Embryology Flashcards
Aortic arch 1 contributes to
maxillary a.
“First is Max”
Aortic arch 2 forms part of
the hyoid and stapedial a.
“Second is Stapedial”
Aortic arch 3 forms the
common carotid a. and proximal portion of the internal carotid a. (C is the 3rd letter)
Aortic arch 4 forms the
Right proximal subclavian a. and part of the aortic arch
“fouRS”
Aortic arch 5
degenerates during early development
Aortic arch 6
Pulmonary arteries and ductus arteriosis
How many pairs of pharyngeal arches are there?
5 (1, 2, 3, 4, 6). 4 and 6 are kind of fused
The pharyngeal arches are seperated by?
Pharyngeal grooves
What are the outter, middle, and inner layers of the pharngeal arches composed of?
outter - ectoderm
middle - mesenchyme
inside - endoderm
What does the neurocest cells of pharyngeal arch 1 become?
The maxillary prominence -> maxillary bone, zygomatic, & squamous portions of temporal bone
Mandibular prominence -> mandible, malleus, incus
Think Trigem structures
Innervation of pharyngeal arch 1 is?
Trigeminal (V)
Innervation of pharyngeal arch 2 is?
Facial (VII)
Innervation of pharyngeal arch 3 is?
Glossopharyngeal (IX)
Innervation of pharyngeal arch 4-6 is?
Vagus (X)
What does the neurocest cells of pharyngeal arch 2 gives rise to?
Lesser cornu of hyoid, stylohyoid ligament, stylohyoid process, stapes
Think Facial n.
What does the neurocest cells of pharyngeal arch 3 gives rise to?
Greater cornu of hyoid
3 is the smallest, think glossopharyngeal n.
What does the neurocest cells of paryngeal arch 4 gives rise to?
Laryngeal cartilages
Think Vagus
What does the mesoderm of pharyngeal arch 1 give rise to?
Muscles of mastication (temporalis, masseter, mylohyoid, ant belly of digastric, tensor tympani)
What does the mesoderm of pharyngeal arch 2 give rise to?
Muscles of facial expression
Stylohyoid, pos digastric
What does the mesoderm of pharyngeal arch 3 give rise to?
Stylopharyngeus
What does the mesoderm of pharyngeal arch 4/6 give rise to?
Pharyngeal constrictors, soft palate, laryngeal muscles
neural crest cells give rise to?
Bone and cartilage
Mesoderm gives rise to?
Muscles
The pharyngeal endoderm becomes the?
Pharyngeal pouches
Pharyngeal pouch 1 becomes the?
tubotympanic recess -> tympanic cavity, mastoid antrum, auditory tube
Pharyngeal pouch 2 becomes the?
Palatine tonsilar bed -> induces lymphoid tissue invasion and together form the palatine tonsil
Pharyngeal pouch 3 becomes the?
Thymus
inferior parathyroid
Pharyngeal pouch 4/6 becomes the?
superior parathyroid
Pharyngeal groove 1 becomes the?
External acoustic meatus
Pharyngeal grooves 2-4 become the?
Cervical sinus -> cervical vesicle
Both degenerate over time, persistance causes and branchial cyst/sinus/fistula
Describe the development of the thyroid
Endoderm between pharyngeal arch 1 and 2 -> thyroid primoridum -> descends below the hyoid.
Mature glad is anterior to trachea, caudal to larynx
The face is formed from what 3 structures?
Frontonasal prominence
Paired maxillary prominence
Paired mandibular promninence
As the maxillary prominence grow they
push the nasal prominences toward the midline of the face
The medial nasal prominences fuse and give rise to
Bridge of the nose
Intermaxillary segment
When the maxillary prominence fuses with the intermaxillary segement it forms
the Smooth upper lip
Fusion of primary and secondary palate
The lateral nasal prominences fuse with the maxillary prominence and form the
alae of the nose and the nasolacrimal duct forms at the site of fusion
The two nasal sacs fuse in the midline to form
A single nasal cavity with a thin membrane that ruptures to create a continuous nasal and oral cavity
What forms to separate the oral and nasal cavities?
the secondary palate is formed. Prevents aspiration of food
The primary palate is derived from
the intermaxillary segment
The secondary palate is derived from
fusion of the palatine shelves on the maxillary prominence (source of cleft lips)
A portion of the neural tube is transiently divided into segments termed
Rhombomeres
How many pharyngeal clefts are present once the final number of pharyngeal arches has been established?
1
The taste buds in the anterior 2/3rds of the tongue are innervated by
Facial n.
Olfactory sensory neurons arise from
nasal placodes within the nasal pits
What are the parts of the middle ear?
incus, stapes, malleous, round window niche
The tensory tympani and mylohyoid arise from which arch?
1st
The stylohyoid arises from which arch?
2nd
The lateral cricoarytenoid arise from which arch?
4th
