The vertebral column pdf - The back

Basic Anatomy

683

C H A P T E R O U T L I N E

(continued)

Splenius 695

Muscular Triangles of the

Back 695

Deep Fascia of the Back

(Thoracolumbar Fascia) 695

Blood Supply of the Back 695

Arteries 695

Veins 695

Lymph Drainage of the Back 695

Nerve Supply of the Back 695

Spinal Cord 697

Roots of the Spinal Nerves 698

Blood Supply of the Spinal

Cord 699

Meninges of the Spinal Cord 699

Cerebrospinal Fluid 707

Radiographic Anatomy 710

Radiographic Appearances of the

Vertebral Column 710

Spinal Subarachnoid Space 710

Computed Tomography and

Magnetic Resonance Imaging

Studies 715

Surface Anatomy 717

Midline Structures 717

External Occipital

Protuberance 717

Cervical Vertebrae 717

Thoracic and Lumbar

Vertebrae 717

Sacrum 717

Coccyx 718

Upper Lateral Part of the Thorax 718

Scapula 718

Lower Lateral Part of the Back 718

Iliac Crests 718

Spinal Cord and Subarachnoid

Space 719

Symmetry of the Back 719

C H A P T E R O B J E C T I V E S

The physician’s task is to identify the likely source of the pain

Back injuries range from a simple muscular or ligamentous back

■

strain to a catastrophic injury of the spinal cord or cauda equina.

■

Automobile accidents, motorcycle accidents, gunshot wounds,

and sports injuries are just some of the common causes of back

injuries found in practice.

■

Because of the anatomic configuration of this region, unpro-

tected movement of the damaged vertebral column during initial

medical care at the site of the accident can result in irreversible

injury to the delicate spinal cord.

■

Back pain provides the practicing physician with a challenge.

and the pathologic process causing it.

■

The purpose of this chapter is to review the basic anatomy of

the vertebral column and related soft nervous tissue structures

so that the physician will feel reasonably confident to institute

the appropriate treatment.

natomy

asic

The back, which extends from the skull to the tip of the

monly fused). Because it is segmented and made up of verte

to form the sacrum), and 4 coccygeal (the lower 3 are com

vertebrae—7 cervical, 12 thoracic, 5 lumbar, 5 sacral (fused

The vertebral column (Figs. 12.1 and 12.2) is composed of 33

Composition of the Vertebral Column

ges, to which the vertebral column gives great protection.

cord, the roots of the spinal nerves, and the covering menin

weight to the lower limbs. Within its cavity lie the spinal

racic cage and, by way of the pelvic girdle, transmits body

It supports the skull, pectoral girdle, upper limbs, and tho

The vertebral column is the central bony pillar of the body.

The Vertebral Column

the scapulae to the trunk.

the thorax are the scapulae and the muscles that connect

Superimposed on the upper part of the posterior surface of

coccyx, can be defined as the posterior surface of the trunk.

-
-

brae, joints, and pads of fibrocartilage called intervertebral

discs, it is a flexible structure. The

ertebral discs form

interv

about one quarter the length of the column.

processes are directed laterally from the junction of the

from the junction of the two laminae. The transverse

is directed posteriorly

spinous process,

The

spinous, two transverse, and four articular (Fig. 12.2).

The vertebral arch gives rise to seven processes: one

posteriorly.

which complete the arch

and a pair of flattened

which form the sides of the arch,

pedicles,

of cylindrical

cord and its coverings. The vertebral arch consists of a pair

through which run the spinal

vertebral foramen,

called the

posteriorly. These enclose a space

vertebral arch

orly and a

anteri

body

consists of a rounded

typical vertebra

sess a common pattern (Fig. 12.2).

Although vertebrae show regional differences, they all pos

General Characteristics of a Vertebra

laminae,

spine,

684

CHAPTER 12

are vertically arranged and

articular processes

The

and ligaments.

processes serve as levers and receive attachments of muscles

laminae and the pedicles. Both the spinous and transverse

The Back

consist of two superior and two inferior processes. They

The pedicles are notched on their superior and

the arch above, forming two synovial joints.

arch articulate with the two inferior articular processes of

The two superior articular processes of one vertebral

their articular surfaces are covered with hyaline cartilage.

arise from the junction of the laminae and the pedicles, and

inferior borders, forming the

inferior

superior and

vertebral notches.
of one vertebra and the inferior notch of an adjacent

On each side, the superior notch

vertebra together form an

rior and posterior nerve roots of a spinal nerve unite

transmit the spinal nerves and blood vessels. The ante

These foramina, in an articulated skeleton, serve to

intervertebral foramen.

within these foramina with their

rings of dura to

cove

form the segmental spinal nerves.

mastoid process

trapezius muscle

superior angle of scapula

acromion

spine of scapula

inferior angle of scapula

latissimus dorsi muscle

twelfth rib

iliac crest

iliac tubercle

ischial tuberosity

tip of coccyx

fold of buttock

natal cleft

greater trochanter

posterosuperior iliac spine

erector spinae muscle

spine of seventh
thoracic vertebra

spine of

third thoracic vertebra

head of humerus

spine of seventh cervical vertebra

spine of first thoracic vertebra

ligamentum nuchae

external occipital protuberance

FIGURE 12.1

Posterior view of the skeleton showing the surface markings on the back.

Basic Anatomy

685

atlas

axis

cervical curve

cervical

vertebrae

(7)

thoracic

vertebrae

(12)

lumbar

vertebrae

(5)

sacral

vertebrae

(5)

coccygeal vertebrae

(4)

sacral curve

lumbar curve

thoracic

curve

lamina

pedicle

transverse

process

body

anterior tubercle

foramen

transversarium

posterior tubercle

superior articular

facet

vertebral foramen

facet for

rib tubercle

vertebral foramen

body

demifacet for rib head

pedicle

superior articular

facet

transverse

process

spine

lamina

superior articular

process

transverse process

pedicle

body

vertebral foramen

inferior articular process

promontory

superior articular process

lateral mass

anterior sacral

foramina

transverse process

of coccyx

spine (bifid)

lamina

spine

FIGURE 12.2

General features of different kinds of vertebrae.

Lateral view of the vertebral column.

686

CHAPTER 12

The Back

Examination of the Back

Lateral rotation, however, is limited by the interlocking of the

normally be tilted 45° to each shoulder. It is important that the

between the atlas and the axis. In lateral flexion, the head can

nearly in line with the shoulder. Half of lateral rotation occurs

lateral rotation, the patient should be able to place the chin

extension he or she should be able to look directly upward. In

should be able to touch his or her chest with the chin, and in

is carried out at the atlanto-occipital joints. In flexion, the patient

Remember that about half of the movement referred to as flexion

ion, extension, lateral rotation, and lateral flexion are possible.

The normal range of movements of the different parts of the

vexity develops on the opposite side, with a compensatory thoracic

tion room so that the normal tilting movement of the pelvis can be

of the hip joints can lead to abnormal curvatures of the vertebral col

and that the shoes be removed. Unequal length of the legs or disease

It is important that the whole area of the back and legs be examined

umn. The patient should be asked to walk up and down the examina-

observed. As one side of the pelvis is raised, a coronal lumbar con-

convexity on the same side. When a person assumes the sitting posi-

tion, it will be noted that the normal lumbar curvature becomes flat-

tened, with an increase in the interval between the lumbar spines.

vertebral column should be tested. In the cervical region, flex-

shoulder is not raised when this movement is being tested.

In the thoracic region, the movements are limited by the pres-

ence of the ribs and sternum. When testing for rotation, make

sure that the patient does not rotate the pelvis.

In the lumbar region, flexion, extension, lateral rotation, and

lateral flexion are possible. Flexion and extension are fairly free.

articular processes. Lateral flexion in the thoracic and lumbar

regions is tested by asking the patient to slide, in turn, each hand

down the lateral side of the thigh.

C L I N I C A L N O T E S

Characteristics of a Typical Cervical Vertebra

veins (note that the vertebral artery passes through the

for the passage of the vertebral artery and

versarium

foramen trans

The transverse processes possess a

(Fig. 12.3):

A typical cervical vertebra has the following characteristics

■

transverse processes C1 to 6 and not through C7).

The vertebral foramen is large and triangular.

The body is small and broad from side to side.

The spines are small and bifid.

■

spine

vertebral foramen

superior articular facet

transverse

process

body

foramen transversarium

anterior tubercle

posterior

tubercle

posterior tubercle

vertebral foramen

transverse

process

tubercle

anterior arch

superior articular facet

foramen transversarium

posterior arch

spine

vertebral foramen

foramen transversarium

transverse process

body

odontoid process

spine

body

superior articular

process

FIGURE 12.3

passage for the vertebral vein but not for the vertebral artery.

7th cervical vertebra, superior aspect; the foramen transversarium forms a

cervical vertebra, from above and behind.

Axis, or 2nd

Atlas, or 1st cervical vertebra, superior aspect.

Typical cervical vertebra, superior aspect.

Basic Anatomy

material. It also contains the lower part of the subarach

coccygeal spinal nerves, the filum terminale, and fibrofatty

contains the anterior and posterior roots of the sacral and

(see Fig. 6.8). The sacral canal

sacral hiatus

forming the

times those of the 4th also, fail to meet in the midline,

The laminae of the 5th sacral vertebra, and some

sacral

The vertebral foramina are present and form the

importance and is used when measuring the size of the pelvis.

sacral promontory in the female is of considerable obstetric

The

sacral promontory.

the pelvic inlet and is known as the

first sacral vertebra bulges forward as the posterior margin of

joints (see Fig. 6.1). The anterior and upper margin of the

articulates with the two iliac bones to form the sacroiliac

rior border articulates with the coccyx. Laterally, the sacrum

articulates with the 5th lumbar vertebra. The narrow infe

concave anteriorly. The upper border, or base, of the bone

brae fused together to form a wedge-shaped bone, which is

The sacrum (Fig. 12.2) consists of five rudimentary verte

tion with ribs and no foramina in the transverse processes.

Note that the lumbar vertebrae have no facets for articula

cesses face laterally.

face medially, and those of the inferior articular pro

The articular surfaces of the superior articular processes

and project posteriorly.

The spinous processes are short, flat, and quadrangular

The transverse processes are long and slender.

The vertebral foramina are triangular.

tant when performing a spinal tap. See page 704).

The laminae are short in a vertical dimension (impor

The pedicles are strong and directed backward.

The body is large and kidney shaped.

(Fig. 12.2):

A typical lumbar vertebra has the following characteristics

Characteristics of a Typical Lumbar Vertebra

erally, as do those of the lumbar vertebrae.

inferior articular processes of the 12th vertebra face lat

rior articular processes face anteriorly and medially. The

posteriorly and laterally, whereas the facets on the infe

The superior articular processes bear facets that face

12 have no facets on the transverse processes).

for articulation with the tubercles of the ribs (T11 and

Costal facets are present on the transverse processes

articulation with the heads of the ribs.

Costal facets are present on the sides of the bodies for

The spines are long and inclined downward.

The vertebral foramen is small and circular.

The body is medium size and heart shaped.

(Fig. 12.2):

A typical thoracic vertebra has the following characteristics

Characteristics of a Typical Thoracic Vertebra

the vertebral vein or veins.

is large, but the foramen transversarium is small and transmits

process, and the process is not bifid. The transverse process

(Fig. 12.3), is so named because it has the longest spinous

vertebra prominens

7th cervical vertebra,

The

atlas that has fused with the body of the axis).

superior surface of the body (representing the body of the

that projects from the

odontoid process (dens)

peglike

(Fig. 12.3), has a

2nd cervical vertebra,

The

(atlantoaxial joints).

surfaces on its inferior surface for articulation with the axis

and articular

(atlanto-occipital joints)

occipital condyles

lar surfaces on its upper surface for articulation with the

posterior arch. It has a lateral mass on each side with articu

possess a body or a spinous process. It has an anterior and

(Fig. 12.3), does not

1st cervical vertebra,

The

The 1st, 2nd, and 7th cervical vertebrae are atypical.

Characteristics of the Atypical Cervical Vertebrae

facets that face inferiorly and anteriorly.

posteriorly and superiorly; the inferior processes have

The superior articular processes have facets that face

687

■

atlas

axis

■

Sacrum

canal.

sacrum; this is usually incomplete and may be limited to

rib. The 5th lumbar vertebra may be incorporated into the

the addition of the 1st lumbar vertebra, which may have a

37). The thoracic vertebrae may be increased in number by

(see page

cervical rib

enth cervical vertebra may possess a

The number of cervical vertebrae is constant, but the sev

Important Variations in the Vertebrae

tures relative to soft tissue injury.

and when noting the precise sites of bony pathologic fea

tebral column is important when interpreting radiographs

Knowledge of the preceding basic anatomy of the ver

fused with the second vertebra.

coccygeal vertebra is usually not fused or is incompletely

base with the lower end of the sacrum (Fig. 12.2). The first

form a single, small triangular bone that articulates at its

The coccyx consists of four vertebrae fused together to

rior and posterior rami of the upper four sacral nerves.

have four foramina on each side for the passage of the ante

The anterior and posterior surfaces of the sacrum each

sacral vertebra.

noid space down as far as the lower border of the second

Coccyx

one side. The 1st sacral vertebra may remain

y or

partiall

inferiorly (Fig. 12.4). They are enclosed by a capsule.

ets on the superior surfaces of the lateral masses of the atlas

either side of the foramen magnum superiorly and the fac

formed between the occipital condyles, which are found on

The atlanto-occipital joints are synovial joints that are

Atlanto-Occipital Joints

Joints of the Vertebral Column

apex of the sacrum.

tebra usually projects downward and anteriorly from the

vertebra may be separate. In this condition, the free ver

brae, may have three or five vertebrae. The 1st coccygeal

The coccyx, which usually consists of four fused verte

fail to develop.

sacral canal may be absent because the laminae and spines

lumbar vertebra. A large extent of the posterior wall of the

completely separate from the sacrum and resemble a 6th

688

CHAPTER 12

The Back

basilar part

of occipital bone

atlanto-occipital

membrane

occipital bone

external occipital protuberance

capsule of

atlanto-occipital

joint

capsule of

atlantoaxial

joint

vertebral artery

longitudinal

ligament

posterior arch of atlas

vertebral artery

ligamentum flavum

spine of axis

superior band of

cruciate ligament

vertebral artery

transverse

band of

cruciate

ligament

posterior arch of atlas

inferior band of

cruciate ligament

spine of axis

body of axis

odontoid

process of axis

arch of atlas

apical

ligament

atlanto-occipital

membrane

basilar part of occipital bone

membrana tectoria

dorsum sellae

membrana tectoria (cut)

superior band of

cruciate ligament (cut)

apical ligament

alar ligament

transverse

process of atlas

accessory

atlantoaxial

ligament

transverse process of axis

membrana tectoria (cut)

inferior band of

cruciate ligament

posterior

atlanto-occipital

membrane

transverse band of

cruciate ligament

posterior

atlanto-occipital

membrane

FIGURE 12.4

Anterior view

Flexion, extension, and lateral flexion. No rotation is

Movements

margin of the foramen magnum.

connects the posterior arch of the atlas to the posterior

is similar to the ligamentum flavum (see page 690) and

This membrane

Posterior atlanto-occipital membrane:

atlas to the anterior margin of the foramen magnum.

umn. The membrane connects the anterior arch of the

as a band down the anterior surface of the vertebral col

uation of the anterior longitudinal ligament, which runs

This is a contin

Anterior atlanto-occipital membrane:

Ligaments

of the atlantoaxial joints. Note that the posterior arch of the atlas and the laminae and spine of the axis have been removed.

and posterior view

of the atlanto-occipital joints. Sagittal section

and posterior view

(A)

(B)

(C)

(D)

■

possible.

Alar ligaments:

margin of the foramen magnum.

nects the apex of the odontoid process to the anterior

This median-placed structure con

Apical ligament:

Ligaments

by capsules.

masses of the bones (Fig. 12.4). The joints are enclosed

of the atlas, and the other two are between the lateral

is between the odontoid process and the anterior arch

The atlantoaxial joints are three synovial joints: one

Atlantoaxial Joints

■

These lie one on each side of the apical

sides of the occipital condyles.

ligament and connect the odontoid process to the medial

Basic Anatomy

is composed of fibrocartilage, in

anulus fibrosus

The

sus, and a central part, the nucleus pulposus (Fig. 12.5).

Each disc consists of a peripheral part, the anulus fibro

resilience is gradually lost with advancing age.

vertebrae to move one on the other. Unfortunately, their

is jumping from a height. Their elasticity allows the rigid

the vertebral column is suddenly increased, as when one

permit them to serve as shock absorbers when the load on

adjacent vertebrae (Fig. 12.5). Their physical characteristics

as semielastic discs, which lie between the rigid bodies of

of the vertebral column are greatest. They may be regarded

in the cervical and lumbar regions, where the movements

column below the level of C2 (Fig. 12.5). They are thickest

responsible for one quarter of the length of the vertebral

to the sacrum (C1 has no vertebral body). The discs are

together the vertebral bodies, and they extend from C2

The intervertebral discs are the main structures that bind

Intervertebral Discs

the upper and lower surfaces of the bodies of the vertebrae.

present at the lateral sides of the intervertebral disc between

In the lower cervical region, small synovial joints are

the disc strongly unite the bodies of the two vertebrae.

tebral disc of fibrocartilage (Fig. 12.5). The collagen fibers of

wiched between the plates of hyaline cartilage is an interver

vertebrae are covered by thin plates of hyaline cartilage. Sand

The superior and inferior surfaces of the bodies of adjacent

Joints between Two Vertebral Bodies

(Fig. 12.5).

ies and by synovial joints between their articular processes

other by means of cartilaginous joints between their bod

remainder of the mobile vertebrae articulates with each

With the exception of the first two cervical vertebrae, the

Joints of the Vertebral Column below the Axis

head on the axis.

There can be extensive rotation of the atlas and thus of the

Movements

and the apical, alar, and cruciate ligaments.

It covers the posterior surface of the odontoid process

to the occipital bone just within the foramen magnum.

the posterior longitudinal ligament. It is attached above

This is an upward continuation of

Membrana tectoria:

margin of the foramen magnum.

posterior surface of the body of the axis to the anterior

anterior arch of the atlas. The vertical part runs from the

mass of the atlas and binds the odontoid process to the

attached on each side to the inner aspect of the lateral

verse part and a vertical part. The transverse part is

This ligament consists of a trans

Cruciate ligament:

689

■

-
-

which the collagen fibers are arranged in

ntric lay

conce

attached to the anterior and posterior longitudinal

in alternate sheets. The more peripheral fibers are strongly

adjacent vertebral bodies, and their inclination is reversed

ers or sheets. The collagen bundles pass obliquely between

ligaments of the vertebral column.

an ovoid mass of gelatinous material containing a large

in children and adolescents is

nucleus pulposus

The

thoracic

superior
articular
process

inferior
articular
process

joint between
bodies
(cartilaginous)

superior articular
process

inferior articular

process

joint between

articular processes

(synovial)

joint between
bodies (cartilaginous)

lumbar

dura mater

arachnoid mater

cauda equina

internal vertebral
veins

nucleus pulposus

anulus fibrosus

intervertebral
disc

spine

intervertebral foramen

spinal nerve

posterior
longitudinal ligament

body

anulus fibrosus

nucleus pulposus

anterior longitudinal ligament

ligamentum flavum

pedicle

interspinous
ligament

joint between
bodies
(cartilaginous
and synovial)

joint between
articular
processes
(synovial)

spine

cervical

joint between articular
processes (synovial)

inferior articular process

superior articular
process

articular
process

joint between
bodies
(cartilaginous)

process

thoracic

inferior articular

process

joint between

articular processes

(synovial)

joint between
bodies (cartilagi

lumbar

dura mater

arachnoid mater

cauda equina

internal vertebral
veins

nucleus pulposus

anulus fibrosus

intervertebral
disc

spine

intervertebral foramen

spinal nerve

posterior
longitudinal ligament

body

anulus fibrosus

nucleus pulposus

anterior longitudinal ligame

ligamentum flavum

pedicle

interspinous

joint between
bodies
(cartilaginous
and synovial)

j
articular
processes
(synovial)

spine

cervical

joint between articular
processes (synovial)

inferior articular process

supraspinous

ligament

FIGURE 12.5

intervertebral foramen and the intervertebral disc.

vertebrae showing ligaments and intervertebral discs. Note the relationship between the emerging spinal nerve in an

Sagittal section through three lumbar

from above showing the relationship between intervertebral disc and cauda equina.

Third lumbar vertebra seen

Joints in the cervical, thoracic, and lumbar regions of the vertebral column. B.

690

CHAPTER 12

With advancing age, the water content of the nucleus

nerve, or even the spinal cord (see page 701).

where it may press on the spinal nerve roots, the spinal

pulposus to herniate and protrude into the vertebral canal,

the anulus fibrosus and it ruptures, allowing the nucleus

lus fibrosus. Sometimes, the outward thrust is too great for

accommodated by the resilience of the surrounding anu

become flattened. The outward thrust of the nucleus is

tebral column causes the semifluid nucleus pulposus to

A sudden increase in the compression load on the ver

vertebral column.

or posteriorly on another, as in flexion and extension of the

change shape and permits one vertebra to rock anteriorly

The semifluid nature of the nucleus pulposus allows it to

Function of the Intervertebral Discs

first two cervical vertebrae or in the sacrum or coccyx.

plates of hyaline cartilage. No discs are found between the

cent vertebrae that abut onto the disc are covered with thin

The superior and inferior surfaces of the bodies of adja

margin of the disc.

ated slightly nearer to the posterior than to the anterior

few cartilage cells. It is normally under pressure and situ

amount of water, a small number of collagen fibers, and a

The Back

pulposus diminishes and is replaced by fibrocartilage. The

pinous ligaments are greatly thickened to form the strong

In the cervical region, the supraspinous and inters

inae of adjacent vertebrae.

(Fig. 12.5): This connects the lam

Ligamentum flavum

transverse processes.

These run between adjacent

Intertransverse ligaments:

cent spines.

(Fig. 12.5): This connects adja

Interspinous ligament

the tips of adjacent spines.

(Fig. 12.5): This runs between

Supraspinous ligament

Ligaments

rounded by a capsular ligament.

are covered with hyaline cartilage, and the joints are sur

cesses of adjacent vertebrae (Fig. 12.5). The articular facets

vial joints between the superior and inferior articular pro

The joints between two vertebral arches consist of syno

Joints between Two Vertebral Arches

of movement to take place between them.

firmly together but at the same time permit a small amount

borders of the discs. These ligaments hold the vertebrae

ment is weak and narrow and is attached to the posterior

bodies and to the intervertebral discs. The posterior liga

is strongly attached to the front and sides of the vertebral

(Figs. 12.5 and 12.14). The anterior ligament is wide and

faces of the vertebral column from the skull to the sacrum

as continuous bands down the anterior and posterior sur

run

posterior longitudinal ligaments

anterior

The

Ligaments

longer possible to distinguish the nucleus from the anulus.

stress. In old age, the discs are thin and less elastic, and it is no

anulus cannot always contain the nucleus pulposus under

collagen fibers of the anulus degenerate and, as a result, the

and

-
-

■

by the small meningeal branches of each spinal nerve

The joints between the vertebral bodies are innervated

Nerve Supply of Vertebral Joints

attached to the cervical spines in between.

ance of the skull, with its anterior border being strongly

the 7th cervical vertebra to the external occipital protuber

The latter extends from the spine of

ligamentum nuchae.

(Fig. 12.6). The nerve arises from the spinal nerve as it exits

between the articular processes are innervated by branches

the meninges, ligaments, and intervertebral discs. The joints

bral canal through the intervertebral foramen and supplies

from the intervertebral foramen. It then re-enters the verte-

from the posterior rami of the spinal nerves (Fig. 12.6).

following regional curves: cervical, posterior concavity;

tebral column therefore exhibits in the sagittal plane the

In the adult in the standing position (Fig. 12.7), the ver

shape of the vertebral bodies and the intervertebral discs.

of these secondary curves results in a modification in the

column becomes concave posteriorly. The development

result of muscular activity, the lumbar part of the vertebral

the first year, when the child begins to stand upright as the

becomes concave posteriorly (Fig. 12.7). Toward the end of

muscular activity, the cervical part of the vertebral column

or her head and keep it poised on the vertebral column by

angle appears. After birth, when the child is able to raise his

rior concavity. As development proceeds, the lumbosacral

In the fetus, the vertebral column has one continuous ante

Curves in the Sagittal Plane

Curves of the Vertebral Column

receive nerve fibers from two adjacent spinal nerves.

It should be noted that the joints of any particular level

articular branch

spinous
process

thoracic

spinal

nerve

posterior ramus

of spinal nerve

anterior ramus

of spinal nerve

gray ramus

communicans

white ramus

communicans

sympathetic

trunk

meningeal
branch of
spinal nerve

anterior ramus
of spinal nerve

posterior
ramus of
spinal nerve

FIGURE 12.6

The innervation of vertebral joints. At any

two adjacent spinal nerves.

particular vertebral level, the joints receive nerve fibers from

Basic Anatomy

691

newborn infant

baby holds head up steadily

(3–4 months)

spinal cord

filum terminale

subarachnoid space
filled with cerebrospinal fluid

adult

FIGURE 12.7

A–C.

present superior and inferior to such a curvature.

thoracic convexity. Slight compensatory curves are always

right-handed persons will often have a slight right-sided

predominant use of one of the upper limbs. For example,

tebral column. This is normal and is usually caused by the

of minor lateral curves in the thoracic region of the ver

In late childhood, it is common to find the development

Curves in the Coronal Plane

anterior concavity.

a gradual return of the vertebral column to a continuous

intervertebral discs atrophy, resulting in a loss of height and

an attempt to preserve their center of gravity. In old age, the

women tend to increase the posterior lumbar concavity in

pregnancy, with the increase in size and weight of the fetus,

and sacral, posterior convexity. During the later months of

thoracic, posterior convexity; lumbar, posterior concavity;

bottom arrow

border of the body of the second sacral vertebra (

), and the subarachnoid space ends at the lower

top arrow

level of the lower border of the body of the first lumbar vertebra (

In the adult, the lower end of the spinal cord lies at the

Curves of the vertebral column at different ages. D.

increase in the weight of the abdominal contents, as with the

degree of movement possible between adjacent vertebrae.

one another by strong ligaments that severely limit the

bral discs. The vertebrae are held in position relative to

positioned one on the other and separated by interverte

column consists of several separate vertebrae accurately

As has been seen in the previous sections, the vertebral

Movements of the Vertebral Column

by disease of the vertebral column such as spondylolisthesis

gravid uterus or a large ovarian tumor, or it may be caused

(see page 693). The possibility that it is a postural compensa-

tion for a kyphosis in the thoracic region or a disease of the

hip joint (congenital dislocation) must not be overlooked.

Scoliosis is a lateral deviation of the vertebral column.

This is most commonly found in the thoracic region and may

be caused by muscular or vertebral defects. Paralysis of

muscles caused by poliomyelitis can cause severe scoliosis.

The presence of a congenital hemivertebra can cause scolio-

sis. Often, scoliosis is compensatory and may be caused by a

short leg or hip disease.

Nevertheless, the

f all these movements gives

summation o

is a combination of all these movements.

Circumduction

least extensive in the lumbar region.

is a twisting of the vertebral column. This is

Rotation

regions but restricted in the thoracic region.

the other side. It is extensive in the cervical and lumbar

is the bending of the body to one or

Lateral flexion

region.

cal and lumbar regions but restricted in the thoracic

posterior movement. Both are extensive in the cervi

is a

extension

is an anterior movement, and

Flexion

sion, lateral flexion, rotation, and circumduction.

The following movements are possible: flexion, exten

mobility.

the vertebral column as a whole a remarkable degree of

■

Abnormal Curves of the Vertebral Column

kyphosis of the upper thoracic region. The person is said to be

study or work over a low desk can lead to a gently curved

Kyphosis is an exaggeration in the sagittal curvature present

in the thoracic part of the vertebral column. It can be caused

by muscular weakness or by structural changes in the verte-

bral bodies or by intervertebral discs. In sickly adolescents,

for example, where the muscle tone is poor, long hours of

“round-shouldered.” Crush fractures or tuberculous destruc-

tion of the vertebral bodies leads to acute angular kyphosis

of the vertebral column. In the aged, osteoporosis (abnormal

rarefaction of bone) and/or degeneration of the intervertebral

discs leads to senile kyphosis, involving the cervical, tho-

racic, and lumbar regions of the column.

Lordosis is an exaggeration in the sagittal curvature

present in the lumbar region. Lordosis may be caused by an

C L I N I C A L N O T E S

(continued)

692

CHAPTER 12

the scalenus anterior and medius and the trapezius and

The Back

sternocleidomastoid muscles. Rotation is produced by

rotation is produced by the

thoracic region,

In the

the other side.

the sternocleidomastoid on one side and the splenius on

unilateral contraction of the semispinalis and rotatores

muscles and the oblique muscles of the anterolateral

in this movement. Rotation is produced by the rotatores

lateral abdominal wall. The psoas may also play a part

tus lumborum, and the oblique muscles of the antero

is produced by the postvertebral muscles, the quadra

produced by the postvertebral muscles. Lateral flexion

rectus abdominis and the psoas muscles. Extension is

flexion is produced by the

lumbar region,

In the

eral abdominal wall.

muscles, assisted by the oblique muscles of the anterolat-

-
-

abdominal wall.

muscles (see page 693). Lateral flexion is produced by

toid muscles. Extension is produced by the postvertebral

longus cervicis, scalenus anterior, and sternocleidomas

flexion is produced by the

cervical region,

In the

ribs or fasciae.

abdominal wall muscles, are attached to the skull or to the

whereas others, such as the sternocleidomastoid and the

cles, many of which are attached directly to the vertebrae,

The vertebral column is moved by numerous mus

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

allow a wide

atlantoaxial joints

extension of the head. The

permit extensive flexion and

atlanto-occipital joints

The

and the sternum severely restrict the range of movement.

cesses. In the thoracic region, the ribs, the costal cartilages,

tebral discs and the shape and direction of the articular pro

the column largely depend on the thickness of the interver

The type and range of movements possible in each region of

-
-

Dislocations of the Vertebral Column

It is possible for nontraumatic compression fractures to

body. Pieces of the vertebral body are commonly forced back into

ruption of the intervertebral disc and breakup of the vertebral

If the neck is slightly flexed, the

the atlas to be disrupted and the lateral masses to be displaced

excessive vertical force applied from above will cause the ring of

umn (Fig. 12.8). In the cervical region, with the neck straight, an

Vertical compression fractures occur in the cervical and lumbar

vertebrae involved are unstable, and the spinal cord is usually

the site is usually where maximum mobility occurs, as in the

sively flexed and twisted on the lower vertebra. Here again,

Fracture dislocations are usually caused by a combination of a

lateral flexion in addition to excessive flexion, the lateral part of

bral ligaments remain intact so that vertebral displacement and

Bilateral cervical dislocations are almost always associated

size of the vertebral canal allows the spinal cord to escape dam

the processes. In the thoracic and lumbar regions, dislocations

Dislocations without fracture occur only in the cervical region

because the inclination of the articular processes of the cervical

vertebrae permits dislocation to take place without fracture of

can occur only if the vertically placed articular processes are

fractured.

Dislocations commonly occur between the 4th and 5th or 5th

and 6th cervical vertebrae, where mobility is greatest. In unilat-

eral dislocations, the inferior articular process of one vertebra is

forced forward over the anterior margin of the superior articular

process of the vertebra below. Because the articular processes

normally overlap, they become locked in the dislocated position.

The spinal nerve on the same side is usually nipped in the inter-

vertebral foramen, producing severe pain. Fortunately, the large

age in most cases.

with severe injury to the spinal cord. Death occurs immediately

if the upper cervical vertebrae are involved because the respira-

tory muscles, including the diaphragm (phrenic nerves C3 to 5),

are paralyzed.

Fractures of the Vertebral Column

Fractures of the Spinous Processes, Transverse
Processes, or Laminae
Fractures of the spinous processes, transverse processes, or

laminae are caused by direct injury or, in rare cases, by severe

muscular activity.
Anterior and Lateral Compression Fractures
Anterior compression fractures of the vertebral bodies are usu-

ally caused by an excessive flexion compression type of injury

and take place at the sites of maximum mobility or at the junction

of the mobile and fixed regions of the column. It is interesting to

note that the body of a vertebra in such a fracture is crushed,

whereas the strong posterior longitudinal ligament remains

intact. The vertebral arches remain unbroken and the interverte-

spinal cord injury do not occur. When injury causes excessive

the body is also crushed.

Fracture Dislocations

flexion and rotation type of injury; the upper vertebra is exces-

lumbar region, or at the junction of the mobile and fixed region

of the column, as in the lower lumbar vertebrae. Because the

articular processes are fractured and the ligaments are torn, the

severely damaged or severed, with accompanying paraplegia.

Vertical Compression Fractures

regions, where it is possible to fully straighten the vertebral col-

laterally (Jefferson’s fracture).

lower cervical vertebrae remain in a straight line and the com-

pression load is transmitted to the lower vertebrae, causing dis-

the spinal cord.

occur in severe cases of osteoporosis and for pathologic frac-

tures to take place.

In the straightened lumbar region, an excessive force from

below can cause the vertebral body to break up, with protrusion

of fragments posteriorly into the spinal canal.

C L I N I C A L N O T E S

(continued)