Dr. Noura El Tahawy
Assist. Professor Of Anatomy
Embryology& Molecular Cell Biology
Faculty of Medicine, Port Said
1. Describe the external ear. (auricle& ext. acoustic meatus,
2. Describe blood &nerve supply& lymphatic drainage of the
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
5. Describe divisions and boundaries of mouth cavity.
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:
■ The slightly curved rim of the
■ A broader curved eminence
internal to the helix, which
divides the auricle into an outer
scaphoid fossa and the deeper
■ The deep cavity in front of the
■ A small projection from the
anterior portion of the external
ear anterior to the concha
■ A structure made up of areolar
tissue and fat but no cartilage.
External acoustic meatus
• External Acoustic (Auditory)
• ■ Is approximately 2.5 cm
long, extending from the
concha to the tympanic
• ■ 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.
■ 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.
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
Middle Ear Walls and boundaries
Dr. Noura El Tahawy
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)
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
■ Has cartilaginous portion that remains closed except during swallowing or
■ Is opened by the simultaneous contraction of the tensor veli palatini and
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.
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.