It is in the anterior compartment of the forearm. It is sometimes considered to be the deepest part of the superficial layer of this compartment,[2][3] and sometimes considered to be a distinct, "intermediate layer" of this compartment.[4] It is relatively common for the Flexor digitorum superficialis to be missing from the little finger, bilaterally and unilaterally, which can cause problems when diagnosing a little finger injury.[5]
Four long tendons come off this muscle near the wrist and travel through the carpal tunnel formed by the flexor retinaculum. These tendons, along with those of flexor digitorum profundus, are enclosed by a common flexor sheath. The tendons attach to the anterior margins on the bases of the intermediate phalanges of the four fingers. These tendons have a split (Camper's Chiasm) at the end of them through which the tendons of flexor digitorum profundus pass.
Innervation
The Flexor digitorium superficialis muscle is innervated by the median nerve (C7, C8, T1).[7]
To test flexor digitorum superficialis, one finger is flexed at the proximal interphalangeal joint against resistance, while the remaining three fingers are held fully extended (to inactivate flexor digitorum profundus).
Additional images
Tendons of forefinger and vincula tendina.
Cross-section through the middle of the forearm.
Transverse section across the wrist and digits.
The mucous sheaths of the tendons on the front of the wrist and digits.
^Townley, W. A.; Swan, M. C.; Dunn, R. L. R. (June 2010). "J Hand Surg Eur". Journal of Hand Surgery (European Volume). 35 (5): 417–418. doi:10.1177/1753193409358523. PMID20515987.
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