Clinical Reasoning and Pathologies of the Thoracic Spine

Original Editor - Jess Bell based on the course by Tanja Bell-Jenje
Top Contributors - Jess Bell, Lucinda hampton, Kim Jackson, Rucha Gadgil, Olajumoke Ogunleye and Carin Hunter

This article or area is currently under construction and may only be partially complete. Please come back soon to see the finished work! (31/08/2021)

Introduction

Like the cervical and lumbar spine, pain in the thoracic spine can be caused by a number of musculoskeletal structures, including thoracic spine muscles, joints, the disc and the ribs. There are also a number of visceral or systemic conditions that can masquerade as musculoskeletal spinal pain. These all need to be considered when assessing the thoracic spine.

Muscles of the Thorax

There are 112 muscle attachments in the thorax. This page will look at major muscle groups that can have a significant impact on the thorax. Additional information on thoracic spine musculature is available here.

Intercostals

There are 11 pairs of intercostal muscles, each consisting of three layers arranged from superficial to deep:

• External
• Internal
• Innermost

The intercostal nerves mostly come from the anterior rami of the T1 to T 11 spinal nerves and, along with the intercostal artery and vein, they run between the intermediate and deep layers of the intercostal muscles. The T7 to T11 intercostal nerves leave the thoracic wall and enter the abdominal wall to innervate the abdominal peritoneum. They supply:

• Ribs and costal cartilages
• Intercostal muscles (all layers)
• Parietal pleura, which lines the inner surface of the thoracic cavity, including the diaphragm, pericardium and thoracic aorta

Because of this shared innervation, diseases of the thoracic wall or cavity may masquerade as dermatomal pain arising from the thoracic spine. Thus, it is essential to constantly assess a patient for red flags, including a poor response to treatment, as this may indicate a more serious pathology.

Iliocostalis

Iliocostalis is the most lateral of the erector spinae muscles. It is divided into three parts:

• Iliocostalis cervicis
• Iliocostalis thoracis
• Iliocostalis lumborum

Iliocostalis lumborum originates at the iliac crest and inserts into the L1 to L4 lumbar transverse processes, the angle of ribs 4 to 12, and the thoracolumbar fascia. Iliocostalis cervicis and thoracis have attachments as high as the upper six ribs and the transverse processes of C4. Iliocostalis, therefore, links lumbo-pelvic dysfunction with thoracic dysfunction and hypertonicity in this muscle can potentially have an impact on the thoracic rings.

Pectoralis Major

The pectoralis major makes up the bulk of the chest muscles. It is a thick, fan-shaped muscle that originates at the:

• Anterior sternum (down to the xiphoid process)
• Clavicle
• Sixth rib (sternal end)
• Upper six costal cartilages
• Aponeurosis of the external oblique

It inserts into the lateral lip of the bicipital groove on the humerus.

Overactivity of pectoralis major is associated with thoracic kyphosis and anterior translation of the humerus.

• Bodybuilders, for example, often have overactive pectoralis major muscles and thoracic dysfunction
  • A key clinical sign to look for is horizontal clavicles

• Pectoralis stretching can help to reduce kyphosis (and forward head position / rounded shoulder position)

NB: pectoralis major also has fascial links with latissimus dorsi (see below).

Figure 1. Exercise to reduce thoracic kyphosis.

The following exercise can be beneficial to improve thoracic and scapula motor control. It can also reduce thoracic kyphosis by increasing the activity of middle and lower trapezius and reducing overactivity in upper fibres of trapezius.

• NB: activating lower trapezius plays a key role in addressing an increased thoracic kyphosis. The cue “down and out” should be given during exercises, rather than “down and in”.