Download Thoracic zygapophysial joint palpation

Anatomy in Practice
Thoracic zygapophysial joint palpation
Jon Cornwall DipPhty, BSc(Physiol), MSc(Anat)
PhD Student, Department of Anatomy & Structural Biology
University of Otago
New Zealand
Susan Mercer BPhty(Hons), MSc, PhD
Associate Professor, School of Biomedical Sciences
The University of Queensland, Australia
Abstract
It is widely accepted that structures in the thoracic region of the vertebral column
are a potential source of pain. Palpation of thoracic zygapophysial joints is therefore
frequently performed during both assessment and treatment of this region. With less
research investigating the thoracic spine than either cervical or lumbar regions, its
unique morphology is often not considered in detail when describing techniques of
manual treatment and assessment. This article addresses vertebral and paravertebral
morphology that may affect accurate palpation of the thoracic zygapophysial joints,
and so highlights practical considerations for clinicians who utilise such procedures.
Cornwall J, Mercer S (2006): Thoracic Zygapophysial joint palpation. New Zealand
Journal of Physiotherapy 34(2): 56-59.
Keywords: thoracic zygapophysial joints, palpation, clinical anatomy.
Introduction
Palpation of the vertebral column is routinely
used in the diagnosis and treatment of disorders
arising from the spine (Greenman 2003, Maitland
et al 2001, Najm et al 2003). During assessment
clinicians palpate spinal levels to identify painful
segments, changes in joint motion and local changes
in tissue texture (Greenman 2003, Maitland et al
2001, Najm et al 2003). The information gathered
in this way contributes to the formation of the
diagnosis. However, fundamental to an accurate
diagnosis is the ability to correctly identify
anatomical structures ( Greenman 2003, Maitland
et al 2001, Mercer and Rivett 2004,).
One of the commonly assessed and treated
structures of the vertebral column is the
zygapophysial joint (Maitland et al 2001), and in
the thoracic region these joints have recently been
documented as a source of symptoms ( Dreyfuss
et al 1994, Manchikanti et al 2004, Wall et al
1999). For example, a prevalence rate of 42% for
pain arising from the thoracic zygapophysial joints
was found in a group of patients presenting with
chronic thoracic pain (Manchikanti et al 2004).
Manual therapists are said to be able to diagnose
conditions such as restrictions of zygapophysial
joint movement (Maitland et al 2001). Treatment
for such segmental dysfunction involves the
application of posterior-anterior (PA) mobilisation
techniques, where the motion of a restricted joint
segment is purportedly restored (Greenman 2003,
Maitland et al 2001). The facilitation of this
restricted movement is alleged to occur through the
application of targeted manual force in the plane of
the joint (Maitland et al 2001). These assessment
and treatment techniques require that the therapist
can accurately identify the joints in question and
can apply forces at the appropriate orientation.
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There are a variety of factors that can influence
the accuracy of palpation in each region of the spine
(Cornwall & Mercer 2004, Dvorak 1998, Najm et al
2003). These factors relate to both the morphology
of the vertebral segments and to the gross anatomy
of the adjacent tissues (Cornwall & Mercer 2004).
For palpation to be as effective as possible it must
be undertaken in the context of the spinal region
being assessed. This article therefore addresses
the concerns that specifically arise with palpation
of the thoracic zygapophysial joints. Issues that
necessitate consideration when this procedure
is used during manual therapy assessment and
treatment are identified.
Morphology
There are eleven pairs of thoracic zygapophysial
joints, with one pair located between each vertebral
level. These joints contribute to the floor of the
‘paravertebral gutter’, the region between the
spinous and transverse processes (Clemente 2006,
Moore et al 2006, Rosse et al 1997, Standring 2005)
(Figure 1). In the cervical and lumbar regions this
gutter is shallow, formed mainly by the laminae
and articular pillars, whereas in the thoracic region
the gutter is deeper and broader, being formed
by the laminae, articular pillars and transverse
processes. The thoracic transverse processes also
articulate with the tubercle of the dorsal surface of
the adjacent rib (Standring 2005) (Figure 1).
Due to the contour of the thoracic laminae
and general orientation of the articular processes
the zygapophysial joints appear to lie flat, close
to the spinous processes with the prominent
costotransverse joints lying more laterally (Figure
1). An informal measurement of six plastinated
vertebral columns revealed that the mid-point of
thoracic zygapophysial joints lay, on average, ten
NZ Journal of Physiotherapy – July 2006, Vol. 34 (2)
millimetres from the lateral edge of the adjacent
spinous process. These measurements were taken
in the coronal plane.
Figure 2. Parasagittal section through the thoracic
spine, highlighting the orientation and location of the
zygapophysial joints. Note how the inferior articular
process overlaps the subjacent superior articular
process, the changing orientation of the joints (red
arrows), and the varying depths of the zygapophysial
joints beneath the skin. Red arrows: zygapophysial
joints (from L to R) at T9/10, T6/7, T2/3. Segmental level
of thoracic vertebral body indicated by number.
Figure 1. Transverse section through the T2 vertebral
body showing the muscles overlying the zygapophysial
joints and paravertebral gutter. Red arrow:
zygapophysial joint; R: rib; TP: transverse process; SS:
semispinalis; M: multifidus; RH: rhomboids; T: trapezius.
When viewed from behind the most superficial
part of the zygapophysial joint is the inferior
articular process of the immediately superior
vertebra. At each level the articular facet of each
superior articular process passes deep (or more
anterior) to the inferior articular process of the
vertebrae immediately above (Moore & Dalley
2006, Rosse & Gaddum-Rosse 1997, Standring
2005) (Figure 2). The distal tip of the inferior
articular process therefore abuts the lamina of the
immediately inferior vertebra, where the joint line is
observed between the two bones (Figures 2 & 3).
Classic anatomical texts (Moore & Dalley 2006,
Standring 2005) have stated that the angle at which
the joint surfaces of thoracic zygapophysial joints
articulate lies close to the coronal plane. A more
precise description was provided by Davis (1959)
who stated that in the thoracic spine the superior
articular facets face posteriorly, slightly superiorly
and slightly laterally (Figure 4). As demonstrated
in Figure 2 the orientation of the articular facets
in the sagittal plane varies throughout the thoracic
region. Valencia (1994) reported these changes
in orientation with respect to the horizontal,
describing a 600 orientation in the upper thoracic
region changing to 900 in the midthoracic region
and almost 00 at lower thoracic levels.
Lying between the skin and zygapophysial joints
are layers of subcutaneous tissue and muscle.
Immediately below the subcutaneous tissue lies
the lower fibres of trapezius, which attaches to
all thoracic spinous processes (Johnson et al
1994) (Figure 1 & 4). Lying under the caudal
half of the lower trapezius muscle are, superficial
to deep, the fibres of the latissimus dorsi muscle
NZ Journal of Physiotherapy – July 2006, Vol. 34 (2)
Figure 3. Dorsal view of the mid-thoracic vertebral
column with the overlying muscles removed. Note
the lack of readily identifiable or palpable landmarks
over the dorsal surface of the zygapophysial joints
and adjacent lamina. Red arrows indicate joint lines
between T8/9 and T9/10 zygapophysial joints; TP10:
transverse process T10; T9, T8, T7: spinous processes of
respective vertebrae; L: lamina of T9 vertebra; Blue
pins: interspinous spaces.
Figure 4. Transverse section through the level of
T9/10 disc, highlights the thickness of the musculature
lying within the paravertebral gutter above the
zygapophysial joints. Note the posterior and slightly
lateral orientation of the facet of the superior articular
process. Red arrow: zygapophysial joint; CV:
costovertebral joint; M: multifidus; LO: longissimus;
TR: trapezius; SS: semispinalis thoracis / spinalis; IL:
iliocostalis.
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or the aponeurotic fibres of the posterior layer
of the thoracolumbar fascia (Figure 4). Further
superiorly the remaining muscles to be considered
are rhomboid minor and major, serratus posterior
superior and splenius cervicis (Clemente 1987,
Moore & Dalley 2006, Rosse & Gaddum-Rosse
1997, Standring 2005).
More intimately associated with the paravertebral
gutter are the short and long rotatores, overlaid by
multifidus, semispinalis cervicis and semispinalis
thoracis (Hollinshead 1969). Fascicles from the
rotatores, multifidus and semispinalis muscles
pass between one and six segments before inserting
into a transverse process (Clemente 2006, Moore &
Dalley 2006, Rosse & Gaddum-Rosse 1997). While
closely approximating the spinous processes, the
very slender spinalis thoracis runs between the
T11-L3 spinous processes to insert into a variable
number of the upper thoracic spinous processes,
usually between the level of T4 and T8 (Hollinshead
1969). The only additional muscle that may be
considered is the longissimus thoracis, overlying
the costotransverse regions but lying lateral to
semispinalis thoracis (Bogduk 1994) (Figure 4).
Embedded in areolar tissue the thoracic dorsal rami
accompanied by arteries and veins passes over the
dorsal aspect of the multifidus muscle covered by
fibres of semispinalis (Chua & Bogduk 1995).
Clinical Implications
Many manual therapy techniques are based on
a mechanical paradigm (Mulligan 1995, Maitland
et al 2001), where restrictions in joint movement
are facilitated by the application of manual force
to symptomatic joints. This facilitation is said to
occur when force is applied that aids the movement
of contributing articular facets in the direction
to which the zygapophysial joint motion is most
inhibited. In this way, the joint is said to be
‘mobilised’ (Maitland et al 2001). Essential to this
paradigm is a precise knowledge of joint margins,
so that force may be directed to the symptomatic
joint(s).
The plane in which the zygapophysial joint lies
must also be identified. This is because facilitation
of joint movement is said to be most effectively
achieved through manual force that is directed
parallel to the plane of the joint (Maitland et al
2001). Therefore, for facilitation of zygapophysial
joint motion in the thoracic spine, PA procedures
in this region should direct force in the plane of
the joint, and not directly in a PA direction. The
direction of applied force will also be individual
to different parts of the thoracic spine, as the
superior, middle and inferior regions all exhibit
different orientations of the zygapophysial joints.
Therefore, precise identification of both the joint
line and the plane of the joint is necessary to
facilitate appropriate manual therapy intervention
as suggested by Maitland et al (2001) and utilised
by clinicians (Mulligan 1995, Jull et al 2002, Lee
2004).
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Given that the zygapophysial joints lie in the
‘paravertebral gutter’, beneath various layers of
subcutaneous fat and dorsal musculature, it seems
unlikely that the joint line will be readily palpable
(Figures 1 & 4). In addition, the similarity in coronal
plane orientation of the dorsal surface of the inferior
articular facet and the adjacent laminae adds to
this difficulty: distinguishing between the lamina
and the projecting aspect of the inferior articular
facet using palpation would be problematic. Figure
3 highlights the congruence between the laminae
and zygapophysial joints, indicating the paucity of a
readily palpable bony landmarks that could facilitate
precise identification of the zygapophysial joints.
These clinically applied anatomical descriptions
highlight the difficulty in accurately palpating
structures of the thoracic spine, thereby confounding
the application of PA mobilisation techniques as
outlined by Maitland et al (2001). As suggested by
Dvorak (1998) palpation under fluoroscopy would
confirm whether the painful level was accurately
located and indicate the orientation of the joint
in question. Investigations into the validity of PA
techniques in mobilising vertebral segments along
the plane of the joint could also be undertaken.
Conclusion
It has been demonstrated that the thoracic
zygapophysial joints are a potential source of pain
(Dreyfuss et al 1994, Manchikanti et al 2004,
Wall & Melzack 1999). However it is unlikely,
given the morphology and location of the thoracic
zygapophysial joints, that individual joints can
be reliably palpated. This becomes problematic
when assessing the thoracic region, or utilising
techniques (such as PA mobilisations) that rely on
either joint line or articular process identification.
Techniques based on such approaches also need
to be re-examined in light of the plane in which the
joints lie, so the application and direction of any
manual force is appropriately applied.
Key Points
The morphology of the thoracic zygapophysial
joints leads to difficulty in accurate palpation.
Thoracic zygapophysial joints lie on the floor of the
thoracic paravertebral gutter, overlaid by a
series of dorsal muscles.
The orientation of the thoracic zygapophysial joints
varies along the vertebral column.
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Address for Correspondence
Jon Cornwall, Department of Anatomy & Structural Biology,
University of Otago, Dunedin, New Zealand. Email: jon.cornwall@
anatomy.otago.ac.nz. Phone: 03 479 7362, Fax: 03 479 7254.
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