Frontonasal process

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Frontonasal process
Gray44.png
Under surface of the head of a human embryo about twenty-nine days old. (Frontonasal process labeled at center left.)
Details
Precursor Ectoderm
Identifiers
TE E5.3.0.0.0.0.6
Anatomical terminology

The frontonasal process, or frontonasal prominence is one of the five swellings that develop into the face. The frontonasal process is unpaired, and the others are the paired maxillary prominences, and the paired mandibular prominences. During the fourth week of embryonic development, an area of thickened ectoderm develops, on each side of the frontonasal process called the nasal placodes or olfactory placodes, and appear immediately under the forebrain. [1]

Maxillary prominence

Continuous with the dorsal end of the first pharyngeal arch, and growing forward from its cephalic border, is a triangular process, the maxillary prominence, the ventral extremity of which is separated from the mandibular arch by a ">"-shaped notch.

The mandibular prominence is an embryological structure which gives rise to the lower portion of the face.

Embryonic development also embryogenesis is the process by which the embryo forms and develops. In mammals, the term refers chiefly to early stages of prenatal development, whereas the terms fetus and fetal development describe later stages.

Contents

By invagination these areas are converted into two nasal pits, which indent the frontonasal prominence and divide it into medial and lateral nasal processes. [2]

Nasal placode

The nasal placode gives rise to the olfactory epithelium of the nose. Two nasal placodes arise as thickened ectoderm from the frontonasal process. During the fifth week of development the placodes increase in size. In the sixth week of development the centre of each placode grows inwards to form the two nasal pits. The invaginations will give rise to the olfactory epithelium that lines the roof of the nasal cavity.

Nasal processes

Medial and lateral nasal processes shown on embryo. Gray45.png
Medial and lateral nasal processes shown on embryo.

The medial nasal process (nasomedial) on the inner side of each nasal pit merge into the intermaxillary segment and form the upper lip, crest, and tip of the nose. [1] The medial nasal processes merge with the maxillary prominences . The lateral nasal process from each side merge to form the alae of the nose. [3]

Intermaxillary segment

The intermaxillary segment in an embryo is a mass of tissue formed by the merging of tissues in the vicinity of the nose. It is essential for human survival. It is primordial, since in the further development of the embryo this particular mass no longer appears, but parts of it remain in "the intermaxillary portion of the upper jaw, the portion of the upper lip, and the primary palate".

Human nose feature of the face

The human nose is the most protruding part of the face. It bears the nostrils and is the first organ of the respiratory system. It is also the principal organ in the olfactory system. The shape of the nose is determined by the nasal bones and the nasal cartilages, including the nasal septum which separates the nostrils and divides the nasal cavity into two. On average the nose of a male is larger than that of a female.

Clinical significance

Failure to fuse can cause a cleft lip.

Genetics

There is some evidence that development involves Sonic hedgehog and Fibroblast growth factor 8. [4]

Sonic hedgehog protein-coding gene in the species Homo sapiens

Sonic hedgehog is a protein in humans("sonic hedgehog") gene. Both the gene and the protein may also be found notated alternatively as "Shh".

Related Research Articles

Lacrimal bone smallest and most fragile bone of the human skull and face

The lacrimal bone is a small and fragile bone of the facial skeleton; it is roughly the size of the little fingernail. It is situated at the front part of the medial wall of the orbit. It has two surfaces and four borders. Several bony landmarks of the lacrimal bone function in the process of lacrimation or crying. Specifically, the lacrimal bone helps form the nasolacrimal canal necessary for tear translocation. A depression on the anterior inferior portion of the bone, the lacrimal fossa, houses the membranous lacrimal sac. Tears or lacrimal fluid, from the lacrimal glands, collect in this sac during excessive lacrimation. The fluid then flows through the nasolacrimal duct and into the nasopharynx. This drainage results in what is commonly referred to a runny nose during excessive crying or tear production. Injury or fracture of the lacrimal bone can result in posttraumatic obstruction of the lacrimal pathways.

Inferior nasal concha facial bone

The inferior nasal concha is one of the three paired nasal conchae in the nose. It extends horizontally along the lateral wall of the nasal cavity and consists of a lamina of spongy bone, curled upon itself like a scroll,. The inferior nasal conchae are considered a pair of facial bones. As the air passes through the turbinates, the air is churned against these mucosa-lined bones in order to receive warmth, moisture and cleansing. Superior to inferior nasal concha are the middle nasal concha and superior nasal concha which arise from the cranial portion of the skull. Hence, these two are considered as a part of the cranial bones.

Vomer facial bone

The vomer is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones. The vomer forms the inferior part of the nasal septum, with the superior part formed by the perpendicular plate of the ethmoid bone. The name is derived from the Latin word for a ploughshare and the shape of the bone.

Nasion intersection of the frontal bone and two nasal bones of the human skull

The nasion is the most anterior point of the frontonasal suture that joins the nasal part of the frontal bone and the nasal bones. It marks the midpoint at the intersection of the frontonasal suture with the internasal suture joining the nasal bones. It is visible on the face as a distinctly depressed area directly between the eyes, just superior to the bridge of the nose. It is a cephalometric landmark that is just below the glabella.

Orbital part of frontal bone

The orbital or horizontal part of the frontal bone consists of two thin triangular plates, the orbital plates, which form the vaults of the orbits, and are separated from one another by a median gap, the ethmoidal notch.

Frontal sinus one of the four pairs of paranasal sinuses that are situated behind the brow ridges

The frontal sinuses are one of the four pairs of paranasal sinuses that are situated behind the brow ridges. Sinuses are mucosa-lined airspaces within the bones of the face and skull. Each opens into the anterior part of the corresponding middle nasal meatus of the nose through the frontonasal duct which traverses the anterior part of the labyrinth of the ethmoid. These structures then open into the semilunar hiatus in the middle meatus.

Semilunar hiatus

The semilunar hiatus or hiatus semilunaris, is a crescent-shaped groove in the lateral wall of the nasal cavity just inferior to the ethmoid bulla. It is the location of the openings for maxillary sinus.It is bounded inferiorly and anteriorly by the sharp concave margin of the uncinate process of the ethmoid bone, superiorly by the ethmoid bulla, and posteriorly by the middle nasal concha.

Ethmoidal labyrinth

The ethmoidal labyrinth or lateral mass of the ethmoid bone consists of a number of thin-walled cellular cavities, the ethmoid air cells, arranged in three groups, anterior, middle, and posterior, and interposed between two vertical plates of bone; the lateral plate forms part of the orbit, the medial plate forms part of the nasal cavity. In the disarticulated bone many of these cells are opened into, but when the bones are articulated, they are closed in at every part, except where they open into the nasal cavity.

Squamous part of the frontal bone

There are two surfaces of the squamous part of the frontal bone: the external surface, and the internal surface.

Primary palate

Around the 5th week, the intermaxillary segment arises as a result of fusion of the two medial nasal processes and the frontonasal process within the embryo. The intermaxillary segment gives rise to the primary palate. The primary palate will form the premaxillary portion of the maxilla. This small portion is anterior to the incisive foramen and will contain the maxillary incisors.

Puinave, AKA Waipunavi (Guaipunabi) or Wanse (Wãnsöhöt), is a poorly attested and generally unclassified language of South America.

Frontonasal dysplasia (FND) is a congenital malformation of the midface. For the diagnosis of FND, a patient should present at least two of the following characteristics: hypertelorism, a wide nasal root, vertical midline cleft of the nose and/or upper lip, cleft of the wings of the nose, malformed nasal tip, encephalocele or V-shaped hair pattern on the forehead. The cause of FND remains unknown. FND seems to be sporadic (random) and multiple environmental factors are suggested as possible causes for the syndrome. However, in some families multiple cases of FND were reported, which suggests a genetic cause of FND.

Pharynx part of the throat that is behind the mouth and nasal cavity

The pharynx is the part of the throat behind the mouth and nasal cavity, and above the esophagus and larynx – the tubes going down to the stomach and the lungs. It is found in vertebrates and invertebrates, though its structure varies across species.

Nasal meatus Wikipedia disambiguation page

A nasal meatus is a nasal passage of the nasal cavity, of which there are three; the superior meatus, middle meatus and inferior meatus. These nasal meatuses are also known as meatus nasi superior, meatus nasi medius, and meatus nasi inferior..

The face and neck development of the human embryo refers to the development of the structures from the third to eighth week that give rise to the future head and neck. They consist of three layers, the ectoderm, mesoderm and endoderm, which form the mesenchyme, neural crest and neural placodes. The paraxial mesoderm forms structures named somites and somitomeres that contribute to the development of the floor of the brain and voluntary muscles of the craniofacial region. The lateral plate mesoderm consists of the laryngeal cartilages. The three tissue layers give rise to the pharyngeal apparatus, formed by six pairs of pharyngeal arches, a set of pharyngeal pouches and pharyngeal grooves, which are the most typical feature in development of the head and neck. The formation of each region of the face and neck is due to the migration of the neural crest cells which come from the ectoderm. These cells determine the future structure to develop in each pharyngeal arch. Eventually, they also form the neurectoderm, which forms the forebrain, midbrain and hindbrain, cartilage, bone, dentin, tendon, dermis, pia mater and arachnoid mater, sensory neurons, and glandular stroma.

References

This article incorporates text in the public domain from page 67 of the 20th edition of Gray's Anatomy (1918)

The public domain consists of all the creative works to which no exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly waived, or may be inapplicable.

<i>Grays Anatomy</i> English-language textbook of human anatomy

Gray's Anatomy is an English language textbook of human anatomy originally written by Henry Gray and illustrated by Henry Vandyke Carter. Earlier editions were called Anatomy: Descriptive and Surgical, Anatomy of the Human Body and Gray's Anatomy: Descriptive and Applied, but the book's name is commonly shortened to, and later editions are titled, Gray's Anatomy. The book is widely regarded as an extremely influential work on the subject, and has continued to be revised and republished from its initial publication in 1858 to the present day. The latest edition of the book, the 41st, was published in September 2015.

  1. 1 2 Sadler, T (2006). Langman's Medical Embryology. pp. 280–282. ISBN   9780781790697.
  2. Larsen, W (2001). Human embryology. pp. 365–368. ISBN   0443065837.
  3. Sadler, T (2006). Langman's Medical embryology. p. 280. ISBN   9780781790697.
  4. Abzhanov A, Cordero DR, Sen J, Tabin CJ, Helms JA (December 2007). "Cross-regulatory interactions between Fgf8 and Shh in the avian frontonasal prominence". Congenit Anom (Kyoto). 47 (4): 136–48. doi:10.1111/j.1741-4520.2007.00162.x. PMID   17988255.
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eMedicine is an online clinical medical knowledge base founded in 1996 by Scott Plantz MD FAAEM, Jonathan Adler MD MS FACEP FAAEM, a computer engineer Jeffrey Berezin MS. The fundamental concept was to create a large repository of professional level medical content that could be both updated and accessed continuously to assist in clinical care and physician education. The eMedicine website consists of approximately 6,800 medical topic review articles, each of which is associated with one of 62 clinical subspecialty "textbooks". Pediatrics, for example, has 1,050 articles organized into 14 subspecialty "textbooks" ; the emergency medicine volume has 630 articles and internal medicine is near 1,400. If the remainder of the specialty textbooks are added to the total 6800+ articles were created in eMedicine. In addition, the knowledge base includes over 25,000 clinically multimedia files. To create this online content over 11,000 board certified healthcare specialists were recruited and managed in a first generation, proprietary learning management system (LMS). To provide some perspective on the amount of content that was created it is estimated that, if hard-copy printed out, it would total over 1 million pages.