General Embryology Mnemonics

2nd, 3rd and 4th weeks of development:

  • Week 2 : Bilaminar germ disc
  • Week 3 : Trilaminar germ disc
  • Week 4 : Appearance of 4 limbs

Major Neural Crest Derivatives:

“GAMES”

  • Glial cells of peripheral ganglia
  • Arachnoid and Pia Sheath
  • Melanocytes
  • Enteric ganglia
  • Schwann cells

Neuroectoderm derivatives

  • Neurons
  • Neuroglia
  • Neurohypophysis
  • piNeurol (pineal) gland

Foregut derivatives

“Little Embryo People Do Like Swallowing, Producing Gas”

  • Lungs
  • Esophagus
  • Pancreas
  • Duodenum (proximal)
  • Liver
  • Stomach
  • Pancreas
  • Gall bladder

Occurrence of Teratogenesis

TEratogenesis

Between Third and Eighth weeks of gestation.

Derivatives of Mesoderm:

Triploblastic animals

Derivatives of 3 germ layers

“MESODERM”

  • Mesothelium (peritoneal, pleural, pericardial)/ Muscle (striated, smooth, cardiac)
  • Embryologic Spleen/ Soft tissue/ Serous linings/ Sarcoma/ Somite
  • Osseous tissue/ Outer layer of suprarenal gland (cortex)/ Ovaries
  • Dura/ Ducts of genitalia
  • Endothelium
  • Renal Microglia
  • Mesenchyme/ Male gonad

Branchial apparatus:

“CAP covers from outside to inside.”

  • C for Clefts : derived from ectoderm
  • A for Arches : derived from mesoderm and neural crest
  • P for Pouches : derived from endoderm

Chromosomal disorders:

  • Edward syndrome : election age-ch-18
  • Down syndrome : drinking age-ch-21
  • Patau syndrome : puberty age-ch-13

Fetal Hemopoesis (for Physiology):

“Young Liver Synthesizes Blood”

  • Y : Yolk Sac (from 3 weeks)
  • L : Liver (from 3 months)
  • S : Spleen (from 3 months)
  • B : Bone marrow (5 month onwards)

After birth hemopoesis occurs only in bone marrow except in case of emergency when bone marrow falls.

Fetal alcohol syndrome (FAS):

“FAS”

  • F : Facial hypoplasia and Forebrain malformation
  • A : Attention defecit disorder and Altered joints
  • S : Short stature, Septal defects and Small I.Q

Neural Crest Derivatives

“4 Gang MEN wore CAP”

A. 4 Gang (4 ganglias)

  • Dorsal root ganglia of spinal nerves
  • Ganglia of V, VII, IX and X cranial nerves
  • Sympathetic & parasympathetic ganglia (autonomic ganglia)
  • Ganglion cell layer of retina

B. MEN

  • Melanoblast of the skin
  • Enamel of teeth
  • Neurilemma (Schwann cells)

C. CAP

  • Chromaffin cells and Cranio-facial skeleton
  • Arachnoid and Pia Maters
Branchial arch derivatives

Derivatives of branchial arches

First Branchial Arch:

“IMPACTS”

Most of the aspects associated with the first arch begin with the letter ‘M’ and the rest with I, P, A, C, T or S.

  • Name : Mandibular arch.
  • Muscles :
    • Muscles of Mastication (Masseter, Temporalis, Medial & Lateral Pterygoids)
    • Mylohyoid
    • Anterior belly of Digastric
    • Tensor tympani and Tensor palatini
  • Cartilage : Meckel’s cartilage
    • Malleus & Incus, Sphenomandibular ligament & Anterior ligament of Malleus
  • Innervation : Mandibular nerve, Chorda tympani

Cartilage derivatives of 2nd branchial arch:

5 “S”

  • Stapes
  • Styloid process
  • Stylohyoid ligament
  • Smaller (lesser) cornu of hyoid
  • Superior part of body of hyoid

Derivatives of Pharyngeal Pouches:

“1A, 2P, 3 TIP, 4 SPUB”

  • 1A (1st Pharyngeal Pouch – Auditory)
    • Epithelial lining of Auditory tube , middle ear cavity and mastoid antrum
  • 2P (2nd Pharyngeal Pouch – Palatine)
    • Epithelial lining of crypts of Palatine tonsil
  • 3 TIP (3rd Pharyngeal Pouch – Thymus and Inferior Parathyroid gland)
    • Thymus and Inferior Parathyroid gland
  • 4 SPUB (4th Pharyngeal Pouch – Superior Parathyroid gland and Ultimobranchial Body)
    • Superior Parathyroid gland and Ultimobranchial Body

Nerves:

“March 5, 7910”

  • 1 : V3 (March for 3  and 5 for V)
  • 2 : VII (7)
  • 3 : IX (9)
  • 4 & 6 : X (10)
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About the Author

Sulabh Shrestha
Intern doctor and Medical Blogger Sulabh Shrestha

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