claustrum

(klaw's trum) [L. barrier.] One of several anatomical structures bearing a fancied resemblance to a barrier; specifically a thin vertically placed lamina of gray matter lying close to the outer portion (putamen) of the lenticular nucleus, from which it is separated by the external capsule, c. gutt'uris, c. o'ris, velum palatinum. c. virgin a'le, hymen.