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Table of Content Volume 3 Issue 1 - July 2017

 


 

Morphological study of lumbrical muscles in human cadaveric hands

 

Vrushali V Maindarkar1*, Santoshkumar A Dope2*, Pramod R Kulkarni3

 

1Assistant Professor, Department of Anatomy, MIMSRMC, Latur, Maharashtra, INDIA.

2Associate Professor, Department of Anatomy, GMC, Latur, Maharashtra, INDIA.

3Professor, Department of Anatomy, Dr. VMGMC, Solapur, Maharashtra, INDIA.

Email: shiledar.vrushali@gmail.com, drdopesantosh@yahoo.co.in  

 

Abstract               The lumbrical muscles of hand, by producing flexion at metacarpo phalangeal (MCP) joints and extension at interphalangeal joints help in writing, stitching and other forms of precision work. Hence philosophically, it may be said that the actions of lumbrical muscles of hand are indices of civilization of a race.1 The variations in origin, insertion  and nerve supply may cause carpal tunnel syndrome. Their hypertrophy may cause compression of radial  and ulnar collateral arteries leading to chronic subischemia. Also they may cause surgical complications in hand surgeries. So this study has been undertaken to know about morphology and morphometry of lumbrical muscles in human hands.

 

 

INTRODUCTION

The human hand is a prehensile organ. It is endowed with grasping and precision movements for skilled work and it acts as a chief tactile apparatus. This is contributed by a high degree of neuromuscular co-ordination  and a larger cortical representation of the hand in sensory  and motor cortex in human brain.2 Evolution of grasping ability of human being contributed by lumbrical muscles is attributed to the ecological context of such skills in the frogs. Hence human hand is revolution in evolution. The lumbricals of the upper limb are 4 small muscles resembling earthworms hence the name. They are numbered 1 to 4 from lateral to medial side. They arise from bare areas of tendons of flexor digitorum profundus (FDP) about the middle of the palm. The narrow tendon of insertion joins the radial margins of extensor expansion (EE) as distal wing tendons1 Normally 1st and 2nd lumbricals are unipennate. They arise from the radial sides of FDP tendons for index and middle fingers. They are supplied by branches from Median nerve. 3rd and 4th lumbricals are bipennate. They arise from adjacent sides of FDP tendons for middle, ring  and little fingers. They are supplied by deep branch of ulnar nerve. Then they pass distally along the radial side of MCP joints anterior to deep transverse metacarpal ligament. The narrow tendon of insertion joins the EE of respective fingers as distal wing tendons. Through EE, they are inserted into dorsal surfaces of bases of middle and distal phalanges.

 

MATERIALS

This study was conducted in the Department of Anatomy in an institutional Medical College, with 50 forearms  and hands (25 Right  and 25 left) of human embalmed cadavers of both sexes with the age range approximately between 45-65 years. 21 cadavers were male (42 hands) and 4 cadavers were female (8 hands). The study was carried out during the routine dissection for undergraduate medical students in the department of Anatomy. Material used for dissection was scalpel, blades, tooth and blunt forceps, scissor, scale, thread, marker pencil.

METHODS

As a guide for dissection, Cunningham’s manual of practical anatomy was used. The dissection was carried out as follows: A longitudinal incision was taken from the distal end of the flexor retinaculum, up to the level of the metacarpophalangeal joint of the middle finger. The skin, the superficial fascia, the deep fascia and the flexor retinaculum were dissected and reflected. Then, the tendons of the flexor digitorum superficialis and the flexor digitorum profundus were identified and reflected distally. The lumbrical muscles which were situated at the distal end of the flexor digitorum profundus tendons were carefully observed. The lumbrical muscles were followed to their tendons and traced up to their insertion.

 

OBSERVATIONS

The following parameters were noted:

    • Site of origin and insertion of the lumbricals.
    • The architecture of the muscles was noted i.e. unipennate orbipennate pattern.
    • Nerve supply of each muscle
    • Variations, if any.

    RESULTS

    Present study was carried out on 50 hands out of which 25 hands were of right side and 25 hands were of left side.

     

    Table 1: Morphological comparison

    Lumbricals

    Right hand

    Left hand

    Normal

    23 (92%)

    20 (80%)

    Bipennate 2nd lumbrical

    2 (8%)

    4 (16%)

    Misplaced insertion of 4th lumbrical

    0

    1 (4%)

    Total

    25 (100%)

    25 (100%)

    Right hand lumbricals- In present study, in 23 hands (92%) muscles were found normal morphologically, while in 2 hands (8%) 2nd lumbricals were bipennate originating from adjacent sides of tendons of flexor digitorum profundus (FDP) for index and middle finger. No misplaced insertions were found in any muscle. Left hand lumbricals- In present study, in 20 hands (80%) muscles were found normal morphologically. While in 4 hands (16%) 2nd lumbricals were bipennate originating from adjacent sides of tendons of FDP for index and middle finger. In 1 hand (4%) misplaced insertion in 4th lumbrical muscle was found at ulnar side of extensor expansion of ring finger instead of radial side of little finger.


    1

    Figure 1: showing bipennate second lumbrical muscle Figure 2: showing all 4 lumbrical muscles

    DISCUSSION

    1st lumbrical muscle

    Table 2: showing comparison of 1st lumbricals

    Sr. no.

    Study

    Year

    No. of hands

    Variation

    Normal

    1.

    Ajmani3

    2001

    68

    Bifid 3 (4.5%), Bipennate 3 (4.5%)

    62 (91%)

    2.

    Hosapatna et al   4

    2013

    30

    Bifid 1 (3.3%),

    Hypertrophied 1 (3.3%)

    28 (93.3%)

    3.

    Sawant et al   5

    2013

    100

    Accessory belly 5 (5%)

    95 (95%)

    4.

    Present study

    2014

    50

    ----------

    50 (100%)


    In a study conducted by Ajmani [2001] in 68 hands, bifid 1st lumbrical was seen in 3 hands (4.5%) out of which 2 originating from flexor digitorum superficialis (FDS) tendon for index finger  and 1 from palmar aspect of 2nd metacarpal bone. While in other 3 hands (4.5%) it was bipennate arising from adjacent sides of tendons of FDP and flexor pollicis longus. In a study done by Hosapatna et al    [2013], bifid 1st lumbrical was found in 1 case out of 30 hands with an incidence of 3.3% and hypertrophied 1st lumbrical, in 1 hand (3.3%) out of 30. In a study conducted by Sawant et al    [2013], 5 cases (5%) of accessory belly of 1st lumbrical were found out of 100 hands. In all cases the belly was originated from radial side of the tendon of FDP going to index finger. In the present study, 1st lumbricals in all 50 hands (100%) were present and found normal. They all were innervated by median nerve.


    2nd lumbrical muscle

    Table 3: showing comparison among 2nd lumbricals

    Sr. no.

    Study

    Year

    No. of hands

    Variations

    Normal

    1.

    Ajmani3

    2001

    68

    Absent 2 (3%),

    Bipennate 16 (24%)

    50 (73%)

    2.

    Joshi et al   6

    2005

    70

    Bipennate 32 (45%)

    38 (55%)

    3.

    Mutalik2

    2011

    60

    Bipennate 2 (3.3%)

    58 (96%)

    4.

    Hosapatna et al   4

    2013

    30

    Bipennate 1 (3.3%)

    29 (96.6%)

    5.

    Sawant et al   5

    2013

    100

    Bipennate 10 (10%),

    Bifid 7 (7%)

    83 (83%)

    6.

    Modasiya et al   7

    2013

    80

    Bipennate 10 (12.5%)

    70 (87.5%)

    7.

    Present study

    2014

    50

    Bipennate 6 (12%)

    44 (88%)

     

     

     

     

     

     

    Ajmani [2001] found absence of 2nd lumbrical in both hands (3%) of a cadaver out of 68 hands. In 16 hands (24%) it was found to be bipennate. Joshi et al    [2005] have found 2nd lumbrical bulkiest amongst all the lumbricals. They have also reported bipennate 2nd lumbricals in 32 hands (45%) out of 70 hands. It was also observed that the proximal attachment of 2nd lumbrical was extending to carpal tunnel compared to the rest of the lumbricals. Mutalik [2011] reports bipennate 2nd lumbrical in 2 cases (3.3%) out of 60 dissected hands. Fibers were arising from adjacent sides of FDP tendons for index and middle fingers. In a study done by Hosapatna et al    [2013], bipennate 2nd lumbrical was found in 1 case (3.3%) out of 30 hands in which fibers were arising from adjacent sides of FDP tendons for index and middle fingers. Its pattern of insertion was normal.       Sawant et al    [2013] have noted 10 cases (10%) of bipennate 2nd lumbrical out of 100 hands, fibers arising from radial side of tendon of FDP for middle finger and ulnar side of FDP tendon for index finger. While in 7 hands (7%), it was found to be bifid originating from radial side of tendons of FDP  and FDS muscles for index finger. Pattern of insertion was normal and there were no associated neurovascular variations. In a study done by Modasiya et al    [2013], in 10 cases (12.5%) out of 80 hands, they found bipennate 2nd lumbrical. In the present study, in 2 right hands (8%) 2nd lumbricals were bipennate originating from adjacent sides of tendons of FDP for index and middle finger out of 25 right hands. While in 4 left hands (16%) of 2nd lumbricals were bipennate originating from adjacent sides of tendons of FDP for index and middle finger out of 25 left hands.

    3rd lumbrical muscles

    Table 4: showing comparison of 3rd lumbricals

    Sr. no.

    Study

    Year

    No. of hands

    Variations

    Normal

    1.

    St. J.Brooks8

    1885

    21

    Median NS 9 (43%),

    Dual NS 3 (14%)

    9 (43%)

    2.

    Ajmani3

    2001

    68

    Unipennate 2 (3%), Split ins 22 (32%), 1st phalanx ins 10 (14%), DTML ins 2 (3%), ins along FDS 2 (3%)

    30 (45%)

    3.

    Mutalik2

    2011

    60

    Split ins 7 (11.6%), mispl ins 1 (1.6%)

    52 (86.6%)

    4.

    Igiri et al   9

    2011

    64

    Unipennate 12 (18.75%)

    52 (81.25%)

    5.

    Parminder Kaur10

    2013

    50

    Split ins 14 (28%), Mispl ins 2 (4%)

    34 (68%)

    6.

    Hosapatna et al   4

    2013

    30

    Absent 1 (3.3%)

    29 (96.6%)

    7.

    Modasiya et al   7

    2013

    80

    Split ins 12 (15%)

    68 (85%)

    8.

    Present study

    2014

    50

    ------------

    50 (100%)

     

     

     

     

     

     


    Where NS = nerve supply, ins = insertion, DTML =deep transverse metacarpal ligament, FDS = along flexor digitorum superficialis, mispl = misplaced St.John Brooks [1887] have reported variation in nerve supply of 3rd lumbrical in 12 hands out of 21 hands. He noticed a twig from median nerve as a sole nerve supply in 9 hands while dual nerve supply in remining 3 hands. In the hands with dual supply, the size of twig was inversely proportional to each other. Ajmani [2001] has reported 3rd lumbrical as the most variable lumbrical. He noted normal origin of all 68 hands but reported normal insertion in 32 hands (47%) only. The muscle was unipennate in 2 hands (3%). Split insertions were noted in 22 hands (32%). Insertion in base of first phalanx was noted in 10 hands (14%). Insertion into deep transverse metacarpal ligament was noted in 2 hands (3%) and along with FDS tendon in 2 hands (3%). Mutalik [2011] have reported split insertion of 3rd lumbrical in 7 cases (11.6%) out of 60 cases. She also noted misplaced insertion of it in 1 case (1.66%) where it was inserted into ulnar side of middle finger. Igiri et al   [2011] have noted unipennate 3rd lumbrical muscle in 12 cases (18.75%) out of 64 hands. Parminder Kaur [2013] has reported variations in insertion rather than origin. It was seen that 14 hands (28%) out of 50 cases showed split insertions in which the tendon divided into 2 slips  and inserted into ulnar side of middle finger and radial side of ring finger. It was also noted to have misplaced insertions in 2 hands (4%) in which it inserted into ulnar side of middle finger.    Hosapatna et al    [2013] reported absence of 3rd lumbrical in 1 hand (3.3%) out of 30 cases. Modasiya et al    [2013] have reported split insertion of 3rd lumbrical in 12 hands (15%) of 80 cases. In the present study, 3rd lumbricals in all 50 hands (100%) were present and found normal. They all were innervated by deep branch of ulnar nerve.

    4th lumbrical muscle

    Table 5: showing comparison of 4th lumbricals

    Sr. no.

    Study

    Year

    No. of hands

    Variations

    Normal

    1.

    Ajmani3

    2001

    68

    Absent 4 (5.88%), Unipennate 6 (8.8%)

    58 (85.4%)

    2.

    Joshi et al   6

    2005

    70

    Absent 3 (4%)

    67 (96%)

    3.

    Mutalik2

    2011

    60

    Mispl ins 6 (10%), Split ins 1 (1.6%)

    53 (88.3%)

    4.

    Igiri et al   9

    2011

    64

    Unipennate 32 (50%)

    32 (50%)

    5.

    Modasiya et al   7

    2013

    80

    Mispl ins 12 (15%)

    68 (85%)

    6.

    Parminder Kaur10

    2013

    50

    Mispl ins 4 (8%), Split ins 8 (16%)

    38 (76%)

    7.

    Present study

    2014

    50

    Mispl ins 1 (2%)

    49 (98%)

    Where mispl ins = misplaced insertion,


    Ajmani 2001 reported absent 4th lumbrical in 4 hands (5.88%) out of 68 hands. He also noted unipennate 4th lumbrical in 6 cases (8.8%) arising from radial side of FDP tendon for little finger. In a study conducted by Joshi et al    2005, the 4th lumbrical in 4% cases was absent out of 70 hands. Mutalik 2011 reported misplaced insertion of 4th lumbrical in 6 cases (10%) out of 60 hands. In which it was inserted in ulnar side of extensor expansion (EE) for ring finger. In 1 case (1.6%) she reported split insertion of 4th lumbrical in that its tendon split into two slips to insert into ulnar side of EE of ring finger and radial side of EE of little finger. Igiri et al    2011 have noted unipennate 4th lumbrical in 32 cases (50%) out of 64 hands dissected. Modasiya et al    2013 reported misplaced insertion of 4th lumbrical in 12 cases (15%) out of 80 hands dissected. Parminder Kaur 2013 noted misplaced insertion of 4th lumbrical in 4 hands(8%) out of 50 hands dissected in which it inserted in ulnar side of EE of ring finger. She also noted split insertion of 4th lumbrical in 8 hands (16%) in which it split into two slips to insert into ulnar side of EE of ring finger and radial side of EE of little finger. In the present study, 4th lumbricals were present in all 50 hands (100%). In all 25 right hands, they were found normal morphologically. While in 1 left hand (4%) out of 25 left hands it showed misplaced insertion at ulnar side of EE of ring finger instead of radial side of little finger. All of them were innervated by deep branch of ulnar nerve.

    CONCLUSIONS

    In the present study, following morphological variations were found.

    1. Bipennate 2nd lumbrical muscles were found in 6 hands (12%) out of 50 hands.
    2.  Misplaced insertion of 4th lumbrical muscle was found in 1 hand (4%) out of 50 hands

    The knowledge of variational anatomy of lumbrical muscles is of fundamental importance to orthopedic and plastic surgeons.

    REFERENCES

    1. Datta AK. Essentials of Human Anatomy. 2nd Ed. Calcutta: Current Books International 1995.
    2. Ashwini M Mutalik. Morphological variations in the origin and insertion of lumbricals of the upper limb in cadavers. JCDR 2011; 5(2): 278-281
    3. Ajmani ML (2001). Morphological variations of lumbrical muscles in the human hand with some observations on its nerve supply. Medical Journal of Iran Hospital, 3: 20-25
    4.  Hosapatna M, Bangera H, Naveenkumar, Sumalatha S, Nitya. Morphological Variations in Lumbricals of Hand–A Cadaveric Study. Plastic Surgery: An International Journal Vol 2013(2013); Article ID no.821692: 7 pages; DOI:10.5171/2013.821692
    5. Sawant S P, Shaikh S T, More R M. An accessory belly of first lumbrical– a case report. IJSER 2012; 3(12): 1-3.
    6. Joshi SD, Joshi SS, Athavale SA. Lumbrical Muscles and Carpal Tunnel. J Anat Soc India 2005. Vol 54(1): 12-15.
    7. Modasiya DUP, Master DNT, Astik DRB, Bissa MA. Clinical Relevance Of Morphological Variations In Origin And Insertion Of Lumbricals Of Hand In South Gujarat Population. NJIRM. (2013); 4(6): 50-53.
    8. Brooks H St. J Variations In The Nerve-Supply Of The Lumbrical Muscles In The Hand And Foot With Some Observations On The Innervation Of The Perforating Flexors. Jour. of Anat. and Phys.,1887; 20:641.
    9.  Igiri AO, Mesembe OE, Ekong MB, Akpan NU. The pattern of arrangement of the lumbrical muscles in an African population. Clin Anat. 2011; 24(4):423–428.
    10. Parminder Kaur. Morphological Study of Lumbricals–A Cadaveric Study. Journal of Clinical and Diagnostic Research. 2013Aug; Vol-7(8): 1558-1560.