Transcription 5/18/2025, 4:39:50 PM

Apuntes

• Germinal Layers and Derivatives **Endoderm:** Forms organs, the gut (stomach, liver, etc.), respiratory tract (lungs), and "tubular structures." **Notochord:** Gives rise to the nucleus pulposus. **Mesoderm:** - *Paraxial:* Sclerotome → vertebra, ribs; Dermatome → skin; Myotome → epimere and hypomere. - *Epimere:* dorsal primary rami, posterior muscles, extensors. - *Hypomere:* ventral primary rami, anterior muscles, flexors. **See exception.** - *Intermediate:* Urogenital system (gonads), adrenal cortex. - *Lateral:* - *Somatic:* muscles, ligaments, tendons. - *Splanchic:* heart, smooth muscle of organs ("visceral"). **Surface ectoderm:** Epidermis, anterior pituitary, lens of the eye, skin, tooth enamel, hair. **Ectoderm:** Neural tube → brain/spinal cord (CNS), posterior pituitary, retina of the eye, oligodendrocytes. **Neuroectoderm:** Neural crest → sympathetic chain ganglion, PNS, ANS, dorsal root ganglion, Schwann cells, parafollicular cells of the thyroid, adrenal medulla. *Note:* Any back muscle innervated by a nerve branching from a plexus is considered innervated by ventral primary rami; examples include th...