Pharyngeal Pouch

Frontonasal prominence

Maxillary prominence "U Stomodeum

Frontonasal prominence Nasal placode

Maxillary prominence

Mandibular arch

Pharyngeal arches, 2nd and 3rd

Frontonasal Prominence

Figure 15.5 A. Frontal view of an embryo of approximately 24 days. The stomodeum, temporarily closed by the buccopharyngeal membrane, is surrounded by five mesenchymal prominences. B. Frontal view of a slightly older embryo showing rupture of the buccopharyngeal membrane and formation of the nasal placodes on the frontonasal prominence. C. Scanning electron micrograph of a human embryo similar to that shown in B.

Figure 15.5 A. Frontal view of an embryo of approximately 24 days. The stomodeum, temporarily closed by the buccopharyngeal membrane, is surrounded by five mesenchymal prominences. B. Frontal view of a slightly older embryo showing rupture of the buccopharyngeal membrane and formation of the nasal placodes on the frontonasal prominence. C. Scanning electron micrograph of a human embryo similar to that shown in B.

mylohyoid, tensor tympani, and tensor palatini. The nerve supply to the muscles of the first arch is provided by the mandibular branch of the trigeminal nerve (Fig. 15.7). Since mesenchyme from the first arch also contributes to the dermis of the face, sensory supply to the skin of the face is provided by ophthalmic, maxillary, and mandibular branches of the trigeminal nerve.

Muscles of the arches do not always attach to the bony or cartilaginous components of their own arch but sometimes migrate into surrounding regions. Nevertheless, the origin of these muscles can always be traced, since their nerve supply is derived from the arch of origin.

Pharyngeal pouch

Pharyngeal pouch

Pharyngeal Pouch

Figure 15.6 A. Pharyngeal arches. Each arch contains a cartilaginous component, a cranial nerve, an artery, and a muscular component. B. Scanning electron micrograph of the pharyngeal region of a mouse embryo, showing the pharyngeal arches, pouches, and clefts. The first three arches (I, II, and III) are visible. A remnant of the buccopharyngeal membrane (arrow) is present at the entrance to the oral cavity. C. Higher magnification of the pharyngeal arches of a mouse embryo. Pharyngeal arches consist of a core of mesoderm lined by endoderm internally (arrowheads) and ectoderm externally (arrows). Pouches and clefts occur between the arches, where endoderm and ectoderm appose each other.

Figure 15.6 A. Pharyngeal arches. Each arch contains a cartilaginous component, a cranial nerve, an artery, and a muscular component. B. Scanning electron micrograph of the pharyngeal region of a mouse embryo, showing the pharyngeal arches, pouches, and clefts. The first three arches (I, II, and III) are visible. A remnant of the buccopharyngeal membrane (arrow) is present at the entrance to the oral cavity. C. Higher magnification of the pharyngeal arches of a mouse embryo. Pharyngeal arches consist of a core of mesoderm lined by endoderm internally (arrowheads) and ectoderm externally (arrows). Pouches and clefts occur between the arches, where endoderm and ectoderm appose each other.

Trigeminal ganglion

Ophthalmic bra nerve V

Maxilla ne

Trigeminal ganglion

Ophthalmic bra nerve V

Maxilla ne

Cranial Nerves Pharyngeal Pouches

Vagus nerve

Mandibular branch nerve V

Figure 15.7 Each pharyngeal arch is supplied by its own cranial nerve. The trigeminal nerve supplying the first pharyngeal arch has three branches: the ophthalmic, maxillary, and mandibular. The nerve of the second arch is the facial nerve; that of the third, the glossopharyngeal nerve. The musculature of the fourth arch is supplied by the superior laryngeal branch of the vagus nerve, and that of the sixth arch, by the recurrent branch of the vagus nerve.

Mandibular branch nerve V

Vagus nerve

Glossopharyngeal nerve

Figure 15.7 Each pharyngeal arch is supplied by its own cranial nerve. The trigeminal nerve supplying the first pharyngeal arch has three branches: the ophthalmic, maxillary, and mandibular. The nerve of the second arch is the facial nerve; that of the third, the glossopharyngeal nerve. The musculature of the fourth arch is supplied by the superior laryngeal branch of the vagus nerve, and that of the sixth arch, by the recurrent branch of the vagus nerve.

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