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Revista chilena de anatomía

versão impressa ISSN 0716-9868

Rev. chil. anat. v.20 n.3 Temuco  2002

http://dx.doi.org/10.4067/S0716-98682002000300001 

Rev. Chil. Anat., 20(3):241-245, 2002.

 

DETERMINATION OF THE LEVELS OF ORIGIN AND POINT OF PENETRATION
OF THE NERVES THAT SUPPLY THE FLEXOR DIGITORUM SUPERFICIALIS MUSCLE

DETERMINACIÓN DE LOS NIVELES DE ORIGEN Y PUNTOS DE PENETRACIÓN DE
LOS NERVIOS QUE SUPLEN EL MÚSCULO FLEXOR DIGITORUM SUPERFICIALIS 

*Renata Frazão; **Nilton Alves & ***Serafim V. Cricenti

FRAZÃO, R.; ALVES, N. & CRICENTI, S. V. Determination of the levels of origin and point of penetration of the nerves that supply the Flexor digitorum superficialis muscle.  Rev. Chil. Anat., 20(3):241-245, 2002.

SUMMARY :Knowing the distribution of the Flexor digitorum superficialis muscle nerve's branches, its origin levels and points of penetration, it makes the treatment of these lesions easier, mainly in cases of surgery where without the adequate anatomic knowledge the nerve's branches could be even more damaged. We dissected 10 corpses fixed with formaldehyde, therefore analyzing in 20 forearms that were measured with the help of a common ruler. We used as reference the articular lines of the elbow and wrist. In our results, we could see that in the left upper limb, the majority of the median nerve's branches (29.7%) began in the distal half of the forearm's middle third part and the majority of median nerve points penetration (30.3 %) began in the proximal half of the forearm's proximal third part. In the right upper limb, the majority of the median nerve branches (25.7%) began in the arm's distal third part and the majority of median nerve penetration (30.5%) began in the distal half of the forearm's proximal third part. Some anatomic variations were observed.

KEY WORDS: 1. Anatomy; 2. Median nerve; 3. Flexor digitorum superficialis muscle. 

INTRODUCTION

Several types of lesions may affect the action exerted by the Flexor digitorum superficialis muscle. Lesions in the entire brachial plexus are rare but may occur due to the stretching of the plexus, in this case all the muscles of the arm, forearm, hand and fingers, as well as the majority of the muscles of the shoulder become paralyzed and suffer atrophy will loss of sensibility found in the entire limb (Didio, 1974).

As the median nerve supplies the major part of the muscles related to the pronation of the forearm, flexion of the hand and fingers and, opposition of the thumb, if it is lesioned the flexion of the wrist becomes deficient and it is accompanied by the ulnar deviation, one loses the pronation of the forearm that is replaced by the rotation of the arm (Didio, 1998 and Stern, 1997). Classical syndromes of compression of the median nerve are described as syndrome of the pronator and syndrome of the anterior interosseous nerve (Dellon & Mackinnon, 1987).

For the correct treatment of all mentioned lesions, and others, it is required an anatomical knowledge that lists the relation of the nerve's branches with the muscle, although there is also the presence of anatomical variations, but they are rare.

In view of relevance for clinical physicians, orthopedists and physical therapists, not only to help in the diagnosis, but also in the treatment, rehabilitation of the lesions, and mainly in cases of surgical interventions in the region where the nerve's branches are located, we intend with this study to provide anatomical information about the levels of origin and point of penetration of the median nerve's branches for the flexor digitorum superficialis muscle, according to statistical data that have been obtained with dissection of twenty upper limbs, as well as, to observe possible anatomical variations.

MATERIAL AND METHOD

Twenty upper limbs were dissected, for this we used ten corpses fixed with formaldehyde, belonging to the Escola Paulista de Medicina, Universidade Federal de São Paulo, Brazil, where the cause mortis did not effect the structure of the forearms. The corpses were from people aging from twenty six to sixty six years old, two of them were female and eight were male, as to the ethnic nature, two of the corpses were white and eight non-white.

The lengths of the forearms were measured with the help of a common ruler. To achieve this we have taken the articular line of the elbow (determined by the humeroradial and the humero-ulnar joints), and the articular line of the wrist joint as reference.

The limbs that were used had been partially dissected, with skin, subcutaneous tissue, cutaneous nerves and fascia already removed. After the identification of the median nerve, the pronator teres muscle was removed to better visualize the nerve, since this is normally found between the humeral and the ulnar heads of this muscle. The Flexor digitorum superficialis muscle was also removed from the anterior margin of the radio (2/3 proximal) because the median nerve is deeply located under the muscle.

The anterior interosseous nerve was identified in the cubital fossa and dissected in its entire extension until the point in which it innerved the pronator quadratus muscle.The ulnar nerve was identified along the medial tricipital groove of the arm and dissected until the articular line of the wrist.

The nerve's branches have also been measured using a common ruler, having as reference the articular line of the elbow, using to measure the length of the forearms. As topographic reference for the levels of origin and penetration of the nerve's branches in the respective muscle, the forearms were divided up into three thirds: proximal, middle and distal, and in each third we considered a proximal and a distal half. With the data obtained we were able to calculate the following averages: the forearm's length; distance of the points of origin of the nerve's branches; number of origins; distance of the points of penetrations of the nerve's branches; number of points of penetrations and the length of the nerve's branches. It was also observed, the most proximal and distal points of origins and penetrations from the articular line of the elbow and the presence and absence of recurrent branches.

All data were statistically compared through the t test for two samples.

RESULT

The Tables I and II exhibit the data about points of origins and penetration of the nerve's branches that supplying the Flexor digitorum superficialis muscle, these nerve's branches were originated of the median and anterior interosseous nerves. The Tables III and IV exhibit the levels frequencies of the points of origins and penetrations of the median nerve's branches.

In 35% of the cases the anterior interossous nerve supplying the Flexor digitorum superficialis muscle. In our results, we could see that in the left upper limb, the majority of the anterior interosseous nerve's branches (75%) began in the arm's distal third part and the majority of anterior interosseous nerve points penetration (81.25%) began in the proximal half of the forearm's proximal third part. In the right upper limb, the majority of the anterior interosseous branches (75%) began in the arm's distal third part and the majority of anterior interosseous nerve penetration (78.6%) began in the proximal half of the forearm's proximal third part.

The median nerve has in both upper limbs nerve's branches with origin in the articular line of the elbow; the nerve's branches with the most distal origin of the same line in the right and left upper limbs were 17.6 cm and 17.7 cm the average of the points origins were 7.7 cm and 8.0 cm in right and left upper limbs respectively. The nerve's branches with the most proximal point of penetration were located 1.0 cm in a right upper limb and 1.1 cm in a left upper limb to the articular line of the elbow; the most distal point of penetration were 20.0 cm in a right upper limb and 19.4 cm in a left upper limb. The average of the points of penetration were 9.5 cm and 8.0 in a right and left upper limbs.

The anterior interosseous nerve with the most proximal origin of the articular line of the elbow were located 0.5 cm in a right upper limb and 1.5 cm in a left upper limb; the nerve's branches with the most distal origin to the same line in the right and left upper limbs were 4.8 cm and 4.4 cm. The averages of points of origins were 3.3 cm and 2.8 cm in a right and left upper limbs respectively. The nerve's branches with the most proximal point of penetration were located 1.9 cm in a right upper limb and 1.6 cm in a left upper limb to the articular line of the elbow; The most distal point of penetration were 9.1 cm in a right upper limb and 6.2 cm in a left upper limb. The average of the points of penetrations were 3.7 cm and 3.3 cm in a right and left upper limbs respectively.

We found in three cases the ulnar nerve issuing branches for the Flexor digitorum superficialis muscle.

When statistically compared by the t test, the muscles of the left and right forearms didn't presented differences when innerved by the median nerve and anterior interosseous nerve because the Star t (calculated t) was smaller than the bi-caudal critical t.

In all dissections of the branches of both nerves, they penetrated through the posterior face of the muscular belly (Fig. 1).

Table I. Data about the Flexor digitourm superficialis muscle supply by the median nerve.


Right

Minimum

Average

Greatest

S.D.

Forearm's length

19.9

24.06

27.4

2.0

Branch's

0.3

3.9

8.8

1.9

Nº of origins

2

3.5

5

1.1

Nº of penetrations

2

15.1

25

6.9

Left

       

Forearm's length

21.6

23.8

27.4

1.9

Branch's

0.1

4.1

8.9

1.8

Nº of origins

1

3.7

6

1.7

Nº of penetrations

3

17.1

29

9.3

Table II. Data about the Flexor digitourm superficialis muscle supply by the anterior interosseous nerve.


Right

Minimum

Average

Greatest S.D.

Forearm's length

19.9

24.06 27.4 2.0

Branch's

2.9

6.7 10.2 1.9

Nº of origins

0

0.4 1 0.5

Nº of penetrations

0

1.6 9 3.0

Left

       

Forearm's length

21.6

23.8 27.4 1.9

Branch's

3.8 6.6 8.8 1.5

Nº of origins

0

0.4

2 0.7

Nº of penetrations

0

2.8 16 5.2

Table III. Levels frequencies of origins of the median nerve’s branches in the right and left upper limbs.


  Right (%) Left (%)

Arm's distal third part

 25.7 24.3

Proximal half of forearm's proximal third part

22.9

21.7

Distal half of of forearm's proximal third part

8.6

10.8

Proximal half of forearm's medium third part

17.1

10.8

Distal half of forearm's medium third part

22.9

29.7

Proximal half of forearm's distal third part

2.8

2.7

Table IV. Levels frequencies of points penetrations of the median nerve’s branches in the right and left upper limbs.


 

  Right (%) Left (%)
Arm's distal third part  

0.6

Proximal half of forearm's proximal third part

23.2

30.3

Distal half of of forearm's proximal third part

30.5

28

Proximal half of forearm's medium third part

7.2

14.8

Distal half of forearm's medium third part

21.2

14.3

Proximal half of forearm's distal third part

17.9

12

Fig. 1. Origin and point of penetration of the nerves that supply the Flexor digitorum superficialis muscle.

DISCUSSION

In our work we didn't observed any upper limb in which median nerve was located anteriorly to the flexor digitorum superficialis muscle, as related by Sunderland, 1968.

According to Collins & Weber (1983), the anterior interosseous nerve issued motor branches to the flexor digitorum superficialis muscle in 30 % of the studied cases. Our results are very similar, since of the twenty dissected upper limbs, we have found 7 cases in which the anterior interosseous nerve issued branches to the Flexor digitorum superficialis muscle (35%).

We observed further that the ulnar nerve could issue branches to the Flexor digitorum superficialis muscle. Several authors such as, Gray (1985), Goss (1988) and Sabongi & Caetano (1996), have made similar observation. Sabongi & Caetano, reported in their study, that only one (3.3 %) of 30 dissected limbs, presented this type of variation, an incidence, therefore, smaller than that found by us, that was of 15 %.

The communication between the ulnar and anterior interosseous nerves, known as Martin-Gruber anastomosis, found in our study, was classified in different ways by some authors. Nakashima (1993) classified as type Ia; Thomson (1983) as type I, and Hirasawa (1931) as oblique anastomosis. Collins & Weber , as well as Thomson (1983), observed the presence of Martin-Gruber anastomosis in 15 % of the studied cases, being that, 50 % of them were derived from the anterior interosseous nerve. Nakashima, made the dissection of 108 forearms, and observed the presence of communication between the anterior interosseous and ulnar nerves in 12 % of the cases. In our study the incidence of the presence of this type of communication was smaller if compared to the studies effected by said authors, since we have found only 1 forearm with this type of communication (5 %). Nakashima further asserts that communications between the median or anterior interosseous and ulnar nerves are common in the proximal part of the forearm. We agree with this author, since, the communication found in our study originated from the anterior interosseous nerve in the proximal half of the proximal third of the forearm and, converged to the ulnar nerve in the proximal half of the middle third of the forearm. Dangelo & Fattini (1987) affirm that the anterior interosseous nerve is the last issued branche of the median nerve at the forearm. We disagree with this affirmation since we checked that the median nerve issued branches to Flexor digitorum superficialis muscle in the distal and middle thirds of the forearms.

Since in our study we have found the most branches of the anterior interosseous nerve converging to the Flexor digitorum superficialis muscle originating in the arm's distal third with the most penetrations occurring in proximal half of forearm's third part, one may conclude that these data suggest that lesions in the branches of this nerve may occur more often in these parts. However, such assumption leads us to think about the effecting of a future work that allows us to make such assertion in a conclusive way.

Olehnik et al. (1994) did surgery decompression of the median nerve at forearm's proximal region in 39 upper limbs and 30 of them were beneficiated with the procedure, with complete or partial relief of the symptoms. The same authors affirm to unknown the reason why some patients presented an uncompleted relief of the symptoms after surgical decompression of the median nerve at the forearm's proximal region.

As verified in our study, only 30% of the median nerve's origins and penetrations occurred at the forearm's proximal third. The related fact by Olehnik et al. could be justified, although we also couldn't affirm it in a conclusive way.

ACKNOWLEDGMENTS

The authors thank the Department of Morphology, Escola Paulista de Medicina, Universidade Federal de São Paulo, for providing access to the corpses, and Prof. Casemiro Fernando Leite (Universidade Metodista de São Paulo) for statistic analyses.

RESUMEN:Conociendo la distribución de los ramos nerviosos destinados al músculo flexor suprficial de los dedos, sus orígenes y puntos de penetración, facilita el tratamiento de lesiones y, principalmente, otorga auxilio al cirujano durante las intervenciones quirúrgicas, donde estos ramos pueden resultar dañados.

Disecamos los miembros superiores de 10 cadáveres formolizados de individuos adultos. Usamos como referencia para las medidas anatómicas, las interlíneas articulares del codo y radiocarpiana.

Observamos que en el miembro superior izquierdo, el 29,7% de los ramos del nervio mediano se originaban en el tercio medio de la mitad distal del antebrazo y en el 30.3% penetraban en el tercio proximal de la mitad proximal del antebrazo. En el miembro superior derecho, el 25.7% de los ramos del nervio mediano se originaban de la parte distal del brazo y penetraban en el tercio proximal de la mitad distal de antebrazo, en el 30,5%. Fueron observadas algumas variaciones anatómicas. 

PALABRAS CLAVE: 1. Anatomía; 2. Nervio mediano; 3. Músculo flexor superficial de los dedos. 

REFERENCES

Collins, D. N. & Weber, E. R. Anterior interosseous nerve syndrome. South. Med. J., 76:1533-7, 1983.         [ Links ]

Dangelo, J. G. & Fattini, C. A. Anatomia humana sistêmica e segmentar. Atheneu, Rio de Janeiro, 1987.         [ Links ]

Dellon, A. L. & Mackinnon, S. E. Musculoaponeurotic variations along the course of the median nerve in the proximal forearm. J. Hand Surg., 12:359-63, 1987.         [ Links ]

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Hirasawa, K. Untersuchungen über das periphere nervesystem, plexus brachialis und die nerven der oberen estremitäten. Arb Anat Inst Kaiserlichen Univ Kioto., A2:135-7, 1931.         [ Links ]

Nakashima, T. An anatomic study on the Martin-Gruber anastomosis. Surg. Radiol Anat., 15:193-5, 1993.         [ Links ]

Olehnik, W. K.; Manske, P.R. & Szerzinski, J. Median nerve compression in the proximal forearm. J. Hand Surg.,19, 121-6, 1994.         [ Links ]

Sabongi, J. J. N. & Caetano, E. B. Estudo anatômico dos ramos musculares do nervo ulnal no antebraço. Rev. Bras. Ortop., 31:193-8, 1996.         [ Links ]

Stern, J. T. Jr. Core concepts in Anatomy. Lippincott, Philadelphia, 1997.         [ Links ]

Sunderland, S. Nerves and Nerve Injuries. Baltimore, William & Wilkins, 1968.         [ Links ]

Thomson, A. Third annual report of the committee of collective investigation of the anatomical society of Great Britain and Ireland for the year 1891-1892. J. Anat., 27:183-94, 1983.         [ Links ]

Correspondence to:
Dra. Renata Frazão
Departamento de Morfologia
Universidade de Santo Amaro
Rua Professor Enéas de Siqueira Neto, 340,
Jd das Embuias, CEP 04829-300
Santo Amaro
São Paulo - SP
BRASILtel: 55-11-5545-8613.

Email: anatomy@bol.com.br

Recibido : 18-06-2001
Aceptado: 23-07-2002


* Department of Morphology, Universidade de Santo Amaro, Santo Amaro, SP, Brasil.

** Department of Morphology,  Faculdade de Odontologia,  Universidade Estadual Paulista Júlio de Mesquita Filho - UNESP, Brasil.

*** Department of Morphology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil.