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Relationship between the tendon of the long head of biceps brachii and the glenoidal labrum in humans.

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THE ANATOMICAL RECORD 229:278-280 (19911
Relationship Between the Tendon of the Long
Head of Biceps Brachii and the Glenoidal Labrum
in Humans
G.P. PAL, R.H. BHATT, AND V.S. PATEL
Department of Anatomy, Government Medical College, Surat, India
ABSTRACT
The relationship between the tendon of the long head of the biceps brachii muscle and the glenoidal labrum was investigated in a large number
of dissected human shoulder joints. In about 70% of the specimens examined, the
labrum was deficient at the posterosuperior margin of the glenoid because the
tendon of the biceps coursed over this margin to blend with the labrum. Because of
this, a small crescentic accessory facet was observed a t the posterosuperior margin
of the glenoid. In the majority of cases, the tendon of the biceps blended with the
glenoidal labrum, and only a small part of the tendon attached to the supraglenoid
tubercle. However, in 25% of the specimens, the major portion of the tendon was
attached to the supraglenoid tubercle.
The standard gross anatomy description of the glenoidal labrum (fibrocartilagenous rim) is that its base
is fixed to the circumference of the glenoid cavity of the
scapula. The tendon of the long head of the biceps
brachii muscle has been described a s taking origin
from the supraglenoid tubercle, which is situated a t the
apex of the glenoid cavity (Woodburne, 1961; Hollinshead, 1958; Hamilton, 1978; Snell, 1981). Many others
believe that, in addition to its attachment to the supraglenoid tubercle, a slip of the tendon of the biceps also
attaches to a n adjoining part of the glenoidal labrum
(Schaeffer, 1953; Gardner et al., 1975; Williams and
Warwick, 1980; Romanes, 1981; Last, 1984). A clear
description of the attachment of the tendon of the long
head of the biceps and its relationship with the glenoidal labrum is lacking in the literature. Recently, Paul
e t al. (1988) noted the presence of a facet at the posterosuperior margin of the glenoid cavity in a large number of dry, macerated scapulae. However, they failed to
investigate its anatomic significance. The present
study was undertaken to investigate the attachment of
the biceps tendon, its relationship with the glenoidal
labrum, and the significance of the facet reported by
Paul e t al. (1988).
OBSERVATIONS
Observations of the Dissected Specimens
In about 25% of the specimens (6 of 241, the glenoidal
labrum was complete and was firmly attached to the
margin of glenoid cavity. At the apex of the glenoid
cavity, a portion of the tendon of the biceps was continuous with the labrum. However, the major portion of
the tendon was attached to the supraglenoid tubercle.
In about 67% of the specimens, the major portion of the
tendon was continuous a t the posterosuperior margin
of the glenoid cavity and blended with the labrum in
the middle of the posterior margin of the glenoid. In
these specimens, the labrum was completely deficient
at its posterosuperior margin and was replaced by the
biceps tendon. In these specimens, the slip of biceps
tendon going to the supraglenoid tubercle was very
thin and, in a few cases (two of 16), even absent. Thus,
in the majority of the specimens, the tendon of the biceps blended with the labrum in the middle of the posterior border of the glenoid (Fig. 1). In two of 24 specimens, in addition to the continuation of the biceps
tendon a t the posterosuperior margin, a prominent slip
of biceps tendon also passed toward the anterosuperior
margin of the glenoid and blended with the labrum.
Thus, in these cases, the labrum was deficient both at
the posterosuperior and anterosuperior margin of the
MATERIALS AND METHODS
glenoid.
The specimens in this study consisted of 24 shoulder
In specimens where the glenoidal labrum was rejoints of adult human males. Observations on this ma- placed by the tendon of the biceps, the joint cavity exterial were made during the course of routine dissec- tended between the tendon and the margin of the gletion for undergraduate students a t the Government noid (Fig. 2). Deep to the tendon, a small crescentic
Medical College, Surat. After opening the joint cavity, facet was observed a t the margin of the cavity. This
the tendon of the long head of the biceps was dissected facet was covered by hyaline cartilage, but separated
to study its attachment to the supraglenoid tubercle
and its continuity with the labrum. In addition, a large
number of dry, macerated adult scapulae (290) of unknown sex were observed for the presence of a small
facet a t the margin of the glenoid cavity. The presence
Received December 26, 1989; accepted May 16, 1990.
of this facet was presumed to represent a deficient laAddress reprint requests to G.P. Pal, M.D., Assoc. Professor, Dept.
brum in the living condition.
of Anatomy, Govt. Medical College, Surat 395 001, India.
c)
1991 WILEY-LISS, INC
279
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Fig. 3. This scapula demonstrates a crescentic facet a t the posterosuperior margin of the glenoid cavity. The margin of the glenoid cavity and the accessory facet are marked with a black line.
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Flg. 1. The diagram demonstrates the various sites for the attachment of the biceps tendon. In about 70% of the specimens, the tendon
blends with the labrum a t the posterosuperior margin of the glenoid
(a).In these specimens, t h e contribution to the supraglenoid tubercle
is very small and sometimes even absent (b). Occasionally it also
sends a slip to the anterosuperior margin ( c ) .
Fig. 2. The major part of the tendon of the biceps courses over the
posterosuperior margin to blend with the glenoid labrum. A marker
between the tendon and the margin of the glenoid cavity demonstrates the continuity of the joint cavity between the two.
from the rest of the glenoid cavity by a faint elevated
ridge. No marked bilateral differences were noted in
these specimens.
Observations on the Dry, Macerated Scapulae
Of 290 scapulae, 201 (69%) showed the presence of a
small crescentic facet at the posterosuperior margin of
the glenoid (Fig. 3). This facet was separated from the
rest of the glenoid cavity by a faint ridge. Only five
scapulae (2%) showed the facet extending both at the
posterosuperior and anterosuperior margin of t h e glenoid. The shape of this facet was like a n inverted “J”
(Fig. 4). In the remaining 84 scapulae (29%), no facet
was observed, and the margin of the glenoid cavity was
elevated throughout its circumference.
DISCUSSION
The present study revealed t h a t in about 70% of specimens examined, the glenoidal labrum was deficient at
its posterosuperior margin and was replaced by the
tendon of biceps. This is in marked contrast to textbook
descriptions which describe the presence of a complete
glenoid labrum. In our study, this was observed in only
about 25% of specimens. The above observations on the
dissected specimens were further supported by observations on dry, macerated scapulae. In about 70% of
cases, a small crescentic facet was observed at the posterosuperior margin of the glenoid. This corresponds
well with the percentage showing a deficient labrum.
The site of the accessory facet and deficient labrum was
the same. Similarly, 29% of the bones showed the absence of the accessory facet, which correlates well with
the finding that in 25% specimens the labrum was
found to be complete. The results from the present
study suggest that, in about 70% of specimens, the tendon of the biceps blends with the glenoid labrum, and
only a small portion of it goes to the supraglenoid tubercle. It is also in marked contrast to what is generally thought to be the morphology of this joint. The
major part of the tendon of the biceps was attached to
the supraglenoid tubercle in only 25% of cases.
Paul et al. (1988)are of the opinion t h a t the presence
of the facet at the posterosuperior margin of the glenoid
cavity might be due to different occupations, but the
present study might indicate t h a t the cause of this
G.P. PAL ET AI,
the posterior margin of the glenoid might be expected
to provide better stability to the shoulder joint a s compared with the attachment of the tendon to the supraglenoid tubercle. Because the tendon has to course over
the head of the humerus to continue with the labrum,
it helps to retain the head of the humerus in the glenoid fossa and thus assist the rotator “cuff.” The course
taken by the biceps tendon also prevents the head of
humerus from being pulled upward too forcibly against
the inferior surface of the acromion. Rupture of the
tendon removes a steadying influence from shoulder
movements (Hollinshead, 1958).
Most tears of the glenoid labrum occur along the superior aspect of the rim. It is possible that what has
been described a s tears of the labrum may be in actual
fact tears of a more loosely adherent tendon, a s the
joint space extends between the tendon and the margin
of the glenoid cavity.
LITERATURE CITED
Fig. 4.An inverted “J”-shaped facet is formed due to a slip of biceps
tendon going both to the posterosuperior and to the anterosuperior
margin of the glenoid cavity.
facet is due to a deficient labrum, which in t u r n is
replaced by the tendon of biceps. The facet occurred
because of the movement of the tendon at the margin of
the glenoid cavity. The rare inverted J-shaped facet
resulted from the tendon passing its slips to both the
anterosuperior and posterosuperior margin of glenoid.
The continuation of the tendon with the labrum a t
Gardner, E., D.J. Gray, and R. O’Rahilly 1975 In: Anatomy. 4th ed.
W.B. Saunders, Philadelphia, p. 122.
Hamilton, W.J. 1978 In: Textbook of Human Anatomy. 2nd ed.
. E.L.B S. and Macmillan, London, p. 169.
Hollinshead W.H. 1958 In: Anatomy for Surgeons, Vol. 3. 1st ed. Hoe’
ber-Harper, New York, p. 361.
Last, R.J. 1984 In: Anatomy-Regional and Applied. 7th ed. Churchill
Livingstone, Edinburgh, p. 74.
Paul, S., J.M. Kaul, and L. Rao 1988 Surface area of gleno-humeral
articulations. Paper read in the 37th National Conference of the
Anatomical Society of India, New Delhi.
Romanes, G.J. 1981 In: Cunningham’s Textbook of Anatomy. 12th ed.
Oxford University Press, Oxford, p. 322.
Schaeffer, J.P. 1953 In: Morris’ Human Anatomy. 11th ed. McGrawHill, New York, p. 462.
Shell, R.S. 1981 In: Clinical Anatomy for Medical Students. 2nd ed.
Little Brown and Company, Boston, p. 385.
Williams, P.L., and R. Warwick 1980 In: Gray’s Anatomy 36th ed.
Longman, Edinburgh, p. 571.
Woodburne, R.T. 1980 In: Essentials of Human Anatomy. 2nd ed.
Oxford University Press, New York, p. 87.
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bicep, head, glenoidal, long, tendon, labrus, brachii, human, relationships
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