28 



THE SKELETON 



the skull. Ill front of the middle it is encroached u])on l)y the condyles. It is 

 bounded posteriorly by the supra-occipital, anteriorly by the basi-occipital, and 

 laterally ])y the ex-occipitals. Sometimes a facet exists at the anterior margin for 

 articulation with the odontoid process. This is the tertiary occipital condyle. The 

 margin of the foramen gives attachment behind the condyles to the posterior occipito- 

 atlantal ligament. 



The condyles are two oval processes of bone, with smooth articular surfaces, 

 covered in tlie recent state with cartilage. They are received into the superior 

 articular cups of the atlas. The condyles converge anteriorly but diverge posteriorly. 

 Their margins give attachment to capsular ligaments, and a prominent tubercle in 

 the middle of the median border of each condjde is for the check ligament. A for- 

 amen, the anterior condyloid, traverses the upper part of each condyle; it trans- 

 mits the hypoglossal nerve, and a twig of the ascending pharyngeal artery with its 

 vense comites; frequently this foramen is divided by a delicate spicule of bone. 

 Posterior to each condyle is a depression, the posterior condyloid fossa, which receives 



Fig. 34. — The Occipital at Birth. (Anterior view.) 



INTERPARIETAL PORTION (DEVELOPS IN 

 MEMBRANE) 



THE INTERPARIETAL AND SUPRA- 

 OCCIPITAL PORTIONS FORM THE 

 SQUAMO- OCCIPITAL OF THE 

 ADULT 



SUPRA-OCCIPITAL PORTION (DEVELOPS 

 IN CARTILAGE) 



BASI-OCCIPITAL 



the hinder edge of the articular cavity of the atlas when the head is extended; the 

 floor of this depression is occasionally perforated by the posterior condyloid foramen, 

 which transmits a vein from the lateral sinus. 



Articulations. — The occipital bone is connected by suture with the two parie- 

 tals, the two temporals, and the sphenoid; by means of the condyles it articulates 

 with the atlas; and under the exceptional condition of a tertiary occipital condyle, 

 with the odontoid process of the axis. 



Muscles. — Attached to the occipital bone: — 



OcciiHto-frontalis. 

 Trapezius. 



Sterno-cleido-mastoid. 

 Complexus. 

 Splenius capitis. 

 Superior oblique. 



Rectus capitis anticus major. 

 Rectus capitis anticus minor. 

 Rectus capitis posticus major. 

 Rectus capitis posticus minor. 

 Rectus capitis lateralis. 

 Azygos pharyngei (when present). 



