Upper Respiratory Tract PDF

Upper Respiratory Tract Prof. Dr. Nour Erekat Clinical Anatomy by Regions by Richard S. Snell 9th Edition 1  The Respiratory System The respiratory system is divided anatomically into 1. Upper respiratory tract...

Upper Respiratory Tract Prof. Dr. Nour Erekat Clinical Anatomy by Regions by Richard S. Snell 9th Edition 1  The Respiratory System The respiratory system is divided anatomically into 1. Upper respiratory tract – Which includes the nose, nasal cavity, pharynx, and associated structures 2. Lower respiratory tract Which includes the larynx, trachea, bronchi, and lungs 2  The Respiratory System The respiratory system is divided functionally into 1. Conducting portion Functions – Filtering, warming and moistening air – Conducting air into the lungs Components – Nasal cavities, nasopharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles 2. Respiratory portion Function – Area of gaseous interchange Components 3 – Respiratory bronchioles, alveolar ducts and alveoli  The Nose The nose consists of the external nose and the nasal cavity – Both of which are divided by a septum into right and left halves External Nose – It has two elliptical orifices called the nostrils Which are separated from each other by the nasal septum Each has an ala nasi – Which is the rounded and mobile lateral margin It has an osseocartilaginous framework that consists of – Nasal bones, frontal processes of the maxillae, and the nasal part of the frontal bone superiorly – Plates of hyaline cartilage inferiorly – Blood Supply Branches of ophthalmic and maxillary arteries – Which supply the skin of external nose Branches from the facial artery – Which supply skin of the ala and the lower part of the septum – Nerve Supply 1. Infratrochlear and external nasal branches of the ophthalmic nerve (CN V) 2. Infraorbital branch of the maxillary nerve (CN V) 4  Nasal Cavity Nasal cavity – It extends from the nostrils in front to the posterior nasal apertures or choanae behind Where the nose opens into the nasopharynx – It has the nasal vestibule Which is the area of the nasal cavity lying just inside the nostril – It is divided into right and left halves by the nasal septum Which is made up of septal cartilage, vertical plate of the ethmoid, and vomer Which rarely lies in the midline – Walls of each half of the nasal cavity are Floor is made up of – The palatine process of the maxilla and the horizontal plate of the palatine bone Roof is narrow and it is formed – Anteriorly beneath the bridge of the nose by the nasal and frontal bones – In the middle by the cribriform plate of the ethmoid, located beneath the anterior cranial fossa – Posteriorly by the downward sloping body of the sphenoid Lateral Wall – Has three projections of bone called the superior, middle, and inferior nasal conchae » The space below each concha is called a meatus Medial Wall – Is formed by the nasal septum which is formed by » Vertical plate of the ethmoid superiorly » Vomer posteroinferiorly » Septal cartilage anteriorly 5  Nasal Cavity (Cont’d) Mucous Membrane of the Nasal Cavity – The vestibule is lined with modified skin and has coarse hairs – The area above the superior concha is lined with olfactory mucous membrane and contains nerve endings – The lower part of the nasal cavity is lined with respiratory mucous membrane A large plexus of veins in the submucous connective tissue is present in the respiratory region Nerve supply – Olfactory nerves from the olfactory mucous membrane They ascend through the cribriform plate of the ethmoid bone to the olfactory bulbs – Branches of the ophthalmic division (V1) and the maxillary division (V2) of the trigeminal nerve For ordinary sensation Blood supply – Branches of the maxillary artery of the external carotid artery The most important branch is the sphenopalatine artery – Which anastomoses with the septal branch of the superior labial branch of the facial artery in the region of the vestibule – The submucous venous plexus is drained by veins that accompany the arteries Lymph Drainage of the Nasal Cavity – The lymph vessels draining the vestibule end in the submandibular nodes The remainder of the nasal cavity is drained by vessels that pass to the upper deep cervical nodes 6 Paranasal Sinuses 7  The Pharynx Pharynx – Is situated behind the nasal cavities, the mouth, and the larynx – It may be divided into nasal, oral, and laryngeal parts – It is funnel shaped Its upper, wider end lies under the skull Its lower, narrow end becomes continuous with the esophagus – Opposite the sixth cervical vertebra – It has a musculomembranous wall Which is deficient anteriorly – Where it is replaced by the posterior » Openings into the nose (called choanae) » Opening into the mouth » Inlet of the larynx – Its mucous membrane is continuous with that of the tympanic cavity By means of the auditory tube 8  Nasal Pharynx Nasal pharynx – It lies above the soft palate and behind the nasal cavities – The submucosa of its roof has pharyngeal tonsil Which is a collection of lymphoid tissue – Its floor has an opening called pharyngeal isthmus Between the soft palate and the posterior pharyngeal wall – Its lateral wall has the opening of the auditory tube Whose ridge is elevated as the tubal elevation – Which has a depression behind it called pharyngeal recess – It has the salpingopharyngeal fold Which is a vertical fold of mucous membrane covering the salpingopharyngeus muscle 9  Oral Pharynx Oral pharynx – Lies behind the oral cavity – Its floor is formed by the posterior one third of the tongue and the interval between the tongue and epiglottis – It has the median glossoepiglottic fold in the midline Which has a depression on each side called vallecula – It has the lateral glossoepiglottic fold on each side – Its lateral wall has the palatoglossal and the palatopharyngeal arches or folds Which have a recess between them that is occupied by palatine tonsil on each side Palatoglossal arch is a fold of mucous membrane covering the palatoglossus muscle – The interval between the two palatoglossal arches is called the oropharyngeal isthmus » Which marks the boundary between the mouth and pharynx Palatopharyngeal arch is a fold of mucous membrane covering the palatopharyngeus muscle 10  Laryngeal Pharynx Laryngeal pharynx – Lies behind the opening into the larynx – Its lateral wall is formed by the thyroid cartilage and the thyrohyoid membrane – The mucous membrane on each side of its inlet has a depression That is called piriform fossa 11  Muscles of the Pharynx Muscles in the wall of the pharynx consist of – Superior, middle, and inferior constrictor muscles Whose fibers run in a somewhat circular direction They extend around the pharyngeal wall to be inserted into a fibrous band or raphe – That extends from the pharyngeal tubercle on the basilar part of the occipital bone of the skull down to the esophagus They overlap each other so that – The middle constrictor muscle lies on the outside of the lower part of the superior constrictor muscle – The inferior constrictor muscle lies outside the lower part of the middle constrictor muscle The lower part of the inferior constrictor muscle arises from the cricoid cartilage – It is called the cricopharyngeus muscle – Its fibers pass horizontally around the lowest and narrowest part of the pharynx – It acts as a sphincter – It is separated from the upper propulsive part of the inferior constrictor by an area called Killian's dehiscence – Stylopharyngeus, salpingopharyngeus and palatopharynegeus muscles 12 Whose fibers run in a somewhat longitudinal direction Muscles of the Pharynx 13  Nerve and Blood supply and Lymph Drainage of the Pharynx Sensory innervation of the pharyngeal mucous membrane – Maxillary nerve (V2) innervates nasal pharynx – Glossopharyngeal (IX) nerve innervates oral pharynx – Internal laryngeal branch of the vagus (X) nerve innervates laryngeal pharynx Around the entrance into the larynx Blood supply of the pharynx – Ascending pharyngeal arteries – Tonsillar branches of facial arteries – Branches of maxillary and lingual arteries Lymph Drainage of the Pharynx – Directly into the deep cervical lymph nodes OR – Indirectly via the retropharyngeal or paratracheal nodes into the deep cervical nodes 14