Ch 24: the tongue

4.5 weeks

when in utero does the tongue begin to form?

intrinsic muscles, extrinsic muscles

what are the 2 groupings of tongue muscles?

stratified squamous epithelium

what is the tongue covered with?

circumvallate (vallte), fungiform, filiform, foliate

what are the 4 types of papillae?

circumvallate papillae

v-shaped row; divides posterior 1/3 and anterior 2/3; under microscope they rest in troughs; many taste buds around lateral surface; small salivary glands lie beneath papilae wash them clean

fungiform papillae

anterior 2/3; tiny, red, round, raised spots; taste bud in these papillae; only on upper portion of tongue

filiform papillae

remainder anterior 2/3; slender, threadlike pointed projections; no taste buds; tactile sensation; epithelia on these papillae may grow very long; if lost the surface becomes very smooth

foliate papillae

posterior 1/3 and on lateral surface; few taste buds, not well developed; hard to see this area with folds of tissue (oral cancer can begin here)

lingual tonsils

region near the midline on the dorsum, just behind circumvallate papillae at the base of tongue

lymphoid tissue

provides defense mechanism for infection; similar to palatine tonsil