Freiburger historische Bestände - digital

33

Elephant.

Maxillo-labialis. Buccinator-group.

34

arise which insert themselves, either into the bottom of a groove
or into the face of a leaf. In this way small »musculi digastrici«
are formed which indeed are rather thin; but as we, as a rule,
always found this arrangement in the longest fascicles, these
»digastric« muscles could span quite a considerable length. The
other fascicles of a groove showed very different lengths, and
gradually inserted themselves, under their course in the groove,
partly into the bottom of the latter partly into the neighbouring
leaves (fig. D). According as the bundles of such a section fail,
new ones arise from the bottom or the walls of the groove, to
insert themselves again in the same way as the former. No fixed
rules were found as to the ways in which such bundles arose
and were inserted: Bundles arising from the bottom of a groove
might again insert themselves into the bottom of the same groove
whereas others inserted themselves into the leaves. Bundles arising
from a leaf often inserted themselves again into the same
leaf, whereas others inserted themselves into the bottom of the
groove. There were, as we have mentioned, numerous »anasto-
moses« and divisions of the leaves, and these points of anastomoses
and divisions are constantly used by the fascicles partly
as insertion partly as origin. Where the leaves after such a formation
of an anastomosis again part from each other and continue
the course, a special arrangement is found. Through the point
of anastomosis there stretches a little thin aponeurosis, which in
the proximal section serves as insertion, in the distal one as
origin, of part of the fascicles of the respective sections; here we
again find a formation that reminds us of the digastric muscles,
only with the difference that the intermedial tendon is here
fastened to the two leaves that limit the section. Finally it must
still be mentioned that the free, sharpty truncated edges with
which the leaves end, or begin, are likewise always used by the
fascicles for insertion or origin, either on one or on both faces,
so that in such places there is found a t}^pical semipennate or
pennate arrangement of the bundles.

It is evident from this account that the maxillo-labialis possesses
a most complicated and also a quite special muscular structure
; the formation of the trunk has been of singular influence
on the structure of this muscle.

4. THE BUCCINATOR-GROUP.

PI. 1, PI. 2, PI. 3, PI. 4; PI. 16, fig. 16.

This group contains all the constituents mentioned in the
General Part. First one finds the m. buccinatorius itself, in which
both transverse and longitudinal fascicles can be distinguished,
and its subdivisions the pars rimana and the pars supralabialis.
Further the m. nasalis and the m. mentalis. But in many respects
this muscular group presents peculiarities which are in the closest
connection with the not insignificant share this group has
in the formation of the muscular system of the trunk, especially
its ventral and partly its lateral parts.

The part of the m. buccinatorius which lies in front of the
anterior margin of the m. masseter and the m. temporalis, and
also forms the base of the cheek, has a rather strange external
shape. It forms a thick, rounded, closely united, muscular mass
(comp. PI. 2 and PI. 4); it is high but very short, and in the
specimen we dissected, of about the circumference of a clenched
fist. Covered by this muscular mass are the gl. buccales, which
are present in so great a number and occupy so considerable a
circumference that they are not altogether without influence on
the formation of the m, buccinatorius (v. Plate 3). Above, between
the muscle and the laterally much expanded maxillary bone a
fissure is formed (PI. 2), 7—8 cm deep and a couple of cm
broad, filled with adipose tissue; the n. facialis runs superficially
in this rather considerable mass of adipose tissue (PI. 1).

The buccinator arises from the hindmost part of the maxillary
bone, a little behind and above the upper molar, further
from the hindmost part of the mucous membrane of the cheek
and from the lower jaw on the inside of the ramus ascendens,
a little behind the lower molar. From this line of origin there
arises a high, flat, but in the lower half, however, a rather full muscular
body, whose fascicles are all longitudinal, that is, form
only one layer (comp. the diagram PI. 16, fig. 16). If one follows
the fascicles onwards, it appears that the part arising from the
lower jaw, the mandibular portion, soon distinguishes itself from
the dorsal portion of the buccinator (arising from the maxillary
bone and the mucous membrane). And this is partly owing to the
fact that it grows thicker, but partly, and more particularly, because
some of its fascicles alter their direction. After having reached
the anterior margin of the mm. masseter and temporalis, the upper
fascicles of the mandibular portion turn upwards, transver-
sally crossing the longitudinal fascicles arising from the maxillary
bone and the mucous membrane, and becomes inserted into the
maxillary bone above the mucous membrane (v. Plate 4 where
the mandibular fascicles appear very distinctly a little in front
of the m. temporalis; they are seen crossing the upper portion,
which is faintly seen in the depth). As an immediate continuation
of these upwardly turning, now transverse, fascicles there
follows a number of coarse thick bundles, which, in the shape
of a transverse layer, arise from the maxillary bone, turn outwards
forming the bottom of the deep fissure under the maxillary
bone, mentioned above, and then bend downwards covering
about the upper half of the buccinator. The hindmost fascicles —
those which join the fascicles of the mandibular portion — are
the longest and coarsest and thrust in between the longitudinal
fascicles that lie below, where they end in short pointed tendons.
In front the fascicles gradually grow shorter and the foremost
do not, with their short pointed tendinous ends, reach farther
down than to the height of the angle of the mouth; from here
the transverse layer proceeds a short distance into the upper lip,
where the fascicles are arranged in several layers, the superficial
ones of which arch over the posterior part of the longitudinal
fascicles of the upper lip, whereas the deep ones cross them and
project between them. The fascicles of the platysma thrust themselves
in between the fascicles of the transverse layer of the buccinator
in several rows, joining the longitudinal fascicles of the
deep layer of the buccinator (PL 4). Immediately in front of the
transverse layer, partly crossing its fascicles, steeps out a thick
mass of thin longitudinal fascicles which make their way down
into the under lip, in the hindmost part of which they end with
thin pointed tendons (PI. 4).

While, as described, the upper fascicles of the mandibular
portion alter their direction and pass into a transverse layer, the
rest — indeed the greater part of the fascicles of this portion —
proceed further on in longitudinal direction. The surface of the
free part of the buccinator thus acquires quite a curious appearance
(PI. 2): in about its upper half a transverse layer is seen,
in the lower half a longitudinal layer — both of them originating
from the mandibular portion and forming the superficial
layer of the buccinator. In front the longitudinal fascicles gather
together in the under lip, where the uppermost, superficial fascicles
end in the connective tissue with short pointed tendons.
The rest, and indeed the principal mass, as one muscular body,
turns upwards and inwards, bending anteriorly around the great
united mass of the undermost glands of the cheek, and inserting
themselves onto the lower jaw (in PI. 3 the greater part of these
fascicles are seen close in front of the glandular mass). Straight
through the longitudinal layer a broad somewhat irregular »in-
scriptio tendinea« passes dorso-ventrad; the fascicles that come
from behind end with pointed tendons in this stripe and from
it arise the anterior fascicles. For some fascicles the tendons
may be prepared out of the tendinous stripe and then appear as
an intermedial tendon between a hindmost and a foremost fascicle.
The tendinous stripe does not extend through the whole height
of the longitudinal layer; in the lower part of the longitudinal
layer the fascicles traverse (PI. 4).

In the other portion of the buccinator, arising from the maxillary
bone and the mucous membrane, — which we term the
maxillary portion — the fascicles are arranged longitudinally
throughout their whole course. Only in front, where a great
part of them thrust down in the under lip, the direction is a
little downward. These longitudinal fascicles run in front inside

5