Lecturer: Dante Roel Fernandez RT, M.D. Associate Professor I Gross Anatomy Fatima

College of Medicine

Central bony pillar of the body. Supports the skull, pectoral girdle, upper

limbs and the thoracic cage. Within its cavity lie the spinal cord, the

roots of the spinal nerves, the covering-meninges.

Composed of 33 vertebrae: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, 4 coccygeal.

It is a flexible structure made up of fibrocartilage called intervertebral discs.

General characterisctics:1.Rounded body anteriorly2.Vertebral arch posteriorlyVertebral foramen: where spinal cord and

meninges run along.Vertebral arch: gives rise to 7 processes1.Spinous2.Transverse3.Articular (zygapophyses)

1. The transverse process has transverse foramina.

2. The spines are small and bifid.

3. The body is small and broad from side to side.

4. Vertebral foramen is large and triagular.

5. Superior articiular facet faces upward backward while inferior articular facet faces downward forward.

First cervical vertebra or Atlas

1. Does not possess a body.

2. Does not have a spinous process.

3. Has anterior and posterior arch.

4. Lateral mass- atlanto-occipital jointLower surface- atlanto-axial joint.

Second cervical vertebra or Axis

1.Has a peg like odontoid process (dens) that projects from the superior surface of the body.

Seventh cervical vertebra or vertebra prominens.

1.It has the longest spinous process, and the process is not bifid.

2.The transverse process is large, but the foramen transversarium is small and transmits the vertebral vein.

1. The body is medium-sized and heart shaped.

2. The vertebral foramen is small and circular.

3. The spines are long and inclined downward.

4. Two pairs of semilunar costal facet.

5. Costal facet is also present on the transverse process for articulation with the tubercles of the ribs.

6. Superior articular processes bear facets that face backward and lateral inferior process face forward medial.

1. T1- with pair of circular costal facet and 1 pair of smaller semilunar facet.-long thick, horizontal spine.

2. T9- often with no inferior pair of demifacets.

3. T10, T11- no inferior demifacets; no facets on the transverse processes.

4. T12- same as 11; with some features of lumbar vertebra.

1. The body is large and kidney shaped.

2. The pedicles are strong and directed bakward.

3. The laminae are thick.4. The vertebral foramina

are triangular.5. The transverse process

are long and slender.6. The spinous process are

short, flat, and quadrangular and project backward.

7. The articular surface of the superior articular process face medially and those of the inferior articular processes face laterally.

The sacrum consists of five rudimentary vertebrae fused together to form a wedge-shaped bone, which is concave anteriorly.

The upper border or base of the bone articulates with the fifth lumbar vertebra.

The narrow inferior border articulates with coccyx.

Laterally, the sacrum articulates with the two iliac bones to form sacroiliac joints.

Sacral promontory.

Vertebral foramina are present and form the sacral canal.

The laminae of the fifth sacral vertebra and sometimes those of the fourth also, fails to meet in the midline, forming the sacral hiatus.

Sacral canal contains the anterior and posterior roots of the sacral and coccygeal spinal nerves, the filum terminale, and fibrofatty material.

It also contains the lower part of the subarachnoid space down as far as the lower border of the second sacral vertebra.

The anterior and posterior surface of the sacrum each have four foramina on each side for the passing of the anterior and posterior rami of the upper four sacral nerves.

The coccyx consists of four vertebrae fused together to form a single, small triangular bone that articulates at its base with the lower end of the sacrum.

The first coccygeal vertebrae is usually not fused, or is incompletely fused, with the second vertebra.

Atlanto-occipital joints1.Are synovial joints

that are formed between the occipital condyles, which are found on either sides of the foramen magnum above and the facets on the superior surfaces of the lateral masses of the atlas.

2.Movements: flexion, extension, lateral flexion, no rotation.

The atlanto-axial joints are three synovial joints.

1.Apical ligament2.Alar ligament3.Cruciate ligament Movements includes

extensive rotation of the atlas and thus of the head on the axis.

Intervertebral disc formed by cartilaginous joint between vertebral bodies.

The intervertebral disc are responsible for one-fourth of the length of the vertebral column.

Each disc consists of a peripheral part, the anulus fibrosus, and a central part, the nucleus pulposus.

Joint between two vertebral arches consists of synovial joint.

Spines, laminae and transverse processes are united by ligaments forming fibrous syndesmosis joints between them.

1. Supraspinous ligament2. Interspinous ligament3. Intertransverse ligament4. Ligamentum flavum

Nerve supply of the vertebral joints

The joints between the vertebral bodies are innervated by the small meningeal branches of each spinal nerve.

The nerve arises from the spinal nerve as it exits from the intervertebral foramen.

It then reenters the vertebral canal through the intervertebral foramen and supplies the meninges, the ligaments, and the intervertebral discs.

The joints between the articular processes are innervated by branches from the posterior rami of the spinal nerve.

In the fetus the vertebral column has one continuous anterior concavity; as development proceeds, the lumbosacral angle appears.

In the adult position, the vertebral column exhibits in the sagittal plane the following regional curves:

1. Cervical-posterior concavity

2. Thoracic-posterior convexity

3. Lumbar- posterior concavity

4. Sacral- posterior convexity

1. Flexion/ Extension Both are extensive in the cervical and lumbar

regions, but restricted in the thoracic region. The atlanto-occipital joints permit extensive

flexion and extension of the head. In the cervical region, flexion is produced by the

longus cervicis, scalenus anterior, and the sternocleidomastoid muscles. Extension is produced by the postvertebral muscle.

In the lumbar region, flexion is produced by the rectus abdominis and the psoas muscles. Extension is produced by the postvertebral muscles.

2. Lateral flexion- is the bending of he body to one or the other side. It is extensive in the cervical and lumbar regions, but restricted in the thoracic region.

Lateral flexion of the neck is produced by the scalenus anterior muscle and medius and trapezius and sternocledomastoid muscle.

Lateral flexion of the lumbar region is produced by the postvertebral muscles, the quadratus lumborum, and the oblique muscles of the anterolateral abdominal wall.

3. Rotation-is a twisting movement of the vertebral column; extensive in the lumbar region.

The atlanto-axial joints allow a wide range of rotation of the atlas and thus of the head on the axis.

Rotation on the neck is produced by the sternocleidomastoid muscle on one side and the splenius on the other side.

In the thoracic region, rotation is produced by the semispinalis and the rotatores muscle, assisted by the oblique muscle of the anterolateral abdominal wall.

4. Circumduction- is a combination of all these movements.

Spinal cord is a cylindrical, grayish-

white structure, 42-45 cm in length that begins above the foramen magnum, where it is continuous with the medulla oblongata of the brain.

It terminates below in the adult at the level of the lower border of the first lumbar vertebra.

In the young child it is relatively longer and ends at the upper border of the third lumbar vertebra.

The spinal cord in the cervical region, where it gives origin to the brachial plexus, and in the lower thoracic and lumbar regions, where it gives origin to the lumbosacral plexus, has fusiform enlargements, called the cervical and lumbar enlargements.

Inferiorly, the spinal cord tapers off into the conus medullaris.

31 pairs of spinal nerves by the anterior, or motor roots and the posterior, or sensory roots.

Each root is attached to the cord by a series of rootlets.

Each posterior nerve root possesses a posterior root ganglion.

Spinal nerve

The spinal cord receives its arterial supply from three small, longitudinally running arteries-the two posterior spinal arteries and the one anterior arteries.

The veins of the spinal cord drain into the internal vertebral venous plexus

1. Dura mater the most external

membrane and is a dense, strong, fibrous sheet that encloses the spinal cord and cauda equina.

Continuous above through the foramen magnum with the meningeal layer of dura covering the brain.

Inferiorly, it ends on the filum terminale at the level of the lower border of the second sacral vertebra.

Epidural space- contains loose areolar tissue and the internal vertebral venous plexus.

2. Arachnoid mater a delicate impermeable

membrane covering the spinal cord and lying between the pia mater internally and the dura mater externally.

Separated from the dura by the subdural space that contains a thin film of tissue fluid.

Separated from the pia mater by a wide space, the subarachnoid space, which is filled with cerebrospinal fluid.

Inferiorly , it ends on the filum terminale.

3. Pia mater A vascular

membrane that closely covers the spinal cord.

Below it fuses with the filum terminale

The pia mater is thickened on either side between the nerve roots to form the ligamentum denticulum, which passes laterally to be attached to the dura.

A clear, colorless fluid formed mainly by the choroid plexuses, within the lateral, third, and fourth ventricles of the brain.

The fluid articulates through the ventricular system and enters the subarachnoid space through the three foramina in the roof of the fourth ventricles.

Circulates above and below.

The fluid enters the bloodstream by passing through the arachnoid villi into the dural venous sinuses, in particular the superior sagittal venous sinus.

In addition to removing waste products associated with neuronal activity, the cerebrospinal fluid provides a fluid medium that surrounds the spinal cord.

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