OF THE NUBIAN GIRAFFE. 233 
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 carneous 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 whole 
length of the neck to its insertion, it is obvious that a great proportion of the muscu- 
lar fibres would have been useless ; for as these have the power of shortening themselves 
by their contractility only one-third of their own length, if they had been continued 
from end to end in the sterno-thyroidei, they would have been able to draw down the 
larynx and os hyoides one-third of the way down the neck ; such displacement, however, 
is neither required nor indeed compatible with the mechanical connexions of the 
parts ; but by the intervention of long and slender tendons, the quantity of the con- 
tractile fibre is duly apportioned to the extent of motion required for the larynx and 
os hyoides. 
The muscle analogous to the omo-hyoideus of other animals is adjusted to its office by 
a different and more simple modification: instead of having a remote origin from the 
shoulder-blade, its fixed point of attachment is brought forward to the nearest bone 
(the third cervical vertebra) from which it could act upon the os hyoides with due power 
and extent of contraction. Its insertion is by a small round tendon. 
The analogue of the sterno-mastoideus should be called sterno-mazillaris. The pair 
arises by a single origin which soon divides, and each division forms a flat muscle, pre- 
serving an uniform breadth of one inch and a half: it continues fleshy the whole way 
to within one foot of the angle of the jaw, where it terminates in a small round tendon, 
which expands to be inserted into the inner side of the angle of the jaw. From the 
freedom of the inflection of the neck, the head can be brought as near to the chest as 
the contraction of these long muscles is designed to effect ; the necessity, therefore, for 
intervening tendons does not exist, and the sterno-mazillares continue fleshy to their 
terminal tendons of insertion. 
The scaleni muscles are most powerfully developed; they consist of four distinct 
masses on each side, arising from the fourth, fifth, sixth, and seventh cervical vertebra, 
and are inserted into the manubrium sterni and first rib. 
The trapezius consists of two pretty distinct portions: one arises from the transverse 
processes of the fifth and sixth cervical vertebre ; its fleshy part is thick and strong, 
but expands as it passes downwards and backwards, and finally is lost in a strong 
Fascia overspreading the large shoulder-joint. The second portion is thin and broad ; 
it arises from the ligamentum nuche, and is inserted into the fascia covering the sca- 
pula. 
The levator scapule arises from the fifth, sixth, and seventh cervical vertebre ; and 
these three bulky origins, of which the lowest is the thickest, converge, unite, and are 
inserted into the outer margin of the scapula near its superior angle. 
