Okajimas Folia Anat. Jpn., 67 (2-3): 161-164, August, 1990

The Rhomboideus Capitis in Man- Correctly Named Rare Muscular Variation

By

Karol M ROGAWSKI

Department of General Anatomy, School of Dentistry, University of the Witwatersrand, 1 Jan Smuts Avenue, Johannesburg, 2001, South Africa.

-Received for Publication, April 30, 1989-

Key words: Rhomboideus Capitis, Muscular Variation

Summary: This is the third original report on the rhomboideus capitis muscle in man, as far as the author is aware. In the earlier descriptions, the muscle was named as the occipito-scapularis and the rhomboideus-occipitalis or capitis. The muscle was situated on the left side of the neck as a muscular band attached cranially to the occipital bone and caudally to the scapula and was closely related to the splenius capitis and the levator scapulae . A revision of previous descriptions and a brief comparative note on the rhomboideus muscle is given.

The muscular system in man is subject to irregu- capitis was presented by Patten (1935). Its origin was larities producing diverse variations. Such variations, at the superior nuchal line deep to the lateral part of solitary or associated with diversities in other systems, the attachment of the trapezius. The muscle was in- attracted attention of anatomists in the past (Wood serted on the scapula between the attachments of the 1866, 1867, Macalister 1871), especially comparative rhomboideus minor muscle inferiorly, and the levator anatomists discussing the question of the position of scapulae muscle superiorly, with two additional slips man in the animal kingdom. Various descriptions given into the fascia of the serratus posterior superior muscle. by them represent great value as in the recent decades The author named the muscle the rhomboideus- of this century the subject of muscular variations occipitalis or capitis. seldom appearin the anatomical literature and occa- No other original descriptions of the rhomboideus sionally some variations not mentioned in the modern capitis muscle have been found by the author except textbooks of human anatomy are still encountered in short notes on variation of the rhomboideus muscle in prosected cadavers. some textbooks of human anatomy (Quain 1892, The rhomboideus capitis muscle, found by chance Kopsch 1911, Schaeffer 1953, Bochenek and Reicher on a human cadaver, is the subject of the present paper. 1958) most probably based on these two reports . The muscle as described for the first time by Wood (1867) was present in the neck as an accessory slip which Materials and Methods passed from the occipital bone to the scapula. It was attached to the occipital bone level with the splenius The muscle was found unilaterally during a prosec- capitis, directly under the line of attachment of the tion of a human cadaver. The photograph (Fig trapezius. Passing downwards and outwards, superficial . 1) shows the muscle which was identified as the thorn- to and obliquely across the splenius capitis and covered boideus capitis. by the trapezius, it was inserted by short tendinous fibres posterior and superficial to the insertions of the rhomboideus minor and major muscles into the medial Observations border of the scapula at the level of the scapular spine. Wood named this muscle the occipito-scapularis. The muscle described clearly presented as a separate A second original description of the rhomboideus entity. In this case the rhomboideus capitis muscle , in

Correspondence: Dr Karol NI, Rog'iwski, Division of Urology, Department of Surgery, Medical .Schoo1,1'nk ersity of the Wit‘‘ at ersrand , York Road, l'ituktown, 2193, South Africa.

161 162 K. M. Rogawski

Fig. 1. Left posterior aspect of the neck.

the form of a muscular slip approximately 150 mm A third head of the biceps brachii muscle, absence long, 6 mm wide and 2 mm thick, was situated of the plantaris muscle and the insertion of the tertius into the distal phalanx of the fifth digit were other posteriorly on the left side of the neck and lay super- ficial to the splenius capitis muscle. It originated from muscular variations noted on the ipsilateral side of the the superior nuchal line, lateral to the attachment of cadaver. the trapezius and descended on the splenius capitis muscle. It then coursed along the medial edge of the Discussion levator scapulae and inserted on to the medial margin of the scapula opposite the base of the scapular spine. It seems that the muscle described has only been No slips of insertions to the neighbouring muscles were reported twice before and it was named occipito- observed. The nerve supply to the muscle could not be scapularis by Wood (1867) and rhomboideus-occipitalis identified. The Rhomboideus Capitis in Man — Correctly Named Rare Muscular Variation 163 or capitis by Patten (1935). Their descriptions vary in minor details and correspond to an example of the References muscle found by the author. 1) Ashton, E.H., Oxnard, C.E.: The musculature of the primate The rhomboideus muscle consists of three parts shoulder. Transactions of the Zoological Society of London, thoracis, cervicis and capitis in many mammals such vol. 29: part 7, 589-592, 1963. as pigs, cats and dogs (Ellenberger and Baum 1932, 2) Balli, Ashton, E.H., Oxnard, C.E.: The musculature of the Nickel, Schummer and Seiferie 1977). The rhomboideus primate shoulder. Transactions of the Zoological Society of London, vol. 29: part 7, 589-592, 1906, 1963. capitis muscle fans out from the other two parts of the 3) Bochenek, A., Reicher, M.: Anatomia czlowieka, torn 2, 40, muscle to be attached at the level of the superior nuchal Warszawa, PZWL, 1958. line. 4) Ellenberger, W., Baum, H.: Handbuch der Vergleichenden A similar pattern of the rhomboideus muscle has Anatomie der Hausterie, 227, Berlin, v. Julius Springer, 1932. been found in primates by Ashton and Oxnard (1963) 5) Kopsch, F.: Rauber's Lehrbuch der Anatomie des Menschen, Muskeln, 27. Leipzig, von George Thieme, 1911. in their extensively detailed comparative study of 6) Macalister, A.: Additional observations on muscular anomalies muscles responsible for stabilizing the shoulder girdle. of human anatomy. Transactions of the Royal Irish Academy, The authors emphasize the occurrence of considerable vol. XXV: 18-20, 1871. varieties in the rhomboideus muscle in four locomotor 7) Schaeffer Moriss 'Human Anatomy', edited by J. Parsons, 444. London, McGraw-Hill Book Company, 1953. groups of primates although no correlation between 8) Nickel, R., Schummer, A., Seiferie, E.: Lehrbuch der them was noted. Surprisingly, the authors do not men- Anatomie Hausterie, 371. Berlin & Hamburg, Paul Parey, tion the presence of the rhomboideus capitis in man and 1977. according to them, in a study of 100 human cadavers 9) Patten, C.J.: Proceedings of the Anatomical Society of Great performed by Balli (1906), the occipital head of the Britain and Ireland. Journal of Anatomy, vol. LXIX: 147, 1935. rhomboideus was not found. 0) Quain, J.: Quain's Elements of Anatomy, vol. II, part II, 207, London, Longmans, Green & Co, 1982. It is suggested that the incidence of the rhomboideus 1) Wood, J.: On human muscular variations and their relation capitis muscle in man is very rare. to comparative anatomy. Journal of Anatomy, vol. I: 44-59, 1886. 2) Wood, J.: Variations in human myology observed during the Acknowledgements winter session of 1866-67 at King's College , London. Pro- ceedings of the Royal Society of London, vol. XV: 518-552, I wish to thank Drs. B. Kramer and C. Reid, 1867. lecturers at the Department of General Anatomy, School of Dentistry, University of the Witwatersrand, for their encouragement and advice during preparation of this paper.