562 
passes from the upper edge of the trans- 
verse process of the atlas to the transverse or 
jugular process of the occiput: the latter, on 
a plane anterior to this, from the anterior root 
of the transverse process and side of the an- 
terior arch, inclines upward and alittle inward, 
to be inserted into the basilar process of the 
occipital bone behind the rectus capitis anticus 
major, between its outer edge and the foramen 
um. The rectus capitis lateralis separates 
the vertebral artery from the jugular vein. _ 
These muscles in approximating their points 
of attachment can give lateral flexion to the 
neck and to the head. 
The sealeni ( Costo-trachelien : Chauss.) are 
situated at the lower lateral part of the neck, 
extending from the transverse processes to the 
first two ribs, and are of triangular form. 
They have been variously described by different 
anatomists, soine considering their fleshy mass 
as a single muscle, others distinguishing in it 
two, three, and even five parts. I shall adopt 
the more usual modern division, which recog- 
nises two muscles, sculenus anticus and scalenus 
posticus. 
Scalenus anticus arises from the third, fourth, 
and fifth cervical vertebrz, at the anterior tuber- 
cles and notched extremities of their transverse 
rocesses, by slips of tendon, to which muscular 
fibres directly succeed, and descends with an 
inclination outward and forward to be inserted 
by a flat strong tendon into a roughness about 
the middle of the anterior third of the first rib. 
This insertion is important as affording a guide 
to the position of the subclavian artery, which, 
in arching over the rib, lies behind this tendon 
and separates it from the insertion of the 
scalenus posticus. It is triangular in shape 
and fleshy in nearly its whole extent: externally 
it presents a free border, from behind which 
emerge the elements of the brachial plexus 
and the subclavian artery ; internally its origin 
adjoins that of the rectus apes anticus major, 
from which it is demarked by the arteria cervi- 
calis ascendens, and toward its insertion is 
separated from the longus colli by a space in 
which the vertebral artery ascends; its anterior 
surface is crossed from above by the phrenic 
nerve, and transversely by branches of the 
thyroid axis; its deep surface is separated from 
the scalenus posticus by the emerging trunks 
of the nerves, and the space between them, 
broadening towards the first rib, includes there 
the brachial plexus and subclavian artery—the 
latter being below and in front of the former, 
and in immediate contact with the rib. 
Scalenus posticus, larger than the preceding, 
behind which it is situated, arises by six ten- 
dons, to which muscular fibres directly succeed, 
from the posterior tubercles of the transverse 
rocesses of the six last cervical vertebre. The 
rst slip (often p iad derived from the atlas) 
is ae} as it descends, by the others in suc- 
cession, and a large triangular muscle results, 
which has its base at the transverse processes 
and its apex at the second rib. It is inserted, 
first, by an anterior broad slip into the outer 
edge of the first rib, from the tubercle behind 
as far forward as the arterial impression in 
NECK. 
longed from the posterior su 
is to the upper edge of the second rib 
near its tuberosity. This muscle correspon¢ 
anteriorly to the scalenus anticus, from wi 
it is separated by the brachial plexus and 
clavian artery; posteriorly to the levator angu 
scapule; by its inner edge to its points ¢ 
origin; by its outer edge to the serratus m: 
and transversalis colli artery, to branches of # 
cervical and brachial plexus of nerves, and t 
the sterno-mastoid muscle ; each 
ferior-internal edge to the longus colli, fro 
which it is divided by the anterior branch 
the first dorsal nerve, and by the (general: 
common trunk of the deep cervical and fil 
intercostal arteries. 5 
The action of the scaleni, as of the r 
previously described, consists rather in nm it 
taining steadiness and resisting lateralisation | 
front ; secondly, by a smaller 9 hich 
Ets 
the neck, than in effecting any considerak 
movement. They may, however, in a sli 
degree, bend the neck laterally. The verteb 
being fixed, their muscles by acting togethe 
may elevate the first two ribs and so assist 
inspiration. The scalenus anticus ean, fro 
its advanced insertion, act more e! li 
thus. This action is illustrated in all 
inspirations; for these differ from 
breathing therein, that the chest is expand 
by the elevation of the ribs and sternum, in 
antero-posterior and transverse diameters, — 
addition to the ordinary increase of capa 
which it gains by the descent of the | 
phragm ; and, in order to the effective ac 
of the intercostals, the first rib must be 
dered immoveable. The scaleni, in raisin 
anterior extremity of the first ribs, fa ai 
advance of the sternum, and then rigidly” 
these bones enable the intercostal muse 
give to the ribs beneath that slight axial 
tion by which the transverse diameter 0 
chest is increased.* sg 
The intrinsic muscles of the larynx 
already been described (see Larynx 
those of the pharynx being for future de 
tion (see Paarynx), our second class wi 
prise only the muscles of the os hyoide 
tongue, viz. depressors of the os hoide 
sterno-hyoid,omo-hyoid, and sterno-thyroi 
its continuation the thyro-hyoid; its ele 
the digastric, stylo-hyoid, mylo-hyoid, 
hyoid ; muscles of the tongue, 
genio- hyo-glossus, and lingualis. 
The sterno-hyvid and sterno-thyroid : 
riband-like muscles, having respect 
attachments denoted by their names,— 
beside the median line, so as to b 
ee 
‘- 
* Within the last year I have observes 
subjects an importantly anomalous i i 
scalenus anticus. Its main bulk of 
on both sides to an insertion behind 
very small slip only taking the usual 
Strong flat tendon, which is usually so trust 
a guide to the artery, would in these cases h 
volved an operator in the misfortane of 
the nerves with his ligature ; and the 
illustrates the necessity of trying the 
porary pressure on a — 2 
canclaelvely tightening the ligature 
