Embryology Neck Flashcards
Embryology of thyroglossal duct ?
3rd week, FORAMEN CECUM develops between anterior 2/3 and posterior 1/3 of the tongue. Then develops into Thyroid GLAND. The latter dives into the neck and creates this DUCT. Process ends 7th week
TGD in relation with hypoid bone?
Usually in the midline, but infrahyoid the duct can move off midline
Types of cells in the TGD?
and
How is TGD cyst formed ?
Walls lymphoid and epithelial cells and stick to each other by third trimester duct gone
It is filled with mucus from epithelial cells.
Complications of a congenital cyst?
Infection -> Respiratory tract -> Cyst
Inflammation more mucus
If the cyst bursts -> Discharging sinus (fistula)
Where is ectopic thyroid located?
Remains in the residual duct
What is the pharyngeal apparatus?
Contents of each arch?
Pairs of branhcia/pharyngeal arches, pouches and clefts
Artery, nerve and cartilage
Embryology of the arches, pouches and clefts
Arches: Mesoderm
Pouches: Endoderm
Clefts: Ectoderm
How many arches?
1-6 but 5 either doesn’t form or regresses immediately
Function of 1st Paryngeal Arch?
Function of 2nd Paryngeal Arch?
Chewing
Facial expressions
Nerves of 1st Pharyngeal Arch
Bones 1st Pharyngeal Arch
Nerves:
Trigeminal n. CN5
Mandibular n. V3
Bones: Mandible, Zygomatic bone, Maxilla, Incus, Malleus
Muscles 1st Pharyngeal Arch
Chewing muscles: Temporalis, Pterygoid, Masseter
Swallowing : Tensor veli palatini, Mylohyoid muscles and ANTERIOR Belly digastric
+
Tensor tympani
Origin of the post belly of digastric mucle?
2nd Pharyngeal Arch
Nerves and bone 2nd Pharyngeal Arch?
Facial N.
Hyoid bone, styloid process, stapes
Embryology of the ossicles?
Upper part malleus - incus = 1st Arch
Lower part malleus - incus and staple = 2nd Arch
BUT FOOTPLATE of stapes from otic capsule (inner ear)
Muscles 2nd Pharyngeal arch?
Sound and swallowing
Post belly digastric and stapedial muscle
Origin of tensor tympani muscle?
Origin of stapedius muscle?
1st Arch
2nd Arch
Muscles, nerve, bones 3rd Arch?
Stylopharyngeus m.
Glossopharyngeal nerve IX
Hyoid bone
Function and derivatives of 4 and 6th Pharyngeal Arches?
Everything we need to speak!
Vagus nerve
Superior Laryngeal n. 4th arch
Recurrent Laryngeal n. 6th arch
Laryngeal Cartilage
Muscles of Larynx, pharynx and mouth
Derivatives of 1st Pharyngeal Cleft?
Helps form EAR
EAC
Ear Drums
What is the location of a First Branchial Cleft cyst?
From EAC to angle of mandible
What is the most common location of a second branchial cleft cyst?
Anteromedially to SCM, laterally to carotid and posteriorly to submandibular . Type II most common
What are the derivatives of the 1st Pharyngeal Pouch?
Cavity that forms IAM and Eustachian tube
2nd Pharyngeal pouch?
Primitive tonsils
Which malformations often come together?
Middle and external ear
What is the importance of 3rd and 4th pharyngeal pouches?
Calcium regulation
3rd primitive thymus
4th parafollicular cells of thyroid gland
What is the origin of the inferior parathyroid?
What is the origin of the superior parathyroid?
3rd pouch
4th pouch
What is the superficial cervical fascia?
Thin layer of fat that lies between the dermis of the skin and the SL of the DCF.
contents of the superficial cervical fascia?
Platysma, nerves, blood/lymphatics fat (σημαντικά για την παθολογία)
Pathology related to the superficial cervical fascia?
Teratoma Vasc Malformations (vessels) Tumors/Haemangioma Cellulitis (fat) NF1 (neuromas along nerves) Subcutaneous fat fibrosis (fat)
3 layers of the Deep Cervical Fascia
Superficial Layer DCF
Middle Layer DCF
Deep Layer DCF
Superficial layer DCF spaces
Suprahyoid:
Masticator space
Parotid space
Part of Carotid space
Infrahyoid:
Surrounds strap m., SCM, trapezius m
Middle layer DCF spaces
SHN: Pharyngeal mucosal space deep margin, contributes to carotid space
IHN: Surrounds visceral space. Contributes to carotid space.
Deep Layer DCF spaces
SHN & IHN: Surrounds perivertebral space (paraspinal and pre-vertibral). Contributes to carotid
What is the Alar Fascia?
Part of the DL-DCF which forms the lateral and posterior walls of the retropharyngeal space and separates from the Danger space
What is the Danger Space?
Virtual space between retropharyngeal space and pre-vertebral component of the perivertebral space
How many arches, clefts, pouches?
5 Arches (1-6 but 5 doesn’t form)
4 clefts
4 pouches
Embryology of the footplate of the stapes
Ottic capsule together with inner ear
Summary of derivatives of the pharyngeal apparatus
Arches - Mesoderm : Bones, muscles of head and neck
Clefts - Ectoderm : Stuctures of ear canal
Pouches - Endoderm: Parts of the ears , Tonsils, Parathyroid, Thyroid
Where is the posterior cervical space?
Space between the SL-DCF surrounding the SCM and the DL of the DCF surrounding the paraspinal muscles. Contains fat and lymph nodes.
Parts of the perivertebral space
Prevertebral space anteriorly
Paraspinal space posteriorly (posterior elements)
Lymph node levels, what are the two horizontal planes?
Hyoid bone and cricoid cartilage
Level I = below the mandible
Behind the mandible/angle = Level II
Down to hyhoid Level III and down to cricoid level IV
