Illustrated Encyclopedia of Human Anatomic Variation: Opus I: Muscular System: Alphabetical Listing of Muscles: S

Supracostalis (Wood)

Ronald A. Bergman, PhD
Adel K. Afifi, MD, MS
Ryosuke Miyauchi, MD
Peer Review Status: Internally Peer Reviewed

Origin

Insertion

Extent of muscle

According to Mori this muscle has a frequency of 5.2% in 2400 sides. Still other slips, e.g., supracostalis posterior (dorsalis) may be placed dorsal to the origin of serratus anterior. They may occur singly or in multiples, bilaterally or unilaterally. They are classed along with the serratus posterior muscles as remnants of the superficial lamellae of the primitive external oblique muscle. Supracostalis posterior is considered to occur in three types according to Eisler (cited by Mori):

1). Located on the dorsal wall of the thorax, its component muscle fibers follow the same direction as the external intercostal muscle. It arises and inserts on ribs, its length determined by whether one or two ribs are skipped.

2). The muscle fibers may arise from ribs as one to three fleshy slips or digitations. The muscle fibers have the same direction as serratus posterior superior (craniomedial direction).

3). The muscle bundles arise from the eighth to tenth ribs and pass in a craniomedial direction. The insertion depends on the degree of development of the muscle bundles. When poorly developed the muscle fibers at the cranial end of the muscle join the fascia over the ribs. When highly developed, the terminal tendon inserts into the fascia of the deep muscles of the trunk (erector spinae). Mori reported 65 cases of supracostalis dorsalis as follows:

Type 1... 19 sides... 3.6%.
Type 2 ... 17 sides ... 3.3%.
Type 3 ... 29 sides ... 5.6%.

Supracostalis Anterior
from Bochdalek, Jr., 1867

Supracostalis Posterior
From Mori, 1964

Varieties of Chest, Neck, and Shoulder Muscles-Sternoscapularis.
modified and redrawn from Wood, 1870.

References

Bochdalek, Jr., -. (1867) Ein anomaler Musculus supracostalis anterior. Arch. Path. Anat. Physiol. Klin. Med. 41:257-258.

Keith, A.M. (1894) Note on supracostalis anterior. J. Anat. Physiol. 27:333-334.

Kurotsu, T. (1932) On the M. supracostalis posterior. Kaibogaku Zasshi 5: 4 42-447. In Japanese.

Livini, F. (1905) Contribuzione alla morfologia des m. rectus abdominis e del m. supra-costalis nell'uomo. Arch. Ital. Anat. Embriol. 4:81-116.

Livini, F. (1905) Contribution à la morphologie du m. rectus abdominis et du m. supracostalus chexz l'homme. Arch. Ital. Biol. 44:116-117.

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. (1976) Four cases of rare supernumerary muscles that were found on the anterior chest wall. Medical Bulletin of Fukuoka University. 3:353-365.

Miyauchi, R. (1986) A case of a rare anomalous muscle of the human anterior thoracic wall. Okajimas Folia Anatomica Japonica 63:331-336.

Mori, M. (1964) Statistics on the musculature of the Japanese. Okajimas Folia Anatomica Japonica 40:195-300.

Mori, M. and M. Nazayoshi. (1938) Two cases of the M. supracostalis anterior. Kyushi Gakuho 2:8-9. In Japanese.

Pye-Smith, -. (1868) Ein zweiter Fall von Musculus supracostalis anterior anomalous. Arch. Path. Anat. Physiol. Klin. Med. 43:142.

Wood, J. (1865) Additional varieties in human myology. Proc. Roy. Soc. Lond. B 14:378-392.

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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