Anatomical Description of the Presence and Variability of the Digital Manica Flexoria in the Equine Digital Flexor Tendon Sheath.
Authors: Jordana, Cornillie, Oosterlinck, Simoens, Pille, Martens
Journal: Anatomia, histologia, embryologia
Summary
# Editorial Summary The digital manica flexoria—a bridge-like structure within the digital flexor tendon sheath—has been poorly characterised in the equine literature despite being routinely encountered during tenoscopy. Jordana and colleagues dissected 144 cadaveric equine limbs to systematically document the presence, morphology and anatomical variation of this structure across fore- and hindlimbs. They found the digital manica flexoria present in all specimens, but with striking differences between limbs: in forelimbs, a membranous synovial bridge predominated (83% of cases), whereas in hindlimbs a tendinous configuration with oblique-crossing bundles was most common (61%), and passage dorsal to the structure—critical for complete endoscopic examination—was only achievable in 22 specimens, all forelimbs. Given these substantial intra- and inter-individual variations, practitioners using ultrasound or tenoscopy to investigate distal digital flexor tendon sheath pathology should recognise normal anatomical variants to avoid false-positive interpretations; the consistent presence of this structure, particularly its variable tendinous form in the hindlimb, may also have implications for understanding how force is distributed through the flexor apparatus during loading.
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Practical Takeaways
- •Expect consistent anatomical variation in the digital manica flexoria between forelimbs and hindlimbs—forelimbs are more likely to have membranous structures while hindlimbs have tendinous structures; this knowledge improves interpretation of ultrasound and endoscopic findings
- •During tenoscopy of the distal DFTS, recognize that dorsal passage around the digital manica flexoria is rarely possible (only ~15% of limbs), so plan endoscopic approach and expectations accordingly
- •Avoid misinterpreting the digital manica flexoria as pathological tissue during diagnostic imaging; understanding normal anatomical variation is critical for accurate diagnosis of true DFTS pathology
Key Findings
- •Digital manica flexoria was present in all 144 cadaveric equine feet examined, but with significant anatomical variation between forelimbs and hindlimbs
- •Forelimbs predominantly featured membranous digital manica flexoria (94%), particularly the synovial bridge type (83%)
- •Hindlimbs predominantly featured tendinous digital manica flexoria (93%), particularly oblique-crossing of tendinous bundles (61%)
- •Dorsal passage toward distal DFTS was only possible in 22 of 144 limbs (all forelimbs, 15%), limiting endoscopic access in most cases