It is perforated by a large oval opening, the foramen magnum, through which the cranial cavity communicates with the vertebral canal. It has two portions: scaly and basilar.

a) Scaly & #8211; curved blade extending posteriorly to the occipital foramen.

b) Basilar & #8211; anterior to the occipital foramen and thick.

Scaly:

Outer Face: posterior and convex. It has the following structures:

 External Occipital Protuberance & #8211; It is located between the apex of the bone and the foramen magnum.

 External Occipital Crest

 Supreme Occipital (Nucal) Line & #8211; aponeurotic galea insertion site. It is located laterally the external occipital protuberance

 Upper Occipital (Nucal) Line & #8211; it is located below the supreme nuchal line

 Lower Occipital (Nucal) Line & #8211; just below the upper nuchal line

Inner Face: is previously located. It has the following structures:

 Cruciform Eminence & #8211; splits the inner face into four pits

 Internal Occipital Protuberance & #8211; intersection point of the four divisions

 Sagittal Groove & #8211; houses the posterior portion of the superior sagittal sinus

 Internal Occipital Crest & #8211; lower portion of the cruciform eminence

 Transverse Sinus Groove & #8211; laterally to the internal occipital protuberance

 Upper Occipital Fossa (Brain)

 Lower Occipital Fossa (Cerebellar)

Basilar:

 Forame Magno & #8211; large oval opening giving way to the oblong medulla (brainstem & #8211; bulb) and its membranes (meninges), cerebrospinal fluid, nerves, arteries, veins and ligaments.

Side:

 Occipital Condyles & #8211; is oval in shape and articulate with the 1st cervical vertebra (Atlas)

 Hypoglossal Channel & #8211; Small excavation at the base of the occipital condyle that exits the hypoglossal nerve (12th cranial pair) and enters a meningeal branch of the ascending pharyngeal artery.

 Condylar Canal & #8211; next to the foramen magnum (gives way to the veins)

 Jugular Process & #8211; located laterally to the occipital condyle

THE Occipital hinges with six bones: Parietal (2), Temporal (2), Sphenoid and Atlas.

OCCIPITAL & #8211; EXTERNAL VIEW

Source: SOBOTTA, Johannes. Atlas of Human Anatomy. 21st. Rio de Janeiro: Guanabara Koogan, 2000.

OCCIPITAL & #8211; INTERNAL VIEW

Source: SOBOTTA, Johannes. Atlas of Human Anatomy. 21st. Rio de Janeiro: Guanabara Koogan, 2000.