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25 Cards in this Set

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When does the face begin to form, and when is it completed?
Development of the Face

(1) Begins-4th wk of embryonic period
(2) Completes-12th wk of FETAL period
(3) FACE Squeezed b/w dev. brain & heart
DEHA Ch 4, p.40
What layers of the embryo are involved in facial development?
Facial Development:

all THREE embryonic layers

(1) Ectoderm (2) Mesoderm (3) Endoderm
DEHA Ch 4, p.40
Facial Development depends on what processes?
Facial Development

Depends on (5) facial processes (aka "prominences)

(1) Single Frontonasal Process
(2) Paired Max. Processes
(3) Paired Mand. Processes
DEHA Ch 4, p.40; Powerpoint
The five facial processes represent centers of growth. What do they correspond to on the face?
Five Facial Processes---and the face

(1) Frontonasal process = upper 1/3
(2) Max. processes = middle 1/3
(3) Mand. processes = lower 1/3
DEHA Ch 4, p.40; Powerpoint
What is the term for the primitive mouth? What is its lining? When does it form?
Oral Cavity Formation

Primitive Mouth = STOMODEUM
FORMS: during 3rd week
LINING: Ectoderm (future oral epithelium)
DEHA Ch 4, p.41; Powerpoint
What purpose does the Oropharyngeal Membrane serve?
Oropharyngeal Membrane

PURPOSE: Separates the stomdeum (mouth) from the primitive pharynx (3rd week)
DEHA Ch 3,p. 41
What occurs during the 4th week in the Oral Cavity formation? What is it's significance?
Oral Cavity Formation: (4th week)

(1) The Oropharyngeal Membrane disintegrates

SIGNIFICANCE: Allowing primitive mouth to INCREASE in depth
DEHA Ch 3, p.41
What is the primitive pharynx?
Primitive Pharynx:

(1) cranial portion of the FOREGUT
(2) beginning of future DIGESTIVE tract
DEHA Ch 3, p.41
What are the mandibular processes, and how do they form portions of the lower face?
The (2) bulges of tissue INFERIOR to the primitive mouth

Lower Face Formation:
Mand. processes + Neural crest cells FUSE Forms:
(1) Mand. Arch (2) Lower Lip
DEHA Ch 3, p.42
What is the first branchial arch and Meckel’s cartilage?
1st BRANCHIAL ARCH =Mand. Arch

Meckel's cartilage:
(1) forms on each side of 1st arch
(2) later disappears w/formation of bony mandible
DEHA Ch 3, p.42
What is the frontonasal process? To what portions of the face does it give rise?
Frontalonasal Process:

single bulge cephalic end of embryo

(2) forehead
(3) primary palate
(4) Nose (Medial, Lateral nasal processes)
DEHA Ch 4, p.44
Define placodes
Frontonasal Process

Rounded proliferations on the frontonasal process that develop into special sense organs
DEHA Ch 4, p.44
Describe the location of the lens, otic, and nasal placodes and what do they form

Lens placodes- each side laterally, migrate medially FORMS EYES

Otic placodes-each side far laterally FORMS INTERNAL EAR

Nasal placodes-sup. stomodeum FORMS OLFACTORY CELLS
DEHA Ch 4, p.44
Describe the further development of the nasal placodes and their relationship to the oronasal membrane.
Nasal placodes -->NASAL PITS--> Nasal Cavities--> Nasal Sacs

Nasal Sacs are separated from stomodeum by ORONASAL MEMBRANE (later disintegrates brings nasal & oral cavities in communication)
DEHA Ch 4, p.44
Describe the medial and lateral nasal processes on an embryo what they form with fusion.
2 crescent shaped swellings b/w nasal pits.
Fusion of both = center of upper lip

2 crescent shaped swellings outer portion of nasal pits.
Fusion of both = Alea of Nose
DEHA Ch 4, p.44
What is the intermaxillary segment? To what does it give rise?
Inter = "inside" Maxillary ="upper arch"

forms from the INTERNAL fusion of the MEDIAL NASAL processes

(1) max. incisor teeth (2) primary palate (3) nasal septum
DEHA Ch 4, p.44
What happens to the mandibular arch during the fourth week. To what does this new process give rise?
With overgrowth of the Mandibular Arch it gives rise to the Maxillary Process

(1) Middle of face
(2) sides of the upper lip (3) cheeks
(4) secondary palate (5) post. maxilla (6) zygoma (7) temporal bone
DEHA Ch 4, p.44
Describe the embryological development of the upper lip.

(1) SIDES OF UPPER LIP: forms from Max. Process

(2) MIDDLE OF UPPER LIP: forms from Medial nasal process

(3) COMMISSURES: fusion of Max & Mand. processes
DEHA Ch 4, p.46
What occurs with failure of fusion during the development of the upper lip, and what are its ramifications orally?

Cleft Lip - when max & medial processes fail to fuse
(1) inherited or acquired
(2) Unilateral or bilateral
(3) With or w/o cleft palate

Ramifications: complicates nursing/feeding of child, speech dev, appearance, oronasal infections
DEHA Ch 4, p.46
How does the primitive pharynx develop? What does the cephalic and caudal parts become?
Develops: from anterior FOREGUT
Origin: Endoderm layer

Cephalic end = oropharynx
Caudal end = esophagus
DEHA Ch 4, p.47
What is the branchial apparatus?
BRANCHIAL = "gills" for resp. function (aka "pharyngeal" humans)

Branchial Apparatus includes:
(1) Branchial ARCHES
(2) Branchial GROOVES
(3) Branchial POUCHES
DEHA Ch 4. p 47
To which tissues does each branchial arch give rise?

1st arch (Mand. Process)
-middle & lower face(maxilla, mand)

2nd arch (Hyoid Arch)
-part of the hyoid bone
3rd arch
-remainder of hyoid bone
4th-6h arches
-laryngeal cartilages
DEHA Ch 4. (p 47-48)
Table 4.2 (p 43)
What are the branchial grooves? What does the 1st groove form?

LOCATED: on outside of embryo b/w the arches

1st Groove: external auditory meatus (eardrum)
DEHA Ch 4. p 49
Name the tissues associated with each pharyngeal pouch.
Branchial (Pharyngeal) Pouches:

LOCATED: on INSIDE pharynx b/w the arches

1st Pouches-forms EAR CANAL


3rd/4th Pouches- Parathyroid, Thymus glands (processes key lymphocytes)
DEHA Ch 4. p 49
What are cervical cysts, and how can they present?

Form when branchial grooves do not obliterate

(1) Can drain through sinuses along neck
(2) slowly enlarging, painless swelling
DEHA Ch 4. p 49