Muscles and Deep fascia of the back pdf - The back

Basic Anatomy

693

Fractures of the Odontoid Process of the Axis

be pressed upon causing low back pain and pain down the leg in

arthritis of the intervertebral joints. Anterior slippage of the fifth

In severe cases, the trunk becomes shortened, and the lower

roots may be pressed on, causing low backache and sciatica.

left behind, the vertebral canal is not narrowed, but the nerve

articular processes, slips forward. Because the laminae are

vertebra, having lost the restraining influence of the inferior

processes remain in position, whereas the remainder of the

and fail to unite. The spine, laminae, and inferior articular

formed and accessory centers of ossification are present

believed that, in this condition, the pedicles are abnormally

the pedicles of the migrating vertebra. It is now generally

portion of the vertebral column. The essential defect is in

vertebra below and carries with it the whole of the upper

vertebra, usually the fifth, moves forward on the body of the

In congenital spondylolisthesis, the body of a lower lumbar

common name. Because the vertebral canal is enlarged by the

result from falls or blows on the head (Fig. 12.8). Excessive mobil

Fractures of the odontoid process are relatively common and

ity of the odontoid fragment or rupture of the transverse ligament

can result in compression injury to the spinal cord.

Fracture of the Pedicles of the Axis (Hangman’s
Fracture)
Severe extension injury of the neck, such as might occur in an

automobile accident or a fall, is the usual cause of hangman’s

fracture. Sudden overextension of the neck, as produced by the

knot of a hangman’s rope beneath the chin, is the reason for the

forward displacement of the vertebral body of the axis, the spinal

cord is rarely compressed (Fig. 12.8).

Congenital Spondylolisthesis

ribs contact the iliac crest.

Degenerative Spondylolithesis

This condition is common in the elderly and involves degenera-

tion of the intervertebral discs in the lumbar region and osteo-

lumbar vertebra often occurs, and the lumbar nerve roots may

the distribution of the involved nerve.

site of destruction
of spinal cord

odontoid process
of atlas

transverse ligament of atlas

anterior arch of atlas

fracture of pedicle

site of nipping
of spinal nerve

posterior arch of atlas

waist fracture of odontoid process

base fracture of odontoid process

FIGURE 12.8

Dislocations and fractures of the vertebral column.

passes through the odontoid process of the axis, posterior

In the standing position, the line of gravity (Fig. 12.9)

to the vertebral column.

belonging

postvertebral muscles

deep muscles

The

Chapter 2.

the thoracic cage. They are described with the thorax in

involved with movements of

intermediate muscles

The

girdle. They are described in Chapter 9.

connected with the shoulder

superficial muscles

The

The muscles of the back may be divided into three groups:

Fractures of the odontoid process and the pedicles (hangman’s fracture) of the axis.

type fracture of the atlas.

Jefferson’s-

Flexion compression–type fracture of the vertebral body in the lumbar region.

ward on the vertebra below.

Bilateral dislocation of the fifth or the sixth cervical vertebra. Note that 50% of the vertebral body width has moved for

bra. Note the anterior displacement of the inferior articular process over the superior articular process of the vertebra below.

Unilateral dislocation of the fifth or the sixth cervical verte

Muscles of the Back

■

Deep Muscles of the Back

(Postvertebral Muscles)

694

CHAPTER 12

The Back

semispinalis capitis

longissimus capitis

longissimus cervicis

iliocostalis cervicis

spinalis thoracis

iliocostalis thoracis

multifidus

longissimus thoracis

iliocostalis lumborum

semispinalis thoracis

FIGURE 12.9

of muscle tissue, which occupies the hollow on each side of

The deep muscles of the back form a broad, thick column

curves of the vertebral column.

major factor responsible for the maintenance of the normal

oped in humans. The postural tone of these muscles is the

that the postvertebral muscles of the back are well devel

vertebral column. It is, therefore, not surprising to find

position, the greater part of its weight falls in front of the

and ankle joints. It follows that when the body is in this

to the centers of the hip joints, and anterior to the knee

tant in maintaining the normal postural curves of the vertebral column in the standing position.

Because the greater part of the body weight lies anterior to the vertebral column, the deep muscles of the back are impor

Lateral view of the skeleton showing the line of gravity.

Arrangement of the deep muscles of the back. B.

the spinous processes of the vertebral column (Fig. 12.9).

Superficial Vertically Running Muscles

The deep muscles of the back may be classified as follows:

processes of adjacent vertebrae.

fibers run between the spines and between the transverse

processes to the spines. The shortest and deepest muscle

of intermediate length run obliquely from the transverse

and the upper vertebral spines (Fig. 12.9). The muscles

from the sacrum to the rib angles, the transverse processes,

cles of longest length lie superficially and run vertically

serve as levers that facilitate the muscle actions. The mus

The spines and transverse processes of the vertebrae

the vertebral column can be made to move smoothly.

of the different groups of muscles overlap, entire regions of

on the vertebra below. Because the origins and insertions

causes one or several vertebrae to be extended or rotated

muscle may be regarded as a string, which, when pulled on,

many separate muscles of varying length. Each individual

ized that this complicated muscle mass is composed of

They extend from the sacrum to the skull. It must be real-

spinalis

Erector spinae

longissimus

iliocostalis

■

■■

Intermediate Oblique Running Muscles

Rotatores

Transversospinalis

multifidus

Semispinalis

êë

■

■■

Intertransversarii

Interspinales

Deepest Muscles

■

Basic Anatomy

Knowledge of the detailed attachments of the various

supply a band of skin at a lower level than the intervertebral

The posterior rami run downward and laterally and

of the head and supplies the skin of the scalp.

) ascends over the back

greater occipital nerve

nerve (the

ply the skin. The posterior ramus of the second cervical

nerves supply the deep muscles of the back and do not sup

eighth cervical nerves and the fourth and fifth lumbar

nerves. The posterior rami of the first, sixth, seventh, and

tal manner by the posterior rami of the 31 pairs of spinal

The skin and muscles of the back are supplied in a segmen

inguinal nodes (see page 127).

below the level of the iliac crests drain into the superficial

the iliac crests drain into the axillary nodes, and those from

drain into the cervical nodes, those from the trunk above

sacral nodes. The lymph vessels from the skin of the neck

the deep cervical, posterior mediastinal, lateral aortic, and

The deep lymph vessels follow the veins and drain into

Lymph Drainage of the Back

lumbar, and lateral sacral veins.

bral plexus and in turn drain into the vertebral, intercostal,

Here, they are joined by tributaries from the external verte

with the spinal nerves through the intervertebral foramina.

which pass outward

intervertebral veins,

is drained by the

and from the meninges and spinal cord. The internal plexus

(Fig. 12.10)

basivertebral veins

the vertebrae by way of the

The internal vertebral plexus receives tributaries from

of the prostate, page 696).

fact is of considerable clinical significance (see carcinoma

ences that exist at any given time between the regions. This

with the direction of flow depending on the pressure differ

thorax, the abdomen, the pelvis, and the vertebral plexuses,

may therefore take place between the skull, the neck, the

venous sinuses within the skull. Free venous blood flow

communicate through the foramen magnum with the

channels have incompetent valves or are valveless. They

cious venous network whose walls are thin and whose

The external and internal vertebral plexuses form a capa

cord (Fig. 12.10).

vertebral canal but outside the dura mater of the spinal

lies within the

internal vertebral venous plexus

The

surrounds the vertebral column.

lies external and

external vertebral venous plexus

The

coccyx.

extending along the vertebral column from the skull to the

The veins draining the structures of the back form plexuses

Veins

artery.

and lateral sacral arteries, branches of the internal iliac

, branches arise from the iliolumbar

sacral region

In the

and lumbar arteries.

, branches arise from the subcostal

lumbar region

In the

intercostal arteries.

, branches arise from the posterior

thoracic region

In the

695

■

Nerve Supply of the Back

muscles of the back has no practical value to a clinical profes

deep cervical artery, a branch of the costocervical trunk.

tebral artery, a branch of the subclavian; and from the

artery, a branch of the external carotid; from the ver

branches arise from the occipital

cervical region,

In the

the quadratus lumborum muscle.

verse processes of the lumbar vertebrae; it lies anterior to

medially and is attached to the anterior surface of the trans

the quadratus lumborum. The anterior lamella passes

anterior to the deep muscles of the back and posterior to

of the transverse processes of the lumbar vertebrae; it lies

middle lamella passes medially, to be attached to the tips

cles of the back and is attached to the lumbar spines. The

three lamellae. The posterior lamella covers the deep mus

Medially, the lumbar part of the deep fascia splits into

oblique muscles of the abdominal wall (see page 117).

ers of the transversus and the upper fibers of the internal

aponeurosis and laterally gives origin to the middle fib

between the iliac crest and the 12th rib. It forms a strong

The lumbar part of the deep fascia is situated in the interval

of the abdomen, and the iliac crest.

dorsi, the posterior border of the external oblique muscle

the abdominal wall. The boundaries are the latissimus

The lumbar triangle is the site where pus may emerge from

Lumbar Triangle

the medial border of the scapula.

The boundaries are the latissimus dorsi, the trapezius, and

breath sounds may be most easily heard with a stethoscope.

The auscultatory triangle is the site on the back where

Auscultatory Triangle

Muscular Triangles of the Back

terior rami of the spinal nerves.

All the deep muscles of the back are innervated by the pos

Nerve Supply

into the transverse processes of the upper cervical vertebrae.

has a similar origin but is inserted

splenius cervicis

The

the temporal bone.

nuchal line of the occipital bone and the mastoid process of

upper four thoracic spines and is inserted into the superior

from the lower part of the ligamentum nuchae and the

arises

splenius capitis

back. It consists of two parts. The

The splenius is a detached part of the deep muscles of the

sional, and the attachments are therefore omitted in this text.

Splenius

Deep Fascia of the Back

(Thoracolumbar Fascia)

Blood Supply of the Back

Arteries

■