The lateral surface of each tonsil is usually covered with a fibrous capsule. The anterior
and posterior tonsillar pillars join to form a triangular fossa, with the posterior lateral
aspects of the tongue at its base. The so-called palatine tonsils are lodged in each
fossa. The adenoids (pharyngeal tonsil) are suspended from the roof of the
nasopharynx and consist of an accumulation of lymphoid tissue.
(2) The arteries of the tonsils enter the upper and lower poles. The tonsils
are supplied with blood primarily by the tonsillar branch and the ascending palatine
branch of the facial artery (branches of the external carotid artery). The external carotid
artery on each side lies behind and lateral to each tonsil. The nerves supplying the
tonsils are derived from the middle and posterior palatine branches of the maxillary and
d. The Larynx and Associated Structures.
(a) The larynx is located at the upper end of the respiratory tract and is
situated between the trachea and the root of the tongue, at the upper front part of the
neck. The larynx has three main functions: a passageway for air, a valve for closing off
air passages from the digestive system, and the pharynx, and a voice box on which
sound and speech depend on to a degree.
(b) The larynx is a cartilaginous box, situated in front of the fourth, fifth,
and sixth cervical vertebrae. The upper portion of the larynx is continuous with the
pharynx above, and its lower portion joins the trachea. The skeletal structure provides
for patency of the enclosed airway. The complex muscle action and arrangement of
tissues within the structure provide for closure of the lumen for protection against
trauma and entrance of foreign bodies and for phonation.
(2) Cartilages. The skeletal framework of the larynx consists of cartilages
and membranes. There are nine separate cartilages-- three of them single and six
arranged in pairs. The main cartilages of the larynx include the thyroid, cricoid,
epiglottis, two arytenoid, two corniculate, and two cuneiform. The thyroid cartilage
(Adam's apple) forms the anterior portion of the voice box. The cricoid cartilage, which
resembles a signet ring, rests beneath the thyroid cartilage and within the
laryngotracheal space. The epiglottis is a slightly curled, leaf-shaped, elastic fibrous
membrane. It is prolonged below into a slender process, attached in the midline to the
upper border of the thyroid cartilage. When the cricothyroid muscle contracts, it pulls
the thyroid cartilage and the cricoid cartilage, thereby tightening the vocal cords and, if
unopposed, closing the glottis. The arytenoid cartilages, which rest above the signet
ring portion of the cricoid cartilage, support the posterior portion of the true vocal cords.