Anatomy Atlases: Illustrated Encyclopedia of Human Anatomic Variation: Opus I: Muscular System: Alphabetical Listing of Muscles: L: Lumbricales (Manus)
Illustrated Encyclopedia of Human Anatomic Variation: Opus I:
Muscular System: Alphabetical Listing of Muscles: L
Ronald A. Bergman, PhD
Adel K. Afifi, MD, MS
Ryosuke Miyauchi, MD
Peer Review Status: Internally Peer Reviewed
The limbricals show frequent variations (20% of individuals).
Wood reported that he found 19 variations in 102 individuals (or
5.3%). They may be reduced to three or even two, and in rare
instances all four are absent. Rarely, the number may be increased by
the development of accessory slips. In the case of the first
lumbrical, an accessory slip may arise from the tendon of flexor
pollicis longus, the tendon of fllexor digitorum superficialis, the
first metacarpal, opponens pollicis, or the palmar carpal
Cases have also been observed in which a fasciculus arose from the
muscular belly of the superficial or deep flexor and joined the first
lumbrical. The second lumbrical may arise from two tendons between
which it lies. On the other hand, the third and fourth may arise from
one tendon only.
Variations of insertion frequently occur with the third and fourth
lumbricals. The origin of one or another of the lumbricals may be
displaced proximally, arising from the flexor retinaculum, from a
special tendon from the deep or superficial flexor, or, in the case
of the first lumbrical, from the tendon of the flexor pollicis
longus. They may be attached in the palm to the superficial as well
as to the deep flexor tendons.
Frequently, the lumbricals may be bifid distally and insert into
two fingers. This occurs in the case of the third lunbrical in about
40% of individuals.
The destination of one or more of the lumbricals may be changed,
and one finger sometimes has two lumbricals inserted into it. They
may be inserted onto the first phalanx instead of or in addition to
the normal attachment to the extensor tendon. The fourth lumbrical
has been observed to replace the fourth tendon of flexor
superficialis. Mori has provided a statistical evaluation of the
lumbrical muscles as follows:
Origin of the lumbrical muscles.
The first lumbrical arises from the radial side of the
terminal tendon of flexor digitorum profundus for the second
finger in 100% of his subjects.
The second lumbrical arises from the radial side of the
terminal tendon of flexor digitorum profundus for the middle
finger in 78%. The second lumbrical arises with two heads. One
arises from the radial side of the tendon of flexor digitorum
profundus for the middle finger, and the second head arises from
the ulnar side of the tendon of flexor digitorum profundus for the
second finger in 22 %.
The third lumbrical arises with two heads from the opposite
surface of the terminal tendons for the middle and fourth fingers
in 98% of subjects.
The fourth lumbrical arises from the ulnar side of the
terminal tendon of flexor digitorum profundus for the fourth
finger in 2%.
Insertion of the lumbrical muscles.
The tendons of the first and second lumbricals are attached
along the side of the first phalanx to the radial border of the
tendon of extensor digitorum for the second and third fingers in
10% of subjects
The third lumbrical is divided into two slips, and one is
inserted on the ulnar surface of extensor digitorum for the fourth
finger in 20%. The terminal tendon of the third lumbrical is
inserted on the radial surface of extensor digitorum for the
fourth finger in 80% of subjects.
The fourth lumbrical is divided into two slips, one is
inserted on the ulnar surface of extensor digitorum for the fourth
finger, and the second is inserted on the ulnar surface of the
terminal tendon of extensor digitorum for the fifth finger in
The fourth lumbrical is inserted on the ulnar surface of extensor
digitorum for the fourth finger in 4%.
The fourth lumbrical is inserted on the radial surface of extensor
digitorum for the fifth finger in 96% of subjects.
Macalister reported the varieties as follows:
The first lumbrical may be doubled, one being normal, the
second arising from the flexor sublimis (digitorum superficialis).
A case of this kind was described by Wood, in which the origin of
the second flexor was a fine tendon which arose from the outside
of the coronoid origin of flexor sublimis. In another case, Wood
found the deviant lumbrical split into two parts, the innermost
being implanted into the tendon of the perforatus (flexor
digitorum superficialis), near its division in the sheath of the
index finger, the outer joined the normal lumbricalis, near its
usual place of insertion;
Macalister and Wood described a slip from flexor pollicis
giving a tendon to the first lumbrical. The same author found the
first lumbrical arising from flexor digitorum superficialis and
the thumb alone. The muscle was bipenniform;
A supplementary head for the first
lumbrical, originating from the first palmar interosseous was found by Wood;
The first has been seen inserted the second finger by
Macalister reports that the first lumbrical may be
The second may also be absent;
Wood reported the second doubled at its insertion, sending
one slip to the radial side of the middle finger, and one to the
ulnar side of the index;
Wood also found the muscle bipenniform in origin, taking
origin from the tendons of the index and middle fingers;
A similar division of the orgin was found for the third
The third has been found bifurcated at insertion-one-half
going to the ulnar side of the middle, and the other to the radial
side of the ring finger by Wood, Froment and by Macalister;
The entire third lumbrical has been seen going to the
ulnar side of the middle finger. Mr Wood found this in a subject
in which the fourth was absent;
The fourth has been noticed as absent by Sömmerring,
Meckel, Weber-Hildebrandt, Wood and by Macalister;
All the lumbricals were found missing in one subject by
Macalister. The fourth has been found bifurcated, supplying the
ulnar side of the ring, and the radial side of the little finger
The fourth was found giving off the perforated flexor for
the little finger in the case of absence of this tendon from the
The first and fourth have been found springing from
special tendons of profundus;
The third and fourth may bifurcate at their insertion
according to Kelly, Gegenbaur, and Macalister;
Five lumbricals have been reported by Walther, by Petsche,
and by Böhmer. In one of these cases, two lumbricals were for
the middle, two were for the ring, and none were for the little
finger; in another, two were for the middle, and the rest were
normal. The varieties of the lumbricals have been investigated by
Froment who found variations in 45% of subjects, Wood finds them
to vary in 18 to 19% (19/102), and Macalister found 50 in 400
The lumbrical to the fourth finger was found by Gruber to
be a bundle of fibers from the third interosseous A lumbrical
muscle was found passing through Guyon's canal. Guyon's canal is
formed by a fascial thickening, which covers the space containing
the ulnar neurovascular bundle, attached to the pisiform and to
hook of the hamate bones. It is also known as the superficial part
of the flexor retinaculum and it is covered by the palmaris brevis
Basu, S.S. and S. Hazary. (1960) Variations of the lumbrical muscles
of the hand. Anat. Rec. 136:501-503.
Butler, Jr.,B. and E.C. Bigley, Jr. (1971) Aberrant index (first)
lumbrical tendinous origin associated with carpal-tunnel syndrome. J.
Bone Joint Surg. (A) 53:160-162.
Durksen, F. (1978) Anomalous lumbrical muscles in the hand: a case
report. J. Hand Surg. 3:550-551.
Goldberg, S. (1970) The origin of the lumbrical muscles in the
hand of a South African native. Hand. 2:168-171.
Gruber, W. (1887) Eine Reihe neuer Varitäten des Musculus
lumbricalis 1 manus. Arch. Path. Anat. Physiol. Klin. Med.
Henle, J. (1871) Handbuch der Muskellehre des Menschen, in
Handbuch der systematischen Anatomie des Menschen. Verlag von
Friedrich Vieweg und Sohn, Braunschweig.
Macalister, A. (1875) Observations on muscular anomalies in the
human anatomy. Third series with a catalogue of the principal
muscular variations hitherto published. Trans. Roy. Irish Acad. Sci.
Metha, H.J. and W.U. Gardner. (1961) A study of lumbrical muscles
in the human hand. Am. J. Anat. 109:227-238.
Mori, M. (1964) Statistics on the musculature of the Japanese.
Okajimas Fol. Anat. Jap. 40:195-300.
Nicola, B. (1906) Sur les insertions distales des musculi
lumbricales dans la main de l'homme. Arch. Ital. Biol.
Reinhardt, E. (1902) Über den Ansatz der Musculi lumbricales
an der hand des menschen. Anat. Anz. 20:129-134.
Russel, K.F. and S. Sunderland. (1937-38) Abnormalities of the
lumbrical muscles of the hand. J. Anat. 72:306307.
Schmidt, H.M., Heinrichs, H.-J. and D. Reissig. (1963) Die Mn.
lumbricales an der Hand des Menschen, ihre Variations in Ursprung und
Ansatz. Anat. Anz. 113:414-449.
Still, Jr., J.M. and H.E. Kleinert. (1973) Anomalous muscles of
nerve entrapment in the wrist and hand. J. Plastic Reconstructive
Wood, J. (1866) Variations in human myology observed during the
winter session of 1865-66 at King's College, London. Proc. Roy. Soc.
Lond. B. 15:229-244.
Wood, J. (1868) Variations in human myology observed during the
winter session of 1867-68 at King's College, London. Proc. Roy. Soc.
Lond. B. 17:483-525.
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