The skeleton and muscles
Frank J. Dye in Human Life Before Birth, 2019
Without our skeleton and muscles, we would not be able to move about or maintain our posture. Moreover, our ability to hear also depends on three small bones—the incus, malleus, and stapes—in our middle ear and the muscles attached to these bones. Like other vertebrates, we have an endoskeleton (internal skeleton), which provides protection for our soft parts. We do not have an exoskeleton (shell) like some animals, but if you have ever banged your head against something hard, you can appreciate the skull's protection of your brain! Our skeleton is divided into two general parts (Figure 14.1): the axial skeleton is composed of the skull, vertebral column (backbone), sternum, and ribs, and the appendicular skeleton is composed of limbs, pelvic girdle, and pectoral girdle.
Special Senses
Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard in Toxicologic Pathology, 2018
The middle ear contains a chain of three small bones called the ossicles. These are most often termed the malleus, incus, and stapes but also termed the hammer, anvil, and stirrup respectively. The malleus (hammer) is attached to the tympanic membrane and articulates with the incus (anvil) (Figure 23.5a). The incus articulates with the stapes (stirrup) and the footplate of the stapes is attached to the membranous oval window of the cochlea. There are two muscles associated with ossicles; the tensor tympani muscle (innervated by the trigeminal nerve) is attached to the malleus and the stapedius muscle (innervated by the facial nerve) is attached to the stapes. Contraction of these muscles is associated with a reflex induced by loud sounds and contraction of the muscles restricts movement of the ossicles and reduces transmission of sound.
Otosclerosis
John C Watkinson, Raymond W Clarke, Christopher P Aldren, Doris-Eva Bamiou, Raymond W Clarke, Richard M Irving, Haytham Kubba, Shakeel R Saeed in Paediatrics, The Ear, Skull Base, 2018
Necrosis of the long process of the incus causes loosening of the attachment of the prosthesis and a conductive hearing impairment. The hearing impairment may fluctuate. Although often attributed to a reduction in blood supply secondary to cutting the stapedial tendon, and pressure on the long process from the prosthetic loop, some authors have claimed two other observations make this unlikely. The marrow of the incus may be able to provide adequate blood supply, and the frequent findings of a circumferential bony defect filled with granulation tissue are said to be more typical of a foreign body reaction.165 It is common for both long process erosion and displacement from the vestibule to coexist. Necrosis should be distinguished from loose attachment of the prosthesis to the long process of the incus through faulty crimping, a complication that may be easily corrected.
Transcanal endoscopic management of isolated congenital middle ear malformations
Published in Acta Oto-Laryngologica, 2023
Licai Shi, Shuainan Chen, Rujie Li, Yideng Huang
All operations in this study were performed by the same experienced ear surgeon (Yideng Huang) by exclusively transcanal endoscopic tympanoplasty surgery. Each patient received general anesthesia. After creating a tympanomeatal flap and removing a small part of the bone in the upper wall of the external auditory canal, the tympanic cavity and ossicular chain can be explored. The ways of hearing reconstruction were mentioned as follows. (1) Malleus-incus complex (MIC) anomalies with normal and mobile stapes. After removing the deformed auditory ossicles, the hearing was reconstructed with partial auditory ossicle prosthesis (PORP) (Figure 1). (2) Abnormal stapes suprastructure with a mobile stapes footplate: after removing the deformed superstructure of stapes and other malformed auditory ossicles, the hearing was reconstructed with complete auditory ossicular prosthesis (TORP) (Figure 2). (3) Stapes footplate fixation or oval window bony atresia/aplasia, with or without other parts of ossicular chain anomalies. Vestibulotomy with piston insertion was performed to establish a connection between the vestibule and the handle of the malleus or the long process of the incus (Figures 3–5).
Effect of ossicular chain deformity on reverse stimulation considering the overflow characteristics of third windows
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Houguang Liu, Lin Xue, Jianhua Yang, Gang Cheng, Lei Zhou, Xinsheng Huang
In the impedance model, the malleus impedance is composed of mechanical mass, mechanical resistance, and mechanical stiffness (O’Connor and Puria 2008). Our study shows that the malleus impedance’s increase boosts obviously the input impedance of the middle ear over the entire frequency. The incus fixation improves the input impedance of the middle ear to varying degrees in the overall frequency. Considering that the incus is modeled with mechanical mass (O’Connor and Puria 2008; Keefe 2015), it is only necessary to consider increasing the mechanical mass of the incus to achieve impedance calibration. For stapes fixation, the input impedance of the middle ear appears to increase slightly below 1000 Hz. The stapes impedance is composed of mechanical mass, mechanical resistance, and mechanical stiffness (Keefe 2015). On one hand, the stiffness mainly affects the low-frequency characteristics of the system, it is considered to increase the single stiffness of the stapes, which can achieve the impedance calibration of the stapes fixation. Also, similar to malleus fixation and incus fixation, increasing the impedance of the stapes can also achieve impedance calibration. It can be seen that the increase in the single stiffness of the stapes impedance dominates the increase of the stapes impedance.
Transcanal endoscopic ear surgery for management of ossicular malformation: clinical outcomes of 17 cases
Published in Acta Oto-Laryngologica, 2022
Alyssa Yoshida, Makoto Hosoya, Sho Kanzaki, Masato Fujioka, Hiroyuki Ozawa
Seventeen cases (seven women and ten men) of ossicular malformation performed using TEES were included in this study. The mean age of the patients was 34.4 years. Of these 17 cases, 13 were performed only by TEES, but 4 cases were supported by a surgical microscope (1 case in 2015, 1 case in 2016, and 2 cases in 2017). After 2018, all the cases were performed using TEES. According to the Teunissen and Cremers classification system, six ears were type I, two ears were typeII, and nine ears were type III. Endoscopic exploratory tympanotomy revealed that cases showing malformations of the stapes superstructure tended to be more common in terms of percentage. Most cases showed normal malleus, except for five ears (29.4%), including the fixation of the incudomalleolar joint or a malleus bar. The malformation of incus was observed in five ears (29.4%). The most common malformation was the missing of the long process. Stapes malformation was observed in 12 ears (70.5%), which often involved the stapes superstructure malformations with a mobile footplate (4 in 12 ears). Oval window aplasia or dysplasia, which was classified as type IV, was not observed.
Related Knowledge Centers
- Bone
- Malleus
- Middle Ear
- Ossicles
- Stapes
- Tympanic Cavity
- Eardrum
- Posterior Ligament of Incus
- Superior Ligament of Incus