Embryology of the Head, Face, and Oral Cavity

A comprehensive set of vocabulary flashcards covering the embryonic development of oral structures, facial features, and the thyroid gland as described in the lecture notes.

Oral Biology

The study of the origin, growth and development, structure and functions of the oral tissues, overlapping basic medical and clinical dental sciences.

Zygote

The term for the fertilized egg after it begins to grow, following the contact of sperm and egg in the distal part of the uterine tube.

Morula

A ball of cells produced from the fertilized egg within the uterine tube.

Proliferative period

The first $2$ weeks of development characterized by implantation and enlargement of the blastocyst.

Embryonic disk

The cell mass formed from the inner cell mass of the blastocyst which later becomes the embryo.

Neural tube

A structure formed from the neural plate on the dorsal surface of the embryonic disk during the second week of gestation.

Germinal period

The stage of development spanning from $0$ to $2$ weeks, including conception and implantation.

Embryonic period

The stage of development from $3$ to $8$ weeks, primarily involving organ development.

Fetal period

The stage of development from $9$ weeks until birth, involving further development and sensory experiences.

Trophoblast

The outer layer of cells in the blastocyst that forms extraembryonic tissues such as the placenta and yolk sac.

Embryoblasts

The inner mass of totipotent embryonic stem cells at one end of the blastocyst.

Bilaminar embryonic disc

A two-layered disk comprised of an upper epiblast and a lower hypoblast.

Gastrulation

The process during the third week of development where the bilaminar embryonic disk converts into a trilaminar disc of ectoderm, mesoderm, and endoderm.

Ectoderm

The germ layer that gives rise to the nervous system, tooth enamel, and the epidermis.

Mesoderm

The germ layer that develops into muscles, bones, cartilage, blood, dentine, pulp, cementum, and the periodontal ligament.

Endoderm

The germ layer that forms the GIT epithelium and associated glands.

Somites

Thirty-eight ($38$) pairs of mesodermal sections that give rise to most skeletal structures of the head, neck, and trunk.

Stomatodeum

The primitive oral cavity formed by the folding of the head fold, separated from the gut by the buccopharyngeal membrane.

Buccopharyngeal membrane

Also known as the oropharyngeal membrane, it separates the stomatodeum from the developing gut.

Branchial arches

A series of externally visible anterior bands lying under the early brain that give rise to structures of the head and neck.

Pharyngeal pouches

Grooves within the pharynx that separate each branchial arch and match external pharyngeal clefts.

Meckel's cartilage

The cartilage of the first branchial arch associated with the formation of the mandible.

Mandibular symphysis

A thin line of cartilage separating the two parts of the mandible at the midline, which fuses shortly after birth.

Primary palate

The anterior wedge-shaped medial part of the palate developed from the median palatine process.

Secondary palate

The part of the palate formed from the two lateral palatine processes or shelves.

Tuberculum impar

A median tongue bud that, along with two distal tongue buds, forms the anterior movable body of the tongue.

Copula

A structure that, along with the hypobranchial eminence, helps form the posterior immovable base of the tongue from arches $2$, $3$, and $4$.

Sulcus terminalis

A $V$-shaped groove that separates the surface of the body and the base of the tongue.

Foramen cecum

The initial site of the descent of the thyroid gland, located on the surface of the tongue at the junction of the body and base.

Thyroglossal duct

An epithelial cord or duct that remains attached to the tongue during the migration of the thyroid gland.

Thyroglossal cyst

A blind pocket lined with thyroid epithelium, commonly found as a swelling in the area of the hyoid bone.

Thyroglossal fistula

A swelling that has an opening on the surface of the neck, occurring along the route of thyroid descent.