Ethmoid bone,

Neurocranium: on either side are parietal bones (2x), Back side by the notochord is occipital bone (1x) and front side by the ethmoid bone are frontal bones (2x)

ethmoid bone

neuracranium

2 parietal bones

2 frontal bones

1 occipital bones

1,2,3,4,6 arches comes from the heart bellow the hand, build on anterior portion on the skul. wrap around to form the neck and human face in anterior part of the skull.

each arches has: artery, vein, cartilage, nerve and muscle unit.

• 1st brachial arch surrounded by 2 boney covering, one on each side become manible and maxilla.
• 1st brachial cartilages give rise to malleus and incus
• 2nd arch cartilage give rise to stapes.

• Nasoplacode: nasal cavity in the front, Nasoplacde goes inside the head and change shape.
• Lens Placode: lens of eyes.
• Otic Placode: ear

• 1st arch: muscle of mastication-->make muscle that chew)
• 2nd arch: muscle of facial expression.
• either side of notochord=post-ortic muscle (behind the ear)= somite.
• around the eys= 3 pre-ortic soites on each eye.

• Reichert's pouch- gap between notochord and neurocranium. in this gap grows pituitary gland. Behind this pituitary gland, we have the pon, medulla and spinal cord.
• Associate with somite, these somite make the tongue muscle (hypoglossal nerve CN XII)
• somite also make trapezius and stenocleinomastoid mm (spinal assessory nerve CN XI)
• eyes muscles has 3 motor nerve, each for each eyes somites (superior/inferior oblique, superior/inferior rectus, medial/lateral rectus). 1. trochlear (IV), 2. Abducent (VI), 3. oculomotor (III).
• Nasocavity has olfactory nerve (CN I).
• nerve associate with brachial arch: 1st arch (V -trigeminal), 2nd arch (VII facial), 3rd arch (VIII- vestibulocochlear- associate with earplacode).

• anterior pituitary: goes through reichert's pouch.
• posterior pituitary: goes from brain down to meet anterior part, forming hypophyseal.

1. neurocranium (endochondral ossification-start as cartilage and becomes bone)

2. Intramembraneous bone (form inside ectoderm): pariental, occipital, mandible, frontal, maxilla.