1.04-1.05 for quizlet

The Nose

External Nose

The external nose consists of a bony and cartilaginous skeleton, which is covered by skin and a mucous membrane. This structure plays an important role in the first stage of respiration.Functions:

  • Entry Point for Air: It acts as the primary way for air to enter the respiratory system.

  • Filtration: The nose filters out large particles from the air, such as dust and pollen, preventing them from entering the lungs.

  • Humidification: The mucous membrane within the nose moistens the air, facilitating gas exchange and protecting the sensitive tissues of the respiratory tract.

  • Warming: The rich blood supply warms inspired air to body temperature, making it less of a shock to the lungs.

Structure:

  • Root: The area between the eyes is known as the nasal root, anchoring the external structure.

  • Bridge: The bony section of the nose, which provides support.

  • Dorsum: The outer surface from the bridge to the tip of the nose.

  • Apex: The tip of the nose, which is more flexible due to the cartilaginous framework.

  • Nostrils (Nares): The openings to the nasal cavity, allowing air to pass through.

  • Alae: The lateral parts that define the external contours of the nose.

Support Structures:

  • Nasal Bones: These are the bony upper parts that form the skeleton of the nose.

  • Cartilage Types:

    • Lateral Nasal Cartilage: Provides structure to the sides of the nose.

    • Alar Cartilage: Forms the curve of the nostrils.

    • Septal Cartilage: The cartilage that divides the two sides of the nasal cavity.

  • Muscles:

    • Nasalis: This muscle compresses the nostrils.

    • Depressor Septi Nasi: This muscle pulls the nasal septum downward, helping to flare the nostrils.

Blood Supply:

  • External Carotid Artery: Divides into several branches that supply the nose.

    • Facial Artery: Supplies blood to the nasal alae.

    • Maxillary Artery: Provides blood to the deeper structures of the nose.

  • Internal Carotid Artery: Supplies internal structures of the nasal cavity.

    • Ophthalmic Artery: Supplies the anterior sections of the nasal cavity.

Innervation:

  • Sensory Innervation:

    • Ophthalmic Nerve (CN V1): Supplies sensation to the external nose.

    • Maxillary Nerve (CN V2): Innervates the lower part of the nose.

  • Motor Innervation: Supplied by the facial nerve (CN VII), enabling the muscles of facial expression related to the nose.

Nasal Cavity (Internal Nose)

Structure:The nasal cavity is divided into two symmetrical halves by the nasal septum.

  • Interior Features:

    • Nasal Vestibule: Lined with skin and hair follicles, this area helps trap larger particles before they enter deeper into the nasal passages.

    • Nasal Septum: Composed of the vomer bone, the perpendicular plate of the ethmoid bone, and septal cartilage, it provides separation between the two sides of the nasal cavity.

    • Lateral Nasal Wall: Contains the nasal conchae (turbinates) that enhance airflow and increase the surface area for warming and humidifying air.

Functions:

  • Air Conduction: Serves as the channel from nasal cavity to the nasopharynx.

  • Filtration: Mucous layers capture debris, preventing them from proceeding to the lungs.

  • Humidification: The mucosal lining protects lower respiratory pathways.

  • Temperature Regulation: The rich blood vascularization heats the incoming air.

Paranasal Sinuses

Function:These are air-filled spaces in the skull bones that communicate with the nasal cavity. Their functions include reducing skull weight, enhancing voice resonance, and playing a role in warming and humidifying air.

  • Frontal Sinuses: Located above the eyes and drains through the frontonasal duct.

  • Maxillary Sinuses: The largest sinus, draining into the middle meatus of the nasal cavity.

  • Ethmoidal Sinuses: Situated between the eyes, these sinuses drain into the nasal cavity.

  • Sphenoidal Sinuses: Located deep within the skull, these drain into the sphenoethmoidal recess.

Sinus Drainage and Obstruction:Drainage occurs through small openings into the nasal cavity, and blockage can lead to significant clinical issues such as sinusitis.

The Pharynx and Larynx

The pharynx and larynx are two important structures in the upper respiratory system that play distinct roles in respiration and voice production.

Pharynx

Anatomy:The pharynx is a muscular tube that extends from the base of the skull to the esophagus, dividing into three sections: nasopharynx, oropharynx, and laryngopharynx.

  • Nasopharynx: Located above the soft palate, it connects the nasal cavity to the oropharynx and is lined with respiratory mucosa.

  • Oropharynx: It is situated between the soft palate and the epiglottis and serves as a passage for air and food; it contains the palatine tonsils.

  • Laryngopharynx: The lowest part of the pharynx, leading to the esophagus and the larynx, and is involved in both respiratory and digestive functions.

Functions:

  • Air Conduction: Transports air from the nose and mouth to the larynx and subsequently to the trachea.

  • Food and Liquid Passage: The oropharynx and laryngopharynx allow food and liquids to pass from the mouth to the esophagus.

  • Immune Defense: The presence of lymphoid tissues like the palatine and pharyngeal tonsils helps to protect against infections.

Larynx

Anatomy:The larynx is a cartilaginous structure located just below the pharynx and connects to the trachea. It consists of several cartilages, including the thyroid, cricoid, arytenoid, and epiglottic cartilages, and contains the vocal cords.

  • Thyroid Cartilage: The largest cartilage, commonly known as the Adam's apple, provides a protective shield for the vocal cords.

  • Epiglottis: A flap-like structure that covers the larynx during swallowing, preventing food from entering the airway.

Functions:

  • Voice Production: The vocal cords open and close to produce sound when air passes through them, allowing for speech.

  • Airway Protection: During swallowing, the larynx elevates, and the epiglottis closes over the glottis to block food from entering the trachea.

  • Cough Reflex: The larynx helps initiate the cough reflex to expel irritants from the airway.

The Nasopharynx

Structure:This is the upper part of the pharynx, with boundaries including the base of the skull superiorly and the vertebral column posteriorly.

  • Pharyngeal Tonsils: These are part of the immune defense system.

  • Eustachian Tube: Connects the nasopharynx to the middle ear, equalizing pressure.

Functions:

  • Air Conduction: Passes air to the trachea for further respiratory processes.

  • Mucus Drainage: Facilitates drainage from the middle ear, helping to equalize pressure and maintain ear health.

Clinical Relevance:Issues may arise such as adenoid hypertrophy leading to airway obstruction, or dysfunction of the Eustachian tube causing middle ear infections.

Clinical Notes

  • Epistaxis: Common nosebleeds can occur, especially in the Kiesselbach's plexus area.

  • Rhinorrhea: Involves excess mucus production, often occurring during allergic reactions or infections.

  • Sinusitis: Inflammation affects the lining of the sinuses, potentially leading to acute or chronic conditions.

  • Deviated Nasal Septum: Displacement of the nasal septum can cause airway obstruction, leading to breathing difficulties.

General Overview of the Thorax

Boundaries:

  • Superior: Thoracic inlet

  • Inferior: Diaphragm

  • Anterior: Sternum and costal cartilages

Regions:

  • Right and Left Pleural Cavities: Surround each lung, crucial for respiratory function.

  • Mediastinum: Contains vital structures such as the esophagus, trachea, and heart.

Thoracic Wall Structure:

  • Bones:

    • Ribs: 12 pairs of ribs with subdivisions:

      • True ribs (1-7): Attach directly to the sternum.

      • False ribs (8-10): Attach indirectly through cartilage.

      • Floating ribs (11-12): Do not attach to the sternum, providing protection but also flexibility.

    • Sternum: Comprises three parts: manubrium, body, and xiphoid process.

    • Thoracic Vertebrae: Provide structural support and flexibility.

Muscles:

  • Intercostal Muscles: Positioned between the ribs, these muscles assist in changing thoracic volume during breathing:

    • External Intercostal Muscles: Elevate ribs during inhalation, aiding lung expansion.

    • Internal Intercostal Muscles: Depress ribs during exhalation, facilitating the expulsion of air.

  • Diaphragm: The primary muscle of respiration, it is a double-domed musculotendinous partition.

    • Innervation: Controlled by the phrenic nerve (C3-C5), it increases thoracic volume during inspiration and plays a role in venous return due to pressure changes.

Pleura and Lungs Structure:

  • Pleura: Consists of two layers:

    • Parietal Pleura: Lines the thoracic cavity.

    • Visceral Pleura: Envelops the lung surface.

  • Pleural cavity: Contains serous fluid, reducing friction during respiration.

  • Lung Lobes:

    • Right Lung: Comprised of three lobes.

    • Left Lung: Consists of two lobes, notable for the cardiac notch for heart accommodation.

Mediastinum Regions:

  • Superior Mediastinum: Houses the trachea and esophagus.

  • Middle Mediastinum: Contains the heart, a critical organ for circulation.

  • Posterior Mediastinum: Contains the esophagus and descending aorta, essential for digestive and circulatory systems.

Neurovascular Structures:

  • Main Nerves:

    • Vagus Nerve (X): Provides parasympathetic innervation to thoracic organs.

    • Phrenic Nerve: Essential for diaphragm innervation, critical for breathing.

Clinical Relevance:

  • Pneumothorax: The presence of air in the pleural cavity can lead to lung collapse.

  • Pleural Effusion: Excess fluid accumulation in the pleural cavity affects lung function and can lead to respiratory complications.

  • Lung Cancer: Often originates from lung parenchyma and poses serious health threats requiring immediate attention and intervention.