Surgical anatomy : a treatise on human anatomy in its application to the practice of medicine and surgery . hen the space is covered by the middle lobe, it is nec-essary either to displace the lobe downward or pass two ligatures around it anddivide it between them. In some instances, however, the width of the middle lobe,or isthmus, is so great that it covers the trachea almost to the sternum. The lowoperation of tracheotomy is performed below the isthmus of the gland. That thisoperation is the more difficult of the two Avill be seen at a glance in the dissectedneck ; this is due to the increa
Surgical anatomy : a treatise on human anatomy in its application to the practice of medicine and surgery . hen the space is covered by the middle lobe, it is nec-essary either to displace the lobe downward or pass two ligatures around it anddivide it between them. In some instances, however, the width of the middle lobe,or isthmus, is so great that it covers the trachea almost to the sternum. The lowoperation of tracheotomy is performed below the isthmus of the gland. That thisoperation is the more difficult of the two Avill be seen at a glance in the dissectedneck ; this is due to the increasing depth of the trachea as it approaches the ster-num, and the presence of the thyroid plexus of veins in fi-ont of this part of thetrachea. An abnormally high position of the large vessels at the root of the neck PLATE CLXXVI, Greater cornu of hyoid bone Lesser cornti of hyoid boneLateral portion of thyro-liyoid membrane Internal laryngeal nSuperior laryngeal a Thyroid cartilage Crico-thyroid membrane Crico-thyroid m i \, Latf:ral lobe of thyroid gland Li. Trachea l|_i Jl_ ^ Isthmus of thyroid gland. Epiglottis Hyoid bone Central portion of thyro-hyoidmembrane nferior constrictorof pharynx Superior thyroid a. Crico-thyroid a. Levator glandulae thyroideaem. Cricoid cartilage \ \ -^ Inferior thyroid veins THYROID BODY,123 DISSECTION OF THE NECK. 125 would add to the difficulty and danger of the low operation. The thyroid glandis closely attached by areolar tissue to the sides of the trachea and the cricoid andthyroid cartilages. During deglutition it rises and falls with the larynx—a factof the utmost value in the differential diagnosis between cervical tumors andenlargement of this gland. It varies in size in different individuals and at differ-ent periods of life, being relatively larger in children and in females. It oftenenlarges during menstruation, owing to increased distention of the blood right lobe is larger than the left. In old age the gland decreases
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectanatomy, bookyear1901
