Anatomy, Biomechanics and Regional Interdependence of the Thorax
Top Contributors - Jess Bell, Lucinda hampton, Kim Jackson, Olajumoke Ogunleye, Merinda Rodseth and Robin Tacchetti
Introduction[edit | edit source]
The thorax is an area of the spine that has, historically, been under-explored. It can, however, be a silent contributor to many presentations in clinical practice.
One cross-sectional survey in Denmark looked at the prevalence of spinal pain. It found that in one year:
- 13 percent of respondents had thoracic pain
- 43 percent had low back pain
- 44 percent had neck pain
However, between 36 to 41 percent of individuals who present with neck or back pain will also have thoracic pain (i.e. around 4 in 10 patients). This is, therefore, a region that should not be ignored in physiotherapy practice.
Anatomy[edit | edit source]
There are 136 joints in the thoracic spine and 112 muscle attachments. The orientation of the thoracic joints and ribs limit flexion, extension and lateral flexion, but facilitate rotation.
Range of Motion[edit | edit source]
The total rotation available in the thoracic spine is 85 degrees (+/- 14.8 degrees). It contributes 80 percent of the total range of axial trunk rotation. Each thoracic segment rotates between 6 and 8 degrees. This is significantly more than the lumbar segments, which only rotate 2 to 3 degrees.
Thoracic movement is critical for optimal performance in rotational sports and the thoracic spine kinematically links the upper and lower quarters. It also contributes 55 percent of the total force during a throw.
Regions of the Thorax[edit | edit source]
- Includes: T3 to T7, true ribs 3 to 7 and sternum
- Includes: T8 to T10 and false ribs 8 to 10
- Includes: T11 and T12, floating ribs 11 and 12
NB: True ribs attach directly to the sternum via cartilage, false ribs attach to the lowest true ribs and floating ribs only have posterior attachments to the spine.
Ribs[edit | edit source]
- Ribs 1, 11 and 12 articulate with the named vertebra (i.e. rib 1 articulates with T1)
- Ribs 2 to 10 articulate with the named vertebra, as well as the body above, the intervertebral disc and the anterior surface of the transverse process of the named vertebra
- More information about the ribs is available here
The Thoracic Ring (T3-T9)[edit | edit source]
'The "thoracic ring” consists of two adjacent vertebrae and the related intervertebral disc, the right and left ribs (attached to the vertebra-disc-vertebra complex at the costovertebral joints), and the anterior attachments to the sternum/manubrium and related cartilages.'
There are 13 articulations per thoracic ring:
- Zygapophyseal / facet = 2 articulations
- Costovertebral = 4 articulations
- Intervertebral = 1 articulation
- Costotransverse = 2 articulations
- Costochondral = 2 articulations
- Sternocostal = 2 articulations
Because of the strong anatomical connections between the ribs and the thoracic spine, mobilising a rib laterally will cause motion at the vertebral segments of that thoracic ring, as well as the rib on the opposite side of the body.
Thoracic Function[edit | edit source]
Lee has described the thoracic spine as a “slinky" or a "shock-absorbing spring”. It consists of a dynamic stack of 10 thoracic rings and has the following functions:
- Force transmission
- Central area for myofascial attachments
- Protects heart, lungs, vessels and digestive tract
- Aids optimal respiratory function 
- Houses the autonomic nervous system
Thoracic Asymmetry[edit | edit source]
It is normal for there to be thoracic asymmetry of the facet orientation in the thoracic spine. Asymmetrical anatomy may, however, cause changes in the coupled motion at a segment.
Regional Interdependence[edit | edit source]
The regional interdependence theory proposes that: “seemingly unrelated impairments in remote anatomical regions of the body may contribute to and be associated with a patient’s primary report of symptoms.” It has been proposed that there may also be central mechanisms involved in mediating regional interdependence.
Examples of interdependency in the thoracic spine include the following:
1. Cervical spine[edit | edit source]
Tsang and colleagues found that motion of the thoracic spine, particularly the upper thoracic spine, contributes to neck mobility. The upper thoracic spine contributes:
- 25 percent to cervical flexion and extension
- 10 percent to cervical rotation
Thoracic spine changes are, therefore, implicated in a loss of cervical range of motion, so this area should always be assessed in patients with neck dysfunction.
Similarly, Engell and colleagues have found that when manual therapy techniques (e.g. high-velocity low-amplitude spinal manipulative therapy) are applied to the thoracic spine, forces can be transmitted to the neck.
2. Shoulder[edit | edit source]
The scapula is a sesamoid bone, which rests upon the thorax. It is influenced by the position of the thoracic spine elements and the ribs. Postures such as thoracic kyphosis, thoracic scoliosis or flattened / inverted thoracic spine, can change the resting position of the scapula.
- Thoracic kyphosis is associated with a loss of glenohumeral range of motion and impingement symptoms
- Treating the thoracic spine has been shown to alter shoulder symptoms 
3. Other Relationships[edit | edit source]
- Sympathetic nerve blocks at the thoracic spine can improve chronic upper extremity neuropathic pain
- 70 percent of patients with lateral elbow pain have co-existing thoracic pain (compared to 16 percent of the control group)
Postural and Positional Implications[edit | edit source]
Certain postural dysfunctions could result in compensatory thoracic dysfunction (i.e. ‘gives’):
- Inextensible hamstrings force the thoracic spine to 'give' into flexion during stride, lunging and long sitting
- Inextensible hip flexors can cause lordosis and kyphosis
- A leg length discrepancy and asymmetrical load can cause thoracic scoliosis
Poor cervico-thoracic postures such as:
- Forward head position (Figure 1)
- Thoracic kyphosis
- Flat / inverted thoracic spine
- Muscle imbalances
- Joint incongruity
- Ligament laxity
- Altered neurodynamics
- Even minor curves cause wedging of the vertebrae and discs
- 80 percent of athletes who experience asymmetrical loading on their trunk and shoulders (e.g. javelin throwers, tennis players) have thoracic scoliosis
- It could, therefore, be proposed that scoliosis provides a mechanical advantage in asymmetrical sports
Summary[edit | edit source]
- Potentially 40 percent of patients presenting for physiotherapy with back or neck pain will have an associated thoracic spine dysfunction which needs to be assessed and managed
- Biomechanics and knowledge of the clinical anatomy of the thorax will help you to better understand the underlying pathogenesis of these conditions
- Thoracic rotation is essential for optimal sports performance and functional activities
- Postural dysfunctions such as tight hamstrings or hip flexors may force compensatory 'gives' in the thoracic spine - it is essential to look for the source of the problem
References[edit | edit source]
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 Bell-Jenje T. The Thorax Simplified - Anatomy, Biomechanics and Regional Interdependence Course. Plus , 2021.
- ↑ 2.0 2.1 Leboeuf-Yde C, Nielsen J, Kyvik KO, Fejer R, Hartvigsen J. Pain in the lumbar, thoracic or cervical regions: do age and gender matter? A population-based study of 34,902 Danish twins 20–71 years of age. BMC Musculoskelet Disord. 2009;10(39).
- ↑ Roquelaure Y, Bodin J, Ha C, Le Marec F, Fouquet N, Ramond-Roquin A et al. Incidence and risk factors for thoracic spine pain in the working population: the French Pays de la Loire study. Arthritis Care Res (Hoboken). 2014;66(11):1695-702.
- ↑ Kenhub - Learn Human Anatomy. Thoracic Spine - Definition & Components - Human Anatomy | Kenhub. Available from: https://www.youtube.com/watch?v=3mniZ_zQuRE [last accessed 28/8/2021]
- ↑ Heneghan NR, Hall A, Hollands M, Balanos GM. Stability and intra-tester reliability of an in vivo measurement of thoracic axial rotation using an innovative methodology. Manual Therapy. 2009; 14(4):452-5.
- ↑ Fujii R, Sakaura H, Mukai Y, Hosono N, Ishii T, Iwasaki M et al. Kinematics of the lumbar spine in trunk rotation: in vivo three-dimensional analysis using magnetic resonance imaging. Eur Spine J. 2007;16(11):1867-74.
- ↑ 7.0 7.1 Lee LJ. A closer look at the thorax [Internet. Physical Therapy Web [cited 30 August 2021]. Available from: https://physicaltherapyweb.com/closer-look-thorax-lj-lee/
- ↑ Heneghan NR, Lokhaug SM, Tyros I, Longvastøl S, Rushton A. Clinical reasoning framework for thoracic spine exercise prescription in sport: a systematic review and narrative synthesis. BMJ Open Sport Exerc Med. 2020;6(1):e000713.
- ↑ Heneghan NR. Webb K, Mahoney T, Rushton A. Thoracic spine mobility, an essential link in upper limb kinetic chains in athletes: A systematic review. Transl Sports Med. 2019;2:301-15.
- ↑ Kaczmarek PK, Lubiatowski P, Cisowski P, Grygorowicz M, Łepski M, Długosz J et al. Shoulder problems in overhead sports. Part I - biomechanics of throwing. Pol Orthop Traumatol. 2014;79:50-8.
- ↑ 11.0 11.1 11.2 11.3 Lee LJ. Thoracic ring approach. Available from: https://ljlee.ca/teaching-models/the-thoracic-ring-approach/ (accessed 28 August 2021).
- ↑ McConnell J. Recalcitrant chronic low back and leg pain--a new theory and different approach to management. Man Ther. 2002;7(4):183-92.
- ↑ Mohanty PP, Pattnaik M. Mobilisation of the thoracic spine in the management of spondylolisthesis. J Bodyw Mov Ther. 2016;20(3):598-603.
- ↑ Cleland JA, Childs JD, McRae M, Palmer JA, Stowell T. Immediate effects of thoracic manipulation in patients with neck pain: a randomized clinical trial. Man Ther. 2005;10(2):127-35.
- ↑ Edmondston SJ, Singer KP. Thoracic spine: anatomical and biomechanical considerations for manual therapy. Man Ther. 1997;2(3):132-43.
- ↑ Kudzinskas A, Callahan AL. Anatomy, Thorax. InStatPearls [Internet] 2021 Jul 31. StatPearls Publishing.
- ↑ Masharawi Y, Rothschild B, Dar G, Peleg S, Robinson D, Been E et al. Facet orientation in the thoracolumbar spine: three-dimensional anatomic and biomechanical analysis. Spine (Phila Pa 1976). 2004;29(16):1755-63.
- ↑ Andriacchi T, Schultz A, Belytschko T, Galante J. A model for studies of mechanical interactions between the human spine and rib cage. J Biomech. 1974;7(6):497–507.
- ↑ Sueki DG, Cleland JA, Wainner RS. A regional interdependence model of musculoskeletal dysfunction: research, mechanisms, and clinical implications. J Man Manip Ther. 2013;21(2):90-102.
- ↑ Ghamkhar L, Arab AM, Nourbakhsh MR, Kahlaee AH, Zolfaghari R. Examination of regional interdependence theory in chronic neck pain: interpretations from correlation of strength measures in cervical and pain-free regions. Pain Med. 2020;21(2):e182-e190.
- ↑ FoundationPT. The truth about aches and pains - Regional Interdependence Overview. Available from: https://www.youtube.com/watch?v=v4YXQgamW2Q [last accessed 28/8/2021]
- ↑ 22.0 22.1 22.2 Tsang SM, Szeto GP, Lee RY. Normal kinematics of the neck: the interplay between the cervical and thoracic spines. Man Ther. 2013;18(5):431-7.
- ↑ Engell S, Triano JJ, Howarth SJ. Force transmission between thoracic and cervical segments of the spine during prone-lying high-velocity low-amplitude spinal manipulation: A proof of principle for the concept of regional interdependence. Clin Biomech (Bristol, Avon). 2019;69:58-63.
- ↑ Barrett E, O'Keeffe M, O'Sullivan K, Lewis J, McCreesh K. Is thoracic spine posture associated with shoulder pain, range of motion and function? A systematic review. Man Ther. 2016;26:38-46.
- ↑ Strunce JB, Walker MJ, Boyles RE, Young BA. The immediate effects of thoracic spine and rib manipulation on subjects with primary complaints of shoulder pain. J Man Manip Ther. 2009;17(4):230-6.
- ↑ Boyles RE, Ritland BM, Miracle BM, Barclay DM, Faul MS, Moore JH et al. The short-term effects of thoracic spine thrust manipulation on patients with shoulder impingement syndrome. Man Ther. 2009;14(4):375-80.
- ↑ Haider R, Bashir MS, Adeel M, Ijaz MJ, Ayub A. Comparison of conservative exercise therapy with and without Maitland Thoracic Manipulative therapy in patients with subacromial pain: Clinical trial. J Pak Med Assoc. 2018 Mar;68(3):381-7.
- ↑ Yoo HS, Nahm FS, Lee PB, Lee CJ. Early thoracic sympathetic block improves the treatment effect for upper extremity neuropathic pain. Anesth Analg. 2011;113(3):605-9.
- ↑ Berglund KM, Persson BH, Denison E. Prevalence of pain and dysfunction in the cervical and thoracic spine in persons with and without lateral elbow pain. Man Ther. 2008;13(4):295-9.
- ↑ Stokes IA, Aronsson DD. Disc and vertebral wedging in patients with progressive scoliosis. J Spinal Disord. 2001;14(4):317-22.
- ↑ Swärd L. The thoracolumbar spine in young elite athletes. Current concepts on the effects of physical training. Sports Med. 1992;13(5):357-64.