The heart existed as a simple pulsating vessel; and the chorda dorsalis took the place of a vertebral column.
But that this vascular change is not the factor determining the lymph-flow is proved by the administration of a small dose of atropine, which arrests the secretion without influencing the vascular reaction following chorda stimulation.
Thus, to take the instance of the submaxillary gland, which at rest does not discharge any lymph, stimulation of the chorda tympani is followed by a flow of lymph accompanying the flow of saliva simultaneously excited.
Running backwards, just below the posterior fold, is the chorda tympani nerve, which may be cut through in the act of paracentesis and in division of the posterior fold.
In doing this the chorda tympani nerve may perhaps also be cut, resulting in loss of taste on the affected side for a time; this is a matter of no importance.
Citharœdus / Ridetur chorda qui semper obberrat eadem=--The harper who is always at fault on the same string is derided.
Ridetur chorda qui semper oberrat eadem=--He is laughed at who is for ever harping away on the same string.
This branch forms the praespiracular nerve of the adult, and is homologous with the chorda tympani of Mammalia.
Fibres connecting the Central Nervous | 443 | System and Chorda in Amphioxus" | | Anat.
Handles for table knives and forks, tools, and other implements have been made from the thick stems of oarweeds, and fishing lines from Chorda filum.
A small form is often found parasitic on Chorda filum, spreading out horizontally like the hairs of a bottle brush.
After the intestinal canal has become separated from the yolk-sac it forms at first a straight tube, running cephalo-caudad beneath the chorda dorsalis.
The entodermal enteric tube is, as already stated, closely attached at an early period along its dorsal surface to the axial rod of mesoderm containing the chorda dorsalis immediately ventrad of the neural canal.
Transverse section of human embryo before development of protovertebrae or chorda dorsalis.
The cranial section of the chorda itself shows no sign of segmentation; but later on the cranial portion of the chorda-sheath ossifies, like the vertebræ, from several centres.
Sometimes the young cells appear to have no nuclei, as in the intracellular brood of chorda cells, but, as a rule, a nucleus is clearly visible.
The analogy indeed in structure and development between chorda and cartilage cells and the cells of plants seemed to him complete.
As regards the vertebræ, Rathke describes them as being formed in the sheath of the chorda from paired rudiments, each of which sends two branches upwards, and two branches downwards.
The chorda (notochord) is prolonged some little way into the head, and the base of the cranium is formed by the expanded sheath, which reaches forward in front of the end of the notochord.
The chorda sheath is the common matrix of the vertebræ and of a large part of the skull.
Defn: A kind of seaweed (Chorda Filum) having blackish cordlike fronds, often many feet long.
The sense of taste is often impaired from involvement of the chorda tympani nerve.
It is accompanied by the chorda tympani branch of the facial, which probably carries the taste fibres.
Beneath the pharynx (d) we see the hypobranchial groove; above it the chorda and neural tube.
In every case the chorda originates from the dorsal wall of the primitive gut; the cells that compose it (Figure 2.
We have previously seen how this very rudimentary beginning of the skull in man is formed ontogenetically from the "head-plates," and thus the fore end of the chorda is enclosed in the base of the skull.
Underneath the axial rod or chorda runs a very simple alimentary canal, a tube that opens on the ventral side of the animal by a mouth in front and anus behind.
There is no trace in the fully-developed Ascidia of a chorda dorsalis, or internal axial skeleton.
Bateson believes he has detected a rudimentary chorda between the two.
They are the only living Vertebrates that have throughout life a chorda dorsalis and a neural string above it; the latter must be regarded as the prolongation of the cerebral ganglion and the equivalent of the medullary tube.
The chorda may have been originally a digestive glandular groove in the dorsal middle line of the primitive gut.
Undoubtedly both the Tunicates and Acrania have inherited the chorda from a common unsegmented stem-form; and these ancient, long-extinct ancestors of all the chordonia are our hypothetical Prochordonia.
This straight, cylindrical rod (somewhat compressed for a time) is the axial rod or the chorda dorsalis; in the lancelet this is the only trace of a vertebral column.
The early stages of the Ascidia possess the beginnings of the spinal marrow and the spinal column (chorda dorsalis) lying beneath it, which are the two most essential and most characteristic organs of the vertebrate animal.
These two groups possess three most important features: (a) A chorda dorsalis, a stiff rod lying in the long axis of the body, dorsally from the gut and below the central nervous system.
In 1829 Baer discovered the human egg, and later the chorda dorsalis.
Under the chorda in the middle is the single aorta, at each side of it a cardinal vein, and below these the primitive kidneys.
The two halves of the vertebrate body that are separated by this horizontal transverse axis and by the chorda have quite different characters.
All these parts develop from a very simple structure, which originally (throughout life in the amphioxus) runs from end to end under the chorda in the shape of a straight cylindrical canal.
The chordula-embryo of all the vertebrates is characterised by the dorsal medullary tube, the neurenteric canal, which passes at the primitive mouth into the alimentary canal, and the axial chorda between the two.
Between the inner borders of the two flat coelom-pouches lies the chorda (Figure 1.
The right and left halves of the head curve over the cerebral vesicle, enclose the foremost part of the chorda below, and thus finally form a simple, soft, membranous capsule about the brain.
Moreover, in the amphioxus the first outline of the chorda appears later than that of the coelom-sacs.
The upper plate presses between the chorda and the medullary tube, the lower between the chorda and the alimentary canal (Figure 1.
Below this the inner and outer edge of the provertebral plate splits on each side into two horizontal plates, of which the upper pushes between the chorda and medullary tube, and the lower between the chorda and gastric tube.
The chorda (ch) has separated from the dorsal middle line of the entoderm; to the right and left of it are the two halves of the mesoderm, or the two coelom-folds.
B In the middle of the germinal disk we find the medullary groove (mr), and underneath it the chorda (ch).
The structure of the chorda also shows the same features in these coelomula-embryos of the amphibia (Figure 1.
Lower down is a little pyramid which transmits the stapedius muscle, and at the base of this is a small opening known as the iter chordae posterius, for the chorda tympani to come through from the facial nerve.
Just in front of the membrane on the outer wall is the Glaserian fissure leading to the glenoid cavity, and close to this is the canal of Huguier for the chorda tympani nerve.
The mucous membrane lining the tympanum is continuous through the Eustachian tube with that of the naso-pharynx, and is reflected on to the ossicles, muscles and chorda tympani nerve.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "chorda" in a variety of sentences. We hope that you will now be able to make sentences using this word.
