NURUL FARHANA HANIF C111 11852

Anatomy of respiratory Organ

The upper airway consists of the nose, oral cavity, pharynx, and larynx. The primary functions of the upper airway are ; to act as a conductor of air, to humidify and warm the inspired air, to prevent foreign materials from entering the tracheobronchial tree and to serve as an important area involved in speech and smell

Lower respiratory tract start from trachea, bronchus, bronchioles and last but not least alveoli. According to is function, respiratory tract are also divided into conducting zone and respiratory zone. Conducting zone is a respiratory passages that carry air to the site of gas exchange without involve in exchange of gasses. Conducting zone start from nose all the way until bronchus. While respiratory zone is the most important zone as it acts as site of gas exchange composed of respiratory bronchioles, alveolar ducts and alveolar sac.

Upper respiratory tract

There are three bony protrusions on the lateral walls of the nasal cavity called the superior, middle, and inferior nasal turbinates, or conchae. The turbinates separate inspired gas into several different airstreams. This action, in turn, increases the contact area between the inspired air and the warm, moist surface of the nasal mucosa. The turbinates play a major role in the humidification and warming of inspired air.

Beneath the superior and middle turbinates are the openings of the paranasal sinuses, which are air-filled cavities in the bones of the skull that communicate with the nasal cavity. The paranasal sinuses include the maxillary, frontal, ethmoid, and sphenoid sinuses . The paranasal sinuses produce mucus for the nasal cavity and act as resonating chambers for the production of sound. The receptors for the sense of smell are located in the olfactory region, which is near the superior and middle turbinates .The two nasal passageways between the nares and the nasopharynx are also called the choanae.

Paranasal sinus

The outer portion of the nose is composed of bone and cartilage. The upper third of the nose (the bridge) is formed by the nasal bones and the frontal process of the maxilla. The lower two-thirds consist of the lateral nasal cartilage, the greater alar cartilage, the lesser alar cartilages, the septal cartilage, and some fibrous fatty tissue .

In the internal portion of the nose a partition, the nasal septum, separates the nasal cavity into two approximately equal chambers. Posteriorly, the nasal septum is formed by the perpendicular plate of the ethmoid bone and by the vomer. Anteriorly, the septum is formed by the septal cartilage. The roof of the nasal cavity is formed by the nasal bones, the frontal process of the maxilla, and the cribriform plate of the ethmoid bone. The floor is formed by the palatine process of the maxilla and by the palatine bones, the same bones that form them hard palate of the roof of the mouth. The posterior section of the nasal cavity floor is formed by the superior portion of the soft palate of the oral cavity, which consists of a flexible mass of densely packed collagen fibers .

Air enters the nasal cavity through the two openings formed by the septal cartilage and the alae nasi, called the nares, or nostrils. Initially, the air passes through a slightly dilated area called the vestibule ,which contains hair follicles called vibrissae. The vibrissae function as a filter and are the tracheobronchial tree’s first line of defense. Stratified squamous epithelium (nonciliated) lines the anterior one-third of the nasal cavity.

Vascularization

• R. sphenopalatinus of a. maxillaris

• R. eithmoidalis anterior et posterior of a. ophtalmica

• R. labialis superior of a. facialis

• R. ascendens of a. palatina major

PLEXUS KIESSELBAC

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Pharynx

After the inspired air passes through the nasal cavity, it enters the pharynx. The pharynx is divided into three parts: nasopharynx, oropharynx, and laryngopharynx. Nasopharynx lies between the posterior nares) and the superior portion of the soft palate. The opening of the eustachian tubes (auditory tubes) are located on the lateral surface of the nasopharynx. The eustachian tubes connect the nasopharynx to the middle ears and serve to equalize the pressure in the middle ear. Inflammation and excessive mucus production in the eustachian tubes may disrupt the pressure-equalizing process and impair hearing.

Oropharynx located between the soft palate and the base of the tongue. Two masses of lymphoid tissue are located in the oropharynx: the lingual tonsil, located near the base of the tongue; and the palatine tonsil, located between the palatopharyngeal arch and the palatoglossal arch while laryngopharynx lies between the base of the tongue and the entrance of the esophagus. The epiglottis, the upper part of the larynx, is positioned directly anterior to the laryngopharynx . The aryepiglottic folds are mucous membrane folds that extend around the margins of the larynx from the epiglottis. They function as a sphincter during swallowing.

Larynx

Consists of a framework of nine cartilages. Three are single cartilages: thyroid cartilage (adam’s apple), cricoid cartilage, and the epiglottis. Paired cartilages: arytenoid, corniculate, and cuneiform cartilages. Cartilages of the larynx are held in position by ligaments, membranes, and intrinsic and extrinsic muscles.

Trachea

The adult trachea is about 11 to 13 cm long and 1.5 to 2.5 cm in diameter. It extends vertically from the cricoid cartilage of the larynx to about the level of the second costal cartilage, or fifth thoracic vertebra. At this point, the trachea divides into the right and left main stem bronchi. The bifurcation of the trachea is known as the carina. Approximately 15 to 20 C-shaped cartilages support the trachea.

These cartilages are incomplete posteriorly where the trachea and the esophagus share a fibroelastic membrane . Clinically, the tip of the endotracheal tube should be about 2 cm above the carina. The correct position of the endotracheal tube is verified with a chest radiogram (i.e., the tip of the tube can be seen about 2 cm above the carina). When an endotracheal tube is inserted too deeply (beyond the carina), it most commonly enters the right main stem bronchus. When this occurs, the left lung receives little or no ventilation and alveolar collapse (atelectasis) ensues .When this condition is identified (via chest radiogram or absence of breath sounds over the left lung), the endotracheal tube should be pulled back immediately

Bronchiole and alveoli

End-point of respiratory tree. It is the structures that contain air-exchange chambers are called alveoli. Respiratory bronchioles lead into alveolar. Ducts: walls consist of alveoli. Ducts lead into terminal clusters called alveolar sacs – are microscopic chambers and there are 3 million alveoli.

Respiratory Muscles

Inhalation (inspiration)

1. Diaphragm

2. External intercostal muscles

3. Accessory muscles

- M. sternocleidomastoideus

- M. serratus anterior

- M. pectoralis minor

- M. scalenius

Exhalation (expiration)

1. M. Rectus abdominis

2. M. Obliqus abdominis ext et int

3. M. Tranversus abdominis

4. Internal intercostal muscles

References

• Cardiopulmonary anatomy &physiology, essential for respiratory care, fourth edition. Jardins.T.D

• Slide anatomy of respiratory system, dr. Hasan Nyambe.