Lecture 7 Head and Neck Embryology Flashcards
What does the neck develop from
Branchial/Pharyngeal arches
Where does the face develop from
5 mesenchymal processes/prominences
Where does the skull develop from
The mesenchyme in the head region of developing embryo
What 2 areas are there no mesoderm
Sites of future mouth and anus- ectoderm stuck directly to endoderm
What does notochord formation lead to
Axis formation in embryo- embryo has left and right
The neural creat mixes with mesoderm to form
Mesenchyme
What arises from neural crests cells
Melanocytes, craniofacial cartilage and bone, smooth muscle, peripheral and enteric neutrons and glia
What are somites
Derived from the paraxial mesoderm and form structures like the axial skeleton and muscles
How many somites develop in human embry
33
Wha are the major and minor somite components
Sclerotome- vertebrae, ribs and cartilage
Myotome-muscle
Dermatome- dermis on back
Syndetome-tendons
What are the pharyngeal/branchial arches
Series of arches which develop around the future mouth and pharynx
How many branchial arches develop in humans
5, 6 arches develop by arch number 5 disappears
What embryological tissues make up the branchial arches
Ectoderm- lines outside
mesoderm- cartilage and muscles
endoderm- pouches between arches and lines inside
What nerve does the 1st arch form
Mandibular branch of trigeminal V3
What nerve does the 2nd arch form
Facial nerve (CN VII)
What nerve does the 3rd arch form
Glossopharyngeal (CN IX)
What nerve does the 4th arch form
Superior laryngeal branch f vagus (CNX)
What nerve does the 6th arch form
Recurrent laryngeal branch of the vagus (CN X)
All facial muscles are innervated by CN VII. What does that mean
All facial muscles developed from 2nd pharyngeal branch
What is the innervation of the digastric muscle
- Anterior belly innervated by mandibular division of trigeminal nerve (V3)-1st pharyngeal arch
- Posterior belly innervated by facial nerve- 2nd pharyngeal arch
What branch does the mylohyoid originate from
1st branch- V3
What branch does the stylohyoid originate from
2nd branch- facial
Your 4th and 6th arch form which structures
Larynx
Thyroid cartilage
Cricoid cartilage
Your 1st arch forms what structure
Mandible
Your 2nd arch forms what structure
Hyoid bone to styloid process
What other structures develop from the branchial arches
- Tongue
- Thyroid gland
- Parathyroid gland
- Part of the pituitary gland
Arch 1 forms what part of the tongue
Anterior 2/3rds- oral
Arch 2 forms what part of the tongue
Initial contribution to surface lost
Arch 3 forms what part of the tongue
Posterior 1/3- pharyngeal
Arch 4 forms what part of the tongue
Epiglottis and adjacent regions
Name the 5 processes the face develops from
Frontonasal process Medial process
Two maxillary processes
Two mandibular processes
The nasal placed invaginated to form what
Nasal pit–> Nostril
The medial process grows down to form th
Philtrum
The 2 maxillary processes originate from
maxillary part of 1st branchial arch mesoderm
The 2 mandibular processes originate from
1st arch mesoderm that fuse
Describe the stages of development for the palate
Medial nasal process grows downwards and forms philtre- primary palate
From maxillary process 2 palatine shelves grow inwards
This separates the oral and nasal cavity
When does cleft palate occur
When palatine shelves formed from the maxillary processes fail to meet in the midline to make the secondary palate
how are cranial vault- left bones formed by
Intramembranous ossification Calcaria
How are irregular bones from base of skull formed
Endochondral ossification
What are Viscercranium
Capsules formed around sensory organs
What is Craniosynostosis
Is a condition in which one or more of the sutures close too early, causing problems with normal brain and skull growth. Premature closure of the sutures may also cause the pressure inside of the head to increase and the skull or facial bones to change from a normal, symmetrical appearance.
(Base of skull) Where is mesenchyme around the notochord derived from
Predominantly neural crest cells that preform in cartilage first and later ossify
Where are sensory capsules derived from
Mesoderm of somites in head and neck region. These preform in cartilage and ossify to form bones around the sense organs, nose, eyes and ears
