MIDDLE EAR

Book Creator
Add this page to your book

Book Creator
Remove this page from your book

Manage book(0 page(s))

Help

Tympanic cavity or middle ear , ear air cavity
- Formed by
  - petrous part of temporal bone
    - between external ear and internal ear
- shape
  - like a Cube , but not perfect cube
    - cube is compressed from side to side
      - lateral and medial walls are large
      - other walls are narrow
      - cavity appears biconcave in coronal section
        
        6mm distance between at upper end
        
        2mm in middle
        
        4mm in lower part or floor
    - parts
      - tympanic cavity proper
        
        opposite the tympanic membrane
      - epitympanic recess
        
        above the level of tympanic membrane
    - Communications
      - anteriorly
        
        nasopharynx through auditory tube
      - posteriorly with
        
        mastoid antrum and mastoid air cells through aditus
    - walls
      - Tegmental wall; tegmental roof
        
        formed by thin plate of bone called tegmen tympani
        
        separates middle ear from middle cranial fossa
        
        prolonged forwards as roof of canal for tensor tympani
        
        transmits a vein from middle ear to superior petrosal sinus
        
        Epitympanic recess
        
        Cupular part
      - Jugular wall; floor
        
        thin plate of bone which is a part of temporal bone
        
        separates middle ear from superior bulb of internal jugular vein
        
        nearer to medial wall floor
        
        tympanic canaliculus
        
        transmits tympanic branch of glossopharyngeal nerve
        
        to medial wall of middle ear
        
        Styloid prominence
      - Labyrinthine wall; medial wall
        
        Oval window
        
        Fossa of oval window
        
        Promontory
        
        Groove of promontory
        
        Subiculum of promontory
      - Sinus tympani
      - Round window
      - Fossa of round window
      - Crest of round window
      - Processus cochleariformis
      - Secondary tympanic membrane
      - Mastoid wall; posterior wall
        
        Above to downwards
        
        Superiorly
        
        Aditus to mastoid antrum
        
        epitympanic recess communicates with tympanic antrum
        
        Prominence of lateral semicircular canal
        
        Prominence of facial canal
        
        Fossa of incus
        
        near junction of posterior and medial walls
        
        Pyramidal eminence
        
        Posterior sinus
        
        Tympanic aperture of canaliculus for chorda tympani
      - Mastoid antrum
        
        Mastoid cells
        
        Tympanic cells
      - Carotid wall or anterior wall
        
        upper most part
        
        opening of canal for tensor tympani
        
        middle part
        
        opening of auditory tube
        
        inferior part
        
        thin plate of bone
        
        forms posterior wall of carotid canal
        
        separates middle ear from internal carotid artery
        
        perforated by
        
        superior and inferior sympathetic carticotympanic nerves
        
        tympanic branch of ICA
        
        Bony septum continues
        
        processus cochleariformis
        
        posterior end forms a pulley around tendon of tensor tympani
      - Membranous wall; lateral wall
        
        formed by tympanic membrane and partly by squamous temporal bone
        
        separates middle ear from external acoustic meatus
        
        near tympanic notch
AUDITORY OSSICLES
- Stapes
  - Head of stapes
  - Anterior limb
  - Posterior limb
  - Base of stapes; footplate
- Incus
  - Body of incus
  - Long limb
    - Lenticular process
  - Short limb
- Malleus
  - Handle of malleus
  - Head of malleus
  - Neck of malleus
  - Lateral process
  - Anterior process
ARTICULATIONS OF AUDITORY OSSICLES
- Incudomallear joint
- Incudostapedial joint
- Tympanostapedial syndesmosis
- Ligaments of auditory ossicles
  - Anterior ligament of malleus
  - Superior ligament of malleus
  - Lateral ligament of malleus
  - Superior ligament of incus
  - Posterior ligament of incus
  - Stapedial membrane
  - Anular ligament of stapes
MUSCLES OF AUDITORY OSSICLES
- Tensor tympani
- Stapedius
Mucosa of tympanic cavity
- Posterior fold of malleus
- Anterior fold of malleus
- Fold of chorda tympani
- Recesses of tympanic membrane
  - Anterior recess
  - Superior recess Prussak
  - Posterior recess
- Fold of incus
- Fold of stapedius
PHARYNGOTYMPANIC TUBE; AUDITORY TUBE
- Tympanic opening
- Bony part
  - Isthmus
  - Tubal air cells
- Cartilaginous part
  - Cartilage of tube
    - Medial lamina
    - Lateral lamina
    - Membranous lamina
  - Mucosa; mucous membrane
    - Tubal glands
  - Pharyngeal opening