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Anatomy of the ear (ecture 2) by dr, noura 2018

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Lectures of Anatomy by Dr. Noura El -Tahawy . Assist. prof. of Anatomy, Faculty of Medicine, Port Said University; Egypt 2018,

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Anatomy of the ear (ecture 2) by dr, noura 2018

  1. 1. Anatomy of The EAR Dr. Noura El Tahawy Assist. Professor Of Anatomy Embryology& Molecular Cell Biology Faculty of Medicine, Port Said University, Egypt
  2. 2. 1. Describe the external ear. (auricle& ext. acoustic meatus, tympanic membrane.) 2. Describe blood &nerve supply& lymphatic drainage of the external ear. 3. Describe the middle ear. (walls, special features in the cavity of middle ear, auditory ossicles& muscles) 4. Describe the course& branches of the facial nerve in the middle ear. 5. Describe divisions and boundaries of mouth cavity. objectives
  3. 3. Auricle
  4. 4. Auricle
  5. 5. Auricle
  6. 6. Auricle: is composed mainly of cartilage, except for the lobule. The auricle collects the sound waves and directs vibrations into the external auditory canal. Has the following features: 1. Helix ■ The slightly curved rim of the auricle. 2. Antihelix ■ A broader curved eminence internal to the helix, which divides the auricle into an outer scaphoid fossa and the deeper concha. 3. Concha ■ The deep cavity in front of the antihelix. 4. Tragus ■ A small projection from the anterior portion of the external ear anterior to the concha 5. Lobule ■ A structure made up of areolar tissue and fat but no cartilage. The Auricle:
  7. 7. External acoustic meatus • External Acoustic (Auditory) Meatus • ■ Is approximately 2.5 cm long, extending from the concha to the tympanic membrane. • ■ Its external one-third is formed by cartilage, and the internal two-thirds is formed by bone. produces earwax. • ■ Is innervated by the trigeminal nerve and vagus nerve, which is joined by a branch of the facial nerve and the glossopharyngeal nerve.
  8. 8. External acoustic meatus
  9. 9. External acoustic meatus (bony part)
  10. 10. External acoustic meatus
  11. 11. Tympanic membrane (Ear drum) ■ Conducts sound waves to the middle ear. ■ Its external (lateral) concave surface is covered by skin and is innervated (sensory) by the trigeminal nerve and the vagus nerve.
  12. 12. Eardrum Tympanic membrane
  13. 13. Consists of three layers: an outer (cutaneous), an intermediate (fibrous), and an inner (mucous) layer. ■ Has a thickened fibrocartilaginous ring at the greater part of its circumference, which is fixed in the tympanic sulcus at the inner end of the meatus. ■ Has a small triangular portion between the anterior and posterior malleolar folds called the pars flaccida (deficient ring and lack of fibrous layer). The remainder of the membrane is called the pars tensa. ■ Contains the cone of light, which is a triangular reflection of light seen in the anterior–inferior quadrant. ■ Contains the most depressed canter point of the concavity, called the umbo (Latin for “knob”). Otoscope ‫االذن‬ ‫منظار‬Tympanic membrane
  14. 14. Middle Ear Walls and boundaries Dr. Noura El Tahawy
  15. 15. Pterous temporal Bone Cranial Cavity
  16. 16. erous temporal Bone
  17. 17. Temporal bone
  18. 18. Temporal bone
  19. 19. Tympanic cavity (Middle Ear Cavity)
  20. 20. Tympanic cavity
  21. 21. Eardrum Tympanic membrane The lateral wall of the Middle Ear
  22. 22. Medial wall of the Middle Ear Promontory
  23. 23. Tegmen tympani Roof of Middle ear
  24. 24. Floor of the Middle Ear Bulb of Internal Jugular vein
  25. 25. Eustachian tube (Pharyngo-tympanic tube) Anterior wall of Middle Ear nasoPharynx
  26. 26. NasoPharynx
  27. 27. Walls of the Middle ear
  28. 28. 1. Boundaries of the Tympanic Cavity ■ Roof: tegmen tympani (temporal bone).■ Floor: jugular fossa. Anterior: carotid canal and Eustachian tube. ■ Posterior: mastoid air cells and mastoid antrum through the aditus ad antrum. ■ Lateral: tympanic membrane. ■ Medial: lateral wall of the inner ear, presenting the promontory formed by the basal turn of the cochlea, the fenestra vestibuli (oval window), the fenestra cochlea (round window), and the prominence of the facial canal. 2. Oval Window (Fenestra Vestibuli) ■ Is pushed back and forth by the footplate of the stapes and transmits the sonic vibrations of the ossicles into the perilymph of the scala vestibuli in the inner ear. 3. Round Window (Fenestra Cochlea or Tympani) ■ Is closed by the secondary tympanic (mucous) membrane of the middle ear and accommodates the pressure waves transmitted to the perilymph of the scala tympani. Consists of the tympanic cavity with its ossicles and is located within the petrous portion of the temporal bone. ■ Transmits the sound waves from air to auditory ossicles and then to the inner ear. A. Tympanic (Middle Ear) Cavity ■ Includes the tympanic cavity proper (the space internal to the tympanic membrane) and the epitympanic recess (the space superior to the tympanic membrane that contains the head of the malleus and the body of the incus). ■ Communicates anteriorly with the nasopharynx via the auditory (eustachian) tube and posteriorly with the mastoid air cells and the mastoid antrum through the aditus ad antrum. ■ Is traversed by the chorda tympani and lesser petrosal nerve. Tympanic cavity (Middle Ear cavity)
  29. 29. Auditory (Pharyngotympanic or Eustachian) Tube ■ Connects the middle ear to the nasopharynx. ■ Allows air to enter or leave the middle ear cavity and thus balances the pressure in the middle ear with atmospheric pressure, allowing free movement of the tympanic membrane. ■ Has cartilaginous portion that remains closed except during swallowing or yawning. ■ Is opened by the simultaneous contraction of the tensor veli palatini and salpingopharyngeus muscles.
  30. 30. Contents of the Middle Ear (tympanic cavity)
  31. 31. Ear Ossicles
  32. 32. Malleus
  33. 33. Malleus
  34. 34. Incus
  35. 35. Stapes
  36. 36. Transmission of Vioce
  37. 37. Muscles inside the Middle ear
  38. 38. Inner Ear
  39. 39. Vestibulocochlear nerve
  40. 40. Cochlear part Vestibular part Facial nerve Vestibulocochlear and Facial nerves
  41. 41. Facial Nerve
  42. 42. Facial nerve
  43. 43. Cochlear part Vestibular part Facial nerve Vestibulocochlear and Facial nerves
  44. 44. Facial nerve
  45. 45. Branches of Facial nerve
  46. 46. 1. The motor nucleus supplies the muscles of facial expression, the auricular muscles, the stapedius, the posterior belly of the digastric, and the stylohyoid muscles 2. Parasympathetic (secretomotor) to submandibular and sublingual salivary glands and the nasal and palatine glands. 3. Parasympathetic (secretomotor) supplies the lacrimal gland. 4. The sensory part receives taste fibbers from the anterior two-thirds of the tongue, the floor of the mouth, and the palate. Distribution Facial nerve Course: 1. The two roots (sensory and motor) of the facial nerve emerge between the pons and the medulla oblongata. They pass laterally in the posterior cranial fossa with the vestibulocochlear nerve (CVIII) and enter the internal acoustic meatus (internal auditory canal) in the petrous part of the temporal bone. 2. At the bottom of the meatus, the nerve enters the facial bony canal and runs laterally through the inner ear. 3. On reaching the medial wall of the middle ear (tympanic cavity) the nerve expands to form the sensory geniculate ganglion and turns sharply backward at the roof of middle ear (above the promontory). 4. Reaching the posterior wall of the tympanic cavity, the facial nerve turns downward, descends to emerge from the stylomastoid foramen to exit the skull and enters the parotid gland. Inside the parotid g. it terminates by dividing into five terminal branches which supply muscles of facial expression.
  47. 47. Atlas of The Ear
  48. 48. Gross Anatomy of the Middle Ear
  49. 49. End