No. 9

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No. 9

• 1. Introduction of the Respiratory System
• 2. The nose
• 3. The pharynx
• 4. The larynx

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Chapter 3 The Respiratory System
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Introduction

• In order for the cells of the body to carry on
  their metabolic activities under aerobic
  conditions, they require a constant supply of
  oxygen and an efficient means of removing the
  carbon dioxide that their activities produce.
  Oxygen is supplied and carbon dioxide is removed
  by the respiratory system, with the assistance of
  the circulatory system.

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• The respiratory system also makes vocalization
  possible. We are able to speak, sing, and laugh
  by varying the tension of the vocal folds as
  exhaled air passes over them.
• The exchange of oxygen and carbon dioxide between
  the air and the blood occurs in the lungs. In
  order to reach the exchange sites in the lungs,
  the air must flow through a series of conducting
  passageways that branch from one another much
  like the branches of a tree.

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• Inclusion of the respiratory system
• The respiratory system includes the respiratory
  tract and lungs.
• The respiratory tract consists of the nose,
  pharynx, larynx, trachea and principal bronchi.
• From the clinical point of views, the upper
  respiratory tract is that above the larynx, and
  the trachea, principal bronchi with their
  branches belong to the lower respiratory tract.
• The right and left lungs are the essential
  respiratory organs.

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• Function of respiratory system
• The primary function of the respiratory system is
  to supply the body with oxygen and to get rid of
  excess carbon dioxide resulting from cell
  metabolism.

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Section 1 The Nose

• The nose is not only the first part of
  respiratory tract but also an organ of smell and
  phonation, it includes external nose, nasal
  cavity and paranasal sinuses.

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?. The External Nose

• It consists of bones and cartilages covered with
  skin.
• It has a root, a back, an apex of nose, two alae
  nasi and two nares.

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?. The Nasal Cavity

• It is divided into right and left halves by the
  nasal septum. The right and left nasal cavities
  open in front through nares and communicate with
  the pharynx behind through the choanae.
• Each nasal cavity may be divided into nasal
  vestibule and proper nasal cavity.

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?) The Nasal Vestibule

• The anterior portion of the nasal cavity is
  called the nasal vestibule which is just inside
  the alae nasi and posteriorly limited by the
  limen nasi.
• The nasal vestibule is surrounded by cartilage
  and lined by skin.

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?) The Proper Nasal Cavity

• Constitution and morphology of the proper
  nasal cavity
• Each cavity has a roof, a floor, a medial wall
  and a lateral wall.
• ? The roof is formed by the nasal bone,
  cribriform plate of the ethmoid bone.
• ? The floor is formed by the upper surface of
  the hard palate in front (2/3) and the soft
  palate behind (1/3).
• ? The medial wall is the nasal septum.

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• ? The lateral wall, which are irregular, are
  formed by the superior and middle conchae of the
  ethmoid bone, the separate inferior concha bones.
• Beneath the shelves formed by the conchae are
  recesses called the superior, middle, and
  inferior meatuses.
• Sphenoethmoidal recess above and behind the
  superior nasal concha there is the
  sphenoethmoidal recess.
• The inferior nasal meatus receives the
  termination of the nasolacrimal duct.
• The middle and superior meatuses and
  sphenoethmoidal recess receive the openings of
  paranasal sinuses.

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• The nasal mucous membrane
• It divided into two regions
• Olfactory region The olfactory receptors lie in
  the mucous membrane lining the upper portion of
  the nasal cavity where is called the olfactory
  region.
• Respiratory region The rest of medial and
  lateral nasal wall covered by a thick glandular
  and vascular mucous membrane constitute the
  respiratory region.

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?. The Paranasal Sinuses

• In the bones around the nasal cavity there
  are some air spaces called paranasal sinuses,
  they are
• the frontal sinus,
• maxillary sinus,
• ethmoidal sinus,
• sphenoidal sinus.
• All these sinuses communicate with the nasal
  cavity and are lined by mucous membrane which is
  continuous with that of the nasal cavity. So the
  infection of nasal cavity may spread to the
  paranasal sinuses, resulting in sinusitis.

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Table 1 The paranasal sinuses
Name Location Opening(s)
Frontal Sinuses In the frontal bone The middle nasal meatuses
Maxillary Sinuses In the bodies of the maxilla The middle nasal meatuses
Ethmoidal Sinuses Within the ethmoid bone Anterior group Middle group Posterior group The middle nasal meatuses The middle nasal meatuses The superior nasal meatuses
Sphenoidal Sinuses Within the body sphenoid bone Sphenoethmoidal recesses
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Section 2 The Pharynx

• The pharynx is the common channel for both
  alimentary system and respiratory system, the
  food and air pathways cross each other in pharynx.

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Section 3 The Larynx

• The larynx is a part of respiratory passage as
  well as the organ of phonation.
• It lies in the neck region in front of the
  fourth, fifth and sixth cervical vertebrae.
• The larynx consists of a framework of cartilages
  that are connected together by ligaments,
  membranes and joints. It also has a number of
  small muscles which move the cartilages.
• The larynx is lined with mucous membrane which is
  continuous with that of pharynx above and that of
  trachea below.

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?. The Laryngeal Cartilages

• The larynx is formed by nine cartilagesthree
  unpaired and three paired.
• These cartilages are held together, and attached
  to the hyoid bone above and the trachea below, by
  ligaments and muscles.

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?) The Thyroid Cartilage

• It is the largest of the unpaired cartilages. It
  is formed by the midline junction of two broad
  plates anteriorly, producing the laryngeal
  prominence. The plates remain separated
  posteriorly, which leaves a wide opening in the
  laryngopharynx.

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?) The Cricoid Cartilage

• Just below the thyroid cartilage is the
  ring-shaped cricoid cartilage. It is composed of
  a lamina of cricoid cartilage behind, a narrow
  arch of cricoid cartilage in front.

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?) The Arytenoid Cartilages

• Each arytenoid cartilages is shaped like a small
  pyramid and rests on the superior-posterior
  border of the cricoid cartilage. They articulate
  with the superoposterior border of the cricoid
  cartilage.
• The base sends a vocal process forward for
  attachment of the vocal ligament and a muscular
  process laterally for muscular attachment.

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?) The Epiglottic Cartilage

• The epiglottic cartilage is the leaf-shaped
  epiglottic cartilage. This cartilage covered by
  mucous membrane and forms the epiglottis.
• The epiglottis is attached by its narrow end to
  the inner surface of the anterior region of the
  thyroid cartilage its free upper portion
  projects like a flap behind the base of the
  tongue.

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?. The Laryngeal Joints

• ?) The Cricothyroid Joint
• Composition
• Inferior cornu of the thyroid cartilage,
• The larteral surface of cricoid cartilage.
• Movements
• It allows rotation of thyroid cartilage around
  the coronal axis, so that the length and the
  tenseness of the vocal fold can be changed.

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• ?) The Cricoarytenoid Joint
• Composition
• The lamina of cricoid cartilage,
• The base of the arytenoid cartilage.
• Movements
• When the arytenoids cartilage glide and rotate on
  the cricoid, apposition and abduction of vocal
  folds occur.

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?. The Laryngeal Ligaments and Membranes

• ?) The Thyrohyoid Membrane
• ?) The Conus Elasticus
• It extends upward from the cricoid cartilage to
  the arytenoid cartilages and the posterior
  surface of the thyroid cartilage.
• Its superior border is free and forms the vocal
  ligament which extends from the posterior surface
  of thyroid to the vocal process of arytenoid
  cartilage.
• ?) The Quadrangular Membranes

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?. The Muscles of Larynx

• They are skeletal muscle.
• They serve to open and close the glottis and
  regulate the tension of the vocal fold.

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?. The Laryngeal Cavity

• ?) Morphology of lateral wall of the laryngeal
  cavity
• 1. Vestibular folds and vocal folds
• The mucous membrane near the entrance to the
  larynx forms two pairs of horizontal folds that
  extend on each side from the thyroid cartilages
  to the arytenoid cartilages.
• The upper pair of folds are called the
  ventricular folds (false vocal cords). The lower
  pair are the vocal folds (true vocal cords).
• The vestibular folds extend anteroposteriorly on
  either side of the larynx and enclose between
  them a slit, the rima vestibuli.

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• The vocal folds are two folds of mucous membrane
  which are closely bound to the underlying vocal
  ligament.
• The slit between the two vocal folds through
  which air enters the larynx is the fissure of
  glottis.
• The glottis consists of the vocal folds and the
  slit between them.
• Air passing through the glottis causes the vocal
  folds to vibrate and produce a sound. The
  frequency of the vibrations, and therefore the
  pitch of the sound produced, depends upon the
  tension of the vocal folds.

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• Division of the laryngeal cavity
• The laryngeal cavity is divided into three
  parts
• The laryngeal vestibule extends from the aperture
  of larynx to the vestibular folds
• The intermedial cavity of larynx, the narrowest
  portion between the level of rima vestibuli and
  the fissure of glottis. The ventricles of larynx
  are the lateral expansions of the laryngeal
  cavity between the vestibular and the vocal
  folds.
• The Infraglottic cavity lies below the vocal
  folds and extending downward to the lower border
  of the cricoid cartilage.

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