Head and Heart

4 weeks, 6 days

If you look just above the heart, it seems like you can look right through the chest.

1. forebrain

2. 1st pharyngeal arch (maxillary process)

3. mouth (stomodeum)

4. 1st pharyngeal arch (mandibular process)

5. auricular groove

6. 2nd pharyngeal arch

7. 3rd pharyngeal arch

8. chest wall

9. liver

10. heart

11. cervical sinus

All ages referenced to fertilization, not last menstrual period.