Ten Question - Anatomy Of Ear

Explanation
The external auditory canal develops from the first branchial groove. The branchial grooves are structures that form during embryonic development and eventually give rise to various structures in the head and neck region. The first branchial groove specifically gives rise to the external auditory canal, which is the passage that leads from the outer ear to the middle ear. Therefore, the correct answer is the first branchial groove.

Explanation
The Santorini fissure is seen in the cartilaginous external auditory canal (EAC). The EAC is divided into two parts - the cartilaginous portion and the bony portion. The Santorini fissure is a small groove or cleft that is present in the cartilaginous portion of the EAC. It is important to note that the Santorini fissure is not seen in the bony EAC or the bony cartilaginous junction of the EAC. Additionally, it is not located near the tympanic membrane (TM). Therefore, the correct answer is the cartilaginous EAC.

Explanation
The pars flacida is a part of the tympanic membrane located in the ear. It is true that it is medial to the notch of the ring of the tympanic membrane, meaning it is positioned closer to the center. Additionally, the pars flacida is more mobile compared to the rest of the tympanic membrane. It lacks a fibrous layer, which is a characteristic feature of the pars flaccida. Therefore, the correct answer is "all" as all the statements are true about the pars flacida.

Explanation
The tegmen tympani is formed from both the squamous and petrous parts of the temporal bone. The squamous part forms the superior portion of the tegmen tympani, while the petrous part forms the inferior portion. Therefore, the correct answer is "both a and b" as both the squamous and petrous parts contribute to the formation of the tegmen tympani.

Explanation
The correct answer is "tensor tympani tendon." The processus cochleariformis is a bony projection in the middle ear that contains the tensor tympani muscle. This muscle is responsible for dampening the sound vibrations that enter the ear, protecting the delicate structures of the inner ear from loud noises. The stapedius tendon is associated with the stapedius muscle, which also helps in reducing sound transmission. The apex of the cochlea is the furthest point of the spiral-shaped cochlea, and the semicircular canal bulge is a protrusion in the semicircular canals, which are responsible for detecting head movements and maintaining balance.

Explanation
The tensor palati muscle helps in opening the Eustachian tube during swallowing. This muscle is responsible for the movement of the soft palate, which in turn helps to equalize the pressure between the middle ear and the throat. When we swallow, the tensor palati muscle contracts, allowing the Eustachian tube to open and air to flow into the middle ear, equalizing the pressure. This prevents discomfort and potential damage to the ear.

Explanation
The three semicircular canals open into the vestibule through five openings.

Explanation
The ductus reuniens connects the utricle and saccule.

Explanation
The stapedius muscle is supplied by the facial nerve (CN 7). This muscle plays a crucial role in dampening sounds and protecting the inner ear from loud noises. When the facial nerve is stimulated, it causes the stapedius muscle to contract, which in turn reduces the movement of the stapes bone in the middle ear. This helps to reduce the transmission of sound vibrations to the inner ear, preventing potential damage. Therefore, the correct answer is CN 7.

Explanation
The basilar membrane is located over the organ of Corti. It is a thin, flexible membrane that runs along the length of the cochlea and separates the scala media from the scala tympani. The organ of Corti, which is responsible for converting sound vibrations into electrical signals, sits on top of the basilar membrane. As sound waves enter the cochlea, they cause the basilar membrane to vibrate, which in turn stimulates the hair cells in the organ of Corti, leading to the perception of sound.