. A treatise on practical anatomy: for students of anatomy and surgery . terior arch formsnearly one-half of the circumference of the bone; itterminates posteriorly in a rudimentary spinous process,or tubercle, for the attachment of muscles. On theupper surface of the posterior arch, just behind thearticular surface for the condyles of the occipital bone, 88 PRACTICAL ANATOMY. is a well-marked groove for the passage of the vertebralartery. The lateral masses present the superior and in-ferior articular surfaces. The superior articular surfacesare strongly concave, oval or reniform; their axes
. A treatise on practical anatomy: for students of anatomy and surgery . terior arch formsnearly one-half of the circumference of the bone; itterminates posteriorly in a rudimentary spinous process,or tubercle, for the attachment of muscles. On theupper surface of the posterior arch, just behind thearticular surface for the condyles of the occipital bone, 88 PRACTICAL ANATOMY. is a well-marked groove for the passage of the vertebralartery. The lateral masses present the superior and in-ferior articular surfaces. The superior articular surfacesare strongly concave, oval or reniform; their axes aredirected forward and outward; they receive the condylesof the occipital bone. The inferior articular surfaces arefiat, directed downward and slightly inward to articu-late with the axis. Projecting inward from the innerborders of the lateral masses are the tubercles for theattachment of the transverse ligament, which passes be-hind the odontoid process of the axis, holding it in placeagainst the anterior arch of the atlas; posterior to the ^rtu. Fig. 37.—The Axis. transverse ligament is the spinal foramen for the trans-mission of the cord. The transverse processes projectfrom the outer border of the lateral mass and are broadand strong. The axis is distinguished by a strong, pivot-likeprocess, the odontoid, which projects upward from itsbody. This process is, in fact, the detached body of theatlas joined to the body of the axis. It forms the axison which the atlas, and with this the head, rotates. Thebody presents anteriorly a ridge, and on each side of theridge a depression for the attachment of muscles. It isprolonged below into a prominent lip, which overlaps theanterior part of the body of the vertebra below. Pos- THE SPINE. 89 teriorly, the body is liat; inferiorly, concave from frontto back. From the upper surface projects the conicalodontoid process, which is sHghtly constricted at thebase, and terminates above in a strong, blunt apex. Onits ant
Size: 2136px × 1169px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomy, bookyear1891
