• Note. If you find that palpation is difficult, use the technique suggested on p. 6 where the fingertips are moved rapidly up and down the spine, in a scanning manner. This method of palpation is useful for locating and mapping structures which lie below the surface. It is, however, rarely used, as it gives the impression of merely moving the skin on the underlying structures. It amounts to the building up of a total picture by adding together many disparate pieces of information. Use the pads of all fingers of one hand (the most sensitive) if possible, to sweep across an area, allowing your fingers to move the skin and superficial fascia on the deeper structures. By using this technique, you will be building up a picture similar to that which would be achieved by the scanning beam of a video camera. Use the other hand to mark certain points and mark from where the previous information was obtained. More refined palpatory techniques can then be used on selected areas.

• The lateral tips of the thoracic transverse processes. These lie 3 cm lateral and parallel to the spines.

• Note. The tip of the spine lies 1 cm below the level of the transverse process of the vertebra below. This measurement remains constant because the shorter spines in the upper thorax are compensated for by the transverse processes being slightly raised.

• The costotransverse joints. Lateral to the tips of the transverse processes is a groove marking the line of the costotransverse joints.

The ribs (Fig. 5.3)

There are 12 ribs on either side. They are convex outwards, the eighth being the longest and the twelfth the shortest. The upper seven ribs articulate with the vertebral bodies and transverse processes posteriorly by the facets on their heads and tubercles. The first, tenth, eleventh and twelfth ribs have only one facet; the rest have two. The eleventh and twelfth ribs have no tubercles. Ribs 1–7 articulate with the sternum anteriorly via a varying length of costal cartilage. These are termed ‘true’ ribs. Ribs 8–10 articulate anteriorly via their costal cartilage, with the costal cartilage above, and are termed ‘false’ ribs. Ribs 11 and 12 do not articulate with their transverse process posteriorly and are free anteriorly. They are therefore termed ‘floating’ ribs (see Fig. 5.1).

Fig. 5.3 (a, b) The ribs of the right side (posterior aspect)

Fig. 5.3 (c, d) The ribs of the right side (lateral aspect)

Palpation

To facilitate the palpation of the ribs, the back muscles need to be relaxed. This is best achieved if the model is in the prone lying position.

• The posterior section of the ribs. Just lateral to the tip of each transverse process the posterior section of each rib can be palpated, being separated from the transverse process by a depression.

• Ribs 1–10. Ask the model to hang the arm over the side of the plinth (i.e. the pectoral girdle is in protraction). Now find and trace the first to tenth ribs laterally. The rib angle lies approximately 3–4 cm lateral to the tips of the transverse processes. It can readily be palpated in the mid-thoracic region, becoming less clear above and below. The first rib does not possess an angle and those of the eleventh and twelfth ribs are slight if present.

• Ribs 1–12 and the intercostal spaces. Each rib, together with the intercostal spaces above and below, can be traced anteriorly to where it joins the sternum. The second to seventh or eighth ribs are usually hidden posterolaterally by the scapula, while the eleventh and twelfth ribs only exist posterolaterally.

• The first rib. This rib is the most difficult to palpate. It lies deep to the clavicle anteriorly and deep to the trapezius and levator scapulae muscles posteriorly. If you apply deep pressure immediately below the clavicle, 1 cm lateral to its medial end, you will be able to palpate the junction of the rib with the manubrium. By applying deep pressure above the middle of the clavicle in the supraclavicular fossa, it is possible to feel the lateral border of the first rib.

• Note. This area is particularly tender and may produce unpleasant reactions in the upper limb due to pressure on the trunks of the brachial plexus and subclavian artery.

• The neck and tubercle of the first rib. Posteriorly, the neck and tubercle of the first rib can be palpated running downwards and laterally approximately 2 cm lateral to the tip of the spine of C7. This, however, is dependent on the thickness of the upper fibres of trapezius.

• Ribs 8–10 and the costal angle. The costal cartilages at the anterior end of the eighth to tenth ribs form the anterior part of the costal margin, running superomedially to join the xiphoid process. At the level of the ninth costal cartilage an angle and projection are formed: the ‘costal angle’. This lies on a level with the transpyloric plane, in common with the spine of L1 and the tip of the twelfth rib.

• Ribs 11 and 12. Just above the twelfth, the eleventh rib can easily be identified, ending in a point just anterior to the mid-axillary line.

Joints

The thoracic vertebral column (Fig. 5.4)

The joints of the thoracic vertebral column are similar to those in the cervical region. They do not, however, possess uncovertebral joints. They do have facets on the side of all of the bodies and the upper 10 transverse processes for the articulation of the ribs. The vertebral bodies articulate centrally by a series of intervertebral discs. These joints are complex cartilaginous symphyses. The intervertebral discs are made up of an outer ring of fibrous bands passing obliquely from one body to the other (the annulus fibrosus) and a central nucleus (the nucleus pulposus) composed of a soft highly hydrophilic substance. These discs are supported by many ligaments, including the very strong anterior and posterior longitudinal ligaments.

Fig. 5.4 (a) The costotransverse joints of the right side (posterior aspect)

Fig. 5.4 (b, c) The costotransverse joints of the right side (posterior aspect)

Fig. 5.4 (d, e) Zygapophyseal joints of thoracic spine. Shaded areas show joint surface deep to inferior articular processes

Fig. 5.4 (f, g) Vertebrae in horizontal position showing effect of pressure on spine in direction of arrow

On either side are the zygapophyseal joints (Fig. 5.4d, e) between the articular facets, two above and two below. In addition there are costovertebral joints (Fig. 5.4c) between the heads of the ribs and the side(s) of the body of the vertebrae and costotransverse joints between the tubercle of the rib and the transverse process (Fig. 5.4 a–c). The zygapophyseal, costovertebral and costotransverse joints are all synovial, surrounded by a capsule which is lined with synovial membrane and supported by ligaments. (For detailed study refer to Palastanga et al 2002.)

Palpation

All but the costotransverse and possibly the zygapophyseal joints are impossible to palpate.

For palpation in this region, the model is in the prone lying position with the forehead resting on the backs of the hands.