Lecture Notes - Ear & Nasal Cavity

1. External Ear:
   1. Auricle - review parts on diagram, concha, helix, antihelix, tragus, antitragus, lobule
   2. External auditory meatus
      1. Structure: outer half cartilage, inner half bone, cerumin glands in outer half, has somewhat tortuous downward and forward course; pull auricle upward and backward to straighten.
      2. Cutaneous sensation - Trigeminal - auriculotemporal, vagus - auricular branch
   3. Tympanic membrane: "ear drum"
      1. Appearance through otoscope: pars tensa, pars flaccida, umbo, "cone of light," faces outward, downward and forward.
      2. Structure:
         1. outer layer- skin,
         2. middle fibrous layer- radial and circular fibres,
         3. inner layer mucosa
         4. myringotomy site
2. Middle Ear:
   1. Parts: auditory (Eustachian) tube, tympanic cavity and membrane, mastoid antrum and mastoid air cells.
   2. Pneumatization from nasopharynx:
      1. Lined with mucosa like pharynx, retrograde infection from pharynx- otitis media, mastoiditis.
      2. Sensory innervation through glossopharyngeal nerve
   3. Auditory ossicles: malleus, incus and stapes, joined by synovial joints-- ankylosis, otosclerosis
   4. Muscles: stapedius (VII) and tensor tympani (V3) dampen sounds and protect inner ear.
   5. Features of walls of Middle ear - see illustrations.
3. Inner ear: for general information will be studied in histo and neuroscience sequence.
4. Cranial Nerves associated with Ear:
   1. Trigeminal (V3): auriculotemporal to external acoustic meatus, nerve to tensor tympani m.
   2. Facial (VII): Geniculate ganglion in temporal bone
      1. Greater petrosal nerve - preganglionic parasympathetic to pterygopalatine ganglion, postganglionics go to lacrimal gland and mucous glands of nasal and oral cavities.
      2. Chorda tympani - preganglionic parasympathetic to submandibular gland, postganglionics to submandibular and sublingual glands.
      3. Geniculate ganglion (sensory ganglion) fibres from chorda tympani carrying taste from anterior 2/3 of the tongue.
   3. Glossopharyngeal (IX): Tympanic nerve:
      1. Superior/inferior ganglia - sensory fibres from whole middle ear cavity and posterior 1/3 of tongue (taste and general sensation).
      2. Lesser petrosal nerve - preganglioinic parasympathetic to otic ganglion, postganglionics hitch-hike with auriculotemporal to innervate parotid gland.
5. External nose
   1. Bony-cartilagenous framework
      
   2. Nostrils
      
   3. Vestibule
6. Nasal cavity proper (internal nose)
   
   1. Nasal mucous lining: respiratory, olfactory
      
   2. Nasal conchae and meatus: superior, middle, inferior
      
   3. Paranasal sinuses: maxillary, frontal, ethmoidal air cells, sphenoid
      
   4. Openings of paranasal sinuses into nasal cavity
      
   5. Nasal septum, deviations
      
   6. Arterial supply of nasal mucosa
7. Nasopharynx
   1. Opening of auditory tube, torus tubarius
      
   2. Pharyngeal tonsil (adenoids)
      
   3. Pharyngeal recess
8. Soft Palate
   1. Functions
      
   2. Muscles of soft palate
      1. Tensor veli palatini (V₃)
      2. Levator veli palatini (X)
      3. Palatopharyngeus (X)
      4. Palatoglossus (X)
   3. Innervation