Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 2: Dia-Ins
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit25760/73/
ARTICULATION OF THE ELBOW. 
the olecranon so prominent, in consequence of 
which extension of the elbow can be carried 
farther than in the adult. At the same period 
the lesser sigmoid cavity of the ulna is pro¬ 
portionally smaller, and the annular ligament 
of the radius much more extensive. 
Varieties.—When a high division of the 
brachial artery takes place, it often happens 
that the radial artery takes a superficial course, 
sometimes under and occasionally over, the 
aponeurosis to its usual destination. The pos¬ 
sibility of this occurrence should be constantly 
held in recollection in performing phlebotomy 
in this region, as it is evident that the vessel, 
when thus superficially situated, is exposed to 
be wounded by the lancet of the operator. 
In considering the relative advantages pre¬ 
sented by each of the superficial veins which 
may be selected for phlebotomy, it is necessary 
to remark that the operation may be performed 
on any of the veins at the bend of the arm ; 
on the cephalic and basilic veins it is un¬ 
attended with any danger; not so, however, 
when either the median basilic or median 
cephalic is the vessel selected. When bleed¬ 
ing in the median basilic vein about the mid¬ 
dle of its course, if the lancet should transfix 
the vein, there is danger of the instrument 
wounding the brachial artery, an accident of 
serious consequence ; the risk of this accident 
is not so great when the vein is opened near 
its lower part, as the brachial artery retires 
from it here towards the bottom of the trian¬ 
gular depression of the elbow ; besides the 
occasional risk of wounding the radial artery, 
which, in consequence of a high bifurcation 
of the brachial, sometimes follows the super¬ 
ficial course already alluded to, the branches 
of the internal cutaneous nerve may be wholly 
or partially divided ; in which latter case sharp 
pains are usually felt extending along the 
course of these nerves. Opening the median 
cephalic vein may be performed without ap¬ 
prehension of injury to the brachial artery; 
the external cutaneous nerve however, the 
trunk of which lies behind this vein, may suffer 
a puncture, in consequence of the lancet being 
pushed too deeply, the consequences follow¬ 
ing which have been in many instances a pain¬ 
ful affection extending along the branches of 
this nerve to their terminations. In those un¬ 
fortunate cases in which the brachial artery is 
punctured, should the wound in the artery 
not be closed and united by properly regulated 
pressure, the consequence likely to ensue may 
be one of the following : 1, the blood escap¬ 
ing from the wound in the artery may become 
diffused through the cellular membrane of the 
limb extending principally upwards towards 
the axilla along the sheath of the vessel, (the 
diffused false aneurism ;) 2, the blood which 
escapes from the artery may be circumscribed 
within a limited space by the cellular mem¬ 
brane which surrounds it becoming condensed, 
(the circumscribed J'alse aneurism ;) 3, the 
wounded orifices of the artery and vein may 
remain in apposition, and adhere to each other, 
allowing the blood to pass from the artery 
VOL. II. 
65 
directly into the vein, constituting the affection 
called aneurismal varix ; 4, or a circum¬ 
scribed sac may be formed between the artery 
and vein, having a communication with both 
vessels, the varicose aneurism. 
(J. Hart.) 
ELBOW (ARTICULATION OF THE), 
ocyttuv, cubitus ; Fr. coude ; Germ, elbogen ; 
Ital. gomito. The elbow or humero-cubital 
articulation is an angular ginglymus formed by 
the inferior articular extremity of the os humeri 
and the superior articular extremities of the 
radius and ulna, the surfaces of which are, in 
the recent state, covered with a cartilaginous 
incrustation, and kept in apposition by an ex¬ 
tensive synovial capsule, an anterior, a poste¬ 
rior, and two strong lateral ligaments. 
The muscles which cover this articulation 
are, the brachiæus anticus, the inferior tendon 
of the triceps, and some of the muscles of the 
fore-arm anteriorly, the triceps and anconæus 
posteriorly, and the superior attachments of 
several of the muscles of the fore-arm laterally. 
Bones.—The lower part of the humerus is 
flattened before and behind, and curved a little 
forwards : an obtuse longitudinal ridge, on a 
line corresponding to the lesser tuberosity at 
its superior extremity, divides it into two slo¬ 
ping surfaces anteriorly, while posteriorly it 
presents a broad, flat, triangular surface : a 
sharp ridge on each side terminates below in a 
rough tuberosity, called a condyle ; the exter¬ 
nal condyle is the smaller of the two, and when 
the arm hangs loosely by the side, it is directed 
outwards and forwards : the internal condyle 
is much larger, more prominent, and directed 
inwards and backwards : a line let fall per¬ 
pendicularly from the most prominent part of 
the greater tuberosity above would fall upon 
the external condyle ; the internal condyle 
bears a similar relation to the centre of the 
superior articular head of the humerus. The 
inferior articulai' surface extends transversely, 
below and between the condyles, and presents 
a series of eminences and depressions ; begin¬ 
ning at the external side, a small spheroidal 
eminence, the eminentia capitata or lesser head, 
situated on the front of the external condyle* 
directed forwards and received into the circular 
cavity on the head of the radius, internal to 
this is a small grooved depression which lodges 
the internal part of the border of that cavity : 
the remainder of this surface forms a sort 'of 
pulley, to which the greater sigmoid cavity of 
the ulna corresponds ; this, which is called the 
trochlea, presents a large depression placed be¬ 
tween two raised ridges : the depressed portion 
of the trochlea winds round the lower extre¬ 
mity of the humerus in an oblique direction 
from before backwards and a little outwards, 
being broader behind than in front ; its external 
border forms a semicircular ridge, smooth in 
front and sharp behind, the anterior part of 
which corresponds to the division between the 
radius and ulna ; its internal margin also forms 
a semicircular ridge, sharper and more promi¬ 
nent than the external, and which projects half 
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