||Ret`i*nac"u*lum (?), n.; pl.
Retinacula (#). [L., a holdfast, a band. See
Retain.] 1. (Anat.) (a)
A connecting band; a frænum; as, the retinacula of
the ileocæcal and ileocolic valves. (b)
One of the annular ligaments which hold the tendons close to the
bones at the larger joints, as at the wrist and ankle.
2. (Zoöl) One of the retractor
muscles of the proboscis of certain worms.
3. (Bot.) A small gland or process to
which bodies are attached; as, the glandular retinacula to
which the pollinia of orchids are attached, or the hooks which support
the seeds in many acanthaceous plants.