8.2 Respiratory system morphology Flashcards
the paranasal sinuses
include the bilaterally paired frontal, ethmoidal, sphenoidal and maxillary sinuses. Each maxillary sinus is somewhat pyramidal in shape, the base forming the lateral wall of the nasal cavity, the roof forming the floor of the orbit. The ethmoidal sinuses (or air cells) are unlike the others, being three groups (anterior, middle and posterior) of small multiple cavities – they are separated from the medial orbit by a very thin layer of bone, the lamina papyracea
What are paranasal sinuses
air-filled cavity in a dense portion of a skull bone. Each sinus is lined with respiratory mucoperiosteum and drains into the lateral wall of the nasal cavity via small openings.
Conchae and meati of the nose
The lateral walls of the cavity show three elevations, the superior, middle and inferior nasal conchae or turbinate bones. The inferior conchae is a separate bone while the superior and middle are part of the ethmoid bone. The conchae greatly increase the surface area of the nasal cavity and produce turbulence in the air flow during inhalation, warming and humidifying the air as it is drawn over the conchal mucosa.
Conchae and meati of the nose
The lateral walls of the nasal cavity show three elevations, the superior, middle and inferior nasal conchae or turbinate bones. The inferior conchae is a separate bone while the superior and middle are part of the ethmoid bone.
Meati= nasal passages
Role of conchae:
greatly increase the surface area of the nasal cavity and produce turbulence in the air flow during inhalation, warming and humidifying the air as it is drawn over the conchal mucosa.
Airway components of pharynx
three anatomical regions:
1) nasopharynx (from the posterior nasal apertures to the lower border of the soft palate)
2) oropharynx (from the soft palate to the superior boundary of the epiglottis, with an anterior border demarcated by the palatal arches / pillars of the fauces)
3) laryngopharynx (from the superior border of the epiglottis to the cricopharyngeus muscle).
Protection of airway during swallowing.
The transverse and oblique arytenoid muscles close the inlet to the larynx by pulling the arytenoids towards each other, providing a protective sphincteric action during swallowing.
Principles of movements of the vocal cords in phonation.
Regulating tension in the vocal ligaments alters pitch:
Cricothyroid muscles are attached to the lower part of the thyroid cartilage, contraction pulling it forwards and downwards on the cricoid, lengthening and tightening the vocal cords. Thyroarytenoid muscles pull the arytenoid cartilages forward, relaxing the vocal ligaments. The vocalis muscles relax the posterior vocal ligament while generating tension in the anterior part, producing fine adjustments used in speech production.
Innervation of nasal cavity
- The upper parts of the lateral nasal wall and the under surface of the cribriform plate possess olfactory mucosa, the site of olfactory receptor cells of the first cranial nerve (I), the olfactory nerve.
- General sensation provided by the trigeminal nerve (V):
- the anterosuperior part of the cavity is innervated by the ophthalmic division (V1) via the anterior ethmoidal nerve.
- remainder of the nasal cavity innervated by the maxillary division (V2), via nasal branches of the greater palatine nerve.
- Sensory nerves also carry sympathetic vasomotor fibres from the carotid plexus to the vasculature and parasympathetic secretomotor fibres from the pterygopalatine ganglia to the mucosal glands.
Innervation of larynx
laryngeal muscles are innervated by branches of the vagus nerve (CN X).
superior laryngeal nerve: provides external laryngeal nerve which innervates the cricothyroid muscle and internal laryngeal nerve which provides sensation to the mucous membrane of the larynx above the vocal ligaments.
inferior laryngeal nerve: a continuation of the recurrent laryngeal nerve. Innervates all other intrinsic laryngeal muscles (except cricothyroid). Also provides sensation to the larynx below the vocal cords.
Innervation of trachea
pulmonary plexus. Parasympathetic supply originates from the recurrent laryngeal nerves, branches of the vagus nerve.
Movements of tongue
The extrinsic muscles of the tongue:
•genioglossus (attached to the midline of the mandible and hyoid, it protrudes the tongue)
•hyoglossus (which is attached to the hyoid bone and depresses and retracts the tongue)
•styloglossus (which is attached to the styloid process of the temporal bone and stylohyoid ligament and retracts and elevates the tongue)
•palatoglossus (which arises from the palatine aponeurosis of the soft palate and elevates the posterior tongue).
Movements of soft palate
Palatopharyngeus aids in tensing the soft palate.
Movements of pharynx
palatopharyngeus pulls the pharynx superioanterior during swallowing.
Movements of larynx
primary function of the larynx is that of a sphincter to protect the respiratory tract and prevent the entry of foreign bodies into the lower respiratory passages. The secondary function of the larynx is the production of the voice.
Rima glottidis shape changes:
Lateral and posterior cricoarytenoid muscles are attached to the muscular process of the arytenoids and modify the shape of the rima glottidis. The lateral cricoarytenoids close the glottis by rotating the arytenoids medially, bringing their vocal processes together: adduction. They are assisted in closing the glottis by the transverse arytenoid muscles. The posterior cricoarytenoids rotate the arytenoids laterally, abducting the vocal processes and opening the glottis – the only laryngeal muscles that do so.
Temporomandibular joint
When the mouth opens, the mandibular condyles rotate upon the cartilaginous articular disc, which allows them to glide forwards and downwards- because of this, the TMJ permits the mandible to be elevated and depressed as well as protracted (moved forwards), retracted (moved backwards) and moved from side-to-side.
To help stabilise the joint, ligaments attach the mandible to the skull. The lateral ligament is a thickening of the joint capsule attaching the mandible to the zygomatic process of the temporal bone; the stylomandibular ligament connects the styloid process to the posterior ramus and angle of the mandible, preventing excessive anterior protrusion; the sphenomandibular ligament arises from the sphenoid spine to a prominent ridge on the medial surface of the mandible, the lingula.
What is the rima glottidis?
the opening between the true vocal cords and the arytenoid cartilages of the larynx.
Pleura (mesothelium):
- Line pleural cavities
- produces a small amount of pleural fluid that allows pleural layers to slide past each other without producing friction.
- two types: Visceral pleura, which covers the lungs (including fissures) & is continuous with parietal pleura at the hilum (parietal pleura lines the walls of the pleural cavity (cervical, mediastinal, diaphragmatic & costal)).
Airway structure:
Trachea bifurcates into left and right main bronchi. Primary bronchi divide into secondary (or lobar) bronchi
Anatomy of bronchial bifurcation -left right differences. Principles of lobar organization and bronchopulmonary segmentation
the right main bronchus forms three secondary bronchi and the left usually two, correlating with the typical number of lobes in each lung.
Secondary bronchi divide again into tertiary (or segmental) bronchi which serve the bronchopulmonary segments of each lobe.
Left and right differences in relation to inhaled foreign bodies
The right primary bronchus is shorter (dividing before it enters the lung), more vertical and wider than the left and consequently inhaled objects are more likely to enter the right main bronchus.
Structural features of the lungs in relation to gas exchange.
bronchioles, alveolar ducts and definitive alveoli have thin-walled pouches where gas exchange takes place and rich capillary network.
What arteries supply lungs?
Pulmonary arterial supply to gas-exchange tissues.
