VERTEBRAL COLUMN DR N SATYANARAYANA

Vertebral column Made up of 33 vertebrae, forms the major part of axial skeleton Extends from skull to the pelvis Contains spinal cord Functions: Transmits weight to pelvis and lower limbs Protects spinal cord Permits movements Muscle attachments - muscles of back, head and neck, upper extremity and thorax Vertebral column

Vertebrae are grouped into 5 types depending on the region where they are present Cervical vertebrae (7) Thoracic vertebrae (12) Lumbar vertebrae (5) Sacral vertebrae (5) Coccygeal vertebrae (4)

Parts of typical vertebra

Typical vertebra Parts of typical vertebra: Has mainly 2 parts Body (anterior part) Vertebral arch (posterior part) Contains vertebral foramen Parts of vertebral arch: Pedicle Lamina Spine Transverse processes Superior articular processes Inferior articular processes Body Pedicle Lamina Transverse process Spine Superior articular process Vertebral foramen

Body Superior surface of body Inferior surface of body Anterior surface of body Superior articular facet Inferior articular process Superior articular process Inferior articular facet Spine Inferior vertebral notch Transverse process Inferior vertebral notch Superior vertebral notch Intervertebral foramen Intervertebral disc

Body: Cylindrical part which lies anterior to vertebral foramen Has 4 surfaces – superior, inferior, anterior and posterior Superior and inferior surfaces are related to inter-vertebral discs Posterior surface is related to the posterior longitudinal ligament and has basivertebral foramen for nutrient artery and basivertebral vein Anterior surface related to anterior longitudinal ligament

Vertebral arch: Situated on the lateral aspect and posterior aspect of vertebral foramen Pedicle: Lies lateral to vertebral foramen Upper margin presents superior vertebral notch Lower margin presents inferior vertebral notch These notches get converted into inter-vertebral foramen when the vertebrae articulate with each other Inter-vertebral foramen transmits spinal nerve Lamina: Lies behind the vertebral foramen Joins the lamina of opposite side in the midline and continue as spine Give attachment to ligamentum flavum

Spine: Situated on the posterior aspect Formed by the union of laminae Gives attachment to supraspinous and interspinous ligaments Transverse processes: one on each side Directed laterally from the junction of pedicle and lamina Superior articular process: one on each side Extend upwards from the junction of lamina and pedicle Has a smooth area called superior articular facet which articulates with inferior articular facet of upper vertebra

Inferior articular process: one on each side Extend downwards from the junction of lamina and pedicle Has a smooth area called inferior articular facet which articulates with superior articular facet of lower vertebra Vertebral foramen: Is surrounded by body, lamina and pedicle Contains spinal cord, spinal meninges, vertebral venous plexus

Cervical vertebrae

7 in number 1 st, 2 nd and 7 th vertebrae are atypical cervical vertebrae 3 rd, 4 th, 5 th and 6 th vertebrae are typical cervical vertebrae Typical cervical vertebrae: Body: Small and broader from side to side than before backwards Vertebral foramen: Larger than body and triangular in shape

Typical cervical vertebra Vertebral foramen Foramen transversarium Transverse process Body Spine - bifid Anterior root Posterior root Anterior tubercle Posterior tubercle Costotransverse bar

Transverse process: Contains a foramen – foramen transversarium which transmits the vertebral artery and veins Has anterior and posterior roots which ends in anterior and posterior tubercles The 2 roots are connected by costotransverse bar Anterior tubercle of 6th cervical vertebra is large and called carotid tubercle because common carotid artery can be compressed against it Anterior tubercles give attachment to scalenus anterior muscle Posterior tubercles give attachment to scalenus medius and posterior muscles Spine: Short and bifid, the notch is filled with ligamentum nuchae

Atlas vertebra

Transverse process Foramen transversarium Lateral mass Superior articular facet Vertebral foramen Inferior articular facet Anterior tubercle Anterior arch Groove on superior surface of posterior arch Posterior arch Posterior tubercle Superior view Inferior view Anterior arch Dens of axis vertebra Transverse ligament of atlas

Atlas (1 st cervical) vertebra: Ring shaped, has no body and no spine Has - short anterior arch and long posterior arch, right and left lateral masses, transverse processes Anterior arch: Has anterior tubercle on its anterior surface which gives attachment to anterior longitudinal ligament Has facet for dens of 2 nd cervical vertebra on the posterior surface Upper margin gives attachment to anterior atlanto-occipital membrane Lower margin gives attachment to anterior longitudinal ligament

Posterior arch: Has posterior tubercle on its posterior surface which gives attachment to rectus capitis posterior minor muscle and ligamentum nuchae Has a groove on the upper aspect for vertebral artery and first cervical spinal nerve Upper margin gives attachment to anterior atlanto-occipital membrane Lower margin gives attachment to ligamentum flavum Anterior arch Dens of axis vertebra Posterior arch Groove Posterior tubercle

Lateral mass: Upper surface presents kidney shaped superior articular facet which articulate with occipital condyles of skull to form atlanto- occipital joint Inferior surface presents round, inferior articular facet which articulate with superior surface of body of 2 nd cervical vertebra and form atlanto-axial joint Has a tubercle on the medial aspect which gives attachment to transverse ligament of atlas Transverse process: Long and projects laterally from lateral mass Has foramen transversarium which transmits vertebral artery and vein

Axis vertebra

Axis (2 nd cervical) vertebra: Superior surface of body presents a projection in the midline called dens or odontoid process Dens on its anterior surface present a facet which articulates with anterior arch of atlas to form median atlanto- axial joint Dens on its posterior aspect related to transverse ligament of atlas Dens gives attachment to apical and 2 alar ligaments Superior articular facet is on the superior surfaces of body and pedicle which articulates with atlas vertebra to form lateral atlanto-axial joint Inferior articular facet articulates with superior articular facet of 3 rd cervical vertebra Transverse process is very small and contains foramen transversarium which transmits vertebral artery and vein Spine is large, thick and bifid

Ligaments Posterior atlanto-occipital membrane Anterior atlanto-occipital membrane Occipital bone Posterior arch of atlas Lamina of axis Ligamentum flavum Anterior longitudinal ligament Anterior arch of atlas Ligamentum nuchae Vertebral artery

Vertebra prominens (7 th cervical vertebra)

Spine is long, thick, horizontal and not bifid Transverse process is large and contains foramen transversarium which transmits accessory vertebral vein Transverse process has only posterior tubercle Transverse process Spine Posterior tubercle Foramen transversarium

Thoracic vertebrae

12 in number Identified by the presence of costal facets on the sides of bodies of vertebrae 1 st, 9 th, 10 th, 11 th and 12 th vertebrae are atypical thoracic vertebrae 2 nd to 8 th vertebrae are typical thoracic vertebrae Typical thoracic vertebra: Body: Heart shaped and size increased in the lower vertebrae On each side contains 2 costal facets for the heads of ribs to articulate Vertebral foramen: Is small and circular

Typical thoracic verterba Transverse process with facet Spine - oblique Body Costal facet Body Vertebral foramen Costal facet Transverse process with facet Lamina Pedicle

Transverse process: Large and extend laterally from the junction of the pedicle and lamina Anterior surface near the tip presents a facet for tubercle of rib to articulate Gives attachment to lateral, superior and interior costotransverse ligaments Spine: Long, oblique, directed downwards and backwards

Costal facet (complete) Costal demi facet 1 st thoracic vertebra 12 th thoracic vertebra Atypical thoracic vertebrae 11 th thoracic vertebra 10 th thoracic vertebra 9 th thoracic vertebra

1 st thoracic vertebra: Body is not heart shaped and resembles the body of cervical vertebrae Body on the lateral aspect presents 2 facets for the heads of the ribs Upper facet is complete and lower facet is a demifacet Spine is thick, long and horizontal Transverse process on its anterior surface presents a facet for tubercle of the rib 11 th thoracic vertebra: Body on the lateral aspect has one single complete costal facet which also extends to the lateral aspect of pedicle No facet on the anterior surface of transverse process Spine is horizontal in position

12 th thoracic vertebra Body on the lateral aspect has single complete facet, which is more on the pedicle than on the body Shape of the body is similar to those of lumbar vetebrae Transverse process is short, has no facet, has 3 tubercles – superior, inferior and lateral tubercles Spine is horizontal in position Body - thick Costal facet Spine Superior tubercle Lateral tubercle Inferior tubercle

Lumbar vertebrae

5 in number These do not have –foramen transversarium at the transverse process –costal facets on the body 1 st to 4 th vertebrae are typical lumbar vertebrae 5 th vertebra is an atypical lumbar vertebra Typical lumbar vertebra: Body is large, wider from side to side Vertebral foramen is triangular in shape, larger than in thoracic vertebrae, smaller than in cervical vertebrae Mamillary process on the superior articular process Accessory process on the transverse process

Spine is horizontal, thick and quadrangular in shape Transverse process are thin, tapering and arise from the junction between lamina and pedicle Transverse process has an elevation called accessory process Superior articular processes are placed away from the midline, present a rough elevation called mamillary process Inferior articular processes are placed nearer to the midline Superior articular process Spine Mamillary process Accessory process

5 th lumbar vertebra Spine Transverse process Superior articular process Mamillary process Body is largest among all the lumbar vertebrae Transverse process is thick, short and pyramidal in shape Transverse process is attached to body and pedicle The distance between superior articular processes is same as that inferior ones Spine is short and rounded at the tip

Sacrum

Large, flattened, triangular bone formed by the fusion of 5 sacral vertebrae Forms the posterior part of bony pelvis Articulates on either side with ilium of hip bone to form sacroiliac joint Has sacral canal which contains sacral and cocygeal spinal nerves, meninges of spinal cord and filum terminale Has a base, apex, pelvic surface, dorsal surface and 2 lateral surfaces The lateral part of sacrum is called lateral mass Base: Is the upper part, formed by superior surface of 1 st sacral vertebra Presents body of S1 vertebra, ala on either side of body, superior articular processes

Sacrum and coccyx Pelvic surface Body of S1 vertebra Ala Superior articular process of S1 vertebra Coccyx Pelvic sacral foramen Lateral surface Sacral canal Lateral mass Apex of sacrum Sacral promontory

Sacrum and coccyx (dorsal surface) Auricular surface Median sacral crest Lateral sacral crest Dorsal sacral foramen Sacral hiatus Sacral cornu Coccyx Intermediate sacral crest Sacral canal

Body of S1 vertebra: Articulates with L5 vertebra In males, width of the body of S1 vertebra is more than width of ala In females, width of the body of S1 vertebra is almost equal to the width of ala Anterior margin of body is prominent – sacral promontory Ala: Has a smooth medial part and rough lateral part Medial part is related to sympathetic chain, lumbosacral trunk, iliolumbar artery and obturator nerve Lateral part gives attachment to iliacus muscle Superior articular process: Presents superior articular facet which articulates with inferior articular facet of L5 vertebra

Apex: Is the lower end of sacrum, formed by inferior surface of body S5 vertebra Articulates with the coccyx Pelvic surface: Concave, presents 4 pelvic sacral formaina on each side which transmit ventral rami of upper 4 sacral spinal nerves and lateral sacral arteries Gives attachment to piriformis muscle Dorsal surface: Is rough, irregular and convex Presents Median sacral crest – situated at the midline 4 dorsal sacral foramina – on either side which transmit dorsal rami of upper 4 sacral spinal nerves

Sacral hiatus – near the apex which transmits 5 th sacral spinal nerve, 1 st coccyngeal spinal nerve and filum terminale Sacral cornu – situated lateral to sacral hiatus, represents the inferior articular process of S5 vertebra Intermediate sacral crest – situated medial to dorsal sacral foramina Lateral sacral crest – situated lateral to dorsal sacral foramina Lateral surface: Upper part is wide and lower part is narrow Upper part presents L-shaped auricular surface which articulates with ilium of hip bone to form sacroiliac joint Lower part gives attachment to gluteus maximus and coccygeus muscles, sacrotuberous and sacrospinous ligaments

Coccyx

Small triangular bone fromed by the fusion of 4 rudimentary coccygeal vertebrae Has a base and apex Base is formed by 1 st coccygeal vertebra and articulates with apex of sacrum Apex lies free gives attachment to anococcygeal ligament