Chapter 26
The Thoracic Spine
Overview


In the thoracic region, protection and
function of the thoracic viscera take
precedence over segmental spinal
mobility
The thoracic complex can be a
significant source of local and referred
pain
Anatomy




The thoracic spine forms a kyphotic curve between
the lordotic curves of the cervical and lumbar
spines
The curve begins at T 1-2 and extends down to T
12 with the T 6-7 disc space as the apex
The thoracic kyphosis is a structural curve, which is
present from birth
Unlike the lumbar and cervical regions, which
derive their curves from the corresponding
differences in intervertebral disc heights, the
thoracic curve is maintained by the wedge-shaped
vertebral bodies, which are about 2 mm higher
posteriorly than anteriorly
Anatomy


The thoracic vertebrae consist of the usual
elements: the vertebral body (centrum),
transverse processes, neural arch, and
spinous process
As elsewhere in the spine, the thoracic
vertebrae are designed to endure and
distribute the compressive forces produced
by weight bearing, most of which is borne
by the vertebral bodies
Anatomy

The thoracic vertebral body is roughly
as wide as it is long so that its
anterior-posterior and medial-lateral
dimensions are of equal length
Anatomy


The height, end-plate cross-sectional area,
and bone mass of the vertebral bodies
increases cranial to caudal, particularly in
the lower levels
Progressive wedging of the thoracic
vertebral bodies occurs with increasing age
in the majority of individuals, with disc
space narrowing at multiple levels occurring
from the third decade of life
Anatomy


The transverse processes of the thoracic
vertebrae differ from those of the cervical
and lumbar spines due to the presence of a
costal articular facet on the transverse
process
The costotransverse joint is formed by an
oval facet on the lateral aspects of all of the
transverse processes to which the rib
attaches, except for T 11 and T 12 to which
no ribs are attached
Anatomy

The thoracic vertebrae are classified as
typical or atypical with reference to
their morphology
– The typical thoracic vertebrae are found
at T 2-9, although T 9 may be atypical in
that its inferior costal facet is frequently
absent
– The atypical thoracic vertebrae are the
first, tenth, eleventh and twelfth
Anatomy



The common spinal ligaments are present at
the thoracic vertebrae, and they perform
much the same function as they do
elsewhere in the spine
The anterior longitudinal ligament in this
region is narrower but thicker compared to
the rest of the spine
The posterior longitudinal ligament, is wider
here at the intervertebral disc level, but
narrower at the vertebral body than in the
lumbar region
Anatomy


The zygapophyseal joints of the
thoracic spine function to restrain the
amount of flexion and anterior
translation of the vertebral segment,
and to facilitate rotation
They appear to have little influence on
the range of side bending
Anatomy


The bony thoracic cage is formed by
twelve pairs of ribs, the sternum, the
clavicle and the thoracic spine
vertebrae
All of the ribs are different from each
other in size, width, and curvature,
although they share some common
characteristics
Anatomy

The ribs are divided into two classifications:
(1) true/false and (2) typical/atypical
– Ribs 1 through 7 are named true ribs because
their cartilage attaches directly to the sternum
– Ribs 3 through 9 are typical ribs. The typical rib
is characterized by a posterior end, which is
comprised of a head, neck and tubercle
Anatomy


The costovertebral articulation also forms an
intimate relationship between the head of
the rib and the lateral side of the vertebral
body
The radiate ligament connects the anterior
aspect of the rib head to the bodies of two
adjacent vertebrae and their intervening
disc, in a fan-like arrangement
Anatomy

The costotransverse joint is a synovial
joint between an articular facet on the
posterior aspect of the rib tubercle and
an articular facet on the anterior
aspect of the transverse process,
which is supported by a thin fibrous
capsule
Anatomy


The sternum consists of three parts:
the manubrium, the body, and the
xiphoid process.
The manubrium is broad and thick
superiorly, and narrower and thinner
inferiorly, where it articulates with the
body
Anatomy


The first, sixth and seventh costal
cartilages are each linked to the
sternum by a synchondrosis
The second to fifth ribs are each
connected to the sternum through a
synovial joint, whereby the cartilage of
the corresponding rib articulates with
a socket-like cavity in the sternum
Anatomy


A large number of muscles arise from
and insert on the thoracic spine and
ribs
The muscles of this region can be
divided into those that are involved in
spinal or extremity motion, and those
that are involved in respiration
Anatomy


The blood supply to this region is
mainly provided by the dorsal
branches of the posterior intercostal
arteries, while the venous drainage
occurs through the anterior and
posterior venous plexuses
The spinal cord region between T 4
and T 9 is poorly vascularized
Anatomy



In the thoracic region there is great
variability in the topography of the nerves,
and the structures that they serve
Typically, the spinal root arises from the
lateral end of the spinal nerve but, in 25%
of cases, the spinal root is made up of two
parts that arise from the superior border of
the spinal nerve
The thoracic spinal nerves are segmented
into dorsal primary and ventral primary
divisions
Biomechanics


The thoracic spinal segments possess the
potential for a unique array of movements
However, there is very little agreement in
the literature with regards to the
biomechanics of the thoracic spine and most
of the understanding is based largely on the
ex vivo studies and a variety of clinical
models
Biomechanics

Flexion of the thoracic spine in weight
bearing is initiated by the abdominal
muscles and, in the absence of
resistance, is continued by gravity,
with the spinal erector muscles
eccentrically controlling the descent.
Flexion may also occur during bilateral
scapular protraction
Biomechanics


Extension of the thoracic spine is produced
principally by the lumbar extensors, and
results in an inferior glide of the superior
facet of the zygapophyseal joint
1-2º of extension is available at each
thoracic segment, giving an overall average
of 15-20º of thoracic extension for the
entire thoracic spine
Biomechanics


Side bending of the thoracic spine is
initiated by the ipsilateral abdominals, and
erector muscles, and then continued by
gravity
A total of 25-45º of side bending is available
in the thoracic spine, at an average of about
3-4º to each side per segment, with the
lower segments averaging slightly more, at
7º to 9º each
Biomechanics


Axial rotation is produced either by the
abdominal muscles and other trunk
rotators, or by unilateral elevation of
the arm
Pure axial rotation (twisting) can only
occur at two points in the spine: at the
thoracolumbar and cervicothoracic
junctions
Biomechanics



Because the anterior end of the ribs is lower than
the posterior, when the ribs elevate they rise
upwards while the rib neck drops down
In the upper ribs, this results in an anterior
elevation (pump handle) which increases the
anterior-posterior diameter of the thoracic cavity
In the middle and lower ribs (excluding the free
ribs), this results in a lateral elevation (bucket
handle), which increases the transverse diameter of
the thoracic cavity
Examination

Differential diagnosis of thoracic pain
can be difficult. This is due to the
complicated biomechanics and
function of the region, the proximity to
vital organs, and the many
articulations
Examination

Pain arising from inflammation of the
axial spine can mimic a variety of
serious conditions, including
cardiac/pulmonary pathology, renal
colic, fracture, a tumor, or numerous
visceral and retroperitoneal
abnormalities, including abdominal
aortic aneurysm
Examination

History
– The clinician must determine if the pain is
provoked or alleviated with movement or
posture (musculoskeletal pain),
respiration (rib dysfunction or pleuritic
pain), eating or drinking (gastric pain), or
exertion (rib dysfunction or cardiac pain)
Examination

Systems Review
– Thoracic pain may originate from just about all
of the viscera
– Both visceral and somatic afferent nerves
transmit pain messages from a peripheral
stimulus and converge on the same projection
neurons in the dorsal horn
– The thoracolumbar outflow of the autonomic
nervous system has its location here. Stimulation
of this outflow can lead to the presence of
facilitated segments, and trophic changes in the
skin of the periphery
Examination

Observation
– The clinician should observe:
The relationship of the bony structures
 Smoothness of the thoracic curve
 The degree of thoracic kyphosis
 The amount of lateral curvature of the
thoracic spine
 Chest wall shape
 Asymmetry in muscle bulk, prominence, or
length

Examination

Palpation
– The areas of spinous process obliquity may be
divided into four regions by the so-called ‘rule of
three’




1st group of 3 spinous processes (T 1-3) are level with
vertebral body of the same level
2nd group of 3 spinous processes (T 4-6) are level with
the disk of the inferior level
3rd group of 3 spinous processes (T 7-9) are level with
the vertebral body of the level below
The 4th group of 3 spinous processes reverse the
obliquity
Examination

Active Motion Testing
– Active range of motion tests are used to determine the
osteokinematic function of two adjacent thoracic vertebrae
during active motions, to determine which joints are
dysfunctional, and the specific direction of motion loss
– Active range of motion is initially performed globally,
looking for abnormalities, such as asymmetrical limitations
of motion
– A specific examination is then performed on any region
that appeared to have either excessive or reduced motion
Examination


For those clinicians heavily influenced
by the muscle energy techniques of
the osteopaths, position testing is
used to determine which segment to
focus on
Other clinicians omit the position tests
and proceed to the combined motion
and passive physiological tests
Examination

Costal examination
– It is well worth postponing the costal, or
rib, examination until after the thoracic
spinal joints have been examined and
treated, or the testing of which proved
negative
Examination




A neurological deficit is very difficult to detect in the
thoracic spine
In this region, one dermatome may be absent with
no loss of sensation
Sensation should be tested over the abdomen; the
area just below the xiphoid process is innervated by
T 8, the umbilicus by T 10, and the lower
abdominal region, level with the anterior superior
iliac spines, by T 12
Too much overlap exists above T 8 to make
sensation testing reliable
Intervention

Acute phase goals include:
–
–
–
–
–
–
–
–
Decrease pain, inflammation, and muscle spasm
Promote healing of tissues
Increase pain-free range of vertebral and costal motion
Regain soft tissue extensibility
Regain neuromuscular control
Initiate postural education
Promote correct breathing
Educate the patient about activities to avoid and positions
of comfort.
– Allow progression to the functional stage
Intervention

Functional phase goals
– To significantly reduce or to completely resolve
the patient’s pain
– The restoration of full and pain-free vertebral
and costal range of motion
– Full integration the entire upper and lower
kinetic chains
– Complete restoration of respiratory function
– The restoration of thoracic and upper quadrant
strength and neuromuscular control