Acta anal. IOS: 284-290 (1979)
Electromyographic study of the subclavius muscle Francisco Prado Reis, Armando M . de Camargo, Mathias Vitti and Claudio A.F.de Carvalho Department of Morphology, Federal University of Sergipe, Aracaju, Department of Morphology, University of Campinas, Piracicaba. and Department of Anatomy, University of Sao Paulo, Sao Paulo, Brazil
Key words. Electromyography • Subclavius muscle Abstract. The electromyographic study of the subclavius muscle (SM) was performed in 31 different movements, in 12 subjects ( 10 male and 2 female) aged from 17 to 28 years. The action potentials were obtained with an electromyograph Teca TE 4. Our findings suggest that the SM acts mainly on the stability of the sternoclavicular joint : with more or less intensity according to the degree of the clavicular interaction with the movements of the peripheral parts of the superior limb. The SM seems to act as a substitute for the ligaments of the sternoclavicular joint.
The electromyographic study of the subclavius muscle (SM) in humans has been considered difficult up to now by many authors [Rasch and Burke, 1967; Gardner et al., 1971 ; Basmajian, 1977] mainly because of its almost inaccessible anatomical position. The function of the muscle as the elevator of the first rib is described in textbooks by Cruveilluer el al. [1877], Road [1913], Paluret [1951] and Rouvière [1971], These authors, as well as Duchenne [1949] and Woodburne [1959], also consider it to assist inspiration. The SM serves as a depressor of the clavicle and scapula. It is described by Cruveilhier et al. [1877], Road [1913], Paluret [1951], Valenti [1951], Llorca [1970], Rouvière [1971], Spaltenholz [1975] and Testât and Latarjel [1975], Sappey [1888] and Benninghoffand Goerttler [1975] refer only to its depressor action. Hollinsltead [1959] and Lockhart et a i (1965], admit ting the above action, consider the SM an antagonist of the fibers of the sternocleidomastoideus muscle which extend to the clavicle.
The action of the SM stabilizing and fixing the medial extremity of the clavicle in the sternum is dis cussed by Brans [1954], Last [1959], Rasch and Burke [1967], Liana [1970], Bairati [1971], Chiarugi and Bucciante [1972] and Benninghoff and Goerttler [1975] during the peripheral movements of the superior limb. According to Chiarugi and Bucciante [1972], this would be the main action on the SM which, in this case, would be an active ligament of the sternoclavicular joint, opposing the luxations. In this paper, our purpose is to analyze electromyograpliically the action of the SM in humans since the majority of the authors have analyzed it only from the mechanical point of view.
Material and method 12 normal volunteers, 10 males and 2 females be tween 17 and 28 years of age acted as subjects. The electrode was inserted with the shoulder flexed for ward. In this position, the clavicule was easier to see
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Introduction
285
Electromyographic study of the subclavius muscle
Fig.l. Dissected subclavius mus cle. The X indicates the approxi mate point of insertion of the elec trode.
Results The electromyographic data recorded in all subclavius muscles during the different move ments performed by the subjects are sum-
1 Donated by the 'Fundaçào de Amparo 4 Pesquisa do Estado de Sào Paulo' (FAPESP) Proc. Med. 70/511 and ‘Conselho Nacional de Desenvolvimento Cientí fico e Tecnológico' (CNPq) Proc. 3834/70.
marized in table I. To avoid repetition, no further account of the results is given here; instead, the main ones are incorporated in the discussion below.
Discussion Moderate or very marked activity of the SM occurred in shoulder movements (fig. 2a-e) except in free elevation and extension. We found moderate or marked activity in the movements of adduction and extension (fig. 2f) against resistance of the arm and whpn raising the body by the arms while hanging from a metal bar (fig.2g). During normal inspiration (fig. 2h), the action potentials were slight to moderate and moderate to marked during forced inspiration (fig. 2i). The action potentials of the SM were nil in the movements of abduction, flexing and rota tion of the arm and in the movements to push and pull the body against an obstacle with the superior limb extended in a perpendicular (90 ) and parallel (180°) position in relation to the shoulder joint.
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and to palpate. In the medial point between the cla vicle extremities in the mass of the SM, we placed a coaxial needle electrode. 3.5 cm long at approximately 45° relative to the anterior wall of the thorax directed in an upward position. Dissections demonstrated the feasibility of percutancously implanting electrodes without risk (fig. 1). Action potentials were amplified and recorded on an electromyograph Teca TE 4' belonging to the De partment of Oral Biologia of Campinas University, Piracicaba. The routine calibration was 100-500 /
Electromyographic study of the subclavius muscle Francisco Prado Reis, Armando M . de Camargo, Mathias Vitti and Claudio A.F.de Carvalho Department of Morphology, Federal University of Sergipe, Aracaju, Department of Morphology, University of Campinas, Piracicaba. and Department of Anatomy, University of Sao Paulo, Sao Paulo, Brazil
Key words. Electromyography • Subclavius muscle Abstract. The electromyographic study of the subclavius muscle (SM) was performed in 31 different movements, in 12 subjects ( 10 male and 2 female) aged from 17 to 28 years. The action potentials were obtained with an electromyograph Teca TE 4. Our findings suggest that the SM acts mainly on the stability of the sternoclavicular joint : with more or less intensity according to the degree of the clavicular interaction with the movements of the peripheral parts of the superior limb. The SM seems to act as a substitute for the ligaments of the sternoclavicular joint.
The electromyographic study of the subclavius muscle (SM) in humans has been considered difficult up to now by many authors [Rasch and Burke, 1967; Gardner et al., 1971 ; Basmajian, 1977] mainly because of its almost inaccessible anatomical position. The function of the muscle as the elevator of the first rib is described in textbooks by Cruveilluer el al. [1877], Road [1913], Paluret [1951] and Rouvière [1971], These authors, as well as Duchenne [1949] and Woodburne [1959], also consider it to assist inspiration. The SM serves as a depressor of the clavicle and scapula. It is described by Cruveilhier et al. [1877], Road [1913], Paluret [1951], Valenti [1951], Llorca [1970], Rouvière [1971], Spaltenholz [1975] and Testât and Latarjel [1975], Sappey [1888] and Benninghoffand Goerttler [1975] refer only to its depressor action. Hollinsltead [1959] and Lockhart et a i (1965], admit ting the above action, consider the SM an antagonist of the fibers of the sternocleidomastoideus muscle which extend to the clavicle.
The action of the SM stabilizing and fixing the medial extremity of the clavicle in the sternum is dis cussed by Brans [1954], Last [1959], Rasch and Burke [1967], Liana [1970], Bairati [1971], Chiarugi and Bucciante [1972] and Benninghoff and Goerttler [1975] during the peripheral movements of the superior limb. According to Chiarugi and Bucciante [1972], this would be the main action on the SM which, in this case, would be an active ligament of the sternoclavicular joint, opposing the luxations. In this paper, our purpose is to analyze electromyograpliically the action of the SM in humans since the majority of the authors have analyzed it only from the mechanical point of view.
Material and method 12 normal volunteers, 10 males and 2 females be tween 17 and 28 years of age acted as subjects. The electrode was inserted with the shoulder flexed for ward. In this position, the clavicule was easier to see
Downloaded by: Stockholm University Library 130.237.165.40 - 12/5/2017 10:05:53 AM
Introduction
285
Electromyographic study of the subclavius muscle
Fig.l. Dissected subclavius mus cle. The X indicates the approxi mate point of insertion of the elec trode.
Results The electromyographic data recorded in all subclavius muscles during the different move ments performed by the subjects are sum-
1 Donated by the 'Fundaçào de Amparo 4 Pesquisa do Estado de Sào Paulo' (FAPESP) Proc. Med. 70/511 and ‘Conselho Nacional de Desenvolvimento Cientí fico e Tecnológico' (CNPq) Proc. 3834/70.
marized in table I. To avoid repetition, no further account of the results is given here; instead, the main ones are incorporated in the discussion below.
Discussion Moderate or very marked activity of the SM occurred in shoulder movements (fig. 2a-e) except in free elevation and extension. We found moderate or marked activity in the movements of adduction and extension (fig. 2f) against resistance of the arm and whpn raising the body by the arms while hanging from a metal bar (fig.2g). During normal inspiration (fig. 2h), the action potentials were slight to moderate and moderate to marked during forced inspiration (fig. 2i). The action potentials of the SM were nil in the movements of abduction, flexing and rota tion of the arm and in the movements to push and pull the body against an obstacle with the superior limb extended in a perpendicular (90 ) and parallel (180°) position in relation to the shoulder joint.
Downloaded by: Stockholm University Library 130.237.165.40 - 12/5/2017 10:05:53 AM
and to palpate. In the medial point between the cla vicle extremities in the mass of the SM, we placed a coaxial needle electrode. 3.5 cm long at approximately 45° relative to the anterior wall of the thorax directed in an upward position. Dissections demonstrated the feasibility of percutancously implanting electrodes without risk (fig. 1). Action potentials were amplified and recorded on an electromyograph Teca TE 4' belonging to the De partment of Oral Biologia of Campinas University, Piracicaba. The routine calibration was 100-500 /
