Fifth annular pulley
Ligamentum anulare quintum
Definition
The fifth annular pulley (A5) is a small fibrous band located over the distal interphalangeal (DIP) joint. It attaches to the palmar plate of the DIP joint and forms the terminal part of the fibrous flexor sheath that encloses the flexor digitorum profundus (FDP) tendon.
The A5 pulley helps maintain the FDP tendon’s alignment as it inserts onto the distal phalanx, prevents bowstringing, and contributes to smooth flexion of the fingertip.
Please click here for detailed description of the annular pulleys and the annular part of fibrous sheath of digit of hand.
References
Hauger, O., Chung, C.B., Lektrakul, N., Botte, M.J., Trudell, D., Boutin, R.D. and Resnick, D., 2000. Pulley system in the fingers: normal anatomy and simulated lesions in cadavers at MR imaging, CT, and US with and without contrast material distention of the tendon sheath. Radiology, 217(1), pp.201-212.
Bianchi, S., Martinoli, C., De Gautard, R. and Gaignot, C., 2007. Ultrasound of the digital flexor system: normal and pathological findings. Journal of Ultrasound, 10(2), pp.85-92.
Makkouk, A.H., Oetgen, M.E., Swigart, C.R. and Dodds, S.D., 2008. Trigger finger: etiology, evaluation, and treatment. Current reviews in musculoskeletal medicine, 1(2), pp.92-96.
Petchprapa CN, Vaswani D. MRI of the Fingers: An Update. AJR Am J Roentgenol. 2019 Sep;213(3):534-548. doi: 10.2214/AJR.19.21217. Epub 2019 Jul 3. PMID: 31268729.
Gupta P, Lenchik L, Wuertzer SD, Pacholke DA. High-resolution 3-T MRI of the fingers: review of anatomy and common tendon and ligament injuries. AJR Am J Roentgenol. 2015 Mar;204(3):W314-23. doi: 10.2214/AJR.14.12776. PMID: 25714317.
Clavero JA, Alomar X, Monill JM, Esplugas M, Golanó P, Mendoza M, Salvador A. MR imaging of ligament and tendon injuries of the fingers. Radiographics. 2002 Mar-Apr;22(2):237-56. doi: 10.1148/radiographics.22.2.g02mr11237. PMID: 11896215.
