The thoracic region is one of the stable and comparatively rigid sections of the vertebral column. Initially, this may appear to be more of a disadvantage. However, on taking a closer look at the functions of the thoracic region it becomes clear that stiffness is actually an advantage.
The thoracic spine, combined with the thoracic cage and the sternum, provides a stabile bony cage that protects the heart, lungs, and other important organs. Small and large mechanical stresses can be absorbed by this stabile, yet elastic, construction. The vertebral canal is very narrow, almost completely enclosed by bones, and home to a large section of the spinal cord.
In addition to maintaining our upright posture, this section of the body must be stable enough to absorb all impulses arising in the arms. Large muscles, such as the latissimus dorsi and pectoralis major, and the scapulothoracic joint surfaces transmit large compressive and tensile loads. Without this central stability we would be unable to carry the weight of our arms, let alone that of larger loads. At the same time, the lateral tract of the erector spinae muscles is very strong in the lumbar region, but gradually loses its effectiveness more superiorly. Other strong muscles such as the spinalis provide the strength for thoracic extension.
The thoracic mobility supports extensive arm movements—though not to the same extent as in the lumbar spine where mobility optimizes leg movement. Nevertheless, full arm elevation is only possible up to approximately 150° when the thoracic region is unable to move into extension. The expected range is generally 180°. Arm elevation causes movement from the cervicothoracic junction down to approximately T6/T7:
Extensive external and internal rotation at one shoulder joint is transmitted onto the thoracic spine as rotation. Bilateral rotation causes the thoracic spine to flex (with internal rotation) or extend (with external rotation).
Anatomically, the mobile sections of the vertebral column can be well differentiated from one another. The thoracic spine stands out as the section that supports the ribs. Functionally, there is a fluent transition between its sections. Both lordotic sections extend functionally into the thoracic section of the vertebral column. It is therefore expected that extensive cervical movements can be palpated down to approximately T4–T5. Lumbar movements are carried over to approximately the level of T10–T11. The real thoracic spine is found between these points.
In healthy people, quiet respiration is completely controlled by activity in the diaphragm. Forced respiration is supported by movement in the thorax. Respiratory movements are the result of the following:
The upper thoracic segmental movement associated with extensive arm elevation can be palpated well. An example of this is seen when the therapist places several finger pads over the cervicothoracic junction on the left side of the spinous process. The therapist can then feel the spinous process’s rotation to the left when the right arm moves into full elevation.
Respiratory movements can also be palpated. The opening and closing of the intercostal spaces provides information on the mobility of the ribs at their articular connections to the vertebral column and the flexibility of the intercostal muscles.
Different techniques can be used to palpate the thoracic segments during movement to assess the presence of restricted mobility. While clear rules exist explaining the relationship between lateral flexion and rotation in the lumbar spine and the cervical spine, it is not possible to set fixed rules for the mid-thoracic region. There is so much variation between individuals that functional relationships have to be newly assessed every time.
The thoracic spine and the thorax are the home for the sympathetic nervous system. It is well known that the central region of the sympathetic nervous system is found in the lateral horn of the thoracic spinal cord. Important thoracic organs are represented in the large Head zones. This close relationship between viscerotomes and dermatomes can be used for diagnosis. Treatment not only affects these organs via the reflexes, it can also affect the neurovegetative control of the head and arms. Preganglionic fibers extend from the upper thoracic segments into the cervical sympathetic chain ganglions. The thoracic spine and the thorax are therefore an ideal location to apply mechanical (Swedish massage, connective-tissue massage, manual therapy), thermal, or electrical stimuli to affect sympathetic nervous system activity. These forms of intervention are the recurring topic of discussion in the treatment of chronic musculoskeletal pain.
The thoracic spine and the thorax are also often directly affected by the almost violent interventions used in open thoracic surgery. In older patients, these joints become rigid as part of the adaptive aging process. During this type of surgery, thoracic segments and costal joints are placed in extreme positions and are then forced into inactivity for weeks on end. In such a case, it takes a lot of effort to train a thorax to breathe properly again. A variety of respiratory parameters are used here for diagnosis: the frequency, rhythm, and direction of respiration, as well as the range of thoracic motion between maximal inhalation and expiration. The compression of the thorax and the mobilization of soft tissues are important manual techniques used in respiratory therapy that require certain basic palpatory dexterity.
Pain and restricted mobility in the costal and vertebral joints not only lead to restrictions in respiration, they also strongly interfere with daily tasks. Hypomobility in connection with pain plays an important role here. In no other section of the vertebral column is the assessment of segmental mobility and extremely localized mobilization as important as in the thoracic spine (▶ Fig. 12.1).
Hypermobility is rarely seen to be a cause of symptoms. For a long time intervertebral disks were not considered a possible source of thoracic symptoms until it became clear that not only protrusions and prolapses, but also internal rupturing of the anulus fibrosus may be a possible source of symptoms. It is recommended that the sudden development of thoracic pain first be treated as an intervertebral disk problem. Axial unloading techniques have been successfully used here (▶ Fig. 12.2).
The first four costovertebral joints are very rigid and tend to be more hypomobile. A link to strenuous arm activity, or a one-off exertion of force, for example, carrying a very heavy weight, or sudden shortness of breath, is often seen as a cause of symptoms. The role of palpation is to accurately locate a level to provoke the costovertebral joints and to ascertain the position of structures during inhalation and expiration (▶ Fig. 12.3).
Symptoms arising from the costovertebral joints are often felt between the shoulder blades. They are also often felt on top of the shoulder. A large portion of the pain in the trapezius probably arises from the first rib being blocked in a position of inhalation.
On further inspection, these sections can also be differentiated from one another morphologically (▶ Fig. 12.4). The shape of the two upper thoracic vertebrae is more similar to a cervical vertebra while the lower thoracic vertebrae gradually take on the shape of a lumbar vertebra. Only the spinous processes in the middle section of the thoracic spine slant down typically at a steep angle.
In the next section, only the typical morphological characteristics of the thoracic vertebra will be discussed. All further important information regarding the parts of a movement segment can be read in Chapter 10 in “Required Basic Anatomical and Biomechanical Knowledge.”
The thoracic kyphosis is not only a result of posture, it is also caused by anatomy. The lumbar lordosis is directly related to the wedge-shaped construction of the intervertebral disks at L4/L5 and L5/S1 and the L5 vertebral body. It is the wedge shape of the vertebral body that causes the kyphotic form (▶ Fig. 12.5). The superior and inferior end plates of the vertebrae are always parallel to one another in one segment. When examined, it can be seen that the vertebral body is more heart shaped. This is probably an adaption to the very anteriorly located center of gravity for this section of the body.
The thoracic intervertebral disks are quite thin and therefore adjust to the comparatively small movements in a segment. The heads of the ribs stabilize the disk on the sides. The posterolateral direction for a thoracic prolapse (not likely) is therefore occupied by bone. It is very unlikely that intervertebral disk substance will cause nerve-root compression. The intervertebral foramina, with their exiting spinal nerves, are found significantly superior to the intervertebral disk. This is another reason why spinal nerves are rarely affected by a thoracic prolapse.
The vertebral foramen is round and, in comparison to the other sections of the vertebral column, very narrow (▶ Fig. 12.6). As the laminae of the thoracic vertebral arch are very high, the foramen is almost completely enclosed by bone from all sides. The spinal cord takes up almost the entire diameter of the foramen and cannot make way for other masses that may intrude on this space (e.g., fracture, bleeding, or intervertebral disk prolapse). The dura mater and the spinal cord have a particularly high chance of being compressed when these pathological conditions are present in the thoracic spine.
The thoracic spinous process is known to be very long and points in an inferior direction (▶ Fig. 12.7). Its shape is the typical characteristic of a thoracic vertebra.
The length and the angle of the spinous process vary between the upper, middle, and lower thoracic sections. The slant results in a significant difference in the level between the tip of the spinous process and the corresponding transverse process. This difference is summarized in the “finger rule.” This rule is used to locate the structures belonging to the same vertebra that can be reached using palpation.
The spinous processes overlap, especially in the mid-thoracic spine. This means that when the thoracic spine is brought into extension, the spinous processes come into contact with each other quickly here and compression increases. Small bursae absorb the friction while the spinous processes slide a little over one another and restrict extension. The thoracic spine is locked in this position.
In a neutral starting position (SP), the very long spinous processes can be easily palpated and differentiated from one another. It is very simple to draw the outline of the tips on the skin. The sitting position is the only position where the active, tensed muscles may make it harder to access the spinous processes. Furthermore, the therapist must be aware that no spaces exist between the spinous processes. The tip of the superior spinous process lies on the posterior side of the inferior spinous process.
The locked position of the thoracic spine resulting from the overlapping thoracic spinous processes in extension is not a suitable SP to palpate segmental mobility. The segments are able to move better when the thoracic spine is slightly flexed—the resting position for the thoracic spine. The therapist should therefore ensure that the thoracic spine is always positioned in a slight kyphosis for all SPs.
The “springing test,” the posteroanterior pressure on the spinous processes, is not suited to assessing mobility in the thoracic spine. Pressure on these long processes does not result in translation movement. The vertebra tilts backward instead.
The anatomical study conducted by Cui et al. (2015) clearly shows that the length of the traverse processes (measured from the base to the tip), at approx. 17 mm, remains nearly constant in all thoracic vertebrae (T1–T10). The transverse processes of T1 and T10 are the shortest. However, the transverse processes appear to become increasingly shorter from cranial to caudal, because they increasingly point more posteriorly. In T1, this posterior tilt angle is approx. 24° and the angle more or less continuously increases down to T10 to up to approx. 64°. The length of the T1 transverse process is of particular interest when searching for the costovertebral joint between the first rib and T1.
Each transverse process has a small joint facet on its anterior aspect that forms the costotransverse joint with a rib. The spatial orientation of the transverse process determines the position of the common axis for both costovertebral joints (see also “Mechanics of the Costovertebral Joints,” see ▶ Fig. 12.14 below).
The direct paravertebral area is covered by less muscle mass in the thoracic spine than in the lumbar spine. This enables the therapist to confidently access the transverse process and provides an extra lever to affect segmental mobility. The question is, how does the therapist find the transverse process belonging to a specific vertebra? This is achieved using two different methods:
Each transverse process is found at the level of the accessible medial end of a rib. When counting the ribs from the 12th rib up to the 8th rib, for example, and consistently following this rib in a medial and cranial direction, the level of the T8 transverse process is reached.
Locating a spinous process and overcoming a difference in height. The difference in position between the spinous process and the transverse process conforms to the finger rule. The therapist can reliably locate the level of a transverse process by first palpating the localized tip of the corresponding spinous process.
The typical thoracic vertebra is constructed with a difference in height between the spinous process and the transverse process. The extent of this difference varies almost from segment to segment. The therapist attempts to determine this difference by using the patient’s index finger during palpation (▶ Fig. 12.8).
The alignment of the thoracic ZAJs is quite different from that seen in the lumbar region. In relation to the end plates, the superior joint processes are tilted upright at an average angle of 70° and are tilted 20° anteriorly on the sides (▶ Fig. 12.9). This means that the processes lie in a perfect circular arc around the rotation axis found in the disk. Rotation is therefore not significantly restricted by either the ZAJ or the ribs and is evenly distributed between all segments (excluding the thoracolumbar junction) (White and Panjabi, 1990).
The bony thorax is formed by 12 pairs of ribs and the sternum. Two kinematic chains meet at the point where the ribs connect to the vertebrae (▶ Fig. 12.10):
The two kinematic complexes affect one another with their mobility and stability. The thorax affects the thoracic spine by increasing its stiffness and reducing its range of motion, for example, during lateral flexion (White and Panjabi, 1990). This is advantageous when concentrating on the protective and supporting functions of the thoracic spine.
A rib is a curved long bone that seeks contact with the sternum as it turns downward from posterior to anterior. It is made up of different sections (▶ Fig. 12.11).
The superior edge of the body of the rib is rounded; the inferior edge is more sharp-edged. With this knowledge, the therapist can assess whether malpositioning is present in fixed inhalation or expiration during the palpation of the thorax.
The ribs are divided into three groups based on the different types of contact with the sternum (▶ Fig. 12.12):
The connecting cartilage of the 8th to 10th ribs forms the costal arch. Both costal arches meet at the epigastric angle on the xiphoid process of the sternum. The distance between the costal cartilages of the 10th ribs demonstrates the size of the inferior thoracic aperture. The connection between the costal cartilage and its superior neighbor is not particularly stabile. Subluxations can occur due to trauma (“slipping ribs,” Migliore et al. 2014).
Most of the costosternal junctions to the true ribs are small true joints, very firm and resilient. The second rib is usually attached to the sternal angle (junction between the manubrium and the body of the sternum). Hardly any variations in anatomy are evident here.
Differences are made depending on which parts of the rib or the vertebra articulate (▶ Fig. 12.13):
Costovertebral joints (joint of the head of the rib): the head of the rib articulates with two vertebral bodies and the disk. Exceptions are the 1st, 11th, and 12th ribs. Only a vertebral body is seen here.
The axis of movement couples both joints functionally and passes through the neck of the rib. The transverse process differs in length and spatial alignment in the upper, middle, and lower thoracic spine. It determines how far posterior and lateral the costotransverse joint is located. Ultimately, it determines the position of the rotational axis for movements of the ribs during inhalation and expiration (▶ Fig. 12.14).
The length and alignment of the transverse processes in the upper thoracic spine (T1–T7) causes the rotational axis to be aligned more in the frontal plane. This results in elevation and expansion of the thorax in the sagittal plane due to the mechanics of the ribs. The more sagittally oriented axes in the middle and lower thoracic spine enable the thorax to expand in a lateral direction.
Forced inhalation (▶ Fig. 12.15) always results in intercostal spaces widening in every section of the thorax. The intercostal spaces become narrower during expiration (▶ Fig. 12.16). This movement pattern allows diagnosing through palpation with movement. Movements of the arm have similar effects on the intercostal spaces:
The inferior or superior edges can be felt at the end of forced inhalation and expiration. The edges are not palpable during quiet respiration. The relationship of structures to one another is interesting when the ribs are pathologically fixed in a position of inhalation or expiration. When the therapist assesses the position of structures, it is noticeable that the blocked rib has another form in comparison to its neighboring mobile ribs (see the section “Assessment of the Costovertebral Joints” below).
As described above, two kinematic chains meet: The vertical chain of thoracic movement segments and the horizontal chain of the ring-like rib segments. Vertical and horizontal chains, meaning the thoracic movements and costovertebral movements, have reciprocal influence.
Practical assessment: Compare the thoracic movements with the patient sitting and breathing in and out deeply (a) in neutral position and (b) in extended thoracic spine position. In extension, expiration decreases (since the thorax is already in relative expiration) and the extent of inhalation increases (since the thorax starts from relative expiration). Many patients with shortness of breath support themselves in thoracic extension in order to exploit this mechanism for deepened inhalation.
Practical assessment: Compare the thoracic movements with the patient sitting and breathing in and out deeply (a) in neutral position and (b) in flexed thoracic spine position. In flexion, inhalation decreases (since the thorax is already in relative inhalation) and the patient would have to increase the extent of expiration (since the thorax starts from relative inhalation), if the abdominal contents did not naturally resist the movement of the thorax.
In the case of lateral flexion of the thorax, for example, to the right, the costovertebral joints on the concave side (in this case, on the right) achieve a relative inhalation position, and on the convex side (in this case, on the left), achieve a relative expiration position.
When examining a patient with thoracic spinal pain, the therapist can use these interactions to distinguish between the thoracic pain generators and pain from the costovertebral joints. According to IAOM doctrine, local segmental mobilizations should not be carried out without the mobilization of the associated rib ring segment in expiration and vice versa.
In respiratory therapy, the patient can be placed in the appropriate position, such as the tripod position or “C positioning,” to enable the kinematic prerequisites for certain respiratory volumes or controlled breathing.
▶ Fig. 12.17 is used in many anatomy books and shows the anatomy of the manubrium as the superior section of the sternum with its articular connections. The edge of the manubrium is equipped with many notches. The jugular notch is the most superiorly lying notch. The medial ends of the clavicles form the sternoclavicular (SC) joints lateral to this. The cartilage of the first rib has an articular connection to the manubrium immediately inferior to the SC joint. The sternal angle is found at the level of the connection to the second rib. This connection is described at times in anatomical literature as an articulation or as a synchondrosis. The manubrium moves on the body of the sternum as the thorax moves during respiration.
The jugular notch is a reliable orientation point to access the manubrium from a superior position. The level of the notch also corresponds to the level of T2 (see the section “Anterior Palpation Techniques” in Chapter 13). It is easy to reach the SC joint from here (see the section “Sternoclavicular Joint Space” in Chapter 2).
The medial end of the first rib is found immediately inferior to the clavicle and extends posteriorly from here with a tight curve. It is very difficult to palpate. In comparison, the sternal angle is easy to reach and can be marked with confidence. The second rib is found at the same level without fail. The first five intercostal spaces can be reliably reached from here.
The anterior thorax is dominated by the pectoralis major (▶ Fig. 12.18). It is divided into three functional sections that are difficult to differentiate from one another anatomically. Their denominations refer to the surface of origin:
The interspinales muscles from several segments unite to form the spinalis thoracis (▶ Fig. 12.19). This muscle can only be found in the thoracic part of the vertebral column. It extends from L1–L3 to C7–T1 and is found directly adjacent to the row of spinous processes. The transition to the semispinalis cervicis is almost completely smooth. It forms the bulge of paravertebral muscles in the neck region and is consciously disregarded here.
The cross-section of the lateral tract gradually decreases here. The spinalis thoracis takes over its function of supporting the weight of the trunk against gravity. It also appears to be the muscle that has enough strength to extend the thoracic spine into extension.
In the lumbar region, a depression is palpated directly next to the row of spinous processes before the palpating fingers rest against the medial side of the erector spinae muscle mass. This is not possible in the thoracic region. When palpating laterally from the tip of the spinous processes, the therapist immediately encounters a spinalis muscle approximately of 1finger width. Enormous muscle tension is frequently found here, which often feels unpleasant when direct pressure is applied to it.
The rotatores thoracis muscles (▶ Fig. 12.20) are short muscles found very deep in the tissue. They are in close contact with the ZAJs (from von Lanz and Wachsmuth, 2004a). The decisive factor for the exact terminology used for the muscles is their length:
Their prominence corresponds well to the ability to rotate to almost the same extent in all thoracic segments. The actions of the rotatores thoracis include the extremely differentiated fine adjustment of position and the local stability of the thoracic movement segments.
Some authors call the rotatores muscles “monitoring muscles.” This means that these muscles tense when disturbances in segmental mobility are present and can provide the therapist with information regarding pathology when they palpate (Dvořák et al., 1998). However, the author doubts whether clinicians are actually able to selectively palpate the rotatores and to clearly perceive increased tension in this muscle group. When examined on an anatomical specimen, their deep position hidden beneath several other muscles is revealed.
The thoracic section of the back is dominated superficially by the latissimus dorsi and the most important representatives of the thoracoscapular muscle group. The latter muscle group extends from the trunk (from the row of spinous processes) to the scapula and belongs functionally to the upper limb. This consists of in particular:
The originating fibers of the latissimus dorsi extend to the level of T7–T8 (see ▶ Fig. 12.21), and therefore also to the thoracolumbar fascia. The thoracolumbar fascia additionally receives fibers from the serratus posterior at this point. In comparison to the lumbar region, the latissimus dorsi fibers do not cross the mid-line in the thoracic region. All further information about this muscle can be found in the section “Detailed Anatomy of the Muscles” in Chapter 10.
The superior sections of the muscles can be recognized only in very muscular and very slim people. It is highly unlikely that this muscle can be reliably differentiated from other structures. Generally, the lateral edge can be demonstrated and palpated on toned people when their arm is active in extension.
According to von Lanz and Wachsmuth (2004), the most important parts of the trapezius for this section (▶ Fig. 12.21) have the following anatomical course:
Ascending part: the fibers converge from their origin on the T4–T11/T12 spinous processes onto the medial end of the spine of the scapula, where they are evident posteriorly. Here they meet with the posterior fibers of the spinal part of the deltoid muscle.
Transverse part: this part generally passes from the C7–T3 spinous processes to the upper edge of the spine of the scapula (lateral half). This is the thickest part of the trapezius. It becomes a prominent bulge when the scapula is adducted toward the vertebral column.
The therapist can generally note that the origins of this very superficially located muscle do not always have to involve attachment to both sides of the spinous processes. The fibers from both sides can merge into one another without bony contact; they sometimes form an aponeurosis that glides freely over the spinous processes, especially at the cervicothoracic junction. Bursae are frequently found on anatomical specimens. These bursae reduce friction. The question is: could bursitis also be a possible cause for gradually developing local symptoms in this area?
The junction between both parts of the muscle can only rarely be identified as a gap on anatomical specimens and is therefore not of interest for palpation. The inferior edge of the ascending part can be palpated when the muscle is active. The superiorly running fibers angled from medial to lateral become distinct when this part of the trapezius pulls the scapula posteriorly and inferiorly against resistance. Therefore, the hand palpates from an inferior position, perpendicular to the edge of the muscle, and hooks into the muscle.
The cervicothoracic junction is located in the sitting SP first and later with the patient pronated. All further sections of the thoracic segments and the ribs will be described after this. The sections of the sternum and the ribs are the subject of local palpation techniques anteriorly. The spatial alignment of some of the ribs will now become clear. The ability to conduct these techniques, especially the intercostal palpation, is the basis for the assessment of movement in the thorax during respiration.
The palpation of the scapula with its individual sections will not be discussed here (see section “Palpation of Individual Structures” in Chapter 2).
Correct palpation in the cervicothoracic region is used as a starting point to access the middle area of the thoracic spine and the posterior thorax. These regions could also be reached by starting inferiorly with the location of the 12th rib or the lumbar spinous processes. This has already been described in Chapter 10.
All SPs used here have been described in detail in Chapter 8.6. The therapist is a new element in the description of the SP in sitting. The therapist stands to the side of the patient, mostly opposite the side to be palpated. If it is necessary to move the head to confirm the correct location of a structure, the therapist facilitates the head movement with one hand and the other hand is used to palpate.
The SPs are always classified as difficult when access to the sought structure is obstructed, strong muscle activity prevents the therapist from being able to recognize a bony point precisely, or when the supportive surface is not large enough to provide a stable position for the patient. These positions can be encountered during clinical work with patients.
The exact palpation of the cervicothoracic junction is equally as important as the correct location of the posterior sacroiliac spine (PSIS) on the pelvis or the C2 spinous process in the upper cervical spine. It enables thoracic structures to be reliably accessed from a superior position and the lower cervical spine from an inferior position. The aim is to precisely visualize the C6–T1 spinous processes as well as the position of the first rib from posterior. This is followed by the location of all thoracic spinous processes and their relationship to their transverse processes and the corresponding ribs. This section concludes with several examples of assessment and treatment of the thoracic spine and the ribs that demonstrate how useful hands-on palpation is.
The following technique aims to differentiate the thoracic and the cervical spines from one another. This cannot be done by locating the longest spinous process. The presumption that the longest spinous process corresponds to the vertebra prominens (C7) is misleading. The T1 spinous process is often the longer of the two.
Several of the following techniques require extensive cervical spine movement, which is not possible with every patient. They are only helpful when a certain amount of movement is available in the cervicothoracic region. When there are enormous restrictions in mobility in this region, differentiation is almost impossible. The only option that remains for differentiation is the palpation of the different contours felt on the spinous processes (e.g., C5 and C6) or by locating the first rib, which leads to the transverse process and ultimately to the T1 spinous process (Loyd et al., 2014).
One or two finger pads are placed over the middle of the posterior lower cervical spine. The anterior hand controls the position of the head (▶ Fig. 12.22).
The position of the C6 spinous process can often be recognized by simply feeling its shape. When using moderate pressure to palpate from superior to inferior along the cervical mid-line, the therapist often feels the finger pads moving down onto a type of platform. The sides of the fingers come from a superior position and encounter the C6 spinous process. The finger pads are then lying on top of the C5 spinous process. As this method of location is not reliable enough, another aid is needed to confirm that it is correct.
The anterior hand is in contact with the patient’s head and facilitates cervical extension by tilting the head backward. The C5 and C6 spinous processes behave typically during this movement. The upper cervical vertebrae move posteriorly during cervical extension. C5 and C6 shift anteriorly (▶ Fig. 12.23). C5 starts moving when extension is minimal, C6 at the end of the extension. These movements are clearly perceived as a spinous process disappears beneath the palpating finger pads.