Cervical Vertebra Number: There are 7 cervical vertebras. Typical cervical vertebra: 3rd to 6th cervical vertebras are typical Atypical cervical vertebra: 1st, 2nd and 7th cervical vertebras are Atypical. Ossification: Intra-cartilaginous in ossification. Type of bone: Irregular bone. Typical cervical vertebra A typical cervical vertebra consists of Body that lies anteriorly. Vertebral arch that lies postero-laterally. Vertebral foramen in between them. Body of typical cervical vertebra: The body of a typical cervical vertebra is smaller. The transverse diameter of the body is more than the Antero-posterior diameter. The body consists of – Superior surface. Inferior surface. Anterior surface. Posterior surface. Superior surface of the body – The superior surface of the body is concave transversely and contains upward projecting lip on each side (Also called uncus). The superior surface articulates with the inferior surface of the body of the vertebra above to form secondary cartilaginous joint. This surface is covered by hyaline cartilage and is related to the inter-vertebral disc. Inferior surface of the body – The inferior surface of the body is convex from side to side and concave Antero-Posteriorly. The inferior surface articulates with the superior surface of the body of the vertebra below to form secondary cartilaginous joint. This surface is covered by hyaline cartilage and is related to the inter-vertebral disc. Anterior surface of the body- The anterior surface gives attachment to the anterior longitudinal ligament. Posterior surface of the body- The posterior surface gives attachment to the posterior longitudinal ligament. This surface is marked by multiple small foramens known as besivertebral foramen which transmits besivertebral vein. The besivertebral vein drains the body of the vertebra and drains into anterior internal vertebral venous plexus. (It drains newly produced blood cells). Vertebral foramen of a typical cervical vertebra: The vertebral foramen is triangular in shape and it is larger than the body of the vertebra. (Due to cervical enlargement of the spinal cord). When two or more vertebra articulates then the vertebral foramen is converted into vertebral canal. The vertebral foramen of a cervical vertebra contains – Spinal cord with its covering meninges. Regional spinal artery. Recurrent meningeal nerve. Internal vertebral venous plexus. Besivertebral vein. Vertebral arch of typical cervical vertebra: The vertebral arch consists of – Pedicle. Lamina. Superior articular process. Inferior articular process. Transverse process. Pedicle of a typical cervical vertebra: It connects the vertebral body with the vertebral arch. Above and below the pedicle presents two notches which are superior and inferior intervertebral notch. The superior and inferior inter vertebral notches are equal in size. Superior intervertebral notch is related to the trunk of the corresponding spinal nerve trunk Inferior intervertebral notch is related to the trunk of the spinal nerve below. The intervertebral notch is converted into intervertebral foramen when two or more vertebra articulates. So, the intervertebral foramen in-between the 5th and 6th cervical vertebra will transmit- 6th cervical spinal nerve. Recurrent meningeal nerve. Meningeal branch of the regional spinal artery. Lamina of a typical cervical vertebra: The lamina is projected backwards and medially for the posterior part of the pedicle. The posterior surface of the lamina gives attachment to the ligamentum flava. Superior articular process of a typical cervical vertebra: The superior articular process is flat and is directed upward s and backwards which articulates with the inferior articular process of the vertebra above to form plane variety of Synovial joint. Inferior articular process of a typical cervical vertebra: The Inferior articular process is also flat and is directed downwards and forwards which articulates with the superior articular process of the vertebra below to form plane variety of Synovial joint. Spinous process of a typical cervical vertebra: The Spinous process is short and bifid projected backwards from the junction of the two lamina. There is a notch within the bifid spine which is filled up by the ligamentum nuchae. The spinous process gives attachment to the deep muscles of the back of the neck, supra spinous and inter spinous ligament. Transverse process of a typical cervical vertebra: The transverse process is projected laterally from the junction of the pedicle and lamina. Each transverse process is marked by an opening called foramen traseverserium which transmits 2nd part of the vertebral artery and vein. Each transverse process consists of two roots which are anterior and posterior roots. The anterior root ends laterally by forming a tubercle called anterior tubercle which gives attachment to – Scalenus anterior, longus capitis and longus coli muscle. The posterior root ends laterally by forming another tuber called posterior tubercle which gives attachment to the scalenus medius and scalenus posterior, levator scapulae, splenius cervisis, longissimus cervicis muscle. The anterior and posterior tubercle are connected with each other by a bar of bone called costo-traseverse bar. The costo-transeverse bar is related to the anterior primary rami of the corresponding spinal nerve. Costal elements of a cervical vertebra: Anterior root of the transverse process. Anterior tubercle. Costo-transverse bar. Posterior tubercle. Transverse element of a cervical vertebra- Posterior root of the transverse process. 1st cervical vertebra /Atlas Special features of Atlas/1st cervical vertebra: It has no body. (The body of the atlas is replaces by the dense of Axis). It is no spinous process (Absence of the spinous process allows the extension of the head at the atlanto axial joint). It is ring shaped. Parts of the 1st cervical vertebra: It consists of – Anterior arch. Posterior arch. Lateral mass. Transverse process. Anatomical points of the atlas: The superior articular facet is elongated, concave directed upwards and medially. The inferior articular facet is almost circular, flat and directed backwards and medially. Anterior arch is smaller than the posterior arch. Anterior arch of the 1st cervical vertebra/atlas: The anterior arch is smaller than the posterior arch. Anteriorly the anterior arch is marked by a tubercle in the middle which gives attachment to the anterior longitudinal ligament. The anterior surface of the anterior arch on each side of the tubercle gives attachment to the longus coli muscle. Middle of the Posterior aspect of the arch is marked by an articular facet which articulates with the anterior aspect of the dense of the axis (2nd cervical vertebra) to form median atlano-axial joint which is a pivot variety of Synovial joint. (Here the articulation is plane variety). Upper border of the anterior arch gives attachment to the anterior atlato-occipital membrane. Lower border of the anterior arch gives attachment to the anterior longitudinal ligament. Posterior arch of the 1st cervical vertebra/atlas: Posterior arch is larger than the anterior arch. Middle of the posterior surface of the posterior arch of the atlas is marked by a tubercle which gives attachment to the ligamentum nuchae. On each side of the tubercle the posterior surface gives attachment to the rectus capitis posterior minor muscle. There is a groove in between the upper border of the posterior arch and lateral mass of the atlas which contains – 3rd part of the vertebral artery. Dorsal rami of the 1st cervical spinal nerve. Rest of the part of the upper border of the posterior arch gives attachment to the posterior atlanto-occipital membrane. The lower border of the poster arch gives attachment to the ligamentum flava. Lateral mass of the 1st cervical vertebra/atlas: The upper surface of the lateral mass bears a large, concave superior articular facet directed upwards and medially which articulates with the occipital condyle to form atlanto-occipital joint which is an Ellipsoid variety of Synovial joint. The lower surface of the lateral mass bears a smaller, circular, flat inferior articular facet directed downwards, backwards and medially which articulates with the superior articular facet of the axis (2nd cervical vertebra) to form lateral atlanto-axial joint which is a plane variety of Synovial joint. The anterior aspect of the lateral mass gives attachment to the rectus capitis anterior muscle. There is a tubercle at the medial aspect of the lateral mass which gives attachment to the transverse ligament of the Atlas. Transverse process of the 1st cervical vertebra/atlas: The transverse process bears a foramen called foramen transverserium which transmits vertebral artery and vein. The transverse process gives attachment to superior oblique, inferior oblique rectus capitis superioris and levator scapulae muscle. 2nd cervical vertebra / Axis Axis: The 2nd cervical vertebra is also known as the axis because the dense of the 2nd cervical vertebra acts as axis which rotates within the median atlanto-axial joint. Special features: it presents dense (also known as odontoid process) which represents the body of the atlas). Dense: Attachment – Apical ligament of the dense at the tip. Alar ligament at both sides. 7th cervical vertebra The 7th cervical vertebra is known as the vertebra prominence because it contains a long spinous process which is thick, long, horizontally placed and not bifid. Importance – The spinous process is so prominent that it can be felt under the skin in the midline which acts as a bony landmark for counting the vertebra in body. Joints formed between two vertebras: In between the body secondary cartilaginous joint. In between the articular processes plane variety of Synovial joint. Inter spinous, inter luminous and inter transverse joint syndesmosis variety of Fibrous joint. Characteristics of secondary cartilaginous joint: The articular surface is covered by hyaline cartilage. In between the hyaline cartilage there is a fibro-cartilaginous disc. It allows some range of movements. It is presents in the midline. Characteristics of Primary cartilaginous joint: The articulating bones are bound together by a hyaline cartilage. No movement occurs. After the age of 18 years the joint is converted into bone and then called synostosis. No ligament is present. Connective tissue fibers presents in the vertebra: Collagen fibers in the vertebra (bone and ligaments). Reticular fibers present in the bone marrow. Elastic fibers present in the ligamentum nuchae and ligamentum flava. Relation of the spinal nerve with vertebra: The spinal nerve of the all region except the cervical region passes below the corresponding vertebra. The spinal nerve of the cervical region passes above the level of the corresponding vertebra except 8th cervical spinal nerve which passes below the level of 8th cervical vertebra.
Posted on: Sun, 30 Jun 2013 04:23:02 +0000