. Cunningham's Text-book of anatomy. Anatomy. 1350 THE DUCTLESS GLANDS. Parathyreoid III. is normally drawn by the thymus as it migrates caudal to parathyreoid IV. As a rule it halts at the level of the inferior extremity of the lateral lobe of the thyreoid gland, but may continue its descent into the thorax or may not descend at all. In the latter case it remains near the bifurcation of the common carotid artery, where it is apt to be confused with the <dandula carotica. It is from this confusion that the idea, that tbe chromaphil glandula carotica arises from the third pharyngeal pouch, h
. Cunningham's Text-book of anatomy. Anatomy. 1350 THE DUCTLESS GLANDS. Parathyreoid III. is normally drawn by the thymus as it migrates caudal to parathyreoid IV. As a rule it halts at the level of the inferior extremity of the lateral lobe of the thyreoid gland, but may continue its descent into the thorax or may not descend at all. In the latter case it remains near the bifurcation of the common carotid artery, where it is apt to be confused with the <dandula carotica. It is from this confusion that the idea, that tbe chromaphil glandula carotica arises from the third pharyngeal pouch, has obtained a foothold in anatomical teaching. (iii.) Thymus. Strictly, there are two thymus glands, a right and a left, but they are so closely bound to one another that it is customary to speak of them as a unit, Sternohyoid muscle Sterno-thyreoid muscle — Sterno-mastoid muscle Thyreoid gland Internal jugular vein M J-^rt" Phrenic nerve Scalenus anterior Subclavian artery (left) Left vagus nerve Subclavian vein (left) Recurrent nerve Inferior thyreoid vein Bight vagus nerve Bifurcation of inno- minate artery Bight subclavian vessels Internal mammary artery If Bight lobe of X-iifsh THYMUS Bight inno- minate vein Common cai-otid artery Left innominate vein. Oh/it Left lobe of THVMUS Basal lobe of right lung SMlL Pulmonary fissure Pericardium Fig. 1060.—Dissection to show the Thymus Gland in an Adult Female. the thymus. This is an irregular pinkish mass of glandular tissue placed in the lower part of the neck and in the superior and anterior mediastina. Its size varies, relatively and absolutely, with age, sex, and nutrition, being relatively largest in infancy, absolutely largest at puberty; larger in females and the well nourished than in males and the emaciated; large in healthy adults accidentally killed; small in persons, even children, who have died of a slow wasting disease. It is supposed that it undergoes a premature permanent involution as the result of severe
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1914
