Embryo

• What are derivatives and innervation of 1st Pharyngeal Arch?

  Derivatives: Muscles of mastication, Mylohyoid, Anterior belly of digastric, Tensor veli palatini, Tensor tympani.

  Bones: Maxilla, zygomatic, mandible, temporal (squamous part), Malleus and incus.

  Innervation: Trigeminal nerve (CN V)
• Derivatives and innervation of 2nd Pharyngeal (Hyoid) Arch?

  Muscles: Muscles of facial expression, stylohyoid, posterior belly of digastric, Stapedius

  Bones: lower wing and body of Hyoid, Stylohoid ligament and Stapes (reichert's cartilage)

  Nerve: Facial nerve (CN VII).
• Derivatives and innervation of 3rd pharyngeal arch?

  Stylopharyngeus muscle, glossopharyngeal nerve CN IX

  
• Derivatives and innervation of 4th- 6th Pharyngeal Arch?

  Derivatives: Muscles of the larynx (except cricothyroid), intrinsic muscles of the larynx, levator veli palitini (4th)

  Cartilage: Thyroid, Arytnoid, cuneform /cornitelletes

  Innervation: Superior laryngeal nerve (4th arch), recurrent laryngeal nerve (6th arch).
• Nerves derived from pharyngeal arches?

  1st- Trigeminal nerve (CN 5)

  2nd- Facial nerve (CN 7)

  3rd- Glossopharyngeal nerve (CN 9)

  4-6th- Vagus nerve (CN 10)

  4: Superior laryngeal nerve (right)

  6: Recurrent laryngeal nerve (left)

  
• Arteries derived from pharyngeal arches?

  Aortic arteries

  1st- Maxillary

  2nd- Stapedial (only 10% ppl have this)

  3rd- Common carotid and internal carotid

  4th- R: Subclavian art

  L: Aortic arch

  6th- R: right pulmonary art

  L: left pul. art, Ductus Arteriosus

  
• Derivative of 1st Pharyngeal pouch?


  Tympanic cavity (middle ear) and eustachian tube

  A) Eustachian Tube

  B) Tympanic membrane

  
• Derivative of 2nd pharyngeal pouch?

  Palatine tonsils and tonsillar fossa

  
• Derivatives of 3rd pharyngeal pouch?

  Dorsal - Inf. parathyroid glands

  Ventral - Thymus

  (Digeorge syndrome, 3rd pouch doesn't develop)
• Derivatives of 4th pharyngeal pouch?

  Dorsal- Sup. parathyroid gland

  Ventral- Ultimopharyngeal body --> C- cells: secrete calcitonin
• What is Cyclopia?

  Birth defect

  Single midline eye due to dysfunction of division of eye field
• When does development of face begin?

  4th week
• When does Intermaxillary segment form and its Derivatives?

  6th week and forms:

  1. Bridge of nose
  2. Philtrum (upper lip)
  3. 4 upper incisors
  4. primary palate

  
• What are Nasal Placodes?

  They are 2 ectodermal thickening on the frontal prominence

  form during 5th week

  
• what are the primary and secondary palate made from?

  Primary- Frontonasal prominence (Medial nasal prominence)

  Secondary- Maxillary process
• What is the definitive palate made from?

  The fusion of frontal prominence and maxillary process
• What is the definitive palate made from?

  Fusion of frontonasal and Maxillary process

  
• When does Palate start forming?

  Embryonic stage 6-12th week
• What are the 3 fusions needed for palate formation?

  1. primitive palate to palatal shelf of maxilla (Y shaped)
  2. Midline fusion of both palatal shelves of maxilla (Ant. to Post.)
  3. Nasal septum to palatal shelf of maxilla
• What type of ossification occurs in Hard palate?


  Intramembranous occurs in ant. 3/4th of the palate

  post. 1/4 remains as soft palate

  
• What is Bilateral complete cleft?


  Facial deformity where failure of fusion of both palatal shelves with the premaxilla

  
• What is Unilateral complete cleft?

  Facial deformity where failure of fusion of one side of palatal shelf and premaxilla

  
• Types of Incomplete clefts?

  1. Hard and soft palate
  2. soft palate
  3. Bifid uvula
• What is Van der woude syndrome?

  Genetic disorder, autosomal dominant due to mutation in IRF6

  most will have pits in lower lip but some will also have failed medial fusion

  
• What is a Oblique Facial Cleft?

  Failure of maxillary prominence to the lateral nasal prominence along the line of nasolacrimal groove.

  Nasolacrimal duct is usually exposed to the surface

  
• When does the Tongue start to develop?

  Around week 4 of intrauterine life
• Which arches is the tongue derived from?

  Ant. 1/3 = 1st pharyngeal arch

  Post. 2/3 = 2,3,4 pharyngeal arch

  
• Development of Ant. 2/3 of tongue?

  1. starts when 1st pharyngeal arch mesoderm proliferates --> Tuberculum Impar
  2. Right/left lateral lingual swellings develop above tuberculum impar
  3. both merge and make Mucosa (structure above the Ant. 2/3 of tongue)

  
• Innervation of Ant 2/3 of tongue?

  Trigeminal nerve CN V --> Mandibular division --> Lingual Branch

  
• Development of Post. 1/3?

  1. Copula forms = proliferation of mesoderm of pharyngeal arch 2 & 3
  2. Hypobranchial eminence = proliferation of mesoderm of 3 & 4 pharyngeal arch which grows and upwards and over the copula
  3. Becomes Mucosa of Post. part and fuses with Ant. portion

  
• Innervation of post. 1/3 of tongue?

  Glossopharyngeal Nerve CN IX
• What is Terminal Sulcus?

  v-shaped depression between the ant and post part of tongue

  at tip of terminal sulcus, endoderm descends down --> Thyroid gland

  descend of endoderm creates a sac-like structure known as foramen cecum

  
• What is the 3rd Median swelling of tongue?

  The most post. part of tongue, develops from 4th pharyngeal arch

  innervated by Vagus nerve CN X via internal Laryngeal nerve (branch of superior laryngeal nerve)
• Muscles innervation of Tongue?

  Hypoglossal Nerve CN XII (except Palatoglossus muscle, Vagus N)

  develop from Occipital somites --> Myoblasts --> skeletal muscles

  
• When do Tastebuds develop?


  Around week 8 and finish differentiating around week 11-13
• Tastebud innervation?

  Ant. = Chorda tympani (Facial N)= Taste

  Lingual branch (Trigeminal N) = Sensation

  Post. = Glossopharyngeal N (CN IX) = muscle
• Which germ layer is the eye derived from?

  Ectoderm
• What is Hillock of His?

  Tissue condensations derived from 1st and 2nd arches and make 6 hillocks

  1st hillock --> 1st arch

  rest --> 2nd arch
• When do Hillock of his join to form ear?

  around 5-6th month
• What is preauricular sinus?


  Congenital indentation, formed by faulty fusion of 1st and 2nd tubercle

  pit located normally in between tragus and crux of helix