A section through the external nostril and cranial part of the pericardial cavity.
Observe:
1. The edge of the cerebral vesicle surrounded by the endo- and ectomeninx.
2. The relation of the nasal elevations to the external nostril.
3. The oblique position of the aortic arch.
4. The muscles and nerves around the scapula.
5. The upper trunk of the brachial plexus passing through the scalene muscles.
Keywords: C-7 neural arch, C-7 spinal ganglion, C-7 spinal nerve, arch of aorta, brachial plexus (upper trunk, C-5 and C-6), deltoid muscle, ectomeninx, edge of cerebral vesicle(s), endomeninx, external nostril, frontal region, frontonasal elevation, jugular lymph sac, lateral nasal elevation, left brachiocephalic vein, left precardinal vein segment, mantle layer, marginal layer, medial nasal elevation, nasal septum, pectoralis muscles, pericardial cavity, scalene muscles, scapula, semispinalis capitis muscle, semispinalis cervicis muscle, splenius muscle, subclavian artery, subclavian vein, suprascapular nerve, thenar area, thyrocervical trunk, tracheal cartilage, trapezius muscle, vagus nerve (CN X)
Source: Atlas of Human Embryos.