NOSE

• 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


  • Has two elliptical orifices called the nostrils, separated by the nasal septum
  • Lateral margin (ala nasi) is rounded and mobile
  • Framework made up above by nasal bones, frontal processes of maxillae, and nasal part of frontal bone
  • Below, framework formed of plates of hyaline cartilage
• Blood supply of external nose


  • Skin supplied by branches of ophthalmic and maxillary arteries
  • Skin of ala and lower part of septum supplied by branches from facial artery
• Nerve supply of external nose


  • Infratrochlear and external nasal branches of ophthalmic nerve (CN V)
  • Infraorbital branch of maxillary nerve (CN V)
• Nasal cavity


  • Extends from nostrils to posterior nasal apertures (choanae)
  • Nasal vestibule is area just inside nostril
  • Divided into right and left halves by nasal septum
• Walls of nasal cavity

  • Floor (palatine process of maxilla, horizontal plate of palatine bone)
  • Roof (nasal and frontal bones, cribriform plate of ethmoid, body of sphenoid)
  • Lateral wall (superior, middle, inferior nasal conchae)
  • Medial wall (nasal septum)
• Mucous membrane of nasal cavity


  • Vestibule lined with modified skin and coarse hairs
  • Area above superior concha lined with olfactory mucous membrane
  • Lower part lined with respiratory mucous membrane
  • Submucous venous plexus in respiratory region
• Function of warm blood and mucus


  • Warm blood in venous plexuses heats inspired air
  • Mucus traps foreign particles and organisms which are then swallowed and destroyed by gastric acid
• Nerve supply of nasal cavity


  • Olfactory nerves from olfactory mucous membrane to olfactory bulbs
  • Nerves of ordinary sensation from ophthalmic (V1) and maxillary (V2) divisions of trigeminal nerve
• Blood supply to nasal cavity


  • From branches of maxillary artery, especially sphenopalatine artery
  • Submucous venous plexus drained by veins accompanying arteries
• Lymph drainage of nasal cavity


  • Vestibule to submandibular nodes
  • Remainder to upper deep cervical nodes
• Paranasal sinuses


  • Cavities in maxilla, frontal, sphenoid, and ethmoid bones
  • Lined with mucoperiosteum and filled with air
  • Communicate with nasal cavity through small apertures
  • Maxillary and sphenoidal sinuses present in rudimentary form at birth, enlarge after 8 years, fully formed in adolescence
• Drainage and function of paranasal sinuses


  • Mucus moved into nose by ciliary action, also drained by siphon action of nose blowing
  • Act as resonators for voice, reduce weight of skull
• Nasal septum rarely lies in midline, increasing size of one nasal cavity and decreasing other
• Fractures of nasal bones common, can involve displacement and involvement of nasal septum
• Infection of nasal cavity can spread to paranasal sinuses, middle ear, and meninges
• Foreign bodies in nose common in children, can get impacted
• Epistaxis (nose bleeding) common, often from septal branches of sphenopalatine and facial vessels
• Development of nose


  1. Roof formed from lateral nasal processes

  2. Anterior openings (nostrils) form from olfactory pits

  3. Floor initially short, formed by medial nasal and maxillary processes

  4. Nasal septum forms as downgrowth from medial nasal process

  5. Palatal processes of maxilla grow and fuse to complete floor of nose
• Maxillary sinus


  • Pyramidal shape, within maxilla behind cheek skin
  • Roof is floor of orbit, floor related to premolar and molar tooth roots
  • Opens into middle meatus of nose through hiatus semilunaris
• Frontal sinuses


  • Two sinuses in frontal bone, separated by septum
  • Triangular shape, extend above medial eyebrow and into medial orbit roof
  • Each opens into middle meatus via infundibulum
• Sphenoidal sinuses


  • Two sinuses in body of sphenoid bone
  • Each opens into sphenoethmoidal recess above superior concha
• Ethmoidal sinuses


  • Anterior, middle, and posterior sinuses in ethmoid bone
  • Anterior open into infundibulum, middle into middle meatus, posterior into superior meatus
• Paranasal sinuses prone to infection, can spread to orbit and meninges
• Frontal sinus pain referred to forehead, maxillary sinus pain referred to upper jaw and teeth
• Maxillary sinus prone to infection due to poorly placed drainage orifice
• Pharynx is where air and food pathways cross, enabled by soft palate acting as flap valve
• Frontal sinus


  Innervated by the supraorbital nerve, pain referred over the forehead and scalp
• Maxillary sinus


  Innervated by the infraorbital nerve, pain referred to the upper jaw and teeth
• Frontal sinus drains into the hiatus semilunaris


  Frontal sinusitis nearly always has a maxillary sinusitis
• Maxillary sinus drainage orifice


  Badly placed near the roof of the sinus, has to fill up with fluid before it can effectively drain
• Apices of the roots of the teeth in the maxilla are related to the floor of the maxillary sinus
• It is in the pharynx that the air and food pathways cross
• Soft palate


  Serves as a flap valve to shut off the mouth from the oropharynx during chewing, and the nasopharynx from the oropharynx during swallowing
• Soft palate raising


  Directs air through the mouth rather than the nose, permits expectoration of mucus and maximum expiration for wind instruments
• Larynx


  Provides a protective sphincter at the inlet of the air passages and is responsible for voice production
• Larynx


  • Situated below the tongue and hyoid bone, between the great blood vessels of the neck, at the level of the 4th-6th cervical vertebrae
  • Opens above into the laryngeal part of the pharynx, and below is continuous with the trachea
  • Covered in front by the infrahyoid strap muscles and at the sides by the thyroid gland
• Cartilages of the larynx


  • Thyroid cartilage
  • Cricoid cartilage
  • Arytenoid cartilages
  • Corniculate cartilages
  • Cuneiform cartilages
  • Epiglottis
• Thyroid cartilage


  Largest cartilage, consists of two laminae of hyaline cartilage meeting in a prominent V angle (Adam's apple)
• Cricoid cartilage


  Shaped like a signet ring, with a broad plate behind and a shallow arch in front