Anatomy of Spinal

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Anatomy of vetebrae

Normal curve of vertebral coloumn

viewed from the anterior or posterior, a normal adult vertebral column appears straight. But when

viewed from the side, it shows four slight bends called normal curves cervical and lumbar curves are convex (bulging out)

the thoracic and sacral curves are concave (cupping in)


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The curves of the vertebral column increase its strength, help maintain balance

in the upright position, absorb shocks during walking, and help protect the

vertebrae from fracture. The fetus has a single anteriorly concave curve

VETEBRAE COLOUMN

At about ! cm ("# in.) in an average adult male and about $! cm ("% in.) in an

average adult female

Functionof vertebral coloumn &rotects the spinal cord and spinal nerves.

'upports the weight of the body superior to the level of the pelvis.

&rovides a partly rigid and exible axis for the body and an extended base on which the head

placed and pivots. &lays an important role in posture and locomotion (the movement from one place to another).

The lumbosacral angleoccurs at the unction of, and is formed by, the long axes of the lumbar

region of the vertebral column and the sacrum The vertebral coloumn is composed of ** vetebrae

cervical + in the neck region

!" thoracal + posterior to the thoracic cavity

lumbar + support the lower back

sacral + fused to form the sacrum % coccygeal + fused to form coccyx

-oints and pads of brocartilage called intervetebral discs

/ach disc has an outer brous ring consisting of brocartilage called the annulus brosusand an

inner soft, pulpy, highly elastic substance called the nucleus !ul!osus intervertebral disc are avascular, the annulus brosus and nucleus pulposus rely on blood vessels

from t"e bodies of vertebraeto obtain oxygen and nutrients and remove wastes. The " cervical, thoracic, lumbar, and rst sacral vertebrae also articulate ats#novial

$#ga!o!"#sial %oints, which facilitate and control the vertebral column0s exibility. Typical vertebrae consist of

1ertebral body

o the more massive, roughly cylindrical, anterior part of the bone that gives strength to

the vertebral column and supports body weight. The si2e of the vertebral bodiesincreases as the column descends, most markedly from T% inferiorly, as each bears

progressively greater body weight.o consists of vascular, trabecular (spongy, cancellous) bone enclosed by a thin external

layer of compact bone

1ertebral arch +

o posterior to the vertebral body and consists of two (right and left) pedicles and laminae

o 3onsist of +

&air of cylindrical pedicles + short, stout cylindrical processes

&air of attened laminae + two broad, at plates of bone, which unite in the

midline

o The vertebral arch and the posterior surface of the vertebral body form the walls of thevertebral foramen.

o The succession of vertebral foramina in the articulated vertebral column forms the

vertebral canal(spinal canal), which contains the spinal cord and the roots of thespinal nerves that emerge from it, along with the membranes (meninges), fat, andvessels that surround and serve them.

o The pedicles are notched on their upper and lower borders, forming the su!erior and

inferior vertebral notc"eso The superior and inferior vertebral notches of adacent vertebrae and the 41 discs

connecting them form the intervertebral foramina 'everal processes

o the vertebral arch given processes +


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! spinous + proects posteriorly (and usually inferiorly, typically overlapping the

vertebra below) from the vertebral arch at the unction of the laminae " transverse + proect posterolaterally from the unctions of the pedicles and

laminae. % articular + two superior and two inferiormalso arise from the unctions of the

pedicles and laminae, each bearing an articular surface (facet).o Both the spinous and transverse processes serve as levers and receive attachments of

muscles and ligamentso The articular processes are vertically arranged and consist of two superior and two

inferior processeso 5enerally, the articular processes bear weight only temporarily, as when one rises from

the exed position, and unilaterally when the cervical vertebrae are laterally exed to

their limit. 6owever, the inferior articular processes of the 7 vertebra bear weight eve

in the erect posture.

RE&'ONAL C(ARACTER')T'C) OF VERTEBRAE

Cervical

3ervical vertebrae form the s*eleton of t"e nec* +

located bet,een t"e cranium and t"e t"oracic vertebrae.

The single8most distinctive feature of each cervical vertebra is the oval transverse foramen in t"e

transverse !rocess -L+ foramen transversarium). The vertebral arteries and their accompanying

veins pass through the transverse foramina, except those in 3, which transmit only small accessoryveins.

The transverse processes of cervical vertebrae end laterally in two proections+ an anterior tubercle

and a !osterior tubercle. provide attachment for a laterally placed group of cervical muscles(levator scapulae and scalenes). 5rooves on the transverse processes between tubercles (the oor ofthe groove being formed by a costotransverse bar) accommodate the anterior rami of the cervicalspinal nerves

The carotid tubercles of vertebra 3$ are so called carotid tuberclesbecause the common carotid

arteries may be compressed here, in the groove between the tubercle and body, to control bleedingfrom these vessels.

The elevated superolateral margin is the uncus of t"e bod# -uncinate !rocess.+

C/is a prominent vertebra that is characteri2ed by a long spinous process, is called the vertebra

!rominens.


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1ertebra C01 also called t"e atlas, is uni9ue in that it has neither a body nor a spinous process.

The atlas is a ring of bone with anterior andposterior arches and large lateral masses. It lacks a body and a spinous

process. The kidney8shaped, concave su!erior articular surfaces of the lateral masses receive two large

cranial protuberances called the occi!ital cond#lesat the sides of the foramen magnum. Vertebra C2, also called t"e a3is, is the strongestof the cervical vertebrae.

The distinguishing feature of the axis is the blunt tooth8like dens -odontoid !rocess.1which proect

superiorly from its body.The dens is held in position against the posterior aspect of the anterior arch of the atlas by the

transverse ligament of t"e atlasT"oracic


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lie in the u!!er back and provide attac"ment for t"e ribs

Thus the primary characteristic features of thoracic vertebrae are the costal facets for articulation

,it" ribs.T0 and T2 are long1 laterall# 4attened1 and directed inferiorl#. 4n contrast, the spinous

processes on T00 and T02 are s"orter1 broader1 and directed more !osteriorl#+ 7onger and larger transverse processes than cervical

Movements of t"e t"oracic region are limitedby the attachment of the ribs to the sternum.

T0has a su!erior facet and an inferior demifacet. T25T6have su!erior and inferior

demifacets. T7has a su!erior demifacet1 and T085T02 "ave a facet+Lumbar

located in the lower back between the thorax and sacrum.

Because the weight they support increases toward the inferior end of the vertebral column, lumbarvertebrae have massive bodies, accounting for much of the thickness of the lower trunk in the mediaplane. :n the posterior surface of the base of each transverse process is a small accessor# !rocesswhich provides an attachment for the medial intertransverse lumborum muscle.

:n the posterior surface of the superior articular processes are mammillar# !rocesses, which give

attachment to the multidus and medial intertransverse muscles (back muscles). 1ertebra 7 is the largest of all movable vertebrae; it carries the weight of the whole upper body. 7 is

distinguished by its massive body and transverse processes. 4ts body is markedly deeper anteriorly;therefore, it is largely responsible for the lumbosacral angle between the long axis of the lumbarregion of the vertebral column and that of the sacrum (


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)acrum 4t is located between the hip bones and forms the roof and posterosuperior wall of the posterior pelvi

cavity. T"e sacrum -L+ sacred or "ol# bone.provides strength and stability to the pelvis and transmits th

weight of the body to the pelvic girdle, the bony ring formed by the hip bones and sacrum, to whichthe lower limbs are attached.

The sacral canal is the continuation of the vertebral canal in the sacrum. 4t contains the bundle of

spinal nerve roots arising inferior to the 7! vertebra, known as t"e cauda e9uina -L+ "orse tail.1that descend past the termination of the spinal cord.

:n the pelvic and posterior surfaces of the sacrum between its vertebral components are typically fou

pairs of sacral foraminafor the exit of the posterior and anterior rami of the spinal nerves. The anterior -!elvic. sacral foraminaare largerthan the posterior (dorsal) ones.

The base of t"e sacrumis formed by the superior surface of the '! vertebra. 4ts superior articular

processes articulate with the inferior articular processes of the 7 vertebra. The anterior proecting edge of the body of the '! vertebra is the sacral !romontor# -L+ mountain

ridge., an important obstetrical landmar*+ The a!e3 of t"e sacrum, its tapering inferior end, has an oval facet for articulation with the coccyx.

The sacrum is tilted so that it articulates with the 7 vertebra at the lumbosacral angle, which varie

from !*>? to !$>?. The sacrum is often wider in proportion to length in the female than in the male,but the body of the '! vertebra is usually larger in males.

The !elvic surface of t"e sacrumis smooth and concave.


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Cocc#3 The cocc#31 like the sacrum, is triangular in s"a!e. 4t is formed by the fusion of usually four

coccygeal vertebrae, indicated inas 3o!3o%. coccygeal vertebrae fuse somewhat later than the sacral vertebrae, between the ages of 28 and :8

The dorsal surface of the body of the coccyx contains two long cocc#geal cornuathat are connected

by ligaments to the sacral cornua. The coccygeal cornua are the pedicles and superior articular processes of the rst coccygeal vertebra

:n the lateral surfaces of the coccyx are a series of transverse !rocesses -the rst pair are the

largest)

The coccyx articulates superiorly with the apex of the sacrum. 4n females, the coccyx points inferiorlyto allow the passage of a baby during birth.


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Anatomy of Spinal

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