Struthers' ligament is a feature of human anatomy, consisting of a band of connective tissue that runs between the shaft of the upper arm bone, the humerus, and a projection at the same bone's lower end.
It was highlighted by John Struthers, who discussed the feature's evolutionary significance with Charles Darwin. Its incidence was estimated by Struthers at 1%, but more recently has been estimated at 13.5%. Its clinical significance arises from the fact that the median nerve and brachial artery may pass through the "arch" formed by the process and ligament over the humeral body. Within this space the nerve may be compressed leading to supracondylar process syndrome.
Struthers' ligament extends between a bony process that may arise from the shaft of the humerus and extends to the medial epicondyle of the humerus, the entire structure forming an arch. It is not a constant ligament, and can be acquired or congenital. Struthers originally reported that bony process arose at a position 3.2 to 6.4 cm from the medial condyle, being 1.2 to 1.9 cm in length, and nearer to the anterior than the medial border of the humerus. This bony process gives attachment to the eponymous ligament, which spans inferiorly and joining the line above the medial condyle.
The ligament is not always present, and there is some debate as to its prevalence. Struthers originally estimated that it was present in 1% of humans. Subsequently there have been studies that have found incidence up to 13.5%.
The structure was originally depicted by Tiedemann, and later by Knox in the early 19th century, but it was John Struthers was the first to draw attention to this structure in 1848 as a "peculiar process" that bore curious resemblance to anatomy that he had seen in cats. This observation was one of many that Struthers made in subsequent investigations of vestigial and rudimentary structures, and in sharing these observations with his contemporary, Charles Darwin, provided significant evidence for the theories of evolution. Charles Darwin took the ligament to mean that humans and other mammals had a common ancestor, and used Struthers' work as evidence in Chapter 1 of his Descent of Man (1871). Struthers went on to create an museum of Comparative Anatomy filled with zoological specimens to illustrate Darwin's theory of common descent.
- Struthers, John, 1854. "On some points in the abnormal anatomy of the arm".
- Wertsch JJ, Melvin J (December 1982). "Median nerve anatomy and entrapment syndromes: a review". Arch Phys Med Rehabil 63 (12): 623–7. PMID 6756339.
- Bilecenoglu B, Uz A, Karalezli N (April 2005). "Possible anatomic structures causing entrapment neuropathies of the median nerve: an anatomic study". Acta Orthop Belg 71 (2): 169–76. PMID 16152850.
- Nigst H, Dick W (April 1979). "Syndromes of compression of the median nerve in the proximal forearm (pronator teres syndrome; anterior interosseous nerve syndrome)". Arch Orthop Trauma Surg 93 (4): 307–12. doi:10.1007/BF00450231. PMID 464765.
- Kett K, Csere T, Lukács L, Szilágyi K, Illényi L (June 1979). "Histological and autoradiographic changes in locally irradiated lymph nodes (an experimental study on rabbits)". Lymphology 12 (2): 95–100. PMID 491743.
- De Jesus R, Dellon AL (May 2003). "Historic origin of the "Arcade of Struthers"". J Hand Surg Am 28 (3): 528–31. doi:10.1053/jhsu.2003.50071. PMID 12772116. Retrieved 2009-05-22.
- Hommel U, Bellée H, Link M (1989). "[The validity of parameters in neonatal diagnosis and fetal monitoring of breech deliveries. 1. Neonatal status after breech delivery]". Zentralbl Gynakol (in German) 111 (19): 1293–9. PMID 2588859.
- Varlam H, St Antohe D, Chistol RO (September 2005). "[Supracondylar process and supratrochlearforamen of the humerus: a case report and a review of the literature]". Morphologie (in French) 89 (286): 121–5. PMID 16444940.
- Dellon AL, Mackinnon SE (October 1987). "Musculoaponeurotic variations along the course of the median nerve in the proximal forearm". [[J Hand Surg [Br]]] 12 (3): 359–63. doi:10.1016/0266-7681(87)90189-6. PMID 3437205.
- Gunther SF, DiPasquale D, Martin R (1993). "Struthers' ligament and associated median nerve variations in a cadaveric specimen". Yale J Biol Med 66 (3): 203–8. PMC 2588859. PMID 8209556. Retrieved 2009-05-22.
- Sigueira, MG; Martins, RS (2005). "The controversial arcade of Struthers". Surg Neurol (Suppl 1:S1 ed.) 64: 20–21. doi:10.1016/j.surneu.2005.04.017. PMID 15967222.
- ‘‘Tabulae Arteriarum’’, Plate 15, Fig 3, 1822
- Knox. Edinburgh Medical and Surgical Journal, 1841, p.125
- Gorman, Martyn. "The Zoology of Professor Struthers". Charles Darwin and Struthers' ligament. University of Aberdeen. Retrieved 1 October 2012.
- Darwin, Charles R. (1871). The descent of man, and selection in relation to sex. John Murray. p. 28.
- Struthers, John (Feb 2007). "Historical Article: On a peculiarity of the humerus and humeral artery". Journal of Hand Surgery. 1 32E: 54–56.