LARYNX, CLINICAL ANATOMY OF LARYNX AND DIAPHRAGM

THE MYSTERY OF SOUND (TMS)

                                                                                    May 18th 2017 seminar material

THEME: VOCAL ANATOMY

TOPIC: LARYNX, CLINICAL ANATOMY OF LARYNX AND DIAPHRAGM

INSTRUCTOR: Dr. Ukiri  Prosper

INTRODUCTION

First, the larnyx is an organ in the neck  that is composed of cartilages and muscles all adapted for the passage of air. It is also known as the voice box because of its role in speech production.

The larynx is an organ made up of nine cartilages (6 different types, 3 of which are paired while 3 are unpaired).  It is also known as the voice box because of its role in sound production. It is located in the anterior aspect of the neck at the level of the 3^rd to 6^th cervical vertebrae(c3-c6).

COMPONENTS

It is composed of 6 cartilages, 3 are paired and 3 are unpaired.

These are:

1.     Thyroid cartilage(unpaired)

2.     Cricoid Cartilage(unpaired)

3.     Epiglottis(unpaired)

4.     Arytenoid(paired)

5.     Corniculate(paired)

6.     Cuneiforms(paired)

It is also made up of muscles and surrounding ligaments. Some of these muscles form the structures we refer to as the vocal cords (already extensively discussed)

STRUCTURE

It is composed mainly of cartilages but also supported by muscles and ligaments.

These cartilages are:

1. Thyroid cartilage- the largest cartilage of the larynx. It forms the protrusion, the laryngeal prominence, which is more pronounced in males the Adam’s Apple.

2. The Cricoid cartilage which lies at the upper part of the trachea.

The larynx can be seen as a resonating chamber. The pharynx is just above the larynx.

Suffice me to add that at the upper part of the larynx, the pharynx divides into the airway and the oesophagus or gullet.

Thereafter, the larynx forms the first part of the airway.

3. The third cartilage, the epiglottis is unpaired like the first two mentioned above. It forms a flap that covers the airway against entry of food and other substances.

4. The arytenoid, cuneiform and the corniculate are the paired cartilages and they are found at the back of the larynx

THE NINE CARTILAGES

2 Ary+ 2 Cun+ 2Corni+ 1 Thyr+ 1Cric + 1 Epigl= 9 cartilages of the larynx.

MUSCLES OF THE LARYNX

The muscles of the pharynx are divided into two categories;

1. The intrinsic and

2. The extrinsic laryngeal muscles

The intrinsic muscles have their origin and insertion(termination) still in the larynx. These muscles are primarily involved in the production of sounds. They directly affect the length and tension of the vocal cords, and therefore function to regulate the intensity and frequency of sounds

These include:

1. The cricothyroid muscle

2. Posterior and lateral cricoarytenoid muscles

3. Transverse and oblique arytenoid muscles.

4. Thyroarytenoid muscles.

You can rightly tell their site of origin to their site of insertion from their names.

The extrinsic muscles have only one attachment to the larynx and the other attachment at another site outside the larynx. These include but not limited to;

1. Digastric

2. Mylohyoid

3. Inferior pharyngeal constrictors

4. Stylohyoid

5. Mylohyoid

6. Hyoglossus

7. Geniohyoid, etc

BLOOD SUPPLY

It is supplied by the ascending pharyngeal arteries, superior and inferior thyroid arteries, branches of the external carotid arteries.

NERVE SUPPLY

All the intrinsic muscles are innervated by the inferior laryngeal nerve, except the cricothyroid, which is innervated by the superior laryngeal nerve.

The extrinsic muscles are innervated by the glossopharyngeal nerve, recurrent branch of the vagus nerve and the hyopglossal nerve.

CLINICAL IMPORTANCE

1.     Inflammation of the larnyx: This may be as result of disease causing organism as in sore throat and common cold, or excessive straining of the muscles of the larynx.

2.     Lesion of the nerve supply to the larynx, results in loss or reduced speech coordination.

3.     Lesion of the brain areas responsible for speech and sound coordination. This can lead to a medical condition called aphasia, where speech is difficult

References

Moore Clinically Oriented Anatomy, 7th ed- Moore et al
Atlas of Human Anatomy, 6th ed- Frank H. Netter, MD
Langman’s Medical Embryology, 12th ed- T.W Sadler


TMS Contact: themysteryofsound1@gmail.com          
Elmond Isaiah
08067370005