Sense organ: auditory organ

Dr. Santosa Budiharjo. MKes., PA(K)

Otitis, mastoiditis

Middle ear

Muscles of middle ear• Tensor tympani muscle • Muscle draws the tympanic membrane medialward increasing its tension. • Nerve supply - branch of the mandibular nerve through the otic ganglion. • Arises from the cartilaginous portion of the auditory tube. In bony canal above the osseous portion of the auditory

tube. • Ends in a slender tendon which enters the tympanic cavity, makes a sharp bend around the extremity of the septum. • Inserted into the manubrium of the malleus, near its root

• Stapedius muscle • Muscle pulls the head of the stapes backward, increasing the tension of the fluid within the inner ear. • Nerve supply - branch of the facial nerve. • Arises from the wall of a conical cavity, hollowed out of the interior of the pyramidal eminence; • Tendon emerges from the orifice at the apex of the eminence. • Inserted into the posterior surface of the neck of the stapes. • Stapedius muscle reflex (SMR) • Sound-evoked contraction of the stapedius muscle used in the diagnostics of auditory processing disorders.

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sumbatan serumen (impacted cerumen prop)

Ruptur ear drum

• The auditory and vestibular systems are intimately connected. • The receptors for both are located in the temporal bone, in a convoluted

chamber called the bony labyrinth. • A delicate continuous membrane is suspended within the bony labyrinth,

creating a second chamber within the first. • This chamber is called the membranous labyrinth. The entire fluid-filled

structure is called the inner ear.

• The inner ear has two membrane-covered outlets into the air-filled middle ear - the oval window and the round window.

• The oval window is filled by the plate of the stapes, the third middle ear bone. The stapes vibrates in response to vibrations of the eardrum, setting the fluid of the inner ear sloshing back and forth.

• The round window serves as a pressure valve, bulging outward as pressure rises in the inner ear.

• The oval window opens into a large central area within the inner ear called the vestibule.

• All of the inner ear organs branch off from this central chamber. On one side is the cochlea, on the other the semicircular canals.

• The utricle and saccule, additional vestibular organs, are adjacent to the vestibule.

• The membranous labyrinth is filled with a special fluid called endolymph. • Endolymph is very similar to intracellular fluid: it is high in potassium and

low in sodium. The ionic composition is necessary for vestibular and auditory hair cells to function optimally.

• The space between the membranous and bony labyrinths is filled with perilymph, which is very much like normal cerebral spinal fluid.

• Central Auditory Pathway Cochlear afferent fibers synapse on neurons of the dorsal and ventral cochlear nuclei.

• These neurons give rise to axons that contribute to the central auditory pathways. Some of the axons from the cochlear nuclei cross to the contralateral side and ascend in the lateral lemniscus, the main ascending auditory tract. Others connect with various ipsilateral or contralateral nuclei, such as the superior olivary nuclei, which project through the ipsilateral and contralateral lateral lemnisci. Each lateral lemniscus ends in an inferior colliculus. Neurons of the inferior colliculus project to the medial geniculate nucleus of the thalamus, which gives rise to the auditory radiation. The auditory radiation ends in the auditory cortex (areas 41 and 42), located in the transverse temporal gyri in the temporal lobe.

• Auditory:• Fibers from the cochlear nuclei and the superior olive

travel up the lateral lemniscus to the inferior colliculus , and then to the medial geniculate .

• Try remembering the mnemonic, "S-L-I-M" .

microtia• Classification:

There are four grades of Microtia:Grade I: A smaller version of a typical sized ear, still having the same physical characteristics of a typical sized ear, and containing a small but present external ear canal.Grade II: A partially formed outer ear with very small or narrow ear canals. The ear canals may be very narrow or closed (canal stenosis) producing a conductive hearing loss.Grade III: Absence of the external ear with a small peanut shaped structure (some cartilage with mostly ear lobe) and an absence of the external ear canal and ear drum (known as aural atresia).Grade IV: Absence of the complete ear (anotia).