Identifier: handbookofphysio00bake (find matches)
Title: Hand-book of physiology
Year: 1892 (1890s)
Authors: Baker, W. Morrant, (William Morrant), 1839-1896 Harris, Vincent Dormer Kirkes, William Senhouse, 1823-1864. Hand-book of physiology. 13th ed
Subjects: Physiology Human physiology
Publisher: London : John Murray
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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tail. (Foster and Balfour.) inferior maxillary divisions supply the maxillary and mandibulararches respectively. The facial nerve distributes one branch (chorda tympani) to thefirst visceral arch, and others to the second visceral arch. Thusit divides, enclosing the first visceral cleft. Similarly, the glosso-pharyngeal divides to enclose the secondvisceral cleft, its lingual branch being distributed, to the second,and its pharyngeal branch to the third arch. The vagus, too,, sends a branch (pharyngeal) along the third CH. XIX.J THE VASCULAR SYSTEM. 819 arch, and in fishes it gives off paired branches, which divide toenclose several successive branchial clefts. The Extremities. The extremities are developed in an uniform manner in allvertebrate animals. They appear in the form of leaf-like elevationsfrom the parieties of the trunk (see fig. 488), at points wheremore or less of an arch will be produced for them within. Theprimitive form of the extremity is nearly the same in all verte-
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Fig. 488.—A human embryo of the fourth week, 3! lines in length.—1, the chorion ; 3, partof the amnion ; 4, umbilical vesicle with its long pedicle passing into the abdomen; 7,the heart; 8, the liver; 9, the visceral arch destined to form the lower jaw, beneathwhich are two other visceral arches separated by the branchial clefts ; 10, rudiment ofthe upper extremity; n, that of the lower extremity; 12, the umbilical cord; 15,the eye ; 16, the ear; 17, cerebral hemispheres; 18, optic lobes, corpora quadrigemina.(Midler.) brata, whether it be destined for swimming, crawling, walking, orflying. In the human foetus the fingers are at first united, as ifwebbed for swimming; but this is to be regarded not so much asan approximation to the form of aquatic animals, as the primitiveform of the hand, the individual parts of which subsequentlybecome more completely isolated. The fore-limb always appears before the hind-limb, and forsome time continues in a more advanced state of development.I

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