Illustrated Encyclopedia of Human Anatomic Variation: Opus I: Muscular System: Alphabetical Listing of Muscles: S
Ronald A. Bergman, PhD
Adel K. Afifi, MD, MS
Ryosuke Miyauchi, MD
Peer Review Status: Internally Peer Reviewed
Another muscle, the sternoscapularis (chondroscapularis or subclavius posticus) [Rosenmüller]), separate from the subclavius and placed behind it, may be regarded as the deepest derivative of the pectoral sheet. It arises from the first rib cartilage, separate from and at a right angle to subclavius, or from the edge of the presternum. It passes behind and beneath the clavicle and normal subclavius (above or beneath the subclavian vessels and brachial plexus) to attach to the upper or cranial border of the scapula or to the fascia over supraspinatus.
Other variations include the scapuloclavicularis, a small muscle passing from the root of the coracoid process and transverse scapular ligament to the back of the clavicle, and pectoralis intermedius, a fleshy slip that arises from the third and fourth ribs between pectoralis major and minor and is inserted onto the coracoid process. All these muscles belong to the fifth cervical to first thoracic myotomes.
M. scapulocostalis minor (Gruber) arises from the scapular notch and inserts onto the first rib. Macalister found this muscle in 7% of cadavers, Mori in 1% of 250 cadavers, Nishi in 12%, and Eisler found only three examples in his entire career. Scapulocostoclavicularis, a variant of scapuloclavicularis cited above, arises from the upper border of the scapula and inserts partly on the clavicle and partly on the first costal cartilage.
A subclavius muscle, originating usually from the junction of the first rib and its costal cartilage, has been found divided into two slips. The upper slip inserted onto the middle third of the clavicle. The lower slip, after crossing the cords of the brachial plexus and axillary artery, passed deep to coracobrachialis and terminated by fusing with the tendons of latissimus dorsi and teres major in the bicipital groove. It may also terminate at the root of the coracoid process. Mori reported this muscle to be present in 16.8 % of Japanese. In a second type, a lateral extension of subclavius may join the scapula at the root of the coracoid process or extend to the superior margin of the scapula.
Several other muscles associated with the clavicle have been described. M. praeclavicularis originates from the sternoclavicular joint, courses abterior to the clavicle and across the acromion to insert into the skin over the deltoid, or into the anterior part of the middle of the clavicle. M. interclavicularis anticus digastricus has two fleshy bellies joining the two clavicles bilaterally across the manubrium, on which it is inserted by a tendinous intersection covered only by fascia and skin.
M. supraclavicularis runs over the clavicle, arising from its lateral one-third, and /or the coracoclavicular ligament to insert on the medial end of the clavicle and / or the interclavicular ligament.
See also supraclavicularis proprius listed under Trapezius.
Syn.: m. Unterschlüsselbein or Schlüsselbeinmuskel, Sousclavier.
Varieties of sterno-clavicularis muscles.
Left:Suprasternal Ossicles and Interclavicular ligament.
Middle:Note similarity with the right image. The interclavicular ligament is replaced by the musculus sterno-clavicularis. The right and left parts of the muscle are joined by a tendon that arises from the manubrium of the sternum.
Right:A second variety of m. sterno-clavicularis is known as musculus interclavicularis.
After Hyrtl, 1858.
Varieties of Chest, Neck, and Shoulder
modified and redrawn from Wood.
Varieties of Chest, Neck, and Shoulder
modified and redrawn from Wood.
Anderson, R.J. (1880) Über einige Varietäten des M. subclavius. Arch. Path. Anat. Physiol. 81:575.
Bant, A.A. (1924) A propos de la question morphologique des muscles périclavicularies surnuméraires chez l'homme. Soc. Biol., Comptes Rendus Hebdomadiares des Séances et Mémoires. 90:900-902.
Bant, A.A. (1924) Deux cas de muscle acromio-claviculare. Soc. Biol., Comptes Rendus Hebdomadaires des Séances et Mémoires 90:902-903.
Cave, A.J.E. and R.W. Brown. (1952) On the tendon of the subclavius muscle. J. Bone Joint Surg. B 34:466-469.
Crerar, J.W. (1892) Note on the absence of the subclavius muscle. J. Anat. Physiol. 26:554.
Datta, K.N. and S.K. Basu. (1954) An abnormal slip of the left subclavius muscle having an additional nerve supply. J. Anat. Soc. India 3:32.
Gruber, W. (1873) Sur un muscle cleido-hyoidien et sur un muscle supraclaviculaire singulier chez l'homme. Bull. l'Acad. Imp. Sci. de St. Petersbourg 18:154-157.
Gruber, W. (1875) Ein Musculus scapulo-clavicularis. Arch. Path. Anat. Physiol. Klin. Med. 65:18-21.
Gruber, W. (1875) Ein neuer Fall des Musculus tensor semivaginae articulationis humeroscapularis. Arch. Path. Anat. Physiol. Klin. Med. 65:21-23.
Gruber, W. (1878) Ein Musculus praeclavicularis subcutaneous. Arch. Path Anat. Physiol. Klin. Med. 72:496-497.
Gruber, W. (1878) Ein Nachtrag zum Vorkommen des Musculus interclavicularis anticus digastricus. Arch. Path. Anat. Physiol. Klin. Med. 72:497-500.
Gruber, W. (1879) Nachtrage zum Vorkommen des Musculus scapulocostalis minor und neuer Musculus scapulo-costoclavicularis. Arch. Path. Anat. Physiol. Klin. Med. 77:123-128.
LeDouble, -. (1881) Muscle sus-claviculaire tenseur de l'aponévrose cervicale superficielle. Bulletins et Mem. de la Société Anatomique de Paris LVI(7):563-564.
von Luschka, H. (1856) Ein Musculus supraclavicularis beim Menschen. Arch. Anat. Physiol. Wissen. Med. 1856:282-285.
Macalister, A. (1875) Observations on the muscular anomalies in the human anatomy. Third series with a catalogue of the principal muscular variations hitherto published. Trans. Roy. Irish Acad. Sci. 25:1-130.
Miyauchi, R. (1977) A case of the m. subclavius posticus. Medical Bulletin of Fukuoka University 4:429-432.
Moody, R.O. (1893) A note on the occurrence of the scapulo-clavicular muscle. Trans. First Pan-Am. Med. Congress. 1893:1165-1166.
Mori, M. (1964) Statistics on the musculature of the Japanese. Okajimas Fol. Anat. Jap. 40:195-300.
Okinaga, H., Ando, K. and T. Mukai. (1960) One case of the M. subclavius posterior. Kurume Igakkai Zasshi 23:1440-1442. In Japanese.
Roegholt, M.N. (1913) Musculus supraclavicularis proprius. Anat. Anz. 117:474-477.
Roesch, W. (1914) Ein Gefässscheidenmuskel am Halse. Anat. Anz. 46:366-368.
Rutherford, N. (1910) A curious arrangement of the retroclavicular musculature. Anat. Anz. 37:148-150.
Stadler, H. (1930) Uber einen Musculus supraclavicularis proprius. Anat. Anz. 69:284-286.
Takano, T., Izuka, K., and H. Adachi. (1955) One case of the M. subclavius posterior. Iwate Ikadaigaku Kaibogakukyoshitsu Gyosekishu 2:125-126. In Japanese.
Umesue, Y. and M. Oshibuchi. (1942) Three cases of the rare anomaly of the breast muscle (M. supracostalis anterior, M. praeclavicularis and M. pectoralis intermedius). Kaibogaku Zasshi 20:27-34. In Japanese.
Wood, J. (1870) On a group of varieties of the muscles of the human neck, shoulder, and chest, and their transitional forms and homologies in the mammalia. Phil. Trans. R. Soc. (Lond.) 160:83-116.
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