Embryology

Front 1

Embryologic derivatives
Ectoderm: Surface Ectoderm

Back 1

Adenohypophysis; lens of eye; epithelial linings of oral cavity, ear, eye, and nose; epidermis;salivary, sweat, and mammary glands

Front 2

Embryologic derivatives
Ectoderm: Neuroectoderm

Back 2

Brain (neurohypophysis, CNS neurons, oligodendrocytes, astrocytes, ependymal cells, pineal gland), retina, spinal cord

Front 3

Embryologic derivatives
Ectoderm: Neural Crest

Back 3

ANS, dorsal root ganglia, cranial nerves, celiac ganglion, melanocytes, chromaffin cells of adrenal medulla, enterochromaffin cells, parafollicular (C) cells of thyroid, Schwann cells, pia and arachnoid, bones of the the skull, odontoblasts, laryngeal cartilage, aorticopulmonary septum

Front 4

Embryologic derivatives
Endoderm

Back 4

gut tube epithelium and derivatives (e.g., lungs, liver, pancreas, thymus, parathyroid, thyroid follicular cells)

Front 5

Embryologic derivatives
Mesoderm

Back 5

muscle, bone, connective tissue, serous linings of body cavities (e.g., peritoneum), spleen (derived from foregut mesentery), cardiovascular structures, lymphatics, blood, urogenital structures, kidneys, adrenal cortex

Front 6

Branchial arch 1 derivatives

Back 6

Meckels cartilage: mandible, malleus, incus, sphenomandibular ligament
Muscles: muscles of mastication (temporalis, masseter, lateral and medial pterygoids), mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palitini, anterior 2/3 of tongue

Front 7

Branchial arch 2 derivatives

Back 7

Reichert's cartilage: stapes, styloid process, lwsser horn of hyoid, stylohyoid ligament
Muscles: muscles of facial expression, stapedius, stylohyoid, posterior belly of digastric

Front 8

Branchial arches 4-6 derivatives

Back 8

Cartilages: thyoid, cricoid, arytenoids, corniculate, cuneiform
Muscles (4th arch): most pharyngeal constrictors, cricothyoid, levtor veli palatini
Muscles (6th arch): all intrinsic muscles of larynx except cricothyroid

Arches 3 and 4 form posterior 1/3 of tongue

Front 9

Branchial cleft derivatives

Back 9

1st cleft develops into external auditory meatus
2nd through 4th clefts form temporary cervical sinuses, which are obliterated by proliferation of 2nd arch mesenchyme
Persistent cervical sinus --> branchial cleft cyst within lateral neck

Front 10

Branchial pouch 1 derivatives

Back 10

middle ear cavity, eustachian tube, mastoid air cells

1st pouch contributes to endoderm-lined structures of ear

Front 11

Branchial pouch 2 derivatives

Back 11

epithelial lining of palatine tonsil

Front 12

Branchial pouch 3 derivatives

Back 12

dorsal wings: inferior parathyroids
ventral wings: thymus

3rd pouch contributes to 3 structures (thymus, left and right inferior parathyroids). 3rd pouch structures end up below 4th pouch structures

Front 13

Branchial pouch 4 derivatives

Back 13

dorsal wings: superior parathyroids

Aberrant devlopment of 3rd and 4th pouches --> DiGeorge syndrome --> leads to T-cell deficiency (thymic aplasia) and hypocalcemia (failure of parathyroid development)

Front 14

Diaphragm is derived from:

Back 14

1) septum transversum -> central tendon
2) pleuroperitoneal folds
3) body wall
4) dorsal mesentery of esophagus --> crura