The middle coat usually escapes, but the tunica externa is generally thickened.
The cells which form this layer appear to be derived from a special investment of the notochord, and to have penetrated through the membrana elastica externa to reach their final situation.
Externally is placed the membrana elasticaexterna (mel), while within is the cuticular sheath of the notochord.
In the Amphibia and in the Amniota no membrane is present which can be identified with the membrana elastica externa of the Elasmobranchii, Teleostei, etc.
Between the membrana elastica externa and the sheath of the notochord a layer of cells becomes interposed (fig.
The following muscles have been removed: extensor iliotibialis lateralis, extensor iliotibialis anticus, gastrocnemius pars externa and pars interna, and peroneus longus.
IV and gastrocnemius pars externa and subdivides into two branches, one of which penetrates the medial surface of M.
III; broad sheet of tough connective tissue extending between distal parts of pars externa and pars interna; covering underlying M.
The sheath of the notochord within the membrana elastica externa is formed of a concentrically striated layer, continuous with the innermost layer of the sheath in the vertebral regions.
During the same period, however, the true sheath of the notochord greatly increases in thickness, and the membrana elastica externa becomes more definite.
The whole sheath is still invested by a very distinct membrana elastica externa (m.
In the intervertebral regions the membrana elastica externa is still present in most parts, but has become absorbed at the posterior border of each vertebra, as shewn in longitudinal section in Plate 42, fig.
In the intervertebral regions the membrana elastica externa has become aborted at the posterior border of each vertebra, and the remaining part is considerably puckered transversely.
Thus, curiously enough, the membrana elastica externa and the sheath of the notochord in the intervertebral regions are folded in different directions, the folds of the one being only visible in transverse sections (Plate 42, fig.
The vasa vasorum course in the external coat and send capillaries into the media, supplying the outer portion of the coat and the externa with nutritive material.
Between the media and the externa the elastic tissue is somewhat condensed to form the external elastic membrane.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "externa" in a variety of sentences. We hope that you will now be able to make sentences using this word.
