Anular part of fibrous sheath [Digital anular ligament]

In dogs:

The two digital flexor tendons (deep and superficial) on each of the four main digits are held in place by three annular ligaments that are composed by thickening of the palmar palmar and digital fascia. So whereas there are commonly termed and used as "ligaments", there are listed in the NAV in the myology chapter with the fasciae of the thoracic limb:

• The superficial transverse metacarpal ligament [palmar anular ligament]: thickening of fascia of metacarpophalangeal area on palmar surface, transversly oriented, that tuns between the collateral borders of the sesamoid bones.
• The proximal digital annular ligament (Ligamentum anulare digiti proximale): thickening of digital fascia on the proximal phalanx, at approximately its middle.
• The distal digital annular ligament (Ligamentum anulare digiti distale): thickening of digital fascia on the proximal phalanx, immediately distal to the proximal interphalangeal joint (lacking in digit I).