-
what are pharyngeal arches
are a series of externally visible anterior tissue bands lying under the early brain that give rise to the structures of the head and neck
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the pharnygeal arches are also called?
branchial arches
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what are the 4 components of the Pahryngeal appartus
- Pharyngeal arches
- 2. Pharyngeal clefts
- 3. Pharyngeal pouches
- 4. Pharyngeal membranes
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where does the pharyngeal pouches comes form
invagination of the internal endoderm
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where does the pharyngeal cleft comes form
invagination of the outer ectodermal layer
-
stomodeum
embryonic mouth
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Each pharyngeal arch has
4 derivative structures
- 1.Bone & Cartilage
- 2. Artery
- 3. Nerve
- 4. Muscle
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Somitomeres
- Units of paraxial mesoderm in the
- head, but not distinct as in the body
-
Somitomeres are involved in formation of..
Arch 1,2,3 uscles
-
tongue muscle innevration comes from
CN XII- hypoglossal
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which arches mainly disappear?
Left & right aortic arches 1, 2, 5 mostly disappears.
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Arch one is the _____ arch and it creates_____
- “Mandibular”
- cartilaginous precursor of mandible
- • malleus, incus
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malleus, incus evolved from which type of bones
jaw bones
-
which early mammalian bones are synonymous to the incus and malleus respectively?
articular and quadrate
-
which muscles comes from PA 1
- muscles of mastication, temporalis. masseter, pteryoids
- tensor tympani, tensor veli palatini, anterior bell of the digastric, mylohyoid
-
function of tensor tympani
tense eardrum
-
what Cn comes from PA 1
trigeminal nerve CN V 5
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PA 2 is called the ?
it creates which bones?
- hyoid
- Cartilage & Bone
- • stapes
- • styloid process
- • hyoid (lesser horn, upper body)
-
PA 2 creates which muscles and nerve?
- Muscles
- • muscles of facial expression
- • stapedius
- • posterior belly of digastric
- Nerve
- • facial (CN VII)
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PA 3 is called the ?
it creates which bones?
- Carotid
- hyoid (greater horn, lower body)
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PA3 creates which arteries and nerves ?
- • internal & external carotid aa.
- Glossopharyngeal IX 9
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PA 3 creates which muscles?
stylopharyngeus
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PA 4 creates which cartilages & bones? exception?
what is it called?
- laryngeal cartilages except for
- epiglottis (with PA6)
- "systemic" arch
-
PA 4 creates which muscles?
- cricothyroid, levator veli palatini,
- constrictors of pharynx, striated mm.
- of esophagus
-
PA 4 creates which arteries and nerve?
- parts of aorta (left arch); right
- subclavian (right arch)
- vagus (CN X): superior laryngeal n.
-
PA 6 creates which cartilage and bones?
what is it called?
- the "pulmonary"arch
- laryngeal cartilages except for
- epiglottis (with PA4)
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Pa 6 creates which muscles ?
- intrinsic laryngeal muscles except
- cricothyroid
-
PA6 creates which arteries and nerves?
pulmonary aa. and vagus nerve CNX and recurrent larygneal
-
 this image represents which pharyngeal arch?
Branchial arch 1
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which clefts and membranes do not contribute to the adult structures>
Clefts and Membranes 2, 3, 4 do not contribute to adult structures
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what is Meckel's cartilages
part of PA 1 and created the jaw and mandibular bones
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what is Reichert's Cartilage
forms the stylohyoid ligament, styloid process, stapes, and part of the hyoid
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Name the follow part of the pharyngeal apparatus
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Pharyngeal cleft 1 (PC 1) becomes the external auditory meatus
external auditory meatus
-
which cleft contributes to adult structure
only cleft 1
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what happed to PC 2,3, and 4
come together to create a large sinus but get obliterated
-
what happens when cleft 2-4 dont get obliterated
lead to fistulas and clefts
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which arch does the left subclavian comes from?
7th arch
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function of stapedius muscles
attaches to stapes and dampens vibrations of stapes bone so that it does not damage the cochlea particularly from loud noises
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the pharyngeal membrane structurally is the ..
pinched part between the cleft and the pouch
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Pharyngeal pouch 1 (PP1) becomes
the tympanic cavity ad the eustachian tube
-
the pharyngeal membrane 1 becomes the
tympanic memebrane
-
-
function of tonsils? what are they ?
they are masses of lymph tissue that trap virus and bacteria and make antibodies to protect against infection
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PP 3 creates the
- thymus
- inferior parathyroid glands
-
PP 4 creates
- superior parathyroid glands
- • ultimobranchial body: gives rise to
- parafollicular/C-cells
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what causes a Branchial fistula ( if it opens externally or internally into the pahrynx) and cysts (arising when cervical sinus )
when clets 2-4 remain into birth /adulthood usually these obliterate
-
internal branchial fistula open at
and is formed from
internal fistula opens at the palatine tonsil formed from Pouch
-
external branchial fistula open at
and is formed from
opens on the skin of the neck anterior to the sternocleidomastoid m.
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How is the tongue formed?
from swellings in Pharyngeal Arch 1–4
-
In regards to the tongue what do the 4 arches form?
- Arch 1 forms mucosa of anterior 2/3 of the tongue.
- • Arch 2 is overgrown by arch 3 but provides taste innervation to anterior 2/3.
- • Arch 3 and 4 form mucosa of posterior 1/3 of the tongue
-
what is the foramen caecum
- *an opening that occurs btwn the naterior 2/3 and the posterior 1/3 of the tongue , remains as a fossa.
- The median pit on the dorsum of the posterior part of the tongue, from which the limbs of a V-shaped furrow run forward and outward; the foramen cecum is the point of attachment of the thyroglossal duct and is formed during the embryological descent of the thyroid gland
-
the posterior 1/3 of the tongue recieve general sensation and taste by CN
IX glossopharngeal
-
the anterior 2/3 of the tongue receive motor innervation by CN ___
except for the palatoglossus muscles which is inv by CN
-
the foramen cecaum is a remnant of
the proximal part of the embryonic thyroglossal duct
-
where does the thyroid originate from
- single outpouching of endoderm on the ventral side of arch 1 & 2 int he primordial pharynx
- the thyroid diverticulum
-
what is the thyroglossal duct
a connection of the tongue to the tyroid via a narrow tube during early dvelopment
-
what is the path of the developing thyroid
descend into the neck, passing through developing hyoid bone and laryneal cartilage
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what happens when there is an incomplete closure of the thyroglossal
duct.
Thyroglossal duct cyst in the midline of the neck
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what happens if a thyroglossal duct cyst is infected..
it could perforate the skin and cause a sinus
-
what are the feature of an ectopic thyroid gland?
there is an additional pyramidal lobe of the thyroid along the path of the thyroglossal duct on the midline
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Placodes
- ectodermal discs that form special
- sense organs of the head.
-
nasal placode >
mucosa of nasal capsule
-
lens placode >
lens of the eye
-
otic placode >
vestibule & cochlea of the ear
-
neurogenic placodes >
parts of CNs
-
nasal placode associated with CN
-
lens placode associated with CN
II optic
-
otic placode associated with CN
VIII vestibulocochlear
-
the actual eyes are formed from
the evagination of the wall of the brain (neuroectoderm)
-
Left & right maxillary prominences:
form
- upper cheek regions and
- upper lip
-
Left & right mandibular
prominences: form
- lower jaw, lower
- lip, and lower cheek regions.
-
Frontonasal prominence: forms
the forehead and dorsum/apex of nose.
-
Lateral nasal prominences forms
-
Medial nasal prominences:
- form the
- intermaxillary segment that eventually gives
- rise to the nasal septum, middle part of
- upper lip, and philtrum (medial cleft).
-
the maxillary and mandibular prominences are derivatives of arch
I
-
The palate forms through two stages
- Primary palate: extension of the intermaxillary segment from the nasal prominences.
- • Secondary palate: joining of the palatine process from the maxillary prominences.
-
define Cleft palate
- caused by incomplete
- closure of palate shelves or primary palatine
-
what is cleft lip
when maxillary prominence and the medial nasal prominece fail to fuse
-
frequency of cleft lip/palate?
Occurs in 1 in ~1,000 births.
-
chondrocranium
- endochondral cranial base
- that later ossifies
- • occipital, sphenoid, ethmoid, temporal (petrous part)
-
desmocranium
- intra)membranous bone to
- the sides and tops of braincase; forms the
- calvaria
- • frontal, occipital, parietal
-
viscerocranium
- derived from pharyngeal
- arches via membranous ossification. • temporal (squamous part), maxilla, zygomatic, mandible
-
what does the brain form from and each part of the brain?
- neural tube
- forebrain> prosencephalon
- midbrain>Mesencepahlon
- hindbrain>rhombencephalon
-
Craniosynostosis
- deformity in the
- cranium due to premature closure of
- sutures. Type of defect depends on which
- suture closes prematurely
-
Microcephaly
- caused by
- abnormal development of the
- brain, rather than premature
- closure of sutures. Often
- results in mental deficiency.
-
Hydrocephalus? and frequency?
- caused by
- elevated pressure in
- ventricles due to CSF
- buildup. Occurs 1 in ~1,000
- births.
-
Pituitary Gland:
- master gland for growth and reproduction
- pea-sized endocrine
- gland that receives signal from the
- brain via the hypothalamus and
- produces hormones for the entire body
- has anterior and posterior lobe that create diff hormones
-
Anterior lobe formed from
- upgrowth of ectodermal
- roof of the mouth
- (hypophyseal pouch)
-
Posterior lobe formed from
- downgrowth of floor of
- diencephalon
- (neurohypophyseal bud)
-
the ectoderm germ layer contribute which part of the head and neck
- brain & cranial nerves: from ectoderm-derived neural tube
- • placodes: eye lens, vestibule, cochlea, nasal cavity
- • parotid gland
-
the mesoderm germ layer contribute which part of the head and neck
- pharyngeal structures: in general from mesoderm but interacts
- with ectoderm-derived neural crest cells. These include
- branchiomeric muscles (e.g., extraocular mm, tongue, trapezius).
- • skull: includes chondro-, desmo-, and viscerocranium
-
the endoderm germ layer contribute which part of the head and neck
- glands (except for parotid gland) & mucosae: interacts with
- neural crest cells.
-
where do NCC comes from
- Ectoderm-derived but forms secondary mesenchyme
- (mesectoderm) to form “mesoderm”-derived structures
-
NCC migrate all over the body to turn into which structures ad is responsible for ?
- Migrates all over the body to turn into cartilage and bone,
- teeth, skin, melanocytes, smooth muscles, glands,
- adipose tissue, neurons, glia, adrenal medulla, etc.
- • Responsible for most of the connective and skeletal
- tissue of the head, nerves, and pigment cells
-
NCC contain information about how to
develop specie specific structure and are able to recruit host tissue to schieve this
-
NCC may ave a key factor in
evolution of animals in entire body and ad skull
-
the nervous system NCC derivatives ?
sensory ganglia of CN V, VII, IX, X, and peripheral nerves
-
the cartilage and bone NCC derivatives ?
- facial bones, some in the cranial base (parts of sphenoid bone),
- middle ear ossicles (malleus, incus, stapes), hyoid, laryngeal
- cartilage.
-
the muscle NCC derivatives ?
none
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