Respiratory Tract Anatomy

• The lecture is about the anatomy of the respiratory tract

Objectives of the Lecture

• Introduction and functions of the respiratory tract
• Structural and functional divisions of the respiratory tract
• Innervation of the respiratory tract
• Structure and functions of the nose, pharynx, larynx, trachea, and their divisions

Parts of Upper Respiratory Tract

• Frontal sinus
• Superior, middle, inferior nasal conchae
• Sphenoidal sinus
• Nasopharynx
• Oropharynx
• Laryngopharynx
• Tongue
• Epiglottis
• Trachea
• Esophagus

Nose - Parts

• External Nose: Pyramidal in shape with parts including the apex (tip), root, and dorsum
• Nostrils/Nares: Pair of piriform apertures
• Nasal Cavity:
  • Medial wall of the nasal cavity is made by the nasal septum
  • Medially, there is the nasal septum
  • Laterally, there is the ala of the nose

Blood Supply and Innervation of the Nose

• Arteries: Dorsal nasal branch (ophthalmic), infraorbital (maxillary), alar, and septal (facial)
• Sensory Innervation: External nasal, infratrochlear (opthalmic), and infraorbital (maxillary)
• Motor Innervation: Facial nerve branches

Nasal Cavity

• Divided into 2 halves by the median nasal septum
• Asymmetrical, with elevations and depressions representing the lateral wall
• Extends from the nostrils to the choanae
• Vestibule: The part of the nasal cavity close to the nostrils
  • Lined by skin with hairs and sebaceous glands

Nasal Cavity - Extent and Division

• External nares are anterior and the posterior nasal aperture (choanae) is posterior
• Nasal septum consists of both bony and cartilaginous parts
• Anteriorly, the nasal septum is made up of nasal cartilage
• Posteriorly, the nasal septum is bone which is vomer

Nasal Cavity - Halves

• Subdivided into two halves
• Each half has a roof, floor, medial wall, and lateral wall
• The roof is made of a hard pallet and the ethmoid bone
• The floor is formed by the hard pallet (anteriorly) and the soft pellet (posteriorly)
• The medial wall is the nasal septum
• Each half measures:
  • 5cm in height
  • 5-7cm in length from slope to slope
  • 1.5cm width near the floor
  • 1-2mm near the roof

Nasal Cavity - Roof

• Anterior slope consists of the nasal bone and nasal catilage
• Posterior consists of the inferior surface of the sphenoid bone
• Ethmoid : cribriform plate

Nasal Cavity - Roof

• 7cm long
• 2mm wide
• Slopes downwards both in front and behind
• Middle horizontal part: cribriform plate of ethmoid
• Anterior slope forms from the nasal part of frontal bone, nasal bone, and nasal cartilages
• Posterior slope forms from the inferior surface of the body of sphenoid

Nasal Cavity - Floor

• 5cm long and 1.5cm wide
• Floor is made of anterior hard pallat and posterior hard packet
• Formed by the palatine process of the maxilla and the horizontal plate of the palatine bone
• Concave from side to side

Nasal Septum (Medial Wall)

• Median osseocartilaginous partition between the two halves of the nasal cavity
• Covered by mucous membrane on each side and forms the medial wall of both nasal cavities
• Consists of bony and cartilaginous parts

Bony Nasal Septum

• Formation includes the perpendicular plate of the ethmoid and the vomer

Cartilaginous Nasal Septum

• Includes the septal cartilage and inferior nasal cartilage (which one can touch)

Cuticular Nasal Septum

• Includes the fibro-fatty tissue and skin lining the anterior part
• The columella, lined by skin, contains sebaceous glands and the vomero-nasal organ of Jacobson

Nasal Septum - Arterial Supply

• The blood drains into the medial wall
• Bleeds Heavily: because 80 many arteries and anastomosing
• Includes the Kiesselbach’s plexus

Venous Drainage

• Accompany by olfactory nerves into inferior cerebral veins
• Superior: Superior ophthalmic vein
• Mobile part of the septum : Facial vein to IJV (dangerous area of face), dental ligures can spread from tooth
• Postero- inferior: Pterygoid venous plexus (surrounds mandible) one of the peripusal

Nasal Septum: Venous Drainage

• Includes the Kiesselbach's plexus
• This drains into the Facial vein which drains into the sphenopalatine vein which drains into the pterygoid venous plexus

Nasal Septum - Nerve Supply

• Only supplied by Olfactory nerves
• Long Sphenopalatine
• Short Sphenopalatine and Greater palatine N. (Pterygo palatine ganglion & Maxillary N)

Nasal Septum: Sensory Nerve Supply

• Involves special sensory and general sensory

Lateral Wall

• Subdivided into 3 parts: vestibule, atrium, and concha
• A small depressed area in the anterior part called the vestibule where hair folicules are located
• Vestibule is lined by modified skin containing short, stiff, curved hairs called vibrissae and contain sweat and sebaceous glands
• Middle part is the atrium of middle meatus
• Posterior part contains the concha: elevations
• Spaces separating the concha called Meatuses: depressions

Lateral Wall of Nose

• Agger nasi: mucous ridge
• Atrium
• Of middle meatus
• Limen nasi: mucocutaneous ridge
• Vestibule

Nasal Conchae (Turbinate Bones)

• Inferior Concha is a separate bone that extends horizontally backwards
• Ends 1.25cm in front of the pharyngeal opening of the auditory tube
• Anteriorly continuous as the vestibule
• Space under the inferior concha is the inferior meatus
  • This is the termination of the naso lacrimal duct
• Sinos open into inferior meatus

Middle Concha

• Middle meatus is under middle concha
• This is a bony bulging of the middle meatus , receives opening of middle ethamoidal air sinuses
• Anterior ethmoidal + frontal sinus sinuses open here
• A short passage at anterior end of the hiatus

Superior Concha

• Shortest concha
• Superior meatus- Posterior ethamoidal sinus opens
• Superior meatus is b/w superior concha & roof of nasal cavity
• Sphenoethamoidal recess is the depression above &behind the superior concha
• Sphenoidal air sinuses opens

Nasal Passage

• Inferior meatus drains the nasolacrimal duct
• Middle meatus drains the frontal sinus, maxillary sinus, anterior ethmoidal cells, middle ethmoidal cells
• Superior meatus drains posterior ethmoidal cells
• Sphenoethmoidal Recess drains Sphenoidal sinus

Lateral Wall of Nose - Arterial Supply

• Involves the Anterior ethmoidal, Posterior ethmoidal, Facial, and sphenopalatine

Lateral Wall of Nose - Nerve Supply

• Anterior ethmoidal : ophthalmic
• Anterior superior alveolar: maxillary
• Posterior superior lateral nasal: Pterygopalatine ganglion (maxillary nerve)
• Anterior palatine: Pterygopalatine ganglion (maxillary nerve)

Olfactory Nerve Supply

• Olfactory nerve is the special sensory nerve for the lateral wall of the nose

Applied Anatomy - Spread of Infection

• Middle cranial fossa via the cribriform plate (infection can go from uge skull)
• Lacrimal apparatus causes Nasolacrimal duct

Applied Anatomy

• Septal deviation of septum any side causes congestion
• Septal deviations corrected by sub mucosal resection of the nasal septum
• Epistaxis - bleeding from the nose, can lead to increase of intracranial pressure
• In older people it is important to go to the hospital for epistaxis
• Dangerous area of the nose infection to the cranial cavity via the olfactory nerves
• Broken nose - nasal fractures that typically occur over the bridge of the nose or in the septum, which is the area that divides your nostrils.

Applied Anatomy - Pathologies of the Nose

• DNS- Deviated Nasal Septum is an abnormal shift in the septum Nasal Polyp - Touched mucous membrane becomes inflamed + enlarged which can be surgical

Little's Area

• Kiesselbach's plexus is in the Kiesselbach's area/triangle, or Little's area
• Region in the anteroinferior part of the nasal septum where four arteries anastomose to form a vascular plexus.
• Common site of bleeding from nose (Epistaxis).
• Involves 4 Arteries:
  • Anterior + posterior ethmoidal
  • Sphenopalatine
  • Greater palatine artery

Applied Anatomy - Allergic Rhinitis

• Hypertrophy of mucosa over inferior nasal concha causing constant sneezing

Pharynx

• The pharynx is a 12-14 cm long
• The pharynx lies behind, and communicates with, the nasal, oral and laryngeal cavities via the nasopharynx, oropharynx and laryngopharynx, respectively.
• It is a musculomembranous tube shaped like an inverted cone
• Extends from the cranial base to the lower border of the cricoid cartilage (at the level of the sixth cervical vertebra), where it becomes continuous with the esophagus.
• Communication between oral cavity & pharynx is oropharyngeal isthmus
• Divisible into nasopharynx, oropharynx,& laryngopharynx.

Features on Nasopharynx:

• Includes opening of auditory tube
• Includes tubal elevation and salpingopharyngeal & salpingopalatine fold
• Communication between naso & oropharynx is pharyngeal isthmus Tubal tonsil & pharyngeal tonsil (adenoids) are present

Features on Oropharynx:

• Lies in front of C2 & upper part of C3 vertebra
• Palatopharyngeal folds/arches
• Palatine tonsil & tonsillar sinus

Pharynx Anatomy

• Isthmus: b/w naso toro pharnyx
• Includes the Nasal Cavity, tongues, lingual tonsils, nasopharynx, oropharynx, laryngopharynx etc

Features on Laryngopharynx:

• Lies in front of C3-C6 vertebra- entry point in blarynx (larynx)
• Upper part formed by inlet of larynx
• Below and posterior surfaces by arytenoid & cricoid cartilages

Wall of Pharynx:

• Formed by skeletal muscles and fascia
• Buccopharyngeal fascia coats outside of muscle wall
• Pharyngobasilar fascia lines inside of the muscle wall

Constrictors Muscles of Pharynx:

• Includes the superior middle & inferior constrictors
• All originate posterior to nasal, oral & laryngeal cavities
• Fibers pass to posterior & lateral walls of pharynx meeting to form midline raphe.
• Longitudinal muscles also present

Longitudinal Muscles of Pharynx:

• Stylopharyngeus, palatopharyngeus & salpingopharyngeus.

Nerve Supply of Muscles of the Pharynx:

• All constrictors & salpingopharyngeus by pharyngeal branch of vagus
• Stylopharyngeus by glossopharyngeal
• Palatopharyngeus by cranial part of accessory

Blood Vessels & Lymphatics of Pharynx:

• Ascending pharyngeal, lingual, facial, maxillary arteries
• Venous plexus surrounding pharynx drains into internal jugular & facial veins
• Lymph vessels drain into deep cervical lymph nodes.

Killian's Dehiscence

• Known as Killian's triangle, which is a triangular area in the wall of the pharynx between the thyropharyngeal and cricopharyngeus of the inferior constrictor of the pharynx.
• Tonsils are arranged in circular arrangement
• Represents a potentially weak spot where a pharyngoesophageal diverticulum (Zenker's diverticulum) is more likely to occur

Paranasal Air Sinus

• Air filled spaces in bones that surround the nasal cavity
• Named according to the bones in which they're located
• There are four types - maxillary, ethmoid, frontal, and sphenoid

Paranasal Air Sinus

• Located in the interior of the maxilla, frontal, sphenoid, and ethmoid bones
• Lined with mucoperiosteum and filled with air and communicate with the nasal cavity
• Lined by pseudostratified ciliated columnar epithelium.
• Maxillary sinuses are aerated at birth
• Frontal and sphenoidal sinuses develop at :age 6-7 years
• Ethmoid develops during and shortly after puberty

Paranasal Sinus

• Sphenoid bone
• Ethmoid bone
• Inferior Nasal Concha
• Vomer
• Palatine are all apart of this sinus

Paranasal Air Sinus - Ethmoid

• Contains the perpendicular plate, ethmoidal sinuses, crista galli, orbital plate, and cribriform

Function of Paranasal Air Sinus

• Decrease skull bone weight
• Warm, moisten and filter incoming air
• Serve as a resonating chamber for voice (which accounts for discomfort in talking when sick)
• Act as shock absorbers in trauma (like air bags in a car)
• Possibly help control Immune system
• The voice quality would markedly changed if the apertures of the sinuses are blocked or they become filled with fluid

Applied Anatomy of Paranasal Air Sinus

• Sinusitis is caused by inflammation or swelling of the tissue lining the sinus, which can block the flow of air
• Healthy sinuses are filled with air, but diseased sinuses are filled with fluid and cause infections
• Sinusitis has a variety of classifications including: acute, subacute, chronic, and recurrent
• Sinusitis also caused by: common cold, allergic rhinitis, nasal polyp and deviated nasal septum

Trachea and Bronchial Tree

• After the larynx
• Involves various bronchioles and aveoli
• Gas exchange takes place from air sacs to tissues Note: Look at figure 9 for gas exchange and aveolar region