Embryology of the Pharynx & Larynx Flashcards
Which embryological germ layer forms the pharyngeal clefts?
Clefts form from the Ectoderm
Which embryological germ layer forms the pharyngeal arches?
Arches form from the Mesoderm
Which embryological germ layer forms the pharyngeal pouches?
Pouches form from the Endoderm
What nerve supplies arch 4-6?
Vagus (CN X)
What muscle and nerve come from pharyngeal Arch 1?
Arch 1 (Mandibular)
Nerve: trigeminal nerve (CN V) maxillary and mandibular divisions
Mandibular divisions provide motor innervation for the muscles of mastication
What muscle and nerve come from pharyngeal Arch 2?
Nerve: facial nerve (CN VII)
Innervates muscles of facial expression
What muscle and nerve come from pharyngeal Arch 3?
Arch 3
Nerve: glossopharyngeal nerve
Innervates the stylopharyngeus muscle by the
What muscle and nerve come from pharyngeal Arch 4?
Arch 4
Nerve: Vagus (CN X)
Superior laryngeal branch - cricothyroid, levator palatine, pharyngeal constrictors
What muscle and nerve come from pharyngeal Arch 6?
Arch 6
Nerve: Vagus (CN X)
Recurrent laryngeal branch - intrinsic muscles of the larynx
What are the derivatives of pharyngeal pouch 1?
Tympanic (middle ear) cavity
Auditory (eustachian) tube
What are the derivatives of pharyngeal pouch 2?
Palatine tonsils
Tonsillar fossa
What are the derivatives of pharyngeal pouch 3?
Inferior parathyroid gland
Thymus
What are the derivatives of pharyngeal pouch 4?
Superior parathyroid gland
Describe the location and cause of branchial cysts.
Branchial cysts are a swelling found along the anterior border of the sternocleidomastoid if the 2nd, 3rd, and 4th arch clefts persist.
Describe the location and cause of Thyroglossal Cysts.
Thyroglossal Cysts are a midline swelling in the neck (under the chin/above hyoid) due to failure of the thyroid gland to descend completely from its site of origin; typically painless
What supplies motor innervation to the tongue?
The hypoglossal nerve (XII) supplies the motor innervation to the tongue.
What innervates the anterior 2/3 of the tongue?
Anterior two-thirds of the tongue:
General sensation - lingual nerve (from V3)
Taste - chorda tympani (from CN VII) is carried by the lingual nerve
What innervates the posterior 1/3 of the tongue?
Posterior one-third of the tongue:
General sensation - glossopharyngeal nerve (CN IX)
Taste - glossopharyngeal nerve (CN IX)
What innervates the base of the tongue?
Base of Tongue:
Taste – vagus (CN X)
