Anatomy of bone system. The manual for medical students / Анатомия костной системы. Учебное пособие для медицинских вузов - Иван Васильевич Гайворонский 5 стр.


2.6. Coccyx

The coccyx, os coccygis (CoI CoIII-V), consists of 35 rudimental vertebrae in adults. Only the I vertebra has rudiments of superior articular processes named coccygeal horns, cornua coccygea, besides the body. The coccygeal horns are connected with the sacral horns by ligaments. The I vertebra also has lateral projections which are rudiments of transverse processes. The other vertebrae are round-shaped and small, they have no arch and no processes.

2.7. Anomalies and Developmental Defects of Vertebrae

Anomalies and developmental defects may be classified according to the following criteria:

I. Vertebral size anomalies:

1. Microspondylia reduction in size of one or more vertebrae.

2. Brachyspondylia reduction in width of one or more vertebrae.

3. Platyspondylia flattening of some vertebrae which get a truncated cone shape.

4. Macrospondylia increase in size of some vertebrae.

II. Slit-like Defects of Vertebrae:

1. Splitting of vertebral bodies (anterior splitspine, spina bifida anterior) a slit-like defect of the vertebral body located more often in the sagittal plane.

2. Splitting of the vertebral arch (posterior split spine, spina bifida posterior) a slit-like defect of the vertebral arch (near a spinous process or on its place).

3. Spondylolysis in this case, the vertebral body is not fused with the pedicles of the vertebral arch: this anomaly may be observed either on one or on both sides, it happens most often in the V lumbar vertebra or in the I sacral vertebra; in case of bilateral spondylolysis, the posterior part of the arch with the inferior articular processes are separated from the pedicles of the arch with the superior articular processes.

4. Spondylolisthesis displacement of the body of the upper vertebra frontwards (very seldom backwards relative to the lower vertebra. Most often it occurs after compressive fracture of a vertebral body when the vertebra becomes wedge-shaped.

5. Rachischisis in this case the vertebral body is not fused with the pedicles of the vertebral arch, and the vertebral arch is splitted.

III. Development anomalies of individual vertebrae:

1. Assimilation of the atlas:

 atlanto-occipital assimilation (occipitalization)  partial or complete fusion of the I cervical vertebra with the occipital bone: two-sided (symmetric) or one-sided (asymmetric);

 atlantoaxial assimilation  partial or complete fusion of the I and II vertebrae.

2. Manifestation of the atlas (formation of the occipital vertebra proatlas) inclusion of the atlas particles into the occipital bone which is manifested in the presence of anomalous bony prominences in the circle of the great (occipital) foramen.

3. Kimmerle`s anomaly transformation of the vertebral artery groove on the atlas into the canal as a result of formation of a bony outgrowth above this groove.

4. Development anomalies of the II cervical vertebra:

 agenesia (absence) of the dens;

 the dens and the body of the II cervical vertebra are not fused together.

5. Thoracolisation of the cervical vertebrae formation of cervical ribs (most often from the VII cervical vertebra).

6. Sacralisation fusion of the V lumbar vertebra with the I sacral vertebra: there are 4 vertebrae in the lumbar part of the vertebral column; the sacrum consists of 6 vertebrae.

7. Lumbarisation the I sacral vertebra and the II sacral vertebra are not fused together: there are 6 vertebrae in the lumbar part of the vertebral column; the sacrum consists of 4 vertebrae.

Назад