8 
consists of the following recognisable elements :—1, M. cleido- 
trapezius (figs. 1 and 3 ¢.t.); 2, M. delto-trapezius (fig. 1 d.t.); 3, 
Mf. acronuo-trapexius (figs. 1, 4, and 5 a.t.); and 4, M. spino- 
trapezius (figs. 1, 4, and 5 s.t.). 
Of these, the first two are semi-conjoint (figs, 4 and 5 c.d.t.), 
while the last two are distinct muscles (figs, 1, 4, and 5, a.¢. and 
Sit.) 
The first, preaxial and ventral, segment or cletdo-trapezius, is 
separated by a preclavicular, narrow, triangular area from the 
sterno-mastoid muscle (figs. 2, 3, and 5 s.m.). It is only separate 
from the second, or delto-trapezius, for a short distance in front 
of, and ventral to, the shoulder. The conjoint muscle arises from 
part of the crista lambdoidalis or occipitalis, described by Stir- 
ling* as “running forwards and outwards, and then downwards 
from the occipital tubercle till it becomes continuous with the 
upper edge of the zygoma.” This ridge in its outer vertical 
part bounds the temporal fossa posteriorly, whilst its horizontal 
inner part, forming the ‘superior curved line,” or nuchal crest 
of the occiput, gives origin to the muscle under notice as far 
forwards as the temporal fossa. It also arises from the liga- 
mentum nuche for 3 or 4 mm. backwards from the occipital 
tubercle. The fibres are at first directed transversely across the 
neck, covered by the cervico-auricularis. Just behind the auricle 
the fibres sweep backwards, becoming at the same time segmented 
into the two component parts (figs. 2 and 5, c.f. and d.t.). 
The ventral, or cleido-trapezial, part now courses beneath the 
shoulder backwards to its attachment to the clavicle, not far 
from the meso-scapular extremity of that bone (fig. 3, ¢.t.). 
The cdelto-trapezial, more dorsal moiety (‘‘ trapezio-deltoid,” 
“cephalo humeral muscle”) covers the ventral aspect of the 
acromion and meso-scapular segment (also overlapping the distal 
half of the acromion laterally), and is then continued on, between 
the scapulo- or spino- and cleido-deltoids, becoming more or less 
united with them, towards a common insertion. 
M. acromio-trapexius (tigs. 1, 4, and 5, a.¢.) forms a transverse, 
almost rectangular, band of fleshy fibres, whose anterior border 
is closely related to the posterior border of the preceding muscle, 
arising mesially from the ligamentum nuche immediately behind 
the delto-trapezius, and extending as far back as the first dorsal 
spine, where it ends, leaving a free hinder margin. Its fibres 
pass laterally, to be inserted into the dorsal surfaces of the meso- 
scapular spine and the proximal half of the acromion, partly con- 
cealing the attachment to the pre-axial lips of the same parts, of 
the extensive subjacent rhomboideus (figs. 1 and 4 rh.). 
aren ted 
