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A block vertebra has been documented in T. rex. This suggests that the basic development pattern of vertebrae goes at least as far back as the most recent common ancestor of archosaurs and mammals. The tyrannosaur's block vertebra was probably caused by a "failure of the resegmentation of the sclerotomes". [8]
In 1953, further complications were later reported by McRae; flexion and extension is concentrated within the C1 and C2 vertebrae. As with aging, the odontoid process can become hypermobile, narrowing the space where the spinal cord and brain stem travel (spinal stenosis). Type II—Long fusion below C2 with an abnormal occipital-cervical junction.
The centra of the tenth neck and first back vertebrae are fused in a similar fashion. [31] In 1923 Moodie reported a T. rex specimen as having spondylitis deformans, probably referring to the fused vertebrae of this specimens. [31] Molnar still maintains that this is a congenital block vertebra. [31] It had fractured ribs, too. [31]
Hassel & Farman (1995) [13] developed an index based on the second, third, and fourth cervical vertebrae (C2, C3, C4) and proved that atlas maturation was highly correlated with skeletal maturation of the hand-wrist. Several smartphone applications have been developed to facilitate the use of vertebral methods such as Easy Age.
The atlas (C1) and axis (C2) are the two topmost vertebrae. The atlas (C1) is the topmost vertebra, and along with the axis forms the joint connecting the skull and spine. It lacks a vertebral body, spinous process, and discs either superior or inferior to it. It is ring-like and consists of an anterior arch, posterior arch, and two lateral masses.
They are located in the cervical region of the vertebral column from C3 to C7. [3] Two lips project upward from the superior surface of the vertebral body below, and one projects downward from the inferior surface of vertebral body above. They allow for flexion and extension and limit lateral flexion in the cervical spine.
Diastematomyelia is a "dysraphic state" of unknown embryonic origin, but is probably initiated by an accessory neurenteric canal (an additional embryonic spinal canal.).) This condition may be an isolated phenomenon or may be associated with other segmental anomalies of the vertebral bodies such as spina bifida, kyphoscoliosis, butterfly vertebra, hemivertebra and block vertebrae which are ...
The superior cervical ganglion (SCG) is the upper-most and largest [1] of the cervical sympathetic ganglia of the sympathetic trunk. [1] [2] It probably formed by the union of four sympathetic ganglia of the cervical spinal nerves C1–C4. [1]