A textbook of obstetrics . ^. Thevisceral clefts close, withthe exception of the first,which eventually formsthe external auditorymeatus, the cavity of thetympanum, and the Eu-stachian tube. The firstvisceral arch, dividinginto two branches, formsthe superior and inferiormaxillary latter, one fromeach side, approach eachother and finally uniteto form the lower superior maxil-lary processes, while ap-proaching each other, are kept from uniting by the interven-tion of the frontal process. At the point of junction of thislast process with the two superior maxillary processes
A textbook of obstetrics . ^. Thevisceral clefts close, withthe exception of the first,which eventually formsthe external auditorymeatus, the cavity of thetympanum, and the Eu-stachian tube. The firstvisceral arch, dividinginto two branches, formsthe superior and inferiormaxillary latter, one fromeach side, approach eachother and finally uniteto form the lower superior maxil-lary processes, while ap-proaching each other, are kept from uniting by the interven-tion of the frontal process. At the point of junction of thislast process with the two superior maxillary processes thereoccurs occasionally the deformity known as harelip, from thefailure of the processes to unite ; but as union is always perfectbefore the end of the second month, the arrest of developmentthat results in this deformity must have taken place at someperiod prior to the third month. During the second month,from the growth of the viscera, the body becomes somewhatstraightened out, and from the development of the brain the. Fig. 67.—Human embryo of about six woolenlarged five times (His). DEVELOPMENT OF THE EMBRYO AND FETUS. 79 head increases in size. The umbilical vesicle atrophies, andmay be found attached to the body by a slender pedicle. Theumbilical ring is somewhat contracted, but still contains a few-loops of intestine ; so that if at this time an arrest in the devel-opment of the abdominal walls should occur, a bad umbilicalhernia or exomphalos might be the result. The umbilical cordruns straight to the periphery of the ovum. The eyes occupy aposition on the side of the head ; behind them may be seen theears, and in front arises the external nose. The limbs are sepa-rated into their three divisions, and the first suggestions of handsand feet appear, with the fingers and toes webbed. The Wolffianbodies are much lessened in size, but the kidneys and suprarenalcapsules are now developed. The external genitals make theirappearance, but neither internally nor externally is
Size: 1383px × 1807px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookidtex, booksubjectobstetrics
