BDS 217 - Head and Neck Anatomy: Development of the Head and Neck

Flashcards covering key vocabulary, structures, and processes related to the development of the head and neck, including embryological stages, pharyngeal apparatus, skull, face, palate, and tongue.

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.

Embryo

Stage of human full in utero development until the end of week 8.

Fetus

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

Bilaminar Disc

Embryo's shape that is flat and composed of two layers of cells: the epiblast and hypoblast, during days 6-8 of development.

Embryoblast (inner cell mass)

Part of the blastocyst that will divide into epiblast and hypoblast; gives rise to all cell types of the embryo.

Epiblast

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

Hypoblast

Layer of cells adjacent to the blastocoel, differentiates into extraembryonic structures only, and represents the ventral side of the embryo.

Trophoblast

Surrounds the embryoblast and is divided into cytotrophoblast and syncytiotrophoblast.

Amnioblast

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

Gastrulation

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

Primitive Streak

Defines the caudal region of the embryo and marks the beginning of gastrulation.

Oropharyngeal Membrane

Defines the location of the cranial region of the embryo.

Trilaminar Germ Disc

Formed by the ectoderm, mesoderm, and endoderm during gastrulation.

Endoderm

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

Mesoderm

Middle germ layer formed by ingressed epiblast cells lying between the epiblast and the newly created endoderm.

Ectoderm

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

Notochord

A tube of mesodermal cells that extends anteroposteriorly along the midline and induces neural differentiation.

Neurulation

The development of the nervous system from the neuroectoderm.

Neuroectoderm

The ectoderm that lies immediately above the notochord.

Neural Tube

Formed when the neural plate folds and elevates, eventually forming the brain and the spine.

Paraxial Mesoderm

Symmetrically divided mesoderm portion along the right-left axis, contributing to head and neck formation.

Intermediate Mesoderm

Symmetrically divided mesoderm portion along the right-left axis.

Lateral Plate Mesoderm

Symmetrically divided mesoderm portion along the right-left axis, contributing to head and neck formation.

Neural Crest

A population of cells emerging at the most dorsal limit of the neural tube during neurulation, contributing to non-neural structures like pigment cells, cartilage, and bone, and forming a major part of the head and neck.

Pharyngeal Arches

Most of the head and neck are formed from these structures, which consist of neural crest cells and paraxial mesoderm.

Placode

Ectoderm thickenings in the cranial region with important roles in the development of sensory and integumentary organs.

Otic Placodes

The first placodes visible on the surface of the embryo, related to hearing.

Olfactory (Nasal) Placodes

Each has medial and lateral components and will form the nose olfactory epithelium.

Optic (Lens) Placodes

Will form the lens of the eye.

Pharyngeal/Branchial Apparatus

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

Pharyngeal Arches

Components of the pharyngeal apparatus (1, 2, 3, 4, 6) formed from neural crest cells and paraxial mesoderm.

Pharyngeal Pouches

Components of the pharyngeal apparatus (1, 2, 3, 4) formed from the internal endoderm sitting between consecutive arches.

Pharyngeal Grooves/Clefts

Components of the pharyngeal apparatus (1, 2, 3, 4) formed from the external ectoderm sitting between consecutive arches.

Pharyngeal Membranes

Components of the pharyngeal apparatus (1, 2, 3, 4) representing a groove + a pouch.

Arch 1 Innervation

Trigeminal nerve (V).

Arch 2 Innervation

Facial nerve (VII).

Arch 3 Innervation

Glossopharyngeal nerve (IX).

Arch 4 and 6 Innervation

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 swelling that is not an arch, contributing to facial development.

Pharyngeal Arch 1 Cartilage Derivatives

Meckel's cartilage (degenerates), malleus, incus, sphenomandibular ligament.

Pharyngeal Arch 2 Cartilage Derivatives

Reichert's cartilage, stapes, styloid process, stylohyoid ligament, upper half of hyoid, lesser cornu of the hyoid.

Pharyngeal Arch 3 Cartilage Derivatives

Greater cornu of the hyoid, inferior part of the hyoid body.

Pharyngeal Arch 4 Cartilage Derivatives

Thyroid cartilage and epiglottic cartilage of the larynx.

Pharyngeal Arch 6 Cartilage Derivatives

Cricoid, arytenoid, and corniculate cartilages of the larynx.

Pharyngeal Pouch 1 Adult Structure

Epithelium of the auditory tube and tympanic cavity (from tubotympanic recess).

Pharyngeal Pouch 2 Adult Structure

Epithelium of the palatine tonsil and tonsillar fossa (from primitive palatine tonsils).

Pharyngeal Pouch 3 Adult Structure

Inferior parathyroid gland (dorsal part) and thymus (ventral part).

Pharyngeal Pouch 4 Adult Structure

Superior parathyroid gland (dorsal part) and ultimobranchial body (ventral part).

Ultimobranchial body

Originates from the ventral part of the 4th pharyngeal pouch and is invaded by neural crest to form parafollicular cells.

Neurocranium

The protective case around the brain, divided into membranous and cartilaginous neurocranium.

Membranous Neurocranium

Flat bones of the cranial vault, formed by intramembranous ossification.

Cartilaginous Neurocranium (Chondrocranium)

The base of the skull (cranial base), formed by endochondral ossification.

Viscerocranium (Facial Skeleton)

The skeleton of the face, undergoing intramembranous ossification (with some endochondral in mandible).

Intramembranous Ossification

Process where neural crest cells differentiate directly into bone, forming flat bones of the skull and cranial vault.

Endochondral Ossification

Process where cells first become hyaline cartilage models, and then become ossified, forming most bones including the base of the skull.

Upper Lip Developmental Origin

Maxillary prominence and Medial nasal prominence.

Lower Lip Developmental Origin

Mandibular prominence.

Lacrimal Sac & Nasolacrimal Duct Developmental Origin

Nasolacrimal groove that separates the lateral nasal prominence and the maxillary prominence.

Nose Developmental Origin

Frontonasal prominence, Medial nasal prominence, Lateral nasal prominence.

Philtrum Developmental Origin

Intermaxillary segment (fusion of medial nasal prominences).

Stomodeum

Invagination of the surface ectoderm of the 1st branchial arch, later connecting to the oral cavity's endodermal epithelium.

Nasal Pits

Formed by the invagination of nasal placodes, creating ridges of tissue (lateral and medial nasal prominences).

Intermaxillary Segment

Formed by the fusion of the medial nasal prominences at the midline, containing the central and lateral incisors and contributing to the philtrum and primary palate.

Oral Cavity

The space located between the lips and cheeks externally to the palatoglossal fold internally.

Primary Palate

The initial portion of the palate in development, formed by the intermaxillary segment, containing central and lateral incisors.

Secondary Palate

Formed by protrusions (shelves) from the maxillary prominences that fuse together when the tongue no longer occupies the space between them.

Incisive Foramen

The point where the primary and secondary palatal tissues meet.

Definitive Palate

Formed by the fusion of the primary and secondary palates and the nasal septum, contributing to both hard and soft palates.

Tongue Anterior 2/3 (Body) Developmental Origin

2 lateral lingual swellings and tuberculum impar (which is overgrown).

Tongue Posterior 1/3 (Base) Developmental Origin

Hypobranchial eminence from the 3rd and 4th arches (with minimal 2nd arch contribution).

Tongue Root Developmental Origin

Epiglottic swelling (from 4th arch), arytenoid swelling, laryngotracheal groove.

GSA (General Somatic Afferent)

Sensory innervation for pain, temperature, and discriminative touch.

SVA (Special Visceral Afferent)

Sensory innervation for taste.

Anterior 2/3 Tongue GSA Innervation

Lingual branch of the mandibular division of the trigeminal nerve.

Anterior 2/3 Tongue SVA Innervation

Chorda tympani of the facial nerve.

Posterior 1/3 Tongue GSA & SVA Innervation

Glossopharyngeal nerve.

Root of Tongue GSA & SVA Innervation

Internal laryngeal branch of the vagus nerve.

Tongue Muscles Origin

Mesoderm from the occipital somites, migrating anteriorly with the hypoglossal nerve.

Hypoglossal Nerve

Associated with the development of the extrinsic and intrinsic muscles of the tongue.