Development of the Head and Neck pt. 2 Flashcards
<p>Incomplete fusion or formation of the medial nasal prominences results in </p>
<p>Midline facial defects
-median cleft lip or synopthalmia with proboscis</p>
<p>Synopthalmia with proboscis is associated with </p>
<p>Holoprosencephaly </p>
<p>Incomplete fusion between the intermaxillary segment and the maxillary prominences results in </p>
<p>Anterior cleft deformities </p>
<p>Anterior cleft deformities are deformities anterior to the incisive foramen such as </p>
<p>Cleft lip or cleft upper jaw </p>
<p>The most common congenital malformation of the head and neck and occurs in 1/700 births </p>
<p>Cleft lip</p>
<p>Forms when a wedge of ectoderm furrows at the junction between the maxillary and lateral nasal prominences </p>
<p>Nasolacrimal groove </p>
<p>The nasolacrimal groove forms the </p>
<p>Nasolacrimal duct and lacrimal sac</p>
<p>Incomplete fusion between the maxillary and lateral nasal prominence along the nasolacrimal groove results in
-Nasolacrimal duct is exposed to surface</p>
<p>Oblique facial cleft (nasolacrimal duct is exposed to surface)</p>
<p>Form the connective tissues, cartilages, and bones associated with the cheeks, lateral upper lip, and secondary palate (posterior to incisive foramen)</p>
<p>Maxillary prominences of the 1st pharyngeal arch</p>
<p>The secondary palate is posterior to the </p>
<p>Incisive foramen </p>
<p>The secondary palate forms from midline fusion of the maxillary prominences' outgrowths called </p>
<p>Palatine shelves </p>
<p>Initially, the palatine shelves are vertically oriented around the </p>
<p>Protruding tongue </p>
<p>As the oral cavity grows and the tongue flattens, the palatine shelves become horizontally-oriented and approximate to fuse in the midline and form the </p>
<p>Secondary palate </p>
<p>The midline nasal septum (from the frontal nasal prominence) fuses with the superior midline surface of the </p>
<p>Palatine shelves</p>
<p>Incomplete midline fusion of the maxillary prominences' palatine shelves, sometimes due to micrognathia and failure of tongue to flatten, results in </p>
<p>Posterior cleft palate</p>
<p>Cleft palate without associated cleft lip occurs in </p>
<p>1/1500 births </p>
<p>Form the mandible and malleus-incus ear ossicles</p>
<p>Mandibular prominences of the first pharyngeal arch</p>
<p>Incomplete midline fusion of the mandibular prominences results in </p>
<p>Cleft chin</p>
<p>The external surfaces of the pharyngeal arches is covered by </p>
<p>Surface ectoderm</p>
<p>The surface ectoderm lines recesses between the pharyngeal arches as 4 bilateral pairs of </p>
<p>Pharyngeal clefts/grooves </p>
<p>Forms the epithelial lining of the external auditory meatus and the epithelial lining of the external surface of the tympanic membrane (ear drum)</p>
<p>The 1st pharyngeal cleft</p>
<p>Clefts 2-4 are overgrown by the 2nd pharyngeal arch and form a </p>
<p>Temporary cervical sinus </p>
<p>Remnants of the cervical sinus of clefts 2-4 may form
-located laterally along anterior border of sternocleidomastoid</p>
<p>Lateral cervical cysts</p>
<p>Not part of the structures derived from the pharyngeal region, but part of it forms from the ectoderm of the stomodeum</p>
<p>Pituitary gland (hypophysis)</p>
<p>Arises as an ectodermal diverticulum from the stomodeum (referred to as Rathke's pouch) which detaches </p>
<p>Glandular anterior lobe (adenohypophysis) of pituitary</p>
<p>Forms as a ventral neuroectoderm envagination from the hypothalamus</p>
<p>Nerual posterior lobe (neurohypohpysis) of the pituitary</p>
<p>Neuron cell bodies located in hypothalamic nuclei produce hormones that are carried through axons in the pituitary stalk to reach the </p>
<p>Posterior lobe for release</p>
<p>The external ear epithelium is derived from ectoderm of the </p>
<p>First pharyngeal cleft</p>
<p>The middle ear is derived from mesoderm-mesenchyme of the </p>
<p>1st and 2nd pharyngeal arches </p>
<p>A thickening of surface ectoderm that invaginates to form the cochlea and vestibular apparatus of the inner ear</p>
<p>Otic placode </p>
<p>The retina, pigmented epithelia, optic nerve, isis smooth muscles, and viterous humor are all derived from </p>
<p>Neuroectoderm of the neural tube </p>
<p>The lens, conjunctival and corneal epithelia, eyelids, and lacrimal apparatus are derived from surface ectoderm that forms a </p>
<p>Lens placode </p>
<p>The remaining ocular structures form from </p>
<p>Mesenchyme </p>
<p>The same endoderm that lines the pharynx of the foregut lines the internal surface of the </p>
<p>Pharyngeal arches and the 4 bilateral pairs of pharyngeal pouches recessed between the arches</p>
<p>The first pouch forms the </p>
<p>Tubotympanic recess</p>
<p>The proximal portion of the tubotympanic recess develops into the </p>
<p>Auditory (Eustachin) tube </p>
<p>The distal portion of the tubotympanic recess develops into the </p>
<p>Tympanic/middle ear cavity</p>
<p>Develops into the epithelial-lined crypts of the palatine tonsil</p>
<p>2nd Pouch</p>
<p>Forms the epithelial glandular cells of the inferior parathyroid glands and epithelial reticular cells of the thymus</p>
<p>3rd pouch</p>
<p>The thymus is infuiltrated by </p>
<p>Lymphocytes </p>
<p>Forms epithelial glandular cells of the superior parathyroid gland </p>
<p>4th pouch </p>
<p>The 4th pouch houses migrated neural crest cells known as the </p>
<p>Ultimobranchial body </p>
<p>Neural crest-derived ultimobranchial cells of the fourth pouch become the calcitonin-producing </p>
<p>Parafollicular cells of the thyroid</p>
<p>Neural crest cells give rise to the supportive stroma surrounding ectoderm or endoderm-derived glandular cells of the</p>
<p>Thymus, pituitary, parathyroid, and salivary glands</p>
<p>Also forms from the endoderm of the pharynx</p>
<p>Thyroid gland</p>
<p>An evagination of endoderm located in the ventral midline of the floor of the pharynx near the posterior/root of the tongue </p>
<p>The thyroid diverticulum (foramen cecum)</p>
<p>The thyroid diverticulum extends and migrates caudally in the midline and temporarily maintains its attachment to the root of the tongue during its migration through the </p>
<p>Thyroglossal duct </p>
<p>The thyroglossal ducts disintegrates, but its persistence results in a midline mass that moves with the tongue protrusion known as the </p>
<p>Thyroglossal duct Cyst</p>
