H&N L10: Branchial Arch Embryology

For quiz 4 and Exam 2

stomatodeum is the

primitive oral cavity

What lines the stomatodeum?

surface ectoderm

Where does the stomatodeum form?

between the developing brain and heart

Oral mucosa, lips, gingiva, enamel, and the anterior pituitary gland are all derivatives of what?

the stomatodeum

What lines the primitive pharynx?

the endoderm

What separates the stomatodeum from the primitive pharynx (disappearing at the end of week 3)?

the buccopharyngeal membrane

What is the level of ectoderm-endoderm junction in adults?

oral fauces (arches)

What is the ectodermal outpocketing from the stomatodeum?

Rathke’s pouch (becomes the anterior pituitary gland)

What does the posterior pituitary gland derive from?

the neural tube

When do teeth begin to form?

week 6

What is the thick line of surface ectoderm along the mandible and maxilla?

dental lamina

What is the ectodermal, primordial, form of enamel?

a dental bud

What is the neural crest-derived mesenchyme that forms dentin and pulp?

dental papillae

Oral and nasal mucosa, the parotid gland, and enamel all derive from?

the surface ectoderm

the olfactory bulb and retina of the eye derive from what?

the neural tube

facial bones, cartilage, the hyoid, and dentin all derive from what?

neural crest cells

The occipital bone and skeletal muscle (somite) derive from what?

the paraxial mesoderm

laryngeal cartilages derive from what?

the lateral plate mesoderm

the pharyngeal epithelium, laryngeal epithelium, taste buds, parathyroid and thymus glands, submandibular and sublingual glands all derive from what?

the endoderm

how many arches form around the gut tube (visceral)?

6, arch 5 degenerates

The lateral plate mesoderm (LPM) core is line with what kind of epithelium?

endoderm epithelium

Neural crest cells invade what arches to form bone, cartilage, and connective tissue?

arches 1-3

laryngeal cartilages arise from what arches?

arches 4 and 6

another word for somites is

paraxial mesoderm, which it invades to form muscle tissue

another word for cranial somites is?

somitomeres

extrinsic eye muscles (CN III, IV, VI; GSE) arise from?

cranial somites

tongue muscles (CN XII; GSE) arise from

occipital somites

1. myoblasts (muscle-forming cells) from the cranial and occipital somites
2. migrate into the branchial arches, follow NCC, to form muscles of the head and neck
3. CN 5, 7, 9, and 11c (SVE)

branchial arches

What arch?


1. CN 5
2. bone and cartilage = maxillary prominence (maxilla, palatine, zygoma, squamous, temporal, and incus) + mandibular prominence (mandible and malleus)
3. skeletal muscles = maxillary prominence (muscle of mastication) + mandibular prominence (mylohyoid, anterior digastric, and tensor tympani)

Arch 1 = mandibular

What arch?


1. CN 7
2. bone and cartilage = styloid, lesser horn and body of hyoid, stapes
3. skeletal muscles = muscle of facial expression, posterior digastric, and stylohyoid, stapedius

arch 2 = hyoid

what arch?


1. CN 9
2. bone and cartilage = greater horn and body of hyoid
3. skeletal muscle = stylopharyngeus

arch 3

What arch?


1. CN 10 (superior laryngeal nerve) and 11c
2. bone and cartilages = laryngeal cartilages
3. skeletal muscles = pharyngeal and palate muscles and cricothyroid muscle

arch 4

what arch?


1. CN 10 (RLN)
2. bone and cartilages = laryngeal cartilages
3. skeletal muscles = intrinsic laryngeal muscles

arch 6

what is inside branchial arches and lined with endoderm

the pharyngeal pouch

what is outside the branchial arches and lined with surface ectoderm?

pharyngeal cleft

what pouch and cleft leads to the middle ear and auditory tube + the external ear (respectively)

pouch 1 + cleft 1 (respectively)

what pouch and cleft leads to the palatine tonsils + cervical sinus (respectively)

pouch 2 + cleft 2 (respectively)

what pouch and cleft leads to the thymus and inferior parathyroid glands + the cervical sinus?

pouch 3 + cleft 3 (respectively)

What pouch and cleft leads to the superior parathyroid and parafollicular cells of the thyroid gland + the cervical sinus

pouch 4 + cleft 4 (respectively)

What clefts fuse to form the cervical sinus before being obliterated during development (which if it fails, a cervical cyst may form)?

clefts 2-4

what are paired arteries associated with the branchial arches?

aortic arches

of the 6 aortic arches, which ones regress?

aortic arches 1, 2, and 5

the common carotid arties derive from what aortic arch?

aortic arch 3

The R brachiocephalic artery, L aortic arch, and L subclavian artery derive from what aortic arch?

aortic arch 4

the pulmonary arteries and ductus arteriosus derive from what aortic arch?

aortic arch 6

The RLNs, which supply the intrinsic muscles of the larynx responsible for speech, is associated with what branchial arch?

branchial arch 6

Neural crest cells give rise to what half of the skull?

the front half

the paraxial mesoderm gives rise to what half of the skull?

the back half of the skull

the laryngeals of the skull derive from what?

the LPM

what developmental part of the skull?


1. arises from the branchial arch-related neural crest
2. examples: mandible, maxilla, zygoma, and hyoid

the viscerocranium (facial skeleton)

what developmental part of the skull?


1. from neural crest and somites (sclerotome)
2. flabones of the braincase (cranial vault)
3. form through intramembranous ossification
4. examples: frontal bone (NCC) parietal and occipital bones (PAM)

the membranous neurocranium

what developmental part of the skull?


1. from neural crest and somites (sclerotome)
2. bones of the skull base (basicranium)
3. form through endochondral ossification
4. examples: sphenoid, ethmoid, petrous part of the temporal bone

neural chondocranium

what part of the skull?


1. depression in sphenoid bone
2. contains the hypophysis

the sella turcica (Turkish saddle)


1. basicranial bone posterior to the sella turcica derived from sclerotome
2. basicranial bone anterior to the sella turcica is derived from the NCC

hyoid bone develops from what?

neural crest cells

the lesser horn and upper body of the hyoid bone derives from what arch?

arch 2

the greater horn and lower body of the hyoid bone derives from what arch?

arch 3

connective tissue for arches 4-6 come from what?

the LPM

thyroid, cricoid, arytenoid, corniculate, and cuneiform are all what?

laryngeal cartilages

the tongue is what kind of innervation?

muscular GSE, tactile sensation (GSA), and chemosensation (SVE)

From what does the muscles of the tongue develop?

What are the tongue muscles’ innervation and CN?

the occipital somites.

GSE innervation from CN 12

What are the two major regions of the tongue?

oral tongue (front 2/3)

pharyngeal tongue (posterior 1/3)

what marks the boundary between the oral tongue and pharyngeal tongue?

the foramen cecum

T/F: innervation to mucosa of tongue is GSA (from oral ectoderm)

True

what is it?


1. form the mucosa of the anterior 2/3 of the tongue
2. arch 1 (CN 5, GSA)

lateral lingual swellings

what is it?


1. tuberculum impar from arch 1 (CN 5, GSA)
2. hypobranchial eminence (AKA copula lingulae) from arch 3 (CN 9, GSA)
3. epiglottis from arch 4 (CN 10, GVA)

medial lingual swellings

where do taste buds come from?

the endoderm lining the branchial arches

CNs that carry taste are?

CN 7, 9, and 10

T/F: oral tongue, pharyngeal tongue, and epiglottis have different cranial nerves for taste (SVA)

True

Tongue innervation

what part of the tongue?


1. associated with arches 1 and 2
2. sensation (GSA): CN 5
3. taste (SVA): CN 7

oral tongue (anterior 2/3)

tongue innervation

what part of the tongue?


1. associated with arch 3
2. sensation (GSA): CN 9
3. taste (SVA): CN 9

pharyngeal tongue (posterior 1/3)

what is it?


1. associated with arch 4
2. sensation (GVA): CN 10
3. taste (SVA): CN 10

the epiglottis

what is it?


1. develops from between arches 1 and 2
2. follicular cells from endoderm
3. parafollicular cells from NCC (pouch 4)

the thyroid gland

what gland descends though the developing tongue

the thyroglossal duct

what marks the position of the thyroglossal duct?

the foramen cecum

a patent thyroglossal duct may give rise to what?

a cyst or fistula

mucosa of the anterior 2/3s of the tongue develops primarily from what?

the lateral lingual swellings

what are the primordial structures of the face?

1. frontonasal prominence
2. maxillary swelling
3. mandibular swelling

what is it?


1. forms the nasal placodes/pits (nasal cavities)
2. placodes surrounded by medial and lateral nasal swellings

the frontonasal prominence

the maxillary swelling and mandibular swelling both derive from what arch?

arch 1, paired

what are the adult structures of the nasofrontal prominence?

the forehead + bridge of the nose

what are the adult structures of the medial nasal prominence?

the philtrum, crest and tip of the nose, and anterior palate

what are the adult structures of the lateral nasal prominence?

alae (wings) of the nose

what are the adult structures of the maxillary?

the cheeks, lateral upper lips, and palate

what is the adult structure of the mandible prominence?

lower lip

fused medial nasal swellings form what?

the intermaxillary segment

2nd most common congenital defect in the U.S.

cleft lip

is cleft lip or cleft palate more common?

cleft lip (11/10,000 vs 6.5/10,000)

cutaneous sensory regions

trigeminal nerve

greater occipital nerve

greater auricular nerve

What nerve?


1. associated with CN V (innervation of the face)
2. CN V1 = opthalmic nerve
3. CN V2 = maxillary nerve
4. CN V3 = mandibular nerve

the trigeminal nerve

what nerve is associated with C2 in innervating posterior scalp and neck?

greater occipital nerve

what nerve is associated with spinal nerves C2-C3: angle of mandible and external ear

greater auricular nerve

What kind of muscles are cause facial expressions?

cutaneous muscles, which insert on the skin, other muscles, or aponeuroses

what muscle is it?


1. derived from and completely surround by superficial fascia
2. innervation = cervical branch, facial nerve (CN 7)

the platysma muscle (clavicle to mouth muscle)

word for flat, broad tendon

aponeurosis

what flat, broad tendon connects the occipital, auricular, and frontal muscles?

epicranial aponeurosis

what distributes forces from the superficial facial muscles to the skin?

the superficial muscular aponeurotic system (SMAS)

What CN is associated with the facial nerve, emerging from the parotid gland

CN 7

The temporal, zygomatic, buccal, mandibular, and cervical are all branches of what?

facial nerve (CN 7)

name for fibromuscular condensation?

facial modiolus

name for:

convergence of 8 muscles:


1. orbicularis oris
2. depressor anguli oris
3. levator anguli oris
4. levator labii superioris
5. depressor labii inferioris
6. buccinator
7. risorius
8. zygmaticus major

facial modiolus (highly fibrous, does not deform easily)