Embryology Flashcards
What is a blastula?
Embryonic ball of cells
What is a bilaminar disc?
Flattened plate of cells with amniotic cavity dorsally and yolk sac ventrally
What does the bilaminar disc form?
Trilaminar disc- ectoderm, mesoderm and endoderm
Why is there no mesoderm at 2 point in the embryo?
Areas that will form the mouth and anus
What causes axis formation in the embryo?
Notochord formation
What germ layer forms the neural tube?
Ectoderm
What forms the neural crest cells?
Some cells at the crest of the neural fold that seperate
When do neural crest cells mix with the mesoderm?
In the head and neck region
What is the cavity at the superior of the embryo?
Amniotic
What cavity is at the inferior of the embryo?
Yolk sac
What are somites?
Cells derived from the paraxial mesoderm and form structures like the axial skeleton and muscles
How many somites are there?
33 in total
What do somites in the head region of the embryo form?
Help in development of cranial skeleton
What are the branchial arches?
Series of arches which develop around the future mouth and pharynx
What is the function of the branchial arches?
Support primitive pharynx
Face and neck development
Hw many branchial arches are there in humans?
5
What does the ectoderm form in the branchial arches?
Clefts between arches
What does the mesoderm form in the branchial arches?
Cartilage
Muscles
What does the endoderm form in the branchial arches?
Pouched between arches
What nerve supplies the 1st branchial arch?
Mandibular branch of trigeminal nerve
What does the 1st branchial arch form?
Anterior belly of digastric muscle
Mandible, males, incus
What nerve supplies the 2nd branchial arch?
Facial nerve
What does the 2nd branchial arch form?
Muscles of the face and posterior belly of the digastric muscle
Hyoid, styloid, stapes
What nerve supplies the 3rd brcnhail arch?
Glossopharyngeal
What nerve supplies the 4th branchial arch?
Superior laryngeal branch of vagus
What does the 4th branchial arch form?
Striated muscle of oesophagus and cricoid cartilage
Thyroid cartilage
What nerve supplies the 6th branchial arch?
Recurrent laryngeal branch of vagus
What does the 6th branchial arch form?
Striated muscle of oesophagus and cricoid cartilage
What does the 3rd branchia; arch form?
Hyoid
What glandular structures develop from the branchial arches?
Thyroid
Parathyroid
Part of pituitary
What does the face develop from?
5 processes
What are the 5 processes that the face will develop from?
Frontonasal process
Two maxillary processes
Two mandibular processes
How are the nasal placodes formed?
Rapid downward growth of the frontonasal process
What happens to the nasal placodes?
Invaginate to form the nasal pit, which will form the nostrils
How are the nostrils and mouth separated?
Formation of 2 medial processes which fuse and 2 lateral nasal processes
What do to medial processed form?
Philtrum and septum
What are the 2 maxillary processes formed from?
Maxillary part of 1st branchial arch
What do the mandibular processes form from?
1st brachial arch mesoderm
What do the mandibular processes do?
Fuse in the middle to separate oral and nasal cavities
What forms the flat bones of the skull?
Membranous ossification
What forms the irregular bones of the skull?
Endochondral ossification
What forms the skeleton of the face?
Branchial arches and sensory capsules
What is the process of membranous ossification?
Mesenchyme directly above the surface of the brain ossifies
What forms the mesenchyme around the notochord?
Mainly neural crest cells
What is the process of endochrondral ossification?
Preform in cartilage, then ossify
What are the sensory capsules derived from?
Mesoderm of somites in head and neck
