Human Tongue Anatomy

Human Tongue AnatomyThe receptive cells for the sensation of taste are arranged in the form of taste-buds which are found chiefly on the tongue, but occur also in the soft palate and neighbourhood. The taste-buds are distributed very irregularly over the tongue, but are most numerous on its upper surface.

They are specially well marked along a A-shaped line near the back of the tongue (Fig. 109), where they are grouped on the sides of papillae; these papillae are designated circumvallate, from the fact that each is surrounded by a little trench and wall.

Taste-buds are small ovoid bodies consisting of hair cells and supporting cells (Figs. 110 and 111). The hair cells form a group in the centre of each bud, the hairlets projecting towards the free surface through a small opening termed the gustatory pore; the supporting cells are arranged around them somewhat like the staves of a barrel.

The terminal filaments of the nerves Gustatory pore and of taste surround the deeper ends of the hair cells. In the anterior two-thirds of the tongue the nerves of taste are the dendrites of cells of the geniculate ganglion - a sensory ganglion on the seventh cerebral nerve. The axons of these ganglion cells run inwards to the medulla and form arborisations around cells of a nucleus at the anterior end of the glossopharyngeal (ix) nucleus.

The pathway is continued from this into the opposite nesial fillet and thence to the cerebral cortex. The nerves of taste for the posterior third of the tongue are dendrites of cells of a ganglion on the glosso-pharyngeal nerve. The axons terminate round the glosso-pharyngeal nucleus whence the pathway of the impulses is continued through the opposite mesial fillet to the cerebral cortex.