Pharyngeal Arches,pouches,clefts. Flashcards
LOOK AT THE OBJECTIVES
In which week do Pharyngeal arches develop?
Week 4
What role do neural crest cells play in pharyngeal arches?
Contribute to most skeletal and connective tissues of head and neck
Describe the pharyngeal system?
It consists of 6 pairs of pharyngeal arches separated by endodermally lined pouches and ectodermly lined clefts.
What does each arch consist of?
Nerve,artery and cartilage
List the three components which make up the pharyngeal arches?
What does each component form?
1.Ectoderm-cleft
2.Mesoderm + neural crest cells-arches
3.Endoderm-pouch
How many pharyngeal arches develop in an embryo?And which if these does not give rise to any derivates?
1.6 pairs
2.the 5th pair
At what stage of development does the tongue develop?
Week 4
From which pharyngeal arch does the anterior two thirds of the tongue develop?
The first pharyngeal arch
Which pharyngeal arches are responsible for the formation of the posterior third of the tongue?
The pharyngeal arches 2 and 3
What are the derivatives of the first pharyngeal arches?
refer to Handout
What are the prominence of the pharyngeal arch 1?
Maxilla,mandible and zygomatic bone
What is the cartilage of the 1st pharyngeal arch and what does it give rise to?
1.Meckel’s Cartilage
2.Malleus,Incus,anterior ligament of the malleus and the sphenomandibular ligament
Muscles of the 1st pharyngeal arch?
1.Muscles of mastication(temporal is,masseter and pterygoids),mylohyoid, tensor tympani
Nerve of the 1st pharyngeal arch.
Trigeminal nerve
Which pharyngeal arches are responsible for the formation of the three bony ossicles of the ear?
The first and second pharyngeal arches
What does the first pharyngeal pouch form?
Eustachian tube,tympanic membrane +cavity and Temporal bone
What does the first pharyngeal groove give rise to?
External acoustic meatus
What does the tubotympanic recess give rise to?
The tympanic cavity and Eustachian tube.
What happens to the other pharyngeal clefts?
The second arches overgrown the clefts and they normally disappear giving rise to the cervical sinus
What do each of the pouches form?
1-Eustachian tube,tympanic cavity and membrane
2-Palatine tonsils
3-Parathyroid glands(inferior) and thymus
4 -superior parathyroid glands and parafollicular thyroid cells(Ultimobranchial body)
What is the name of the cartilage of the second pharyngeal arch?And what does it give rise to?
1.Reichert’s Cartilage
2.Stapes,the upper body &lesser Cornu of the hyoid bone,the styloid process of the temporal bone,Stylohyoid ligament
Muscles of the 2nd pharyngeal arch?
Platysma,muscles of facial expression,Stylohyoid and stapedius
Nerve and artery of the 2nd pharyngeal arch?
1.Facial nerve
2.Stapedial artery
What does the 2nd pharyngeal pouch give rise to?
Palatine tonsils
What does the tubotympanic recess contribute to?
The tympanic cavity and Eustachian tube
What does the the third pharyngeal arch form?
Lower body of hyoid and greater Cornu of hyoid bone
Muscles of the 3rd pharyngeal arch?
Stylopharyngeus and Superior and middle pharyngeal constrictors
Nerve and artery of the 3rd pharyngeal arch?
1.Glossopharyngeal arch
2.Common carotid artery and the proximal portions of the internal and external carotid canal
Which pharyngeal arches are responsible for the formation of the three bony ossicles of the ear?
1 and 2
What does the 3rd pharyngeal pouch give rise to ?
Inferior parathyroid glands
Thymus gland
What does the thyroid gland develop as?
Diverticulum from the foramen cecum.
What do the 4th and 6th pharyngeal cartilages form?
They fuse to form laryngeal cartilages
What does the fourth arch give rise to?
Muscles,nerve and artery?
Muscles-cricothyroid,inferior pharyngeal constrictors
Nerve:Superior laryngeal branch of the Vagus nerve
Artery: Right Subclavian and aortic arch
What does the 4th pouch give rise to?
The superior parathyroid glands and the parafollicular thyroid cells(ultimobranchial body)
What does the 6th pharyngeal arch give rise to?
Muscles,nerves and artery?
1.Muscles-remaining intrinsic laryngeal musculature
2.Nerve -Recurrent laryngeal nerve branch of vagus nerve
3.Artery-pulmonary artery and ductus arteriosus
What nerves innervate muscles derived from pre optic somites
Occulomotor,trochlear and Abducens
Which nerve innervates muscles derived from occipital somites?
Hypoglossal nerve
Where do bronchial cysts develop?
And where are most of them found?
1.Anterior border of the stercleidomastoid muscle
2.Most are found inferior to angle of mandible
In which age group are the branchial cysts usually seen and what do they represent?
1.Adulthood
2.Remnants of cervical sinus/second pharyngeal clef
What are branchial vestiges?And where are they located?
1.Cartilaginous or bony remnants
2.anterior to inferior third of SCM muscle
What is a first arch syndrome? It
And what causes it?
Various congenital anomalies of eyes,ear,mandible and palate.
Migration of neural crest cells into the pharyngeal arch is implicated
What are the two manifestations of first syndrome arch syndrome?
1.Treacher Collins Syndrome
2.Pierre Robin Syndrome
Where is the thyroid gland located?
Endoderm of the floor primitive pharynx between 1&2nd pharyngeal arches
Describe its descend?
It descends as a bilobed diverticulum from the foramen cecum around the 4th week and migrates anterior to the hyoid bone and descends into the inferior aspect of the neck by the 7th-8th week
What are the anomalies/tissue deficiencies of Treacher Collins Syndrome?
1.underdevelopment of zygomatic bones of the face,defects of the lower eyelids,external ear deformations
What are the manifestations of Pierre Robin Syndrome?
Hypoplasia of the mandible,cleft palate and eye,and ear defects
