Medicine and Health related Information

Derivatives of Skeletal Elements of Arches

a) The cartilage of 1st arch is called ” THE MECKELS CARTILAGE”. The INCUS and MALLEUS of the middle ear are derived from the dorsal end. The ventral part of the cartilage is surrounded by the developing mandible and is absorbed. The part of the cartilage extending from the region of the middle ear to [...]

Continue reading...

Fate of Endodermal Pouches

The endodermal pouches take part in the formation of several important organs:- 1) FIRST POUCH:- Its ventral part is obliterated by the formation of the tongue. Its dorsal part receives a contribution from the dorsal part of second pouch and these together form a diverticulum that grows towards the region of developing ear. This diverticulum [...]

Continue reading...

Fate of Ectodermal Clefts

After the formation of pharyngheal arches the region of the neck is marked on outside by series of grooves or ectodermal clefts. 1) The dorsal part of 1st cleft develops into epithelial lining of the external auditory meatus. 2) The pinna is formed from a series of swellings, which arise on the 1st and 2nd [...]

Continue reading...

Pharyngeal arches or Bronchial arches or Gill arches

These are mesodermal bars of arches which develop in the region of the pharynx. Since in lower animals they form the respiratory organs they are called as BRONCHIAL or GILL ARCHES. Initially there are six pair of arches, later the 5th pair disappears. Each arch has an outer ectodermal covering, inner endodermal and in the [...]

Continue reading...