreight, whether ward toward the lateral parts of the bodies of the verte- in ftanding or fitting, both mufcles preferve the head in bras, palfes on the fore-fide of the firft and fecond, with- that pofture againft any force by which it would othcrwiie out being inferted in them; and, approaching gradually be moved backward. towards the fame mufcle on the other fide, it is inferted One of thefe' mufcles adling alone, may have the fame near it in the fore-part of the lower fide of the apophy- ufe, if the force to pufh the head back be applied between the anterior and lateral parts of it. fis bafilaris, or great apophyfis of the os occipitis. They both ferve likewife to perform the rotations of the head, that is, to make it turn to either fide as on a RECTUS ANTICUS BREVIS. pivot; and, in this cafe, when we turn the head to one the fternb-maftoidasus on the other fide a<5ts, and This is a fmall flat mufcle, about the breadth of one fide,that on the fame fide. finger, fituated laterally on the anterior part of the body notThey ferve, in the next place, to bring the head of the firfl: vertebra. It is fixed below to the bafis or near the both thorax when$^ lie on the back, or bend backroot of the tranfyerfe apophyfis of that vertebra, near ward in fitting! In this cafe, the fternum, being the the anterior eminence. point, muft remain immoveable; but as its connecFrom thence it runs obliquely upward and inward to a fixed tion with'the firft rib, and the inflexibility of the cartitranfverfe impreflion in the lower fide of the apophyfis ba- lage of that rib, are not always fufficient for this, the filaris of the occipital bone, immediately, before the con- mufeuli refti of the abdomen muft, lend their afiiftance in dyle on the fame fide, being covered by, the red us anti- great efforts. cus.longus. The two fplenii ferve to fupport the head in an ereft pofture, whether in ftanding or fitting ; to moderate the TRANSVERSALIS ANTICUS PRIMUS. flexion of the head forward, and to bring it back again ' This is a fmall, pretty thick, and wholly ilefhy muf- to its natural'poftdrel cle, about the breadth of a finger, fituated between the They ferve alternately to co-operate with either of the bafis of the os occipitis and the tranfverfe apophyfis of fterno-maftoidaei, for the rotation of the head: Thus the firft vertebra. It is fixed by one end in the anterior when the right fterno-maftoidaeus turns the head, the left part of that apophyfis ; and from thence running up a fplenius correfponds with it by its upper part; while the 1 little obliquely, it is inferted, by the other end, in a par- lower part at the fame time turns the vertebrae of the ticular impreffion, between the condyle of the os occipi- neck! tis and the maftoid apophyfis of the fame fide, behind the The complex! are afliftants to the .fplenii, to keep the the apophyfis ftyloides, and under the edge of the jugu- head ftreight in fitting or ftanding, to hinder it from in- “ dining forward, and to raife'it when inclined. lar foflula. The redi majores, and minores poftici, and obliqui fuperiores, turn the head a little backward on the firft TRANSVERSALIS ANTICUS SECUNDUS. vertebra of the neck. The reCti majores contribute moft This is a fmall mufcle, fituated between the tranfverfe to this motion ; and the minores feem likewife to hinder apophyfes of the firft two vertebras of the neck. It is the articular membranes from being pinched between the fixed, by one extremity, very near the middle of the fe- bones in great motions. cond apophyfis, and, by the other, near the root or bafis The redi majores and minores antici, and the two of the firft; and therefore it is a mufcle of the neck, ra- tranfverfales antici, move the head forward on the firft ' ther than of the head. vertebra; and the redi minores, and tranfverfales breves, likewife defend the capfular ligaments. The obliqui inferiores or majores are true rotators of MUSC.ULI ACCESSORII. the head, by turning the firft vertebra upon the Odontoid W e fometimes meet with a fmall mufcle, fixed, by apophyfis of the fecond; all which alternate motions the one end, to the extremity of the firft tranfverfe apophy- head follows, without being hindered in the motions forfis of the neck, near the infertions of the two obliqui, ward and backward in any degree of rotation. from whence, running up obliquely, it is again inferted Of the tranfverfales antici, the firft only move the behind phe maftoid apophyfis. This mufcle is commonly head in the manner above mentioned; neither can they thought to be a third fmall tranfverfalis on that fide perform any other motions, their infertions being confiwhere it is found, but it feems rather to be an additional ned to the os Qccipftis and firft vertebra. The tranfvermufcle to the obliquus fuperior. fales antici fecundi have no (hare in the particular motions ' of the head, but ought rather to be ranked among the which move the vertebrse of the neck. Uses of the Mufcles •which move the Head on the mufcles The complex! minores belong to the head only by their Trunk. fuperior portions; the other portions belonging rather to The aftion of the fterno-maftoidsei is dilterent, accor- the neck. They may ferve alternately in the lateral-mo ding as either both mufcles, or only one, of them, afts, tions of fhe head, and thereby co-operate with the fpleVol. I, No. io.2 3I nius