Upper resp tract ~ medium

• The lecture covers the anatomy of the respiratory tract.
• Discussed are the structures and functions of the:
  • Nose
  • Pharynx
  • Larynx
  • Trachea
  • Divisions of each structure

External Nose

• The external nose is pyramidal in shape.
• Its parts include the apex (tip), root, and dorsum.
• The nostrils (nares) are a pair of piriform apertures.
• The nasal septum is medial to the nostrils.
• The ala of the nose is lateral to the nostrils.

Nasal Cavity

• The nasal cavity is divided into two asymmetrical halves by the median nasal septum.
• Extends from the nostrils to the choanae.
• The vestibule is located close to the nostrils and lined by skin with hairs and sebaceous glands.

Dimensions of Nasal Cavity Halves

• Each half contains a roof, floor, medial and lateral wall.
• Each half's measures are:
  • 5cm in height
  • 5-7cm in length
  • 1.5cm width near the floor
  • 1-2mm near the roof

Roof of Nasal Cavity

• Formed by the cribriform plate of the ethmoid bone.
• 7cm long and 2mm wide.
• It slopes downwards both in front and behind.
• The middle horizontal part - cribriform plate of ethmoid.
• The anterior slope comprises the nasal part of the frontal bone, nasal bone, and nasal cartilages.
• The posterior slope consists of the inferior surface of the body of the sphenoid.

Floor of Nasal Cavity

• Approximately 5cm long and 1.5cm wide.
• Formed by the palatine process of the maxilla and the horizontal plate of the palatine bone.
• It has a concave shape from side to side.

Nasal Septum (Medial Wall)

• The nasal septum is the median osseocartilaginous partition between the two halves of the nasal cavity.
• Each side is covered by a mucous membrane, forming the medial wall of both nasal cavities.
• It contains bony and cartilaginous parts.

Nasal Septum: Bony Formation

• Formed by the perpendicular plate of the ethmoid bone and the vomer.

Nasal Septum: Cartilaginous Formation

• Formed by septal and inferior nasal cartilage.

Nasal Septum: Cuticular Formation

• Formed by fibro-fatty tissue and skin.
• Includes the columella and the Vomero-nasal organ of Jacobson.

Arterial Supply of the Nose

• Dorsal nasal branch (ophthalmic).
• Infraorbital (maxillary).
• Alar and Septal (facial).

Innervation of the Nose

• Sensory: external nasal, infratrochlear (ophthalmic), and infraorbital (maxillary) nerves.
• Motor: facial nerve branches.

Nasal Septum Arterial Supply

• Kiesselbach's Plexus.
• Ant. Ethmoid.
• Post. Ethmoid.
• Sphenopalatine.
• Sup. Labial (from the facial a.).
• Greater Palatine.

Nasal Septum Venous Drainage

• Superior ophthalmic vein accompanies olfactory nerves into inferior cerebral veins.
• Facial vein to IJV drains the mobile part of the septum.
• the dangerous area of the face.
• Pterygoid venous plexus drains the posteroinferior.

Lateral Wall Divisions of the Nose

• The lateral wall is subdivided into three parts:
  • Vestibule
  • Atrium of middle meatus
  • Concha

Vestibule of Lateral Wall

• Small, depressed area in the anterior part.
• Lined by modified skin with short, stiff, curved hairs (vibrissae) and contains sweat and sebaceous glands.

Parts of the Lateral Wall of the Nose, diagrammatically

• Concha
• Meatus
• Agger nasi, mucous ridge
• Atrium (of middle meatus)
• Limen nasi, mucocutaneous ridge
• Vestibule

Conchae and Meatuses

• Inferior Concha: A separate bone that extends horizontally backwards, ending 1.25cm in front of the pharyngeal opening of the auditory tube, continuous with the vestibule anteriorly; contains the inferior meatus
• Middle Concha:
  • Contains the bulla ethamoidalis, a bony bulging.
  • Middle ethamoidal air sinuses open into the meatus or above the bulla.
  • Consists of the Cresentric space below the bulla, hiatus semilunaris.
  • Maxillary sinus opens into the posterior part of the hiatus semilunaris.
  • Includes the ethmoidal infundibulum i.e. a short passage at the anterior end of the hiatus.
  • Anterior ethmoidal and frontal sinus opens into it.
• Superior Concha:
  • Shortest.
  • Includes the superior meatus, posterior ethamoidal sinus
  • Supreme meatus is b/w superior concha & roof of nasal cavity.
  • Sphenoethamoidal recess, depression above &behind the superior concha.
  • Sphenoidal air sinuses opens.

Key Structures that open into specified Nasal Passages/Meatus

• Inferior meatus is where the nasolacrimal duct opens.
• Middle meatus:
  • Frontal sinus
  • Maxillary sinus
  • Anterior ethmoidal cells
  • Middle ethmoidal cells
• Superior meatus is where the posterior ethmoidal cells open.
• Sphenoethmoidal Recess is where the Sphenoidal sinus opens.

Nerve Supply and Arterial Supply of the Lateral Wall

• Anterior ethmoidal nerve provides opthalmic nerve

• Posterior superior lateral nasal (maxillary nerve)

• Anterior superior alveolar (maxillary)

• Anterior palatine i.e. Pterygopalatine ganglion (maxillary nerve)

• Special sensory comes from the olfactory nerve

• Arteial: Anterior ethmoidal, Posterior ethmoidal, Facial, Sphenopalatine, Greater palatine

Applied Anatomy of the Nose

• Septal deviation causes congestion and obstruction, which is corrected by sub mucosal resection.
• Epistaxis is bleeding from the nose.
• Dangerous area: Nose infections can spread along the olfactory nerves to the cranial cavity.
• A broken nose is a nasal fracture in the bone or cartilage, typically over the bridge or septum.

Little's Area

• An anteroinferior region of the nasal septum where four arteries anastomose to form a vascular plexus.
• Importance: Common site of nose bleeds (epistaxis).

Allergic Rhinitis

• Hypertrophy of mucosa over inferior nasal concha

Functions of the paranasal air sinuses

• Decrease skull bone weight
• Warm, moisten and filter incoming air
• Serve as a resonating chamber for voice
• Act as shock absorbers in trauma (like air bags in a car)
• Possibly help control Immune system
• Voice quality is affected markedly in cases where is affected by a blockage or fluid filling

Applied Anatomy of Paranasal Air Sinus

• Sinusitis is inflammation/swelling of the lining, blocking air filling and leading to fluid/germ growth.
• Varieties: acute, subacute, chronic, recurrent.
• Common cold, allergic rhinitis, nasal polyp, and deviated nasal septum leads to sinusitis.

Pharynx

• The pharynx is a 12–14 cm long musculomembranous tube shaped like an inverted cone.
• It 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.
• It lies behind and communicates with the nasal, oral, and laryngeal cavities via the nasopharynx, oropharynx, and laryngopharynx.
• Divisible into nasopharynx, oropharynx, & laryngopharynx
• Communication between oral cavity & pharynx is oropharyngeal isthmus

Features of the Nasopharynx

• Opening of the auditory tube.
• Tubal elevation.
• Salpingopharyngeal & salpingopalatine fold.
• Tubal tonsil & Pharyngeal tonsil (adenoids).
• Communication between naso & oropharynx is pharyngeal isthmus.

Features of the Oropharynx

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

Features of the Laryngopharynx

• Lies in front of C3-C6 vertebra
• Upper part formed by inlet of larynx
• Below and posterior surfaces by arytenoid & cricoid cartilages.

Structures of the Pharynx Wall

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

Constrictors of the Pharynx

• Superior, middle, & inferior constrictors originate posterior to nasal, oral & laryngeal cavities.
• Fibers pass to posterior & lateral walls of pharynx to form midline raphe.

Longitudinal Muscles of the 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 and Lymphatics of the Pharynx

• Ascending pharyngeal, lingual, facial, maxillary arteries supply the pharynx.
• The venous plexus surrounding the pharynx drains into the internal jugular & facial veins.
• Lymph vessels drain into deep cervical lymph nodes.
• The Pharyngeal plexus is formed by branches of glossopharyngeal, vagus,& cranial accessory

Killian's Dehiscence

• Killian's dehiscence, also known as Killian's triangle: a triangular area in the pharynx wall between the thyropharyngeal and cricopharyngeus of the inferior constrictor.
• It signifies a weak spot and possible site for pharyngoesophageal diverticulum i.e. Zenker's diverticulum.