Cruciate pulleys
Ligamenta cruciformia
Definition
The three cruciform pulleys (C1–C3) are three thin, cross-shaped (X-shaped) fibrous bands that form part of the fibrous flexor sheath of each finger. They are located between the annular pulleys along the palmar surface of the digits.
Locations
The first cruciate pulley (C1) is located between A2 and A3 pulleys, immediately proximal to the PIP joint and attach to the volar aspect of the proximal phalanx.
The second cruciate pulley (C2) is located between A3 and A4 pulleys, immediately distal to the PIP joint.
The third cruciate pulley (C3) is located between A4 and A5 pulleys, immediately proximal to the DIP joint.
Functions
Cruciate pulleys provide flexibility to the fibrous sheath, allowing the sheath to fold and accommodate finger flexion and extension without restricting tendon movement. They help maintain smooth gliding of the flexor tendons while preventing buckling or kinking of the sheath during motion.
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.
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.
