| Lab 10 Respiratory System: 1) Index 2) Introduction 3) Things to Identify 4) Olfactory Epithelium 5)Larynx and Vocal Cords 6) Trachea 7) Lung 8) Practical |
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Larynx
and Vocal Cords
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# 149 - Larynx with vocal cords, monkey, h - e # 155 - Vocal cord, human, h - e |
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The larynx is the sound-producing organ lying between the pharynx and the trachea. The walls are supported by a number of cartilaginous plates interconnected by ligaments and voluntary muscles. Projecting medially from the inner lateral walls are two folds of the mucosa, one pair lying above the other. The upper vestibular folds ("the false vocal cords") are lined with pseudostratified epithelium and have a core of connective tissue and glands. The lower vocal folds ("true vocal cords") are covered by nonkeratinized stratified squamous epithelium and have a core of elastic tissue and skeletal muscle. There are areas of transition between the two types of epithelium that line the two pairs of folds. Slide 149 shows the larynx and vocal cord of a monkey. Note the cartilages that support the walls of this tubular structure. The inverted V-shaped tissue at the periphery is the hyaline cartilage of the thyroid cartilage. Two pieces of cartilage to either side of the triangular central lumen form the arytenoid cartilages. Slide 155 shows the true and false vocal cords of a human. There is a considerable variation in the epithelium of the mucous membrane in both of these areas. Covering the vocal folds is non-keratinized stratified squamous epithelium which protects against abrasion or a strong flow of air. Above and below these structures (e.g., at the false vocal cords above the true cords) pseudostratified ciliated columnar epithelium with many goblet cells can be found. The lamina propria of the mucous membrane is richly supplied with capillaries, venous plexuses, elastic fibers, and lymphatic vessels. Lymphatic nodules may be present. Seromucous glands, skeletal muscle (i.e., the vocalis) and the vocal ligament may be seen. Hyaline cartilage is also visible REFERENCES: : Gartner, pp. 240 - 241, Fig. 4 Ross, pp. 535, 550 - 551 DiFiore, p. 235, Fig. 15-4 |
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This is an image of the transition between the True vocal cords and the False (vestibular) folds. The blue arrow is indicating the point where the transition takes place. You can see that an epithelium change takes place at that point from Psuedostratified Ciliated, from below the arrow that covers the False cords, to the Non-Keratinized Stratified Squamous, located above the arrow coverinig the True Vocal Cords. This epithelium makes functional sense becuase when we phonate or talk, we will cause rubbing of the two vocal cords. If there was no stratified squamous epithelium, we would be causing damage every time we talk. The red arrow is indicating a certain type of tissue, can you guess what kind? This is the skeletal muscle of the vocalis, that plays a role in speech. Red arrow - Vocalis Blue arrow - Transition from False to True Vocal cords.
This is a closer view of the transition point (black arrow) between the True Vocal Cords (yellow arrow) which is non-keratinized stratified squamous and the False Vocal Cords (green arrow) which is psuedostratified ciliated. You can see a better view of the differences in the epithelia in this image. Can you notice that on the left of the black arrow there are no cilia but on the right of it there are (red arrow). This is another way to know you are at the transition. The orange arrows are again showing the muscle fibers of the vocalis (skeletal muscle). Yellow arrow - True Vocal Cords (Non-keratinized stratified squamous) Green Arrow - False Vocal Cords (Psuedostratified Ciliated) Black arrow - Transition Point Red arrow - Cilia Orange arrow - Skeletal Muscle (Vocalis) This is a close up of the Epithelium of the Larynx, which also is the covering of the False Cords. Notice the characteristic Psuedostratified Ciliated appearance. The Cilia (red arrows) serve a function which is to deliver the mucus and debris collected and delivered to them from the lungs to the oral cavity so it can be swallowed. Red arrow - Cilia
RELATED IMAGES:
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Larynx (Vocal Folds and Vocalis muscle)
Larynx (Vocal and Vestibular Folds)
Larynx Epithelium |
