Bauhaus-Universität Weimar

The Cyclopaedia of Anatomy and Physiology, vol. 4: Pla [corr.: Ple] - Wri
Todd, Robert Bentley
the inner part of the coronoid process of the 
ulna, and then takes a vertical course down 
the fore arm, covered over by the flexor carpi 
ulnaris, and between it and the flexor digi- 
torum profundus. It gradually inclines to the 
surface, and at the lower third of the fore¬ 
arm becomes sub-aponeurotic, and passes 
from between the flexor carpi ulnaris and 
inner tendon of the flexor sublimis to the 
lower part of the anterior surface of the 
annular ligament, passing along it in a distinct 
sheath with the artery, in close contact with, 
and external to, the pisiform and unciform 
bones, and divides into its terminal branches. 
In the upper part of the arm the ulnar nerve 
is in relation with the axillary artery, which is 
placed between it and the median, nearer 
however the latter. In the upper part of the 
fore-arm it is about half an inch or more dis¬ 
tant from the artery, but gradually inclines, so 
as to come in close relation with, but internal 
to it, in the two lower thirds of the fore-arm, 
and in the palm of the hand. 
The ulnar gives off’ no branches in the arm ; 
and the first that comes off’ from it, is when 
the nerve is placed between the two heads of 
the flexor carpi ulnaris. There are several 
small articular filaments which enter the inner 
part of the joint, and three or four which are 
distributed to the above muscle. In the 
upper third of the fore-arm some filaments are 
again given off to the flexor carpi ulnaris, and 
others for the supply of the inner half of the 
flexor digitorum profundus. About the mid¬ 
dle a small branch is given off, which, after 
sending satellite filaments to accompany the 
ulnar artery, perforates the fascia, and be¬ 
comes cutaneous to communicate with the 
internal cutaneous. The largest branch, how¬ 
ever, given off from the ulnar, comes away 
about two inches above the wrist-joint, and is 
named, its dorsal branch (dorsalis carpi ulna¬ 
ris : internal dorsal nerve). This winds down¬ 
wards and inwards, and having passed be¬ 
tween the tendon of the flexor carpi ulnaris 
and the bone, perforates the fascia at the back 
of the fore-arm, and becomes cutaneous a 
little above the styloid process. It runs then 
along the inner edge of the carpus ; and on 
the posterior annular ligament terminates in 
two branches. The inner branch passes along 
the inner and back part of the metacarpal 
bone, and phalanges of the little finger, supply¬ 
ing the integument as far as its extremity, and 
sending in its course some small filaments to 
the abductor minimi digiti. The outer branch 
crosses obliquely the tendon of the extensor 
minimi digiti, and on the fourth intei'osseous 
space sub-divides. The inner sub-division 
at the extremity of the space bifurcates in 
order to supply the opposed sides of the little 
and ring finger. The outer sub-division at 
the lower extremity of the third interosseous 
space having communicated with the dorsal 
branch of the radial, similarly bifurcates for 
the supply of the integument of the opposed 
sides of the middle and ring finger. The 
dorsalis carpi ulnaris, independently of the 
above branches, sends numerous filaments to 
the inner and back part of the wrist and hand, 
and communicates above with the external or 
posterior cutaneous. 
The terminal branches of the ulnar nerve are 
two in number, a superficial external, and deep 
internal.—The former, after a very short course, 
divides into two branches, a small internal, and 
large external. The internal branch passes 
along the ulnar side of the little finger to its 
extremity, giving filaments in its course to the 
muscles of the little finger. The external 
passes obliquely across the flexor tendons 
for the ring finger, gives a filament to the 
fourth lumbricus, and one of communication 
with the median, and over the fourth inter¬ 
osseous space at a variable distance from its 
inferior extremity bifurcates : the divisions of 
the bifurcation being distributed in a similar 
manner with the median to the opposed sur¬ 
face of the ring and little finger. 
The deep branch is directed backwards 
and outwards between the abductor minimi 
digiti, and the flexor brevis to the posterior 
aspect of the adductor minimi digiti, having 
first given off on the palm a small branch 
which sends filaments to these three muscles. 
It passes downwards in a curved manner, the 
convexity of the curve looking downwards 
and inwards, and after a short course passes at 
an acute angle behind the deep palmar arch of 
arteries. No branches come off from its con¬ 
cavity. From its convexity and back part 
and outer termination are derived filaments 
which supply the two inner lumbricales, the 
palmar and dorsal interossei, the adductor 
and flexor brevis pollicis. The deep or per¬ 
forating interosseous branches can be traced 
through the two layers of interossei to the 
skin on the back of the hand, where they com¬ 
municate with the dorsal cutaneous from the 
radial and ulnar nerves. 
The musculo-spiral nerve (’radial) slightly 
larger than the median, arises from the inner 
and back part of the plexus, and is formed 
particularly by the three inferior cervical and 
first dorsai nerves. The trunk from which it 
arises also gives origin to the circumflex nerve. 
It passes attirstfrom before backwards, running 
behind the ulnar, and in front and below the 
circumflex nerve, and having crossed the con¬ 
joined tendons of the teres major, and latissi- 
mus dorsi, inclines downwards, backwards and 
outwards to the posterior surface of the hu¬ 
merus, between it and the long head of the 
triceps. It continues gradually inclining more 
outwards, till it reaches the lower third of the 
arm where it gains the outer aspect of the 
bone, and here it passes forwards in company 
with the superior profunda artery, to the an¬ 
terior and outer aspect of the arm lying in¬ 
ternal to the outer head of the triceps which 
it perforates. It is now directed between 
the supinator longus and brachialis anticus, 
and then between the latter and extensor 
carpi radialis longior, and, having reached 
the outer and anterior part of the elbow- 
joint, divides into an anterior and posterior 
terminal branch. 
The branches given off from the musculo-


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