.12 HANDBOOK OF ANATOMY 



Articulation of Skull with Spinal Column. 



The skull articulates with, the spinal column by means of the 

 condyles of the occipital bone and the articular facets on the 

 lateral masses of the atlas. The condyles are convex in both 

 lateral directions, and the facets concave, so the joint is freely 

 movable round two axes. 



Transverse flexion and extension. 



Antero-posterior lateral flexion. 



A combination of these movements causes rotation or "rolling." 



A capsule, which is complete, surrounds both the joints. 



A synovia! membrane lines both the joint cavities. 



Accessory Ligaments. These are very numerous and more 

 important than the ligaments of the actual joints. 



Odontoid ligaments, are three in number, one from the apex of 

 the odontoid peg and one on either side; these latter are called 

 check ligaments. 



Occipito-Atlantoid ligaments, anterior and posterior ; their 

 membranous structure continuous with the capsules of the 

 joints, thus forming a complete ligament between the foramen 

 magnum and the anterior and posterior arches of the atlas. 



Posterior Occipito-Axoid ligament, a continuation upwards of 

 the posterior longitudinal ligament. 



Ligamentum Cruciatum, a cross- shaped ligament, the hori- 

 zontal part formed by the transverse ligament of the atlas, the 

 vertical bars being attached to the occipital bone and axis 

 respectively. 



Muscles acting 1 on the Joints of the Skull. 



The muscles of the head and face are divided into four sets : 



1. Muscles of the scalp. 



2. Muscles of expression. 



3. Muscles of mastication. 



4. Muscles connecting the skull to the spinal column. 



1: The Muscles of the Scalp are the occipito-frontalis muscle 

 :and the muscles of the external ear. 



The OeeipitO-Frontalis muscle does not act on any joint. 



