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Full text of "Diseases Of The Nose Throat And Ear"

146

THE LARYNX, BRONCHI AND OESOPHAGUS

supply is one of the reasons for different positions of the vocal cord after
neural paralysis. The longer course of the left recurrent laryngeal nerve makes
left-sided lesions commoner than right-sided ones {Fig. 65).

Fig. 64. Nerves and lymphatics of larynx. 1,
Hyothyroid membrane; 2, Small lymphatic
gland over front of cricothyroid membrane,
and lymphatics draining into it; 3, Crico-
tracheal membrane; 4, Recurrent laryngeal
nerve; 5, Lower group of lymphatic glands;
6, Cricothyroid membrane; 7, Bifurcation of
common carotid artery; 8, Group of glands at
bifurcation, with lymphatics draining upper
region of larynx; 9, Superior laryngeal nerve,
with internal (sensory mostly) and external
(motor to cricothyroid) divisions.

Fig. 65. To show the comparative course of the
right and left recurrent laryngeal nerves (back
view). 1, Left recurrent laryngeal; 2, Left
vagus; 3, Left common carotid artery; 4, Left
subclavian artery; 5, Aorta; 6, Left bronchus;
7, Oesophagus; 8, Right bronchus; 9, Inno-
minate artery; 10, Right subclavian artery; 11,
Trachea; 12, Right vagus; 13, Right recurrent
laryngeal.

BLOOD SUPPLY

The larynx above the vocal cords is supplied and drained by the superior
laryngeal_jffi£exy and vein which enter the larynx through the thyrohyoid
membrane. The region below the cords is supplied and drained by the inferior
laryngeal artery and vein—branches of the inferior thyroid artery.

LYMPHATIC DRAINAGE

The vocal cords have, to all intents and purposes, no lymph drainage;
occasionally a small node on the cricothyroid membrane (Fig. 64) is
described, the delphian node, but its involvement in tumour spread is very rare.
The cords thus act as a lymphatic watershed and very effectively divide the
supraglottis from the subglottis, a most important fact in partial laryngectomy.

The supraglottis drains upwards via the superior laryngeal lymphatic
pedicle which pierces the thyrohyoid membrane and ends in the upper deep
cervical chain (Fig. 64).

The subglottis drains to both the prelaryngeal and the paratracheal nodes
and from there lymph drains to the lower deep cervical chain and also to the
mediastinum (Fig. 64).

HISTOLOGY

The larynx is lined by two different types of epithelium—squamous over the
true cord and the upper quarter of the posterior surface of the epiglottis, and