BDS 217 - HEAD and NECK ANATOMY Sec 1: MoWe, 09.30-10.45; Sec 2: TuSu, 14.00-15.15 Topic 2: Development of the Head and Neck

Vocabulary flashcards covering key terms, stages of development, and anatomical structures related to the development of the head and neck, extracted from lecture notes for BDS 217.

Bucc

Related to the cheek.

Constrictor

A muscle whose contraction narrows a vessel or passage.

Crico

Ring-like.

Depressor

A muscle whose contraction pulls down the part of the body to which it is attached.

Genio

Related to chin.

Glossal

Related to tongue.

Hyoid

Has an upsilon shape (a "Y" shape or "u" shape).

Inferioris

Located below another structure.

Labii

Related to labia (an anatomical part that has a lip shape).

Oculi

Related to eye.

Orbicularis

A muscle that surrounds a cavity.

Paired

Exists in two copies, one in the right side and one in the left side.

Process

Swelling.

Quadrilateral

Square-shaped.

Stylo

Connected to the styloid process of the temporal bone.

Sulcus

Groove, furrow, trench, or gap.

Vallecula

Depression in a structure.

Human full in utero development

40 weeks of pregnancy or 38 weeks after the first missed period.

Embryo

Stage of human development until the end of week 8.

Fetus

Stage of human development from week 9 until the end of pregnancy.

Bilaminar disc

Embryo at 6-8 days, flat in shape, composed of two layers of cells (epiblast and hypoblast).

Embryoblast (inner cell mass)

Part of the blastocyst that will divide into Epiblast and Hypoblast.

Epiblast

Layer of cells adjacent to the amniotic cavity; differentiates into all cell types of the embryo and some extraembryonic structures; represents the dorsal side of the embryo.

Hypoblast

Layer of cells adjacent to the blastocoel; differentiates into extraembryonic structures only; does not give rise to any tissues of the embryo itself; represents the ventral side of the embryo.

Trophoblast

Surrounds the embryoblast; divided into Cytotrophoblast and Syncytiotrophoblast.

Cytotrophoblast

Surrounding layer of trophoblast, consists of mononucleated cells.

Syncytiotrophoblast

Part of trophoblast, consists of multinucleated cells.

Amniotic cavity

Formed when the epiblast slits into two layers.

Amnioblast

Layer of cells from the epiblast that will form the membrane of the amniotic cavity.

Gastrulation

Process beginning with primitive streak formation on the epiblast surface, resulting in the formation of three germ layers.

Primitive streak

Defines the caudal region of the embryo; its formation on the epiblast surface signals the start of gastrulation.

Oropharyngeal membrane

Defines the location of the cranial region of the embryo.

Endoderm

Innermost germ layer, formed when ingressed epiblast cells displace the hypoblast.

Mesoderm

Middle germ layer, formed when ingressed epiblast cells lie between the epiblast and newly created endoderm.

Ectoderm

Outermost germ layer, formed by epiblast cells that do not migrate and remain in the epiblast.

Trilaminar germ disc

Composed of the three germ layers: Ectoderm, Mesoderm, and Endoderm.

Notochord

A tube of mesodermal cells extending anteroposteriorly along the midline, induces neural differentiation.

Neural differentiation

Development of the nervous system from the neuroectoderm.

Neurulation

The process of neural differentiation, leading to the formation of the neural tube.

Neuroectoderm

The ectoderm immediately above the notochord.

Neural plate

Thickened columnar epithelium formed from the neuroectoderm.

Neural tube

Formed when the neural plate elevates and folds; develops into the brain and spine.

Paraxial mesoderm

A subdivision of the mesoderm.

Intermediate mesoderm

A subdivision of the mesoderm.

Lateral plate mesoderm

A subdivision of the mesoderm.

Yolk sac

Extraembryonic membrane that will become part of the guts (intestines).

Neural crest

Population of cells emerging at the dorsal limit of the neural tube, migrating to contribute to non-neural structures like pigment cells, cartilage, and bone.

Placode

Ectoderm thickenings in the cranial region, involved in the development of sensory (vision, hearing, smell) and integumentary organs.

Otic placodes

First placodes visible on the surface of the embryo, involved in hearing development.

Olfactory (Nasal) placodes

Each has two components (medial and lateral), will form the nose olfactory epithelium.

Optic (Lens) placodes

Will form the lens of the eye.

Pharyngeal/branchial apparatus

Most distinctive feature in head and neck development, forming structures of the head, neck, and chest.

Pharyngeal arches

Structures within the pharyngeal apparatus (1, 2, 3, 4, 6 in humans), formed from neural crest cells and paraxial mesoderm.

Pharyngeal pouches

Structures within the pharyngeal apparatus (1, 2, 3, 4 in humans), formed from the internal endoderm between consecutive arches.

Pharyngeal grooves/clefts

Structures within the pharyngeal apparatus (1, 2, 3, 4 in humans), formed from the external ectoderm between consecutive arches.

Pharyngeal membranes

Structures within the pharyngeal apparatus (1, 2, 3, 4), which represent a groove + a pouch.

Pharyngeal Arch 1 nerve

Trigeminal nerve (V).

Maxillary nerve (V2)

Innervates the maxillary part of Pharyngeal Arch 1.

Mandibular nerve (V3)

Innervates the mandibular part of Pharyngeal Arch 1.

Pharyngeal Arch 2 nerve

Facial nerve (VII).

Pharyngeal Arch 3 nerve

Glossopharyngeal nerve (IX).

Pharyngeal Arch 4 nerve

Vagus nerve (X).

Pharyngeal Arch 6 nerve

Vagus nerve (X).

Mandibular processes

Two processes originating from the 1st pharyngeal arch that rapidly extend to the facial midline and merge.

Maxillary processes

Two processes originating from the 1st pharyngeal arch.

Frontonasal prominence

A facial prominence (not an arch) that forms along with mandibular and maxillary processes.

Skeletal components of head and neck

Develop primarily from neural crest cells (with some paraxial mesoderm contribution).

Muscular structures of head and neck

Develop from mesodermal cells.