Development of the Head and Neck Flashcards
Occipital sclerotomes form the upper half of the ____ and the rest fuse to form the occipital bone
atlas
occipital myotomes will form the muscles of the ____
tongue
The nerves of the occipital somites fuse, become entrapped in the occipital bone and innervate the muscles of the tongue as the ____ nerve
hypoglossal
Sclerotomes in the cervical region form cervical vertebrae and the bottom half of the atlas. Myotomes in this region form the muscles of the neck. True or false?
true
The nerves of the cervical somites innervate the neck muscles via _____ ____ nerves
cervical spinal
Most typical features in development of head and neck are formed by _____ arches.
pharyngeal
The following description is of what pharyngeal arch:
muscle: muscles of mastication, mylohyoid, anterior belly of digastric, tensor tympani, tensor palatini
bone: premaxilla, maxilla, zygomatic bone, part of temporal bone, mandible, malleus, incus
ligament: anterior ligament of malleus, sphenomandibular
nerve: V2 and V3 of trigeminal
1st (Mandibular) arch
The following description is of what pharyngeal arch:
muscles: muscles of facial expression, sylohyoid, posterior belly of digastric, stapedius
bone: stapes, stylohyoid process of temporal bone, lesser horn of hyoid, upper part of body of hyoid
ligament: stylohyoid
nerve: facial
2nd (hyoid) arch
The following description is of what pharyngeal arch:
muscle: stylopharyngeus
bone: greater horn of hyoid, lower part of body of hyoid
nerve: glossopharyngeal
3rd arch
What muscles do the 4th and 6th pharyngeal arches form?
4th: cricothryoid, levator palatine, constrictors of pharynx
6th: intrinsic muscles of larynx
What nerve do the 4th and 6th pharyngeal arches form?
vagus
4th: superior laryngeal branch
6th: recurrent laryngeal branch
The ____ ____ lining of the pharyngeal pouches gives rise to a number of important organs
epithelial endodermal
The first pharyngeal pouch, forms a diverticulum which comes in contact with epithelial lining of the first pharyngeal cleft, the ____ _____ meatus
external auditory
note: expands to form middle ear tympanic cavity and auditory tube
The second pharyngeal pouch forms what?
palatine tonsils
The dorsal wing of the third pharyngeal pouch differentiates into the ____ ____ gland. The ventral wing differentiates into the ____.
inferior parathyroid; thymus
The dorsal wing of the fourth pharyngeal pouch becomes the ____ ____ gland. The ventral wing gives rise to the ______ body.
superior parathyroid; ultimobranchial
What is the function of the ultimobranchial body?
is incorporated into the thyroid gland and secretes calcitonin
This syndrome occurs because the third and fourth pharyngeal pouches fail to differentiate into thymus and parathyroid glands. In most cases there is a micro deletion in the q11.2 region of the chromosome 22 and neural crest defects.
DiGeorge syndrome
What are the clinical signs of DiGeorge syndrome?
infants born without thymus and parathyroid gland and have defects in their cardiac outflow tracts; anomalies of mouth (small mouth and chin), prominent nose with rounded tip, unusually shaped ears
There is a period of overlapping growth between pharyngeal arches 2,3,4 and pharyngeal clefts 2,3,4. During this time, what is formed? it usually disappears with further growth
cervical sinus
The skeletal structures of the face are formed by mesenchyme that is derived from ____ ___. The other elements in the head, such as the parietal, occipital, temporal bones, and voluntary muscles are formed by mesenchyme that is derived from ____ ____.
neural crest; paraxial mesoderm
Mesenchyme derived from the lateral plate mesoderm will form what?
cartilages of the larynx
During the fourth week, the center of the face is formed by the _____, surrounded by first pair of pharyngeal arches.
stomodeum
On both sides of frontonasal prominence, thickenings of surface ectoderm, the nasal _____ originate under the influence of the ventral portion of forebrain
placodes
During the fifth week, the nasal placodes invaginate, forming nasal pits, which are surrounded by ridges of tissue that form what?
lateral and medial nasal prominences
The _____ lip is formed by two medial nasal prominences and the two maxillary prominences
upper
The maxillary prominences are separated from the lateral nasal prominences by the _______ groove
nasolacrimal
Describe how the tongue appears and forms in week 4
appears in the form of two lateral lingual swellings and one medial lingual swelling (from first pharyngeal arch)
A second medial swelling of the tongue, the _____, is formed by mesoderm of the 2nd, 3rd, and 4th arch.
copula
The third median swelling, formed by the posterior part of the 4th arch marks development of the ____
epiglottis
note: immediately behind this is the laryngeal orifice, flanked by arytenoid swellings
Since the mucosa covering the body of the tongue originates form the first pharyngeal arch, sensory innervation is done by what nerve?
mandibular branch of trigeminal
Tongue musculature is derived from myoblasts originating in occipital somites, thus tongue musculature is innervated by which nerve?
hypoglossal
What is ankylogossia?
tongue-tie - frenulum extends to tip of tongue, anchoring it down
The thyroid gland appears as an epithelial proliferation in the floor of the pharynx between the tubercular impar and the copula at a point later indicated by the _____ _____
foramen cecum
The thyroid gland reaches its final position at week _____ and begins to function at the end of the ____ month
7; 3rd
The fusion of the primary and secondary palate is marked by what foramen?
incisive
During the ____ week, the nasal pits deepen considerably. At first, the oronasal membrane separates the nasal pits from the primitive oral cavity by way of the newly formed foramina, the ____ ____
6; primitive choanae
note: the definitive choanae lie at the junction of the nasal cavity and the pharynx
Paranasal air sinuses develop their maximum size during ____
puberty
Lateral cleft lip happens more in males and is partial or complete lack of fusion of ____ prominences with the ____ ____ prominences on one or both sides
maxillary; medial nasal
Cleft palate is the lack of fusion between what?
primary and secondary palates
Median cleft lip is due to incomplete fusion of the two ____ ____ prominences, usually accompanied by a deep groove between the two halves of the nose.
medial nasal
This occurs more freq in females, due to incomplete fusion of the palatine shelves
cleft palate
What causes oblique facial clefts?
failure of the maxillary prominence to fuse with the lateral nasal prominence - leaves nasolacrimal duct exposed
