Pharyngeal Apparatus Development Quiz

Premature fusion of skull bones, leading to an abnormal head shape.

A congenital condition where the upper lip and/or palate have a gap.

Underdevelopment of one side of the face.

Underdevelopment of facial bones, particularly the cheekbones.

The formation of the cheeks starts with the pharyngeal arches from the mesoderm.

Fusion of the medial nasal prominence forming the frontal nasal prominence, which will give rise to the nose.

Invagination of nasal placodes to form nasal pits.

Separation and deepening of the nasal septum to form two nasal cavities.

The second pharyngeal arch gives rise to the muscles involved in facial expression and chewing. These include the stylohoid muscle, posterior belly of the digastric muscle, and stapedius muscle of the middle ear.

The third pharyngeal arch contributes to the hyoid bone and a single throat muscle called the stylopharyngeus.

The fourth pharyngeal arch develops into muscles involved in swallowing and vocalization. These include the levator palatini, pharyngeal constrictors, and cricothyroid muscles.

The sixth pharyngeal arch is responsible for the development of the rest of the intrinsic muscles of the larynx, which are crucial for voice production.

The first pharyngeal pouch develops into the middle ear and Eustachian tube, while the first pharyngeal cleft forms the external auditory meatus and ear drum.

The second to fourth pharyngeal clefts degenerate, while the cells from the second pouch form the primitive tonsils.

The dorsal portion of the third pharyngeal pouch develops into the inferior parathyroid gland, while the ventral portion becomes the primitive thymus.

The dorsal portion of the fourth pharyngeal pouch forms the superior parathyroid gland. The ventral portion forms the ultimo-pharyngeal body, which contributes to the parafollicular/C-cells of the thyroid.

The development of the nose, starting from the 12th week after conception, involves the refinement and maturation of its structures, including the nasal passages, septum, and conchae.

A congenital condition where there is a gap or groove in the nose.

A birth defect where the nose is either absent or underdeveloped.

A birth defect where a tubular structure protrudes from the nose.

A blockage of the nasal passages that is present at birth.

A condition where the nasal septum is shifted to one side, causing breathing difficulties.

A condition where growths develop in the nasal passages, blocking airflow and causing discomfort.

The initial stage of palate development, occurring during the 6th to 7th week of gestation, involves the fusion of the medial nasal prominences.

A clear gel-like substance that fills the vitreous space, providing support and cushioning to the retina.

Collagen fibers that are part of the vitreous body, adding structure and strength to the eye.

A congenital condition where the eye is smaller than normal.

The absence of one or both eyes, a rare birth defect.

A gap or defect in the iris, retina, or optic nerve.

Drooping of one or both eyelids, often caused by muscle weakness.

Thinning and conical shape of the cornea, causing distorted vision.

A genetic disorder causing progressive deterioration of the retina, leading to vision loss.

The transparent, outer layer of the eye that helps focus light.

The corneal epithelium, stroma, and endothelium form during the first 12 weeks of embryonic development, becoming more organized and structured.

The choroid, located between the retina and sclera, develops from mesenchymal cells migrating between the RPE and sclera.

The choroid differentiates into two layers: the choriocapillaris (capillary layer) and larger vessels, becoming more vascularized and organized during the first 12 weeks of development.

The sclera, the white outer layer of the eye, develops from mesenchymal cells migrating around the optic cup.

The scleral mesenchyme differentiates into scleral fibroblasts, which produce collagen, making the sclera more dense and organized during the first 12 weeks of development.

The iris, the colored part of the eye, develops from the anterior portion of the optic cup, forming two layers: the stroma and epithelium.

The stroma of the iris is derived from the mesenchyme, while the epithelium originates from the neuroectoderm.

The cochlear duct forms as a tubular outgrowth from the saccule, spiraling through the mesenchyme to complete 2.5 turns by the 8th week of development.

Two epithelial ridges, inner and outer, develop in the cochlear duct at the 7th week. The inner ridge forms the spiral liumbus, while the outer ridge gives rise to the sensory hair cells.

Flattened outpouchings on the dorsal otic vesicle at the 6th week develop into three semicircular canals: superior, posterior, and lateral.

The development of the middle ear begins with the formation of the first pharyngeal arch during the 4th week.

During the 5th week, the endoderm-lined pharynx invaginates between the first and second pharyngeal arches to form the first pharyngeal pouch.

By the 6th week, the first pharyngeal pouch differentiates into the proximal tubotympanic recess, which forms the eustachian tube, and the distal tympanic cavity, which develops into the middle ear cavity.

Cartilage templates for the malleus, incus, and stapes are formed during the 6th week of embryonic development.

Absence, underdevelopment, or abnormal development of the cochlea, semicircular canals, and other inner ear structures can occur.