PHARYNGEAL APPARATUS Flashcards
(45 cards)
PHARYNGEAL APPARATUS
Pharyngeal groove (from ectoderm)
Pharyngeal arches(from mesoderm)
Pharyngeal pouch (from endoderm)
PHARYNGEAL APPARATUS
Thepharyngeal apparatusis an embryological structure.
It consists of:
……….
……….
………..
Pharyngeal (fromectoderm)
Pharyngeal arches(frommesoderm)
Pharyngeal pouches(fromendoderm)
and related membranes
PHARYNGEAL ARCHES
Thepharyngeal arches, also known as……..,are structures seen in theembryonic developmentofvertebratesthat are recognisable precursors for many structures.
visceral arches
Infish, the arches are known as the……., or gill arches.
branchial arches
In thehuman embryo, the arches are first seen during the …… ofdevelopment.
They appear as a series of …… ofmesodermon both sides of the developingpharynx.
In fish, the branchial arches support thegills.
fourth week
The vasculature of the pharyngeal arches is known as the………
aortic arches.ou
The vasculature of the pharyngeal arches is known as the………
aortic arches.
In vertebrates, the pharyngeal arches are derived from all threegerm layers(the primary layers of cells that form during embryogenesis).Neural crest cellsenter these arches where they contribute to features of theskullandfacial skeletonsuch as bone and cartilage.However, the existence of pharyngeal structures before neural crest cells evolved is indicated by the existence of neural crest-independent mechanisms of pharyngeal arch development.The first, most anteriorpharyngeal archgives rise to the oral jaw. The second arch becomes thehyoidand jaw support.In fish, the other posterior arches contribute to the branchial skeleton, which support the gills; in tetrapods the anterior arches develop into components of the ear, tonsils, and thymus. The genetic and developmental basis of pharyngeal arch development is well characterized. It has been shown thatHox genesand other developmental genes such asDLXare important for patterning the anterior/posterior and dorsal/ventral axes of the branchial arches.
During human development, a series of pharyngeal arch pairs form in the developingembryo. These project forward from the back of the embryo toward the front of the face and neck. Each arch develops its own artery, nerve that controls a distinct muscle group, and skeletal tissue. The arches are numbered from 1 to 6, with 1 being the arch closest to the head of the embryo, and arch 5 existing only transiently.
These grow and join in the ventral midline. The first arch, as the first to form, separates the mouth pit orstomodeumfrom thepericardium. By differential growth the neck elongates and new arches form, so the pharynx has six arches ultimately.
Each pharyngeal arch has acartilaginousstick, amusclecomponent that differentiates from the cartilaginous tissue, an artery, and acranial nerve. Each of these is surrounded bymesenchyme as shown in the picture bellow. Arches do not develop simultaneously but instead possess a “staggered” development.
Pharyngeal pouchesform on theendodermalside between the arches, andpharyngeal grooves(or clefts) form from the lateralectodermalsurface of theneckregion to separate the arches.In fish the pouches line up with the clefts, and these thin segments becomegills. In mammals theendodermandectodermnot only remain intact but also continue to be separated by amesodermlayer.
The development of the pharyngeal arches provides a useful landmark with which to establish the precise stage of embryonic development. Their formation and development corresponds toCarnegie stages10 to 16 inmammals, andHamburger–Hamilton stages14 to 28 in thechicken. Although there are six pharyngeal arches, in humans the fifth arch exists only transiently duringembryogenesis.
FIRST PHARYNGEAL ARCH
Thefirst pharyngeal archalsomandibular arch(corresponding to the firstbranchial archorgill archoffish), is the first of six pharyngeal arches that develops during the fourth week ofdevelopment.It is located between thestomodeumand thefirst pharyngeal groove.
This arch divides into amaxillary processand amandibular process, giving rise to structures including thebonesof the lower two-thirds of the face and the jaw. The maxillary process becomes themaxilla(orupper jaw), andpalatewhile the mandibular process becomes themandibleorlower jaw. This arch also gives rise to themuscles of mastication.
Meckel’s cartilageforms in themesodermof the mandibular process and eventually regresses to form theincusandmalleusof themiddle ear, the anterior ligament of the malleus and thesphenomandibular ligament. Themandibleor lower jaw forms by perichondralossificationusing Meckel’s cartilage as a ‘template’, but the maxillary doesnotarise from direct ossification of Meckel’s cartilage.
Derivatives of first pharyngeal arch.
The skeletal elements and muscles are derived from mesoderm of the pharyngeal arches.
Skeletal derivatives
malleusandincusof themiddle ear
maxillaandmandible
spine of sphenoid bone
sphenomandibular ligament
palatine bone
squamous part of temporal bone
anterior ligament of malleus
Muscles
muscles of mastication(chewing)
masseter
medialandlateral pterygoid muscles
temporalis
mylohyoid muscle
digastric muscle, anterior belly
tensor veli palatini muscle
tensor tympani muscle
Other derivatives of first pharyngeal arch
Mucous membraneand glands of theanterior two thirds of the tongueare derived fromectodermandendodermof the arch.
Nerve supply
The mandibular and maxillary branches of thetrigeminal nerve(CN V) innervate the structures derived from the corresponding processes of the first arch. In some lower animals, each arch is supplied by two cranial nerves. The nerve of the arch itself runs along the cranial side of the arch and is called post-trematic nerve of the arch. Each arch also receives a branch from the nerve of the succeeding arch called the pre-trematic nerve which runs along the caudal border of the arch. In human embryo, a double innervation is seen only in the first pharyngeal arch. The mandibular nerve is the post-trematic nerve of the first arch andchorda tympani(branch of facial nerve) is the pre-trematic nerve. This double innervation is reflected in the nerve supply of anterior two-thirds oftonguewhich is derived from the first arch.
V) Blood supply
The artery of the first arch is the firstaortic arch,which partially persists as themaxillary artery.
SECOND PHARYNGEAL ARCH
Thesecond pharyngeal archorhyoid arch, is the second of fifth pharyngeal arches that develops infetal lifeduring the fourth week of developmentand assists in forming the side and front of theneck.
Cartilage in the second pharyngeal arch is referred to as Reichert’s cartilage and contributes to many structures in the fully developed adult.In contrast to theMeckel’s cartilageof thefirst pharyngeal archit does not constitute a continuous element, and instead is composed of two distinct cartilaginous segments joined by a faint layer ofmesenchyme.Dorsal ends of Reichert’s cartilageossifyduring development to form thestapesof themiddle earbefore being incorporated into the middle ear cavity, while the ventral portion ossifies to form the lesser cornu and upper part of the body of thehyoid bone. Caudal to what will eventually become thestapes, Reichert’s cartilage also forms thestyloid processof thetemporal bone. The cartilage between thehyoid boneandstyloid processwill not remain as development continues, but itsperichondriumwill eventually form thestylohyoid ligament.
Derivatives of the second pharyngeal arch
Skeletal
From the cartilage of the second arch arises
Stapes,
Temporal styloid process,
Stylohyoid ligament, and
Lesser cornuof thehyoid bone.
Muscles
Facial muscles
Occipitofrontalismuscle
Platysma
Stylohyoidmuscle
Posterior belly ofdigastric muscle
Stapediusmuscle
Auricular muscles
Nerve supply
Facial nerve(CN VII)
Blood supply
The artery of the second arch is the secondaortic arch, which gives origin to thestapedial arteryin some mammals but atrophies in humans.
THIRD PHARYNGEAL ARCH
Derivatives of the third pharyngeal arch
Skeletal
From the cartilage of the third arch arises
the lower body and greater horn of thehyoid.
Muscles
stylopharyngeus
Nerve supply
The stylopharyngeus and other structures from the third pharyngeal arch are all innervated by theglossopharyngeal nerve.
Blood supply
The artery of the third pharyngeal arch becomes thecommon carotid arteryand the proximal portion of the internal carotid artery.
Fourth pharyngeal Arch
Derivatives of the fourth pharyngeal arch
Skeletal
The fourth arch gives rise tolaryngeal cartilages–namely the thyroid cartilage andepiglottic cartilage.
Muscles
The muscular derivatives of the fourth arch; the constrictors of the pharynx, levator palatini and cricothyroid.
Nerve supply
The associated nerve is thesuperior laryngeal branchof thevagus nerve (CN X), which innervates the muscular derivatives of the fourth arch; the constrictors of the pharynx, levator palatini and cricothyroid.
Innervation to theroot of the tongueis provided by the superior laryngeal branch.
iv) Blood supply
The vascular derivatives of the fourth pharyngeal arch differ between the left and right:
Right– proximal portion of the subclavian artery
Left– aortic arch
SIXTH PHARYNGEAL ARCH
Skeletal
Cricoid cartilage,arytenoid cartilages,corniculate cartilage,cuneiform cartilages
Muscles
Intrinsic muscles of the larynxexcept thecricothyroid muscle
Blood supply
The vascular derivatives of the sixth pharyngeal arch differ between the left and right:
Right– proximal portion of the pulmonary arteries
Left– ductus arteriosus
Nerve supply
The associated nerve is therecurrent laryngeal branchof thevagus nerve (CN X).
The associated nerve is therecurrent laryngeal branchof thevagus nerve (CN X).It innervates the intrinsic muscles of the larynx(with the exception of cricothyroid), which are derived from the sixth arch.
The sensory field of the recurrent laryngeal branch is widespread. It includes taste sensation from the epiglottis and pharynx, general sensation in the pharynx, larynx, oesophagus, tympanic membrane, external auditory meatus and part of the external ear. It also provides the efferent limb of thegag reflex, and parasympathetic innervation to viscera.
In humans, Since no human structures result from the fifth arch, the arches in humans are I, II, III, IV, and VI.More is known about the fate of the first arch than the remaining four. The first three contribute to structures above the larynx, whereas the last two contribute to thelarynxandtrachea.
In vertebrates, the pharyngeal arches are derived from all threegerm layers(the primary layers of cells that form during embryogenesis).Neural crest cellsenter these arches where they contribute to features of theskullandfacial skeletonsuch as bone and cartilage.However, the existence of pharyngeal structures before neural crest cells evolved is indicated by the existence of neural crest-independent mechanisms of pharyngeal arch development.The first, most anteriorpharyngeal archgives rise to the oral jaw. The second arch becomes thehyoidand jaw support.In fish, the other posterior arches contribute to the branchial skeleton, which support the gills; in tetrapods the anterior arches develop into components of the ear, tonsils, and thymus. The genetic and developmental basis of pharyngeal arch development is well characterized. It has been shown thatHox genesand other developmental genes such asDLXare important for patterning the anterior/posterior and dorsal/ventral axes of the branchial arches.
During human development, a series of pharyngeal arch pairs form in the developingembryo. These project forward from the back of the embryo toward the front of the face and neck. Each arch develops its own artery, nerve that controls a distinct muscle group, and skeletal tissue. The arches are numbered from 1 to 6, with 1 being the arch closest to the head of the embryo, and arch 5 existing only transiently.
These grow and join in the ventral midline. The first arch, as the first to form, separates the mouth pit orstomodeumfrom thepericardium. By differential growth the neck elongates and new arches form, so the pharynx has six arches ultimately.
Each pharyngeal arch has acartilaginousstick, amusclecomponent that differentiates from the cartilaginous tissue, an artery, and acranial nerve. Each of these is surrounded bymesenchyme as shown in the picture bellow. Arches do not develop simultaneously but instead possess a “staggered” development.
Pharyngeal pouchesform on theendodermalside between the arches, andpharyngeal grooves(or clefts) form from the lateralectodermalsurface of theneckregion to separate the arches.In fish the pouches line up with the clefts, and these thin segments becomegills. In mammals theendodermandectodermnot only remain intact but also continue to be separated by amesodermlayer.
The development of the pharyngeal arches provides a useful landmark with which to establish the precise stage of embryonic development. Their formation and development corresponds toCarnegie stages10 to 16 inmammals, andHamburger–Hamilton stages14 to 28 in thechicken. Although there are six pharyngeal arches, in humans the fifth arch exists only transiently duringembryogenesis.
FIRST PHARYNGEAL ARCH
Thefirst pharyngeal archalsomandibular arch(corresponding to the firstbranchial archorgill archoffish), is the first of six pharyngeal arches that develops during the fourth week ofdevelopment.It is located between thestomodeumand thefirst pharyngeal groove.
This arch divides into amaxillary processand amandibular process, giving rise to structures including thebonesof the lower two-thirds of the face and the jaw. The maxillary process becomes themaxilla(orupper jaw), andpalatewhile the mandibular process becomes themandibleorlower jaw. This arch also gives rise to themuscles of mastication.
Meckel’s cartilageforms in themesodermof the mandibular process and eventually regresses to form theincusandmalleusof themiddle ear, the anterior ligament of the malleus and thesphenomandibular ligament. Themandibleor lower jaw forms by perichondralossificationusing Meckel’s cartilage as a ‘template’, but the maxillary doesnotarise from direct ossification of Meckel’s cartilage.
Derivatives of first pharyngeal arch.
The skeletal elements and muscles are derived from mesoderm of the pharyngeal arches.
Skeletal derivatives
malleusandincusof themiddle ear
maxillaandmandible
spine of sphenoid bone
sphenomandibular ligament
palatine bone
squamous part of temporal bone
anterior ligament of malleus
Muscles
muscles of mastication(chewing)
masseter
medialandlateral pterygoid muscles
temporalis
mylohyoid muscle
digastric muscle, anterior belly
tensor veli palatini muscle
tensor tympani muscle
Other derivatives of first pharyngeal arch
Mucous membraneand glands of theanterior two thirds of the tongueare derived fromectodermandendodermof the arch.
Nerve supply
The mandibular and maxillary branches of thetrigeminal nerve(CN V) innervate the structures derived from the corresponding processes of the first arch. In some lower animals, each arch is supplied by two cranial nerves. The nerve of the arch itself runs along the cranial side of the arch and is called post-trematic nerve of the arch. Each arch also receives a branch from the nerve of the succeeding arch called the pre-trematic nerve which runs along the caudal border of the arch. In human embryo, a double innervation is seen only in the first pharyngeal arch. The mandibular nerve is the post-trematic nerve of the first arch andchorda tympani(branch of facial nerve) is the pre-trematic nerve. This double innervation is reflected in the nerve supply of anterior two-thirds oftonguewhich is derived from the first arch.
V) Blood supply
The artery of the first arch is the firstaortic arch,which partially persists as themaxillary artery.
SECOND PHARYNGEAL ARCH
Thesecond pharyngeal archorhyoid arch, is the second of fifth pharyngeal arches that develops infetal lifeduring the fourth week of developmentand assists in forming the side and front of theneck.
Cartilage in the second pharyngeal arch is referred to as Reichert’s cartilage and contributes to many structures in the fully developed adult.In contrast to theMeckel’s cartilageof thefirst pharyngeal archit does not constitute a continuous element, and instead is composed of two distinct cartilaginous segments joined by a faint layer ofmesenchyme.Dorsal ends of Reichert’s cartilageossifyduring development to form thestapesof themiddle earbefore being incorporated into the middle ear cavity, while the ventral portion ossifies to form the lesser cornu and upper part of the body of thehyoid bone. Caudal to what will eventually become thestapes, Reichert’s cartilage also forms thestyloid processof thetemporal bone. The cartilage between thehyoid boneandstyloid processwill not remain as development continues, but itsperichondriumwill eventually form thestylohyoid ligament.
Derivatives of the second pharyngeal arch
Skeletal
From the cartilage of the second arch arises
Stapes,
Temporal styloid process,
Stylohyoid ligament, and
Lesser cornuof thehyoid bone.
Muscles
Facial muscles
Occipitofrontalismuscle
Platysma
Stylohyoidmuscle
Posterior belly ofdigastric muscle
Stapediusmuscle
Auricular muscles
Nerve supply
Facial nerve(CN VII)
Blood supply
The artery of the second arch is the secondaortic arch, which gives origin to thestapedial arteryin some mammals but atrophies in humans.
THIRD PHARYNGEAL ARCH
Derivatives of the third pharyngeal arch
Skeletal
From the cartilage of the third arch arises
the lower body and greater horn of thehyoid.
Muscles
stylopharyngeus
Nerve supply
The stylopharyngeus and other structures from the third pharyngeal arch are all innervated by theglossopharyngeal nerve.
Blood supply
The artery of the third pharyngeal arch becomes thecommon carotid arteryand the proximal portion of the internal carotid artery.
Fourth pharyngeal Arch
Derivatives of the fourth pharyngeal arch
Skeletal
The fourth arch gives rise tolaryngeal cartilages–namely the thyroid cartilage andepiglottic cartilage.
Muscles
The muscular derivatives of the fourth arch; the constrictors of the pharynx, levator palatini and cricothyroid.
Nerve supply
The associated nerve is thesuperior laryngeal branchof thevagus nerve (CN X), which innervates the muscular derivatives of the fourth arch; the constrictors of the pharynx, levator palatini and cricothyroid.
Innervation to theroot of the tongueis provided by the superior laryngeal branch.
iv) Blood supply
The vascular derivatives of the fourth pharyngeal arch differ between the left and right:
Right– proximal portion of the subclavian artery
Left– aortic arch
SIXTH PHARYNGEAL ARCH
Skeletal
Cricoid cartilage,arytenoid cartilages,corniculate cartilage,cuneiform cartilages
Muscles
Intrinsic muscles of the larynxexcept thecricothyroid muscle
Blood supply
The vascular derivatives of the sixth pharyngeal arch differ between the left and right:
Right– proximal portion of the pulmonary arteries
Left– ductus arteriosus
Nerve supply
The associated nerve is therecurrent laryngeal branchof thevagus nerve (CN X).
The associated nerve is therecurrent laryngeal branchof thevagus nerve (CN X).It innervates the intrinsic muscles of the larynx(with the exception of cricothyroid), which are derived from the sixth arch.
The sensory field of the recurrent laryngeal branch is widespread. It includes taste sensation from the epiglottis and pharynx, general sensation in the pharynx, larynx, oesophagus, tympanic membrane, external auditory meatus and part of the external ear. It also provides the efferent limb of thegag reflex, and parasympathetic innervation to viscera.
In humans, Since no human structures result from the fifth arch, the arches in humans are I, II, III, IV, and VI.More is known about the fate of the first arch than the remaining four. The first three contribute to structures above the larynx, whereas the last two contribute to thelarynxandtrachea.
In vertebrates, the pharyngeal arches are derived from all threegerm layers(the primary layers of cells that form during embryogenesis).Neural crest cellsenter these arches where they contribute to features of theskullandfacial skeletonsuch as bone and cartilage.However, the existence of pharyngeal structures before neural crest cells evolved is indicated by the existence of neural crest-independent mechanisms of pharyngeal arch development.The first, most anteriorpharyngeal archgives rise to the oral jaw. The second arch becomes thehyoidand jaw support.In fish, the other posterior arches contribute to the branchial skeleton, which support the gills; in tetrapods the anterior arches develop into components of the ear, tonsils, and thymus. The genetic and developmental basis of pharyngeal arch development is well characterized. It has been shown thatHox genesand other developmental genes such asDLXare important for patterning the anterior/posterior and dorsal/ventral axes of the branchial arches.
During human development, a series of pharyngeal arch pairs form in the developingembryo. These project forward from the back of the embryo toward the front of the face and neck. Each arch develops its own artery, nerve that controls a distinct muscle group, and skeletal tissue. The arches are numbered from 1 to 6, with 1 being the arch closest to the head of the embryo, and arch 5 existing only transiently.
These grow and join in the ventral midline. The first arch, as the first to form, separates the mouth pit orstomodeumfrom thepericardium. By differential growth the neck elongates and new arches form, so the pharynx has six arches ultimately.
Each pharyngeal arch has acartilaginousstick, amusclecomponent that differentiates from the cartilaginous tissue, an artery, and acranial nerve. Each of these is surrounded bymesenchyme as shown in the picture bellow. Arches do not develop simultaneously but instead possess a “staggered” development.
Pharyngeal pouchesform on theendodermalside between the arches, andpharyngeal grooves(or clefts) form from the lateralectodermalsurface of theneckregion to separate the arches.In fish the pouches line up with the clefts, and these thin segments becomegills. In mammals theendodermandectodermnot only remain intact but also continue to be separated by amesodermlayer.
The development of the pharyngeal arches provides a useful landmark with which to establish the precise stage of embryonic development. Their formation and development corresponds toCarnegie stages10 to 16 inmammals, andHamburger–Hamilton stages14 to 28 in thechicken. Although there are six pharyngeal arches, in humans the fifth arch exists only transiently duringembryogenesis.
FIRST PHARYNGEAL ARCH
Thefirst pharyngeal archalsomandibular arch(corresponding to the firstbranchial archorgill archoffish), is the first of six pharyngeal arches that develops during the fourth week ofdevelopment.It is located between thestomodeumand thefirst pharyngeal groove.
This arch divides into amaxillary processand amandibular process, giving rise to structures including thebonesof the lower two-thirds of the face and the jaw. The maxillary process becomes themaxilla(orupper jaw), andpalatewhile the mandibular process becomes themandibleorlower jaw. This arch also gives rise to themuscles of mastication.
Meckel’s cartilageforms in themesodermof the mandibular process and eventually regresses to form theincusandmalleusof themiddle ear, the anterior ligament of the malleus and thesphenomandibular ligament. Themandibleor lower jaw forms by perichondralossificationusing Meckel’s cartilage as a ‘template’, but the maxillary doesnotarise from direct ossification of Meckel’s cartilage.
Derivatives of first pharyngeal arch.
The skeletal elements and muscles are derived from mesoderm of the pharyngeal arches.
Skeletal derivatives
malleusandincusof themiddle ear
maxillaandmandible
spine of sphenoid bone
sphenomandibular ligament
palatine bone
squamous part of temporal bone
anterior ligament of malleus
Muscles
muscles of mastication(chewing)
masseter
medialandlateral pterygoid muscles
temporalis
mylohyoid muscle
digastric muscle, anterior belly
tensor veli palatini muscle
tensor tympani muscle
Other derivatives of first pharyngeal arch
Mucous membraneand glands of theanterior two thirds of the tongueare derived fromectodermandendodermof the arch.
Nerve supply
The mandibular and maxillary branches of thetrigeminal nerve(CN V) innervate the structures derived from the corresponding processes of the first arch. In some lower animals, each arch is supplied by two cranial nerves. The nerve of the arch itself runs along the cranial side of the arch and is called post-trematic nerve of the arch. Each arch also receives a branch from the nerve of the succeeding arch called the pre-trematic nerve which runs along the caudal border of the arch. In human embryo, a double innervation is seen only in the first pharyngeal arch. The mandibular nerve is the post-trematic nerve of the first arch andchorda tympani(branch of facial nerve) is the pre-trematic nerve. This double innervation is reflected in the nerve supply of anterior two-thirds oftonguewhich is derived from the first arch.
V) Blood supply
The artery of the first arch is the firstaortic arch,which partially persists as themaxillary artery.
SECOND PHARYNGEAL ARCH
Thesecond pharyngeal archorhyoid arch, is the second of fifth pharyngeal arches that develops infetal lifeduring the fourth week of developmentand assists in forming the side and front of theneck.
Cartilage in the second pharyngeal arch is referred to as Reichert’s cartilage and contributes to many structures in the fully developed adult.In contrast to theMeckel’s cartilageof thefirst pharyngeal archit does not constitute a continuous element, and instead is composed of two distinct cartilaginous segments joined by a faint layer ofmesenchyme.Dorsal ends of Reichert’s cartilageossifyduring development to form thestapesof themiddle earbefore being incorporated into the middle ear cavity, while the ventral portion ossifies to form the lesser cornu and upper part of the body of thehyoid bone. Caudal to what will eventually become thestapes, Reichert’s cartilage also forms thestyloid processof thetemporal bone. The cartilage between thehyoid boneandstyloid processwill not remain as development continues, but itsperichondriumwill eventually form thestylohyoid ligament.
Derivatives of the second pharyngeal arch
Skeletal
From the cartilage of the second arch arises
Stapes,
Temporal styloid process,
Stylohyoid ligament, and
Lesser cornuof thehyoid bone.
Muscles
Facial muscles
Occipitofrontalismuscle
Platysma
Stylohyoidmuscle
Posterior belly ofdigastric muscle
Stapediusmuscle
Auricular muscles
Nerve supply
Facial nerve(CN VII)
Blood supply
The artery of the second arch is the secondaortic arch, which gives origin to thestapedial arteryin some mammals but atrophies in humans.
THIRD PHARYNGEAL ARCH
Derivatives of the third pharyngeal arch
Skeletal
From the cartilage of the third arch arises
the lower body and greater horn of thehyoid.
Muscles
stylopharyngeus
Nerve supply
The stylopharyngeus and other structures from the third pharyngeal arch are all innervated by theglossopharyngeal nerve.
Blood supply
The artery of the third pharyngeal arch becomes thecommon carotid arteryand the proximal portion of the internal carotid artery.
Fourth pharyngeal Arch
Derivatives of the fourth pharyngeal arch
Skeletal
The fourth arch gives rise tolaryngeal cartilages–namely the thyroid cartilage andepiglottic cartilage.
Muscles
The muscular derivatives of the fourth arch; the constrictors of the pharynx, levator palatini and cricothyroid.
Nerve supply
The associated nerve is thesuperior laryngeal branchof thevagus nerve (CN X), which innervates the muscular derivatives of the fourth arch; the constrictors of the pharynx, levator palatini and cricothyroid.
Innervation to theroot of the tongueis provided by the superior laryngeal branch.
iv) Blood supply
The vascular derivatives of the fourth pharyngeal arch differ between the left and right:
Right– proximal portion of the subclavian artery
Left– aortic arch
SIXTH PHARYNGEAL ARCH
Skeletal
Cricoid cartilage,arytenoid cartilages,corniculate cartilage,cuneiform cartilages
Muscles
Intrinsic muscles of the larynxexcept thecricothyroid muscle
Blood supply
The vascular derivatives of the sixth pharyngeal arch differ between the left and right:
Right– proximal portion of the pulmonary arteries
Left– ductus arteriosus
Nerve supply
The associated nerve is therecurrent laryngeal branchof thevagus nerve (CN X).
The associated nerve is therecurrent laryngeal branchof thevagus nerve (CN X).It innervates the intrinsic muscles of the larynx(with the exception of cricothyroid), which are derived from the sixth arch.
The sensory field of the recurrent laryngeal branch is widespread. It includes taste sensation from the epiglottis and pharynx, general sensation in the pharynx, larynx, oesophagus, tympanic membrane, external auditory meatus and part of the external ear. It also provides the efferent limb of thegag reflex, and parasympathetic innervation to viscera.
In humans, Since no human structures result from the fifth arch, the arches in humans are I, II, III, IV, and VI.More is known about the fate of the first arch than the remaining four. The first three contribute to structures above the larynx, whereas the last two contribute to thelarynxandtrachea.
What are the pharyngeal arches derived from?
All three germ layers
The primary layers of cells that form during embryogenesis.
What do neural crest cells contribute to in the pharyngeal arches?
Features of the skull and facial skeleton such as bone and cartilage.
What does the first pharyngeal arch give rise to?
The oral jaw.
What does the second pharyngeal arch become?
The hyoid and jaw support.
In fish, what do the posterior arches contribute to?
The branchial skeleton, which supports the gills.
In tetrapods, what do the anterior pharyngeal arches develop into?
Components of the ear, tonsils, and thymus.
What genes are important for patterning the pharyngeal arches?
Hox genes and DLX.
How are the pharyngeal arches numbered?
From 1 to 6, with 1 being closest to the head.
What is unique about the fifth pharyngeal arch in humans?
It exists only transiently during embryogenesis.
What do pharyngeal pouches form from?
The endodermal side between the arches.
What do pharyngeal grooves form from?
The lateral ectodermal surface of the neck region.
What is the significance of the development of pharyngeal arches?
Provides a useful landmark to establish precise stages of embryonic development.
What Carnegie stages correspond to the formation of pharyngeal arches in mammals?
Stages 10 to 16.
What is the first pharyngeal arch also known as?
The mandibular arch.
What structures arise from the first pharyngeal arch?
- Maxilla
- Mandible
- Muscles of mastication
- Malleus
- Incus
