Embryology of the Pharynx & Larynx

Question 1

Which embryological germ layer forms the pharyngeal clefts?

Answer 1

Clefts form from the Ectoderm

Question 2

Which embryological germ layer forms the pharyngeal arches?

Answer 2

Arches form from the Mesoderm

Question 3

Which embryological germ layer forms the pharyngeal pouches?

Answer 3

Pouches form from the Endoderm

Question 4

What nerve supplies arch 4-6?

Answer 4

Vagus (CN X)

Question 5

What muscle and nerve come from pharyngeal Arch 1?

Answer 5

Arch 1 (Mandibular)

Nerve: trigeminal nerve (CN V) maxillary and mandibular divisions

Mandibular divisions provide motor innervation for the muscles of mastication

Question 6

What muscle and nerve come from pharyngeal Arch 2?

Answer 6

Nerve: facial nerve (CN VII)

Innervates muscles of facial expression

Question 7

What muscle and nerve come from pharyngeal Arch 3?

Answer 7

Arch 3

Nerve: glossopharyngeal nerve

Innervates the stylopharyngeus muscle by the

Question 8

What muscle and nerve come from pharyngeal Arch 4?

Answer 8

Arch 4

Nerve: Vagus (CN X)

Superior laryngeal branch - cricothyroid, levator palatine, pharyngeal constrictors

Question 9

What muscle and nerve come from pharyngeal Arch 6?

Answer 9

Arch 6

Nerve: Vagus (CN X)

Recurrent laryngeal branch - intrinsic muscles of the larynx

Question 10

What are the derivatives of pharyngeal pouch 1?

Answer 10

Tympanic (middle ear) cavity

Auditory (eustachian) tube

Question 11

What are the derivatives of pharyngeal pouch 2?

Answer 11

Palatine tonsils

Tonsillar fossa

Question 12

What are the derivatives of pharyngeal pouch 3?

Answer 12

Inferior parathyroid gland

Thymus

Question 13

What are the derivatives of pharyngeal pouch 4?

Answer 13

Superior parathyroid gland

Question 14

Describe the location and cause of branchial cysts.

Answer 14

Branchial cysts are a swelling found along the anterior border of the sternocleidomastoid if the 2nd, 3rd, and 4th arch clefts persist.

Question 15

Describe the location and cause of Thyroglossal Cysts.

Answer 15

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

Question 16

What supplies motor innervation to the tongue?

Answer 16

The hypoglossal nerve (XII) supplies the motor innervation to the tongue.

Question 17

What innervates the anterior 2/3 of the tongue?

Answer 17

Anterior two-thirds of the tongue:

General sensation - lingual nerve (from V3)

Taste - chorda tympani (from CN VII) is carried by the lingual nerve

Question 18

What innervates the posterior 1/3 of the tongue?

Answer 18

Posterior one-third of the tongue:

General sensation - glossopharyngeal nerve (CN IX)

Taste - glossopharyngeal nerve (CN IX)

Question 19

What innervates the base of the tongue?

Answer 19

Base of Tongue:

Taste – vagus (CN X)