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Face and Pharynx

Branchial Apparatus

The branchial (Gk. gill) apparatus of a four-week-old embryo consists of the branchial arches, pouches, grooves (clefts), and membranes.

Each branchial arch (1, 2, 3, 4 and 6) is composed of lateral mesoderm and neural crest cells and each is associated with a cranial nerve and an aortic arch.

Table 9 - Adult Derivatives of Pharyngeal Arches

 

 

Adult Derivatives

Arch

Nerve

Muscles (Mesoderm)

Skeletal Structures (Neural Crest)

First (mandibular)

Trigeminal
(CN V)

Muscles of mastication, mylohyoid muscle tensor veli palitini muscle, tensor tympani muscle, anterior belly of the digastric muscle

Maxilla, zygomatic bone, temporal bone, palatine bone, vomer, mandible, malleus, incus, sphenomandibular ligament

Second (hyoid)

Facial
(CN VII)

Muscles of facial expression, stylohyoid muscle, stapedius muscle posterior belly of digastric muscle

Stapes, styloid process, stylohyoid ligament, lesser horn and superior body of the hyoid bone

Third

Glossopharyngeal
(CN IX)

Stylopharyngeus muscle

Greater horn and inferior body of the hyoid bone

Fourth

Vagus
(CN X) – Superior laryngeal branch

Muscles of soft palate (except tensor veli palatini) and muscles of pharynx (except stylopharyngeus), cricothyroid muscle, cricopharyngeus muscle,

Thyroid cartilage, cricothyroid cartilage, arytenoid cartilage, laryngeal cartilages

Sixth[1]

Vagus
(CN X) –Recurrent laryngeal branch

Intrinsic muscles of the larynx (except cricothyroid), upper (skeletal) muscles of esophagus

Laryngeal cartilages

 

Table 10 - Adult Derivatives of Pharyngeal Pouches

Pouch

Adult derivatives

1

Lining of auditory tube and tympanic cavity (middle ear cavity)

2

Largely obliterated, lining of intratonsillar cleft (tonsilar fossa)

3

Inferior parathyroid glands, thymus

4

Superior parathyroid glands, parafollicular cells of thyroid gland

Figure 6 - Pharyngeal arches and pouches

Figure 7 - Development of hard palate

Thyroid Gland

The thyroid gland begins as a downgrowth of the floor of the pharynx called the thyroid diverticulum. As it descends down the neck it remains connected to the tongue via the thyroglossal duct. In the adult a remnant of this duct persists in the tongue as the foramen cecum.

 

Figure 8 - Development of the face


[1] The fifth branchial arch degenerates in humans

 

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Send comments to Dr. Tom Gest <gest@umich.edu>.
Last modified: Thursday, 06-Jan-2000 13:16:24 EST