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Occipital Bone Anatomy

Introduction to the Occipital bone anatomy:

  • The occipital bone (L., occipital – “back of the head”) is a cranial bone that surrounds the back and base regions of the brain.
  • Along with its inferior and internal surfaces is the prominent foramen magnum, which allows the spinal cord to pass through the skull.
  • The broad, curved region superior to the foramen magnum is called the squamous part (= squama occipitalis) of the bone. Anterior to the foramen magnum is the basilar part and to the sides are the lateral parts.

Markings of the Occipital Bone:

  1. External occipital protuberance – elevation (larger in men) near the center of the squamous part; attachment point for ligamentum nuchae and trapezius muscle.[Posterior view/ Inferior view]
  1. Superior nuchal line – a ridge that runs horizontally from either side of the external occipital protuberance; attachment point for several muscles that control the position of the head and neck. [Posterior view/ Inferior view]
  1. Highest nuchal line – a slight ridge above the superior nuchal line; attachment point for galea aponeurotica (connective tissue membrane that attaches the occipitalis and frontalis portions of occipitofrontalis muscle).[Posterior view]
  1.  Median nuchal line – a slight vertical ridge that runs from external occipital protuberance to foramen magnum; attachment point for ligamentum nuchae. [Posterior view/ Inferior view]
  1. Inferior nuchal line – a ridge that runs horizontally from both sides of the median nuchal line below the superior nuchal line; attachment point for several muscles that control the position of the head and neck. [Posterior view/ Inferior view]
  1. Foramen magnum – large, oval opening at the base of the skull; passageway for spinal cord. [Inferior view/Superior View]
  1. Occipital condyle – prominent, rounded elevation located to the side of the foramen magnum; articulates with the superior articular facet of the atlas (1st) vertebra. [Inferior view]
  1. Jugular foramen – large, irregular opening along the junction of occipital and temporal bones; passageway for internal jugular vein and glossopharyngeal, vagus, and accessory nerves. [Inferior view/Superior View]
  1. Hypoglossal canal – hole located in basilar part of bone superior to occipital condyle; passageway for the hypoglossal nerve that controls movement of tongue. [Superior View]
  1. Internal occipital protuberance –  elevation at the center of the cruciform eminence (= vertical and horizontal grooved ridges that divide internal surface of occipital bone into four fossa). [Superior View]
  1. Internal occipital crest – ridge that runs vertically from internal occipital protuberance to foramen magnum; attachment point for connective tissues (falx cerebelli) that anchors the brain. [Superior View]
  1. Groove (sulcus) for transverse sinus – indentations running horizontally from internal occipital protuberance; provide channels for transverse sinuses that drain venous blood from the brain to jugular foramen; also serve as attachment points for tentorium cerebelli (= dura mater that runs between the cerebellum and occipital lobes of the brain). [Superior View]

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