Struthers' ligament

Struthers' ligament is a feature of human anatomy consisting of a band of connective tissue at the medial aspect of the distal humerus. It courses from the supracondylar process of the humerus (also known as avian spur) to the medial humeral epicondyle.[2] It is not a constant ligament,[3][4][5] and can be acquired or congenital. The structure was highlighted by John Struthers, who discussed the feature's evolutionary significance with Charles Darwin. Struthers originally reported that the ligament usually 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.[1]

Diagram showing location of Struthers' ligament
Illustration by John Struthers, 1854:[1]
a) osseous process
b) ligament

The clinical significance of this structure is due to the median nerve and brachial artery which may pass underneath 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.[6][7][8][9] The ligament may also affect the ulnar nerve after an anterior transposition surgery, which is a commonly performed to manage patients with a cubital tunnel syndrome, a form of ulnar nerve entrapment. It is unlikely that the ulnar nerves are affected in patients without transposition surgeries.[10]

Prevalence

The ligament is not always present,[11] and there is some debate as to its prevalence. Struthers originally estimated that it was present in 1% of humans.[2]

Historical significance

The structure was originally depicted by Tiedemann,[12] and later by Knox in the early 19th century,[13] but 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).[14][15] Struthers went on to create a museum of Comparative Anatomy filled with zoological specimens to illustrate Darwin's theory of common descent.[16]

References
  1. Struthers, John, 1854. "On some points in the abnormal anatomy of the arm".
  2. 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.
  3. 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.
  4. 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. doi:10.1016/S1286-0115(05)83248-5. PMID 16444940.
  5. 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.
  6. Wertsch JJ, Melvin J (December 1982). "Median nerve anatomy and entrapment syndromes: a review". Arch Phys Med Rehabil. 63 (12): 623–7. PMID 6756339.
  7. 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.
  8. 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. S2CID 10677076.
  9. 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.
  10. Campbell, William W.; Landau, Mark E. (2008). "Controversial Entrapment Neuropathies". Neurosurgery Clinics of North America. 19 (4): 597–608. doi:10.1016/j.nec.2008.07.001. PMID 19010284.
  11. 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.
  12. ‘‘Tabulae Arteriarum’’, Plate 15, Fig 3, 1822
  13. Knox. Edinburgh Medical and Surgical Journal, 1841, p.125
  14. Gorman, Martyn. "The Zoology of Professor Struthers". Charles Darwin and Struthers' ligament. University of Aberdeen. Archived from the original on 8 September 2014. Retrieved 1 October 2012.
  15. Darwin, Charles R. (1871). The descent of man, and selection in relation to sex. John Murray. p. 28.
  16. Struthers, John (2007). "On a Peculiarity of the Humerus and Humeral Artery". Journal of Hand Surgery (European Volume). 32 (1): 54–56. doi:10.1016/j.jhsb.2006.09.001. PMC 5873049. PMID 17097780.

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