Embryology 1 Flashcards
What does the face look like in week 4?
No face- no distinguishing external features
What is the Head and neck like in the 4th week?
1/2 of the length of the embryo
What do the pharyngeal arches become?
Brain, CVS and special sensory organs
What do the arches mean by segmental development?
Each arch has its own neurovascular plan and develops its own muscles and skeletal elements
Where is the gut tube made?
Pharynx
What is te gut tube made of?
Endoderm
What are pharyngeal arches?
System of mesenchmyal proliferations in the neck region of the embryo
How many pharyngeal arches are there?
5 in total
numbered 1-6
5 is not in humans
What cranial nerve is associated with the 1st arch?
Trigeminal nerve
What does arch 1 become?
pharyngeal
Muscles of mastication, Digastic and mylohyoid
Meckels cartilage- mandible, malleus and incus
What is arch 1 sensory become?
pharyngeal
Skin og the face and lining of the mouth and nose
part of tongue
What nerve is associated with Arch 2?
pharyngeal
Facial
What does Arch 2 become?
pharyngeal
Muscles of facial expression
Reicherts cartilage- stapes, upper body of hyoid and lesser horn, styloid process and stylohoid ligament
What is arch 2 sensory?
Pharyngeal
part of the tongue
What nerve is associated with arch 3?
Pharyngeal
Glossopharyngeal
What does the 3rd arch become?
Pharyngeal
Stylopharyngeus
lower body of hyoid and greater horn
What is the sensory of the 3rd arch?
Pharyngeal
part of the Tongue
What is the associated nerve with the 4th arch?
Pharyngeal
Vagus- superior laryngeal branch
What does the 4th arch become?
Pharyngeal
Pharyngeal muscles, cricothyroid
Thyroid cartilage and cricoid cartilage
What is the nerve associated with the 6th arch?
Pharyngeal
Vagus
recurrent laryngeal branch
What does the 6th arch become?
Pharyngeal
Intrinsic muscles of the larynx
Arytenoid cartilage
What does the 1st and 2nd aortic arch become?
Disappear
What does the 3rd artic arch become?
Internal carotid
What does the 4th aortic arch become?
Arch of the aorta and Brachiocephalic
What does the 6th aortic arch become?
Pulmonary arch
What are pharygeal pouches?
Endoderm lined pockets in the pharynx
Why is the first pharyngeal pouch important?
Largest and becomes the tympanic cavity
What do pharyngeal pouches become?
Palatine tonsils
Parathyroid gland
thymus
What does the 1st pharyngeal cleft become?
external acoustic meatus
What does the 2nd pharyngeal cleft do?
Grow down and covers others so obliterates other clefts
What happens if there are remnants of the pharyngeal clefts?
Brachial cyst or fistula
What drives development of the face?
Expansion of the cranial neural tube
Appearance of a comples tissue system associated with- cranial gut tube, outflow of the developing heart
Development of sense organs and need to seperate the resp tract from Gi
How does the face develop?
Facial primordia- first pharyngeal arch and frontonasal prominence
Where is teh FNP?
surrounds the ventral lateral part of the forebrain
What are the components of the face?
Stomatodeum- becomes buccopharyngeal membrane
Frontonasal prominence
1st pharyngeal arch which had maxillary and mandibular prominence
What facial features does the FNP develop into?
forehead
Brige of nose
Nose
Philtrum
What does the maxillary prominence become?
Cheeks
lateral upper lip and jaw
What does the mandibular prominence become?
Lower lip and jaw
Where do nasal placodes appear?
Frontonasal prominence
What do nasal placodes sink to become?
Nasal pits
What from either side of nasal pits?
Nasal promincence
Where do maxillary promineces grow?
Medially pushing the nasal prominence together in the midline
Fuse with medial nasal prominence and then fuse with the midline
How are the nasal and oral cavities separated?
Fusion of medial nasal prominence created the intermaxillary segment
What is the secondary palate (Main part) derived from?
Palatal shelves from maxillary prominence
How do the maxillary promience grow?
Vertically downwards into the oral cavity on each side of the developing tongue
How does the tongue develop?
What is a lateral cleft lip?
Failure of fusion of medial nasal prominence and maillary prominence
What is cleft lip and cleft palate?
Combined with failure of shelves to meet in midline and lateral cleft lop
What does the middle ear cavity and ossicles develop from?
1st pharangeal pouch and cartilage and 1st and 2nd arches respectively
How do auricles develop?
proliferation within 1st and 2nd pharngeal arches surrounding the meatus
What is the position of the ear?
External ears develop in neck to begin with
Mandible grows the ears ascend and lie in line with the eyes
What do all common chromosomal abnormalities have?
Abnormalities associated with external ear
Why is fetal alcohol syndrome a thing?
Face is derived from neural crest cells in pharyngeal arches which migration is sensitive to alcohol
As is brain development
