perimysium

from WordNet (r) 3.0 (2006)

perimysium
    n 1: the sheath of connective tissue that covers a bundle of
         muscle fibers

from The Collaborative International Dictionary of English v.0.48

Perimysium \Per`i*my"si*um\, n. [NL., fr. Gr. peri` about + my^s
   muscle.] (Anat.)
   The connective tissue sheath which surrounds a muscle, and
   sends partitions inwards between the bundles of muscular
   fibers.
   [1913 Webster]