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Initial stage of fetal development of the pharyngotympanic tube cartilage with special reference to muscle attachments to the tube.

Katori Y, Rodríguez-Vázquez JF, Verdugo-López S, Murakami G, Kawase T, Kobayashi T - Anat Cell Biol (2012)

Bottom Line: In large fetuses, this loose tissue was occupied by an inferior extension of the temporal bone to cover the artery.This later-developing anterior wall of the carotid canal provided the final bony origin of the levator veli palatini muscle.Consequently, the tubal cartilage development seemed to be accelerated by a surrounding muscle, and conversely, the cartilage was likely to determine the other muscular and bony structures.

View Article: PubMed Central - PubMed

Affiliation: Division of Otorhinolaryngology, Sendai Municipal Hospital, Sendai, Japan.

ABSTRACT
Fetal development of the cartilage of the pharyngotympanic tube (PTT) is characterized by its late start. We examined semiserial histological sections of 20 human fetuses at 14-18 weeks of gestation. As controls, we also observed sections of 5 large fetuses at around 30 weeks. At and around 14 weeks, the tubal cartilage first appeared in the posterior side of the pharyngeal opening of the PTT. The levator veli palatini muscle used a mucosal fold containing the initial cartilage for its downward path to the palate. Moreover, the cartilage is a limited hard attachment for the muscle. Therefore, the PTT and its cartilage seemed to play a critical role in early development of levator veli muscle. In contrast, the cartilage developed so that it extended laterally, along a fascia-like structure that connected with the tensor tympani muscle. This muscle appeared to exert mechanical stress on the initial cartilage. The internal carotid artery was exposed to a loose tissue facing the tubal cartilage. In large fetuses, this loose tissue was occupied by an inferior extension of the temporal bone to cover the artery. This later-developing anterior wall of the carotid canal provided the final bony origin of the levator veli palatini muscle. The tubal cartilage seemed to determine the anterior and inferior margins of the canal. Consequently, the tubal cartilage development seemed to be accelerated by a surrounding muscle, and conversely, the cartilage was likely to determine the other muscular and bony structures.

No MeSH data available.


Related in: MedlinePlus

Pharyngotympanic tube and the levator veli palatini muscle in a crown-rump length 125-mm fetus. Hematoxylin and eosin staining. Frontal sections. (A [E]) is the most posterior (or anterior) side of the figure: the distance is 3.3 mm. The superior or lateral orientation is shown by arrows in (A). The internal carotid artery (ICA with arrow) enters the brain cavity immediately posterior to (A). (A) and (B) display the most superior part or the origin (arrowheads) of the levator veli palatini muscle (LVP): because of the lack of a bony structure (star) near the pharyngotympanic tube (PTT), the origin has not yet become attached to the temporal bone, but extends along the inferior aspect of the PTT. The tubal cartilage (C) is divided into two fragments in (B). The levator muscle extends anteriorly along the inferior aspect of the PTT and its cartilage (C-E). ATN, auriculotemporal nerve; CPS, constrictor pharyngis superior muscle; ECA, external carotid artery; ICN, internal carotid nerve; MC, Meckel's cartilage; MH, mylohyoideus muscle; MP, medial pterygoid muscle; OG, otic ganglion; PG, parotid gland; SB, sphenoid bone (body); SG, styloglossus muscle; SMG, submandibular gland; SP, salpingopharyngeus muscle; TG, trigeminal nerve ganglion; TT, tensor tympani muscle; TVP, tensor veli palatini muscle; VN, Vidian's nerve (nerve of the pterygoid canal). Scale bar=1 mm (A-E).
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Figure 4: Pharyngotympanic tube and the levator veli palatini muscle in a crown-rump length 125-mm fetus. Hematoxylin and eosin staining. Frontal sections. (A [E]) is the most posterior (or anterior) side of the figure: the distance is 3.3 mm. The superior or lateral orientation is shown by arrows in (A). The internal carotid artery (ICA with arrow) enters the brain cavity immediately posterior to (A). (A) and (B) display the most superior part or the origin (arrowheads) of the levator veli palatini muscle (LVP): because of the lack of a bony structure (star) near the pharyngotympanic tube (PTT), the origin has not yet become attached to the temporal bone, but extends along the inferior aspect of the PTT. The tubal cartilage (C) is divided into two fragments in (B). The levator muscle extends anteriorly along the inferior aspect of the PTT and its cartilage (C-E). ATN, auriculotemporal nerve; CPS, constrictor pharyngis superior muscle; ECA, external carotid artery; ICN, internal carotid nerve; MC, Meckel's cartilage; MH, mylohyoideus muscle; MP, medial pterygoid muscle; OG, otic ganglion; PG, parotid gland; SB, sphenoid bone (body); SG, styloglossus muscle; SMG, submandibular gland; SP, salpingopharyngeus muscle; TG, trigeminal nerve ganglion; TT, tensor tympani muscle; TVP, tensor veli palatini muscle; VN, Vidian's nerve (nerve of the pterygoid canal). Scale bar=1 mm (A-E).

Mentions: Figs. 1-3 show horizontal sections, Fig. 4 frontal sections and Fig. 5 sagittal sections. The initial appearance of the tubal cartilage is evident in Fig. 1, and a fascial connection between the cartilage and the tensor tympani muscle is evident in Figs. 1 and 2. Likewise, the topographical relationship between the cartilage and the levator veli palatini muscle is shown in Figs. 1, 3, and 4. Finally, Fig. 5 displays the pharyngeal recess. In addition, all the figures show the underdeveloped carotid canal of the temporal bone, in contrast to the late stage (Fig. 5D inset).


Initial stage of fetal development of the pharyngotympanic tube cartilage with special reference to muscle attachments to the tube.

Katori Y, Rodríguez-Vázquez JF, Verdugo-López S, Murakami G, Kawase T, Kobayashi T - Anat Cell Biol (2012)

Pharyngotympanic tube and the levator veli palatini muscle in a crown-rump length 125-mm fetus. Hematoxylin and eosin staining. Frontal sections. (A [E]) is the most posterior (or anterior) side of the figure: the distance is 3.3 mm. The superior or lateral orientation is shown by arrows in (A). The internal carotid artery (ICA with arrow) enters the brain cavity immediately posterior to (A). (A) and (B) display the most superior part or the origin (arrowheads) of the levator veli palatini muscle (LVP): because of the lack of a bony structure (star) near the pharyngotympanic tube (PTT), the origin has not yet become attached to the temporal bone, but extends along the inferior aspect of the PTT. The tubal cartilage (C) is divided into two fragments in (B). The levator muscle extends anteriorly along the inferior aspect of the PTT and its cartilage (C-E). ATN, auriculotemporal nerve; CPS, constrictor pharyngis superior muscle; ECA, external carotid artery; ICN, internal carotid nerve; MC, Meckel's cartilage; MH, mylohyoideus muscle; MP, medial pterygoid muscle; OG, otic ganglion; PG, parotid gland; SB, sphenoid bone (body); SG, styloglossus muscle; SMG, submandibular gland; SP, salpingopharyngeus muscle; TG, trigeminal nerve ganglion; TT, tensor tympani muscle; TVP, tensor veli palatini muscle; VN, Vidian's nerve (nerve of the pterygoid canal). Scale bar=1 mm (A-E).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 4: Pharyngotympanic tube and the levator veli palatini muscle in a crown-rump length 125-mm fetus. Hematoxylin and eosin staining. Frontal sections. (A [E]) is the most posterior (or anterior) side of the figure: the distance is 3.3 mm. The superior or lateral orientation is shown by arrows in (A). The internal carotid artery (ICA with arrow) enters the brain cavity immediately posterior to (A). (A) and (B) display the most superior part or the origin (arrowheads) of the levator veli palatini muscle (LVP): because of the lack of a bony structure (star) near the pharyngotympanic tube (PTT), the origin has not yet become attached to the temporal bone, but extends along the inferior aspect of the PTT. The tubal cartilage (C) is divided into two fragments in (B). The levator muscle extends anteriorly along the inferior aspect of the PTT and its cartilage (C-E). ATN, auriculotemporal nerve; CPS, constrictor pharyngis superior muscle; ECA, external carotid artery; ICN, internal carotid nerve; MC, Meckel's cartilage; MH, mylohyoideus muscle; MP, medial pterygoid muscle; OG, otic ganglion; PG, parotid gland; SB, sphenoid bone (body); SG, styloglossus muscle; SMG, submandibular gland; SP, salpingopharyngeus muscle; TG, trigeminal nerve ganglion; TT, tensor tympani muscle; TVP, tensor veli palatini muscle; VN, Vidian's nerve (nerve of the pterygoid canal). Scale bar=1 mm (A-E).
Mentions: Figs. 1-3 show horizontal sections, Fig. 4 frontal sections and Fig. 5 sagittal sections. The initial appearance of the tubal cartilage is evident in Fig. 1, and a fascial connection between the cartilage and the tensor tympani muscle is evident in Figs. 1 and 2. Likewise, the topographical relationship between the cartilage and the levator veli palatini muscle is shown in Figs. 1, 3, and 4. Finally, Fig. 5 displays the pharyngeal recess. In addition, all the figures show the underdeveloped carotid canal of the temporal bone, in contrast to the late stage (Fig. 5D inset).

Bottom Line: In large fetuses, this loose tissue was occupied by an inferior extension of the temporal bone to cover the artery.This later-developing anterior wall of the carotid canal provided the final bony origin of the levator veli palatini muscle.Consequently, the tubal cartilage development seemed to be accelerated by a surrounding muscle, and conversely, the cartilage was likely to determine the other muscular and bony structures.

View Article: PubMed Central - PubMed

Affiliation: Division of Otorhinolaryngology, Sendai Municipal Hospital, Sendai, Japan.

ABSTRACT
Fetal development of the cartilage of the pharyngotympanic tube (PTT) is characterized by its late start. We examined semiserial histological sections of 20 human fetuses at 14-18 weeks of gestation. As controls, we also observed sections of 5 large fetuses at around 30 weeks. At and around 14 weeks, the tubal cartilage first appeared in the posterior side of the pharyngeal opening of the PTT. The levator veli palatini muscle used a mucosal fold containing the initial cartilage for its downward path to the palate. Moreover, the cartilage is a limited hard attachment for the muscle. Therefore, the PTT and its cartilage seemed to play a critical role in early development of levator veli muscle. In contrast, the cartilage developed so that it extended laterally, along a fascia-like structure that connected with the tensor tympani muscle. This muscle appeared to exert mechanical stress on the initial cartilage. The internal carotid artery was exposed to a loose tissue facing the tubal cartilage. In large fetuses, this loose tissue was occupied by an inferior extension of the temporal bone to cover the artery. This later-developing anterior wall of the carotid canal provided the final bony origin of the levator veli palatini muscle. The tubal cartilage seemed to determine the anterior and inferior margins of the canal. Consequently, the tubal cartilage development seemed to be accelerated by a surrounding muscle, and conversely, the cartilage was likely to determine the other muscular and bony structures.

No MeSH data available.


Related in: MedlinePlus