Anatomy of the larynx

The Larynx
Anatomy of the larynx
*cartilages

The larynx is an integral part of the respiratory system and is the organ of voice production .The larynx consists of a cartilaginous framework bound together by ligaments and covered muscle and mucous membrane. The cartilage of the larynx is either unpaired or paired cartilage.
Unpaired cartilages:
1.Thyroid cartilage
2.Cricoid cartilage
Paired cartilages:
1.Arytenoid car.
2.Corniculate car.
3.Cuniform
Laryngeal Muscles:
Are of 2 types:
Intrinsic muscle of larynx:?
?Abducors(opens):
It is one muscle (posterior cricoarytenoid muscle)paired muscle
? Adductors(closes)
?Lateral cricoarytenoid muscle,paired also.
?? interarytenoid muscle which is unpaired
?Muscle adjust the tension of vocal cord
? Thyroarytenoid muscle with its specialized free edge portion,vocalis muscle ? Muscle adjust the length of vocal cord ? Cricothyroid muscle (the only intrinsic muscle which lies on the out side)
Extrinsic muscle of larynx: ?
?Strap muscle of the neck
?Sternothyroid muscle
??Sternohyoid muscle
???Thyrohyoid muscle
*Nerve supply:
All above muscle are supplied by recurrent laryngeal nerve except cricothyroid muscle which is supplied by external laryngeal nerve which is branch of superior laryngeal nerve.
Recurrent laryngeal nerve is branch of vagus that has different courses on each side.
In the left side it passes under the aortic arch and ascend in the tacheo-oesophageal groove, entering the larynx underneath the inferior constrictor muscle.
Right recurrent laryngeal nerve is shorter than the left looping around the subclavian artery , because of its long intrathoracic course,the left recurrent laryngeal is more likely to be involved in cases of bronchogenic carcinoma
The recurrent laryngeal nerve is sensory to the mucosa below the vocal cord .while the internal laryngeal nerve is sensory to the mucosa of the larynx above the vocal cords.
*Blood supply:
The larynx above the vocal cords is supplied and drained by the superior laryngeal artery 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 inferior thyroid artery.
*Lymphatic drainage:
The vocal cords have no lymph drainage, the supraglottis drains upwards via the superior laryngeal lymphatic pedicle which ends in the upper deep cervical chain.
The subglottics drain to both the prelaryngeal and paratracheal nodes and also directly to the lower deep cervical chain and the mediastinum.
**Histology:
The larynx is lined by two different types of epithelium: squamous over the true vocal cords and the upper quarter of posterior surface of epiglottis and columnar ciliated over the rest of the larynx which commonly undergoes squamous metaplasia in response to air pollution and smoking.

Functions of the larynx
?Phonation
Vocal cords act as vibrator
?Protection of respiratory tract by:
?Laryngeal elevation
??Epiglottis
???Sensory nerve supply(cough)
????Vocal cords