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Some observations on the anatomy of the upper extremities of an infant with complete bilateral absence of the radius.

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The Anatomical Laboratory of the Yale Medical School
On February 20, 1913, the body of a white, male infant, aged
on\ day, of average size and weight reached the anatomical rooms
of tAe Yale Medical School. On inspection the body appeared
to bt well developed and normal, save for an odd-appearing
defor iity of both upper extremities. At autopsy the pleural
caviti s were found to contain a considerable amount of blood,
doubtnss the result of a birth injury.
Upon examination of the deformed upper extremities, it was
found in possible to pronate or supinate the antebrachium and
hand, sav for a slight alteration in position allowed by turning
the humerus and ulna on their vertical axes. The hands were
fixed in marked adduction; the right one making a right angle
and the left one considerably less than a right angle with the
antebrachium. Both hands were rotated on the ulnae so that
their dorsa presented ventrad, that is, they were fixed in pronation and abutted the ulnae a t their medial aspects (figs. 1 and 5).
The position of the hands indicated lack of radial support.
Careful examination failed to reveal any trace of a radius in
either arm. A provisional diagnosis of complete absence of both
radii was made. This was later confirmed by Rontgen rays and
by dissection (figs. 2 and 5).
The ulnae seemed normal in position and size. However, due
to the faulty position of the hands, the distal extremities of the
ulnae formed very prominent subcutaneous points at the wrists
(figs. 1 and 2).
J 4NU.4RY.
The fact of observing the absence of both radii and of the
resultant faulty position of the hands seemed of little value. It
was, therefore, deemed advisable to make a careful dissection of
at least one of the extremities to ascertain to what extent other
anatomical errors were present. In order to study the feasibility
of tendon transplantation in such cases, in an attempt to lessen
the deformity and to increase the efficiency of the member, a
dissection of the antebrachium and hand was deemed of especial value.
The dissection was done by the junior author (Nachamofsky,
Class of 1916, Yale Medical School). Some of the facts disclosed by this dissection will be discussed in subsequent paragraphs.
One of the first important facts brought out by the dissection
was the marked failure in the differentiation of many muscle
masses into individual muscles. This led to only a partial differentiation of some muscles and to a complete absence of others.
Throughout the upper extremity there was a marked failure in
very many instances in the formation of tendons; the muscles
arising or inserting by fleshy contacts where normally tendons
are present.
Another fact to be noted is that those muscles normally associated with the radius, but in this case only partly differentiated,
were found to attach to the ventral surface and lateral border
of the ulna.
Not only the muscles of the antebrachium and hand but many
of the brachium and shoulder likewise were found t o be abnormal.
Muscles of shoulder. The origin of the deltoid muscle was
approximately normal. Its insertion was, however, markedly
altered. It passed distally from its origin; its fibers converging
towards the lateral intermuscular septum, to which it gained
insertion just proximal to the lateral epicondyle of the humerus.
The deltoid had no insertion on the humerus, but became
continuous with the teres major dorsally; with the brachio-
Fig. 1. Sketch of a n infant with complete bilateral absence of the radius.
Especially note t h e abnormal position of the hands. The prominence at t h e wrist
is caused by t h e distal extremity of t h e ulna. See text for further description of
the upper extremities.
Fig. 2. Skiagrams of the upper extremities of infant sketched in fig. 1. Note
the characteristic position of the hands and the complete absence of both radii.
As usual the carpal bones show no ossification a t this age.
radialis and the extensor carpi radialis longus and brevis muscles
distally; and more or less with the pectoralis major muscle
The supraspinatus and the infraspinatus and the teres minor
muscles were normal save that the latter and last were inseparably mingled.
The teres major muscle at its origin was undifferentiated from
an abnormally extensive origin of the long head of the triceps
brachii muscle. Contrary to the normal course of the muscle, in
passing from origin t o insertion, it coursed lateral to the upper
extremity of the humerus and became continuous with the
deltoid, the brachio-radialis, and the extensor carpi radialis
longus and brevis muscles. A t no point was the teres major
muscle directly attached to the humerus.
The latissimus dorsi muscle was inserted by two distinct tendinous slips. Near its insertion the lateral and somewhat larger
slip terminated in a fleshy band which became incorporated with
the common mass of the heads of the triceps brachii muscle. The
faulty course of this portion of the latissimus dorsi muscle, as
well as that of the teres major muscle mentioned above should
here be noted. A shorter medial head of the latissimus dorsi
muscle coursed cephalically and ventrally, giving a tendinous portion to insert on the humerus just distal to the subscapularis
muscle and a caudal fascia1 expansion which gave origin to a part
of the medial head of the triceps brachii muscle.
The pectoralis major muscle in addition to its normal insertion
sent fibers into the deep aspect of the deltoid muscle, thus forming
an accessory muscular band one em. wide.
Muscles of brachiurn. The biceps brachii muscle attempted an
origin from the supraglenoid tubercle, and some of its tendinous
fibers could be traced to it, but its long head mainly arose from
the capsule of the shoulder joint which it materially strengthened.
The short head of the muscle arose as usual from the coracoid
process of the scapula. The belly of the biceps brachii inserted
(?) along the distal half of the medial and lateral surfaces and the
medial and lateral epicondylic ridges of the humerus. The interval between the epicondylic ridges was bridged over by some
biceps brachii fibers which passed distally to insert onto the coronoid process of the ulna and to give origin to the extensor digitorum communis and the extensor digiti quinti proprius muscles.
The canal thus formed between the epicondyles of the humerus
transmitted the median nerve laterally and the brachial artery
medially .
The brachialis (anticus) muscle as such was absent. The apparent absence of this muscle together with the fact that some
biceps brachii fibers inserted on the coronoid process of the ulna
leads one to believe that the brachialis was incorporated with
the biceps brachii fibers and that it had not differentiated from
The coraco-brachialis muscle arose with the short head of the
biceps brachii muscle from the coracoid process. It had an abnormally extensive insertion on the humerus and into the brachial
An acromio-humeral muscle appeared as an anomalous band,
arising from the inferior surface of the overhanging acromion
process and the capsule of the shoulder joint. It inserted on the
humerus just lateral to the major tubercular crista. It lay beneath the deltoid muscle. This may explain the absence of a
bony insertion of the latter muscle and might be considered an
isolated deep portion of it.
The long head of the triceps brachii muscle arose very extensively not only from the infraglenoid tubercle but from a goodly
portion of the axillary border of the scapula where it was intimately blended with the teres major muscle as mentioned in the
previous paragraph. The medial head of the triceps brachii arose
along the distal third of the dorsal surface of the humerus. The
lateral head was partly incorporated with the long head and in
part arose from the tendon of insertion of the latissimus dorsi
muscle. As usual it gained insertion on the olecranon process of
the ulna and into the antebrachial fascia in the immediate neighborhood.
The anconaeus muscle was normal in its origin but its area of
insertion was abnormally extensive; the whole proximal half of
the dorsal or extensor surface of the ulna was occupied by it.
Muscles of the antebrachiurn and hand. The brachio-radialis
muscle took its origin from the distal fibers of the deltoid muscle
and from the over-lying fascia. It inserted into the transverse
carpal ligament and into the antebrachial fascia. The peculiar
insertion of this muscle was probably due to the rotation of the
hand about the ulna. The muscle took a rather devious course:
Turning ventrally from its origin, it occupied a position between
the extensor carpi radialis longus and brevis muscles medially,
and the extensor pollicis longus muscle (?) laterally, lying over a
mass of undifferentiated muscular tissue.
The extensor carpi radialis longus and brevis muscles arose by
a common fleshy head of origin from the caudal portions of the
deltoid and the triceps brachii muscles. They coursed distally
Fig. 3. Diagrammatic sketches of superficial (to t h e left) and deep (to t h e
right) dissections of t h e ventral aspect of t h e right antebrachium and hand. The
details of t h e dissection are purposely omitted. See text for description of figure.
z = flexor carpi ulnaris muscle; a = palmaris longus muscle; e = flexor carpi
radialis muscle; T = ext,ensor carpi radialis longus et brevis muscles; b = brachioradialis muscle; n = ulnar nerve; p = flexor profundus digitorium muscle; y =
hypothenar muscle; s = flexor digitorum sublimis muscle; u = ulna; I = lumbrical muscles undifferentiated; m = undifferentiated muscle.
over the latero-central aspect of the antebrachiurn, following the
course of the brachio-radialis muscle. Both muscles inserted on
the transverse carpal ligament medial to the brachio-radialis.
The brevis was distinguishable from the longus only after they
had traversed half their course (fig.3).
An extensor muscle of the thumb was present but did not correspond to any of the normal thumb extensors. It arose partly
from the most distal biceps brachii fibers and was intimately associated with a common muscle mass adherent to the ventral surface
of the ulna. The muscle passed distally and became superficial
at the region of the carpus where it was lateral to the ext.ensor
digitorum communis muscle. Its tendon gained the dorsum of
the hand by passing through the first osteo-fibrous canal on the
dorsum of the wrist, and it inserted on the base of the distal phalanx of the thumb. On the dorsum of the hand a small muscular
sheet arose from the thumb extensor which passed medially under
the tendons of the other extensors to insert on the hypothenar
fascia over the fifth metacarpal bone (fig. 4).
The extensor digitorum communis muscle was a round muscle
which arose in common with the extensor digiti quinti proprius
muscle from the distal fibers of the biceps brachii muscle, from
the lateral epicondyle of the humerus, and from the antebrachial
fascia. It passed superficially and distally through the second
osteo-fibrous canal onto the dorsum of the hand. It coursed
between the extensor digiti quinti proprius muscle medially and
tb.e extensor of the thumb laterally, lying over the ulna and
an undifferentiated mass of muscle deeply placed. On the dorsum of the hand the extensor digitorum communis muscle gave
off four tendons which inserted by broad fascial expansions on
the phalanges of the second, third, fourth and fifth fingers. The
more direct tendinous insertions were, however, to the distal segments (fig. 4).
The extensor digiti quinti proprius muscle arose in common
with the extensor digitorum communis muscle. It was quite
superficial on the antebrachium with the extensor carpi ulnaris
muscle medial to it. On the dorsum of the hand its tendon divided,
one part going to insert with a tendon from the extensor communis digitorum muscle and the other becoming continuous with
the fascia over the fifth metacarpal bone (fig. 4).
The extensor carpi ulnaris muscle was normal except for the
absence of a distinct tendon of insertion. The muscle terminated
in a broad fascial band which inserted on the medial aspect of the
distal extremity of the ulna. Its usual insertion on the fifth
metacarpal bone was wanting.
The remaining muscles of the extensor group were either totally
missing, as in the case of the supinator (brevis) muscle, or were
not differentiated, but remained merely a muscle mass which lay
between the extensor of the thumb and the flexors of the antebrachium. Since the flexor pollicis longus muscle was absent, it is
likely that it had not differentiated from this mass. It should
here be noted that the absent and undifferentiated muscles in the
specimen are normally intimately associated with the radius, both
with respect to their origin and their course.
The flexor carpi ulnaris muscle was normal in size and position.
It, however, lacked a clean-cut tendon and did not find an insertion on the carpus. The only point of insertion was to the capsule of the joint between the ulna and the carpus.
The palmaris longus muscle (?) arose together with the flexor
carpi ulnaris from the medial epicondyle of the humerus, and
passed into the antebrachium lateral to the latter muscle. The
palmaris longus and the flexor carpi ulnaris had a common insertion on the capsule of the joint between the carpus and the ulna
(fig. 3).
The flexor carpi radialis muscle (?) took its origin from the
medial epicondyle of the humerus in common with other flexors,
and from the distal fibers of the biceps brachii and the intermuscular septum. It passed lateral to the palmaris longus (?) and
was separated from it in the distal half of the antebrachium by
the ulnar nerve. The fibers of the muscle converged to a point at
the junction of the middle and distal thirds of the antebrachium.
From this point the muscle again spread out into a triangular
muscular sheet to ultimately insert on the ventral surface of the
ulna and the proximal aspect of the carpus. It is probable that
the flexor carpi radialis muscle in its distal third is normally more
or less supported and directed by the radius. The latter being
absent, the muscle dropped to a secondary support on the ulna
(fig. 3).
The pronator (radii) teres muscle was entirely wanting.
The flexor digitorum sublimis muscle (?) arose by two heads:
that from the medial epicondyle was extremely small, and barely extended to this bony point. It also gained a slight origin
from the medial intermuscular septum. The radial head of the
muscle dropped more distally and deeply, due to the absence of
the radius, and arose from the lateral border of the ulna near the
carpus. The latter origin was found on a deeper level than that
of the flexor digitorum profundus muscle, and in its passage into
the hand it lay ventral to the mass of thenar muscles. The two
heads joined in the hand to form a distinct tendon which inserted
on the base of the distal phalanx of the index finger. I n the
palm of the hand a sheet of muscle tissue extended from the tendon
of the flexor sublimis digitorum (?) over the flexor profundus
digitorum towards the fifth metacarpal bone. It was not clear
what this muscle represented (fig. 3).
The flexor digitorum profundus muscle arose beneath the superficial muscles from the whole ventral surface of the ulna. It
lay ventral to the second head of the flexor digitorum sublimis
muscle. The muscle was fan-shaped, converging to a point on
the carpus and continuing into a tendon which sent three slips
to the bases of the distal phalanges of the third, fourth and
fifth fingers (fig. 3). I n the palm the tendon passed beneath the
flexor sublimis digitorum. From the ventral surface of the tendon an undifferentiated sheet of muscle extended toward the
fifth metacarpal bone and lay beneath the accessory sheet of
muscle given off from the flexor digitorum sublimis. From this
muscular mass two lumbrical muscles were given off for the fourth
and fifth fingers (fig. 3).
The thenar muscles were represented by a small mass of undifferentiated muscular tissue. This muscular mass arose from the
superficial fascia and from the undifferentiated extensor muscular
mass. It extended to the base of the second phalanx of the thumb.
A distinct tendon for the mass was wanting.
The extensor pollicis longus muscle was absent as a distinct
muscle. It was probably incorporated in the undifferentiated
extensor mass.
The hypothenar muscles were not differentiated into individual
muscles, but together formed a triangular sheet of muscle which
arose from the transverse carpal ligament. The muscular sheet
inserted on the medial border of the fifth metacarpal bone.
The pronator quadratus muscle was probably represented by
a mass of muscular tissue which surrounded the distal extremity
of the ulna (fig. 4).
The palmar interossei muscles were normal.
The dorsal interossei muscles were absent except the one for
the index finger.
Fig. 4. Diagrammatic sketch of a dissection of the lateral aspect of the antebrachium and of the dorsum of the hand of the right upper extremity. Only t h e
muscles are indicated. a = flexor carpi ulnaris; b = palmaris longus and flexor
carpi radialis (?) muscles; c = extensor carpi radialis longus et brevis muscles; d
= brachio-radialis muscle; e = extensor of thumb; f = extensor digitorum communis muscle; 9 = extensor digiti quinti proprius muscle; h = undifferentiated
muscle; i = extensor carpi ulnaris muscle; j = pronator quadratus muscle (?);
k = tendons of extensor digiti quinti proprius muscle; I = sheet of muscle from
thumb extensor.
Fig. 5. Outline drawing of the bones of the right brachium and antebrachium
after the muscles were removed. The hand is also shown in its fixed position.
The humerus was shorter than normal, measuring only 5 cm
in length. The proximal epiphysis was relatively extensive, 1.9
cm. in length. It projected cephalically and ventrally from the
shaft at an angle of about 135" (fig.5). The shaft of the humerus
was more or less rounded and not easily divisible into surfaces
and borders.
The capsule of the elbow joint was very lax and thin. It had
incorporated in it many muscle fibers, and the differentiation of
the various ligaments of the joint was very slight. The size of
the capsular ligament permitted a rather complex elbow motion.
Not only was the normal ginglymoid movement possible in its
full extenk, but a distinct trocoidal movement of the ulna on the
humerus was also possible. This condition in a measure compensated for the absence of the radius and made a small degree of
pronation and supination of the antebrachiurn possible.
Nerves to Coraco-brachialis
d. Ant.
Thorac. N.
Axillary N.
Fig. 6. Diagram of the brachial plexus of the right upper extremity.
text for description of it.
It should also here be noted that the medial aspect of the distal extremity of the ulna formed a diarthrodial joint with the
The osteology of the hand and carpus appeared normal for the
age of the infant.
The distribution of the nerves was more or less normal, hut
the altered musculature necessarily complicated the arrangement of the nerves. However, the nerve supply was an aid in
differentiating the various muscles of the antebrachiurn and
hand. The one striking thing about the nerves t,hroughout the
upper extremity was the unusually large size of the main trunks.
The brachial plexus also deviated from its normal arrangement.
As is indicated in the diagram of the plexus (fig. 6), the medial
and lateral components of the median nerve remsined independent to the level of the bend of the elbow. Here the components
united t o form the median nerve proper. =Inother peculiar condition of the median nerve was the origin of its medial component
(inner head) from both the medial and dorsal cords of the plexus.
The musculo-cutaneous nerve (?) ended in the substance of the
biceps muscle and another small nerve from the lateral cord ended
in the coraco-brachialis muscle. I n the diagram these nerves are
designated “nerves to coraco-brachialis and biceps muscles.”
The medial anterior thoracic nerve was a branch of the middle
t’runk. At least the nerve so designated filled the description of
the medial anterior thoracic nerve in every way save its point of
The medial brachial (lesser internal) cutaneous nerve was
entirely absent.
The agenesis of the radius in this case must have been due either
to a failure of the radial portion to give rise to an anlage, or if the
latter were established, some affection must have destroyed the
skeleton anlage after it had begun t o differentiate. I n view of
the fact that there was a complete absence of the radius the natural inference is that there was a lack of origin of the element.
It is difficult to say to what extent the absence of the radius
was responsible for the marked errors in the musculature of the
upper extremity. Certainly the absence of radial support and
stimulus must have to a great extent influenced the muscles that
normally arise and insert on this bone (it will be recalled that the
latter muscles were in many instances profoundly altered).
Other antebrachial muscles, as well as those of the hand showed
marked errors. The faulty position of the hand, doubtless primarily caused by lack of radial support, may have been responsible
for some muscle alterations, especially those of the hand and
those that normally insert on the carpus. Lack of radial guidance and stimulus may have influenced others. It is, however,
difficult to see how the absence of the radius could have had any
bearing on the development of the muscles of the shoulder and
proximal half of the brachium. Notwithstanding, many of these
muscles were quite anomalous in their anatom,y, as is indicated
in the text.
It would: therefore, seem that the whole error-complex of the
upper extremity was primarily due t o the lack of a proper formative stimulus or stimuli, and that the absence of the radius could
merely account for secondary muscular errors due to the lack of
support and stimulus normally supplied by this bone. The
faulty position of the hand seemed purely secondary, due to lack
of radial support and muscular contraction.
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infant, anatomy, complete, absence, observations, upper, bilateral, radius, extremities
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