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THORACIC VERTEBRAE Vertebral Column (Spine) • Collection of vertebrae • Forms the central axis • Supports skull • Gives attachment to – Thoracic cage by ribs – Upper limb by pectoral girdle – Lower limb by pelvic girdle • Flexible due to various joints b/w vertebrae • Contains spinal cord in its cavity Vertebral Column (Spine) • Made up of five regions – Cervical – Thoracic (Dorsal) – Lumbar – Sacral – Coccygeal Spinal Curvatures • Primary curvature – Anterior flexion in fetus – Persist in adults in • Thoracic, • Sacral & • Coccygeal • Secondary curvatures – Anterior convexity (Lordosis) in adults – Develop in • Cervical & • Lumbar Relation of Spinal Cord & Nerve Roots with Vertebral column General Characteristics of a Vertebra Vertebra consists of two essential parts: • an anterior segment, the body • a posterior part, the vertebral or neural arch • these two together enclose a foramen, the vertebral foramen. • vertebral foramina constitute a canal for the protection of the spinal cord Vertebral body • More or less cylindrical in shape. • Its upper and lower surfaces are flattened and rough • Give attachment to the intervertebral fibrocartilages • convex from side to side • concave from above downward • Anterior surface presents a few small apertures, for the passage of nutrient vessels • On the posterior surface is a single large, irregular aperture for the exit of the basi-vertebral veins from the body of the vertebra. Intervertebral discs (or intervertebral fibrocartilage) • Lie between adjacent vertebrae in the spine. • Each disc forms a cartilaginous joint to allow slight movement of the vertebrae, and acts as a ligament to hold the vertebrae together. The vertebral arch Consists of a pair of pedicles and a pair of laminæ Supports seven processes • Four articular • Two transverse • one spinous. PEDICLES • Two short, thick processes, • project backward, one on either side, • project from the upper part of the body, at the junction of its posterior and lateral surfaces. • Concavities above and below the pedicles are named the vertebral notches INTERVERTEBRAL FORAMINA • When the vertebrae are articulated, the superior and inferior notches of each contiguous pair of bones form the intervertebral foramina • through it spinal nerve leaves the vertebral canal as ventral and dorsal rami LAMINAE • Two broad plates directed backward and medially from the pedicles. • fuse in the midline posteriorly, and so complete the posterior boundary of the vertebral foramen. • Their upper borders and the lower parts of their anterior surfaces are rough for the attachment of the ligamenta flava PROCESSES • Single Spinous Process • Paired Transverse Processes • Paired Superior Articular Processes • Paired Inferior Articular Processes . SPINOUS PROCESS • Is directed backward and downward from the junction of the laminæ • serves for the attachment of muscles (which are extensors of vertebral column)and ligaments. ARTICULAR PROCESSES • Two superior and two inferior, spring from the junctions of the pedicles and laminæ. • The superior project upward, and their superior articular facets backwardare directed more or less • The inferior project downward, and their inferior articular facets look more or less forward. • The articular surfaces are coated with hyaline cartilage. TRANSVERSE PROCESSES • Two in number • project one at either side from the point where the lamina joins the pedicle, between the superior and inferior articular processes. • serve for the attachment of ligaments & muscles( that cause lateral bending and rotation of vertebral column) THORACIC VERTEBRAE General Features • intermediate in size between cervical and lumbar vertebrae • increase in size from above downward, the upper vertebrae being smaller than those in the lower part of the region. • The bodies are heart-shaped particularly in the middle of the thoracic region, almost equal in the antero-posterior and in transverse dimensions. • The vertebral foramen is small, and of a circular form. • The spinous process is long, triangular ,directed obliquely downward, and ends in a tuberculated extremity • The transverse processes are thick, strong, of considerable length, directed obliquely backward and laterally, and each ends in a clubbed extremity THORACIC VERTEBRAE Distinguishing Features • They present on either side, two costal demi- facets on the sides of the bodies (one above, near the root of the pedicle, the other below, in front of the inferior vertebral notch)for articulation with the heads of the ribs (costovertebral joint) • facets on the transverse processes for articulation with the tubercles of the ribs (costotransverse joint) ATYPICAL THORACIC VERTEBRAE • The thoracic vertebrae which present certain peculiarities, and must be specially considered are: • First • ninth • tenth • eleventh • twelfth ATYPICAL THORACIC VERTEBRA: FIRST It has, on either side of the body, • an entire articular facet for the head of the first rib, and • a demi-facet for the upper half of the head of the second rib Atypical Thoracic Vertebra ninth & tenth • The Ninth Thoracic Vertebra may have no demifacets below. • The Tenth Thoracic Vertebra has an entire articular facet on either side, which is placed partly on the lateral surface of the pedicle. Atypical Thoracic Vertebra eleventh & twelfth • The articular facets for the heads of the ribs are of large size, circular, and placed chiefly on the pedicles • The spinous process is short, and nearly horizontal in direction. • The transverse processes are very short and have no articular facets for tubercle of ribs • both approaches in its form and size to that of the lumbar vertebræ ATTACHMENTS • Anterior longitudinal ligament • Posterior longitudinal ligament • Ligamentum flavum • Interspinous ligament • Supraspinous ligament ANTERIOR LONGITUDINAL LIGAMENT It runs down the anterior surface of the spine. It traverses all of the vertebral bodies and intervertebral discs. POSTERIOR LONGITUDINAL LIGAMENT • It is situated within the vertebral canal, and extends along the posterior surfaces of the bodies of the vertebrae, from the body of the axis, where it is continuous with the membrana tectoria, to the sacrum LIGAMENTA FLAVA • ligamentum flavum (yellow ligament) are ligaments which connect the laminae of adjacent vertebra, all the way from the axis to the first segment of the sacrum (C2 to S1). They are best seen from the interior of the vertebral canal; • Their marked elasticity serves to preserve the upright posture, and to assist the vertebral column in resuming it after flexion. INTERSPINOUS LIGAMENTS &SUPRASPINOUS LIGAMENT • interspinous ligaments: thin and membranous, connect adjoining spinous processes and extend from the root to the apex of each process. • supraspinous ligament is a strong fibrous cord, which connects together the apices of the spinous processes from the seventh cervical vertebra to the sacrum KYPHOSIS • It is an exaggerated posterior) curvature in the thoracic region. • It produces the so-called "humpback", a condition commonly observed in osteoporosis. THORACIC DISC HERNIATION • A tear in the outer, fibrous ring (annulus fibrosus) of an intervertebral disc allows the soft, central portion (nucleus pulposus) to bulge out.