The caudal end of the spinal cord (conus medullaris) is anchored to the inner aspect of the spinal dural sac by which of the following?
a. filum terminale externum
b. filum terminale internum
c. coccygeal ligament
d. denticulate ligament
e. arachnoid trabeculae

Agroup of engineering students from purdue university reported that its licking machine, modeled after a human tongue, took an average of 364 licks to get to the center of a tootsie pop. twenty of the group's volunteers assumed the licking challenge-unassisted by machinery-and averaged 252 licks each to the center.