Atlas

ATLAS

1st cervical vertebrae,atypical vertebrae. Known as atlas because in humans it holds the round head. Consists of a large neural ring,a bodyand two wings. Wings are bony plate and projects laterally.supraspinous process is absent or, may be in the form of a tubercle. Two foramens are present on the medial side and known as intervertebral foramen. Two foramen are present on lateral side and called alar foramen. Intervertebral foramen gives rise to 1st spinal nerve and alar foramen gives rise to dorsal primary branch of 1st spinal nerve. Caudal side of floor of atlas consists of a dperession known as fovea dentis which gives lodgement to the dense or, odontoid process of axis. On ventral side there is a shallow depression called fossa atlantis. In horse transverse foramen is present and fossa atlantis is deeper.caudal articular process is saddle shaped where as in case of horse it is nearly flattened. Dog-wings are wide,flattened and horizontal. Alar foramen is absent in that place a notch is present known as alar notch. Fowl-it is ring like bone.cranial surface is concave and gives lodgement to the single occipital condyle of occipital bone. Caudally there are three articular area for the attachment with axis.