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Anatomy, Biomechanics and Regional Interdependence of the Thorax

Original Editor - Jess Bell based on the course by Tanya Bell-Jenje
Top Contributors - Jess Bell, Lucinda hampton, Ewa Jaraczewska, Kim Jackson, Olajumoke Ogunleye, Merinda Rodseth and Robin Tacchetti

Introduction

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.[1]

One cross-sectional survey in Denmark[2] looked at the prevalence of spinal pain. It found that in one year[2]:

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).[3] This is, therefore, a region that should not be ignored in physiotherapy practice.[1]

Anatomy

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.[1]

[4]

Range of Motion

The total rotation available in the thoracic spine is 85 degrees (+/- 14.8 degrees).[5] It contributes 80 percent of the total range of axial trunk rotation.[6] Each thoracic segment rotates between 6 and 8 degrees. This is significantly more than the lumbar segments, which only rotate 2 to 3 degrees.[7]

Thoracic movement is critical for optimal performance in rotational sports and the thoracic spine kinematically links the upper and lower quarters.[8][9] It also contributes 55 percent of the total force during a throw.[10]

Regions of the Thorax

  • Vertebromanubrial:
    • Includes: T1 and T2, ribs 1 and 2, the manubrium and clavicle
  • Vertebrosternal
    • Includes: T3 to T7, true ribs 3 to 7 and sternum
  • Vertebrochondral:
    • Includes: T8 to T10 and false ribs 8 to 10
  • Thoracolumbar
    • Includes: T11 and T12, floating ribs 11 and 12[1]

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

  • 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)

'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.'[11]

There are 13 articulations per thoracic ring[1][11]:

  • 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.[1]

Thoracic Function

Lee[11] has described the thoracic spine as a “slinky" or a "shock-absorbing spring”. It consists of a dynamic stack of 10 thoracic rings[11] and has the following functions[7]:

  • Force transmission
    • NB: many patients with chronic low back pain or cervical pain have a stiff thoracic spine and increasing thoracic mobility allows for more even distribution of load through the spine with movement[12] [13][14]
  • Central area for myofascial attachments
  • Protects heart, lungs, vessels and digestive tract[15]
  • Aids optimal respiratory function [16]
  • Houses the autonomic nervous system

Thoracic Asymmetry

It is normal for there to be thoracic asymmetry of the facet orientation in the thoracic spine.[17] Asymmetrical anatomy may, however, cause changes in the coupled motion at a segment.[18]

Regional Interdependence

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.”[19] It has been proposed that there may also be central mechanisms involved in mediating regional interdependence.[20]

[21]

Examples of interdependency in the thoracic spine include the following:[1]

1. Cervical spine

Tsang and colleagues[22] found that motion of the thoracic spine, particularly the upper thoracic spine, contributes to neck mobility. The upper thoracic spine contributes:[22]

  • 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.[22]

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.[23] A randomized placebo-controlled trial by Cevik and Pala concluded that mobilisation applied to the upper thoracic region improve pain, ROM and functionality in patients with mechanical neck pain.[24]

2. Shoulder

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.[1]

  • Thoracic kyphosis is associated with a loss of glenohumeral range of motion and impingement symptoms.[25] However, a systematic review and meta analysis by Manoso-Hernando indicated that thoracic kyphosis may not contribute to the development of shoulder pain.[26]
  • Treating the thoracic spine has been shown to alter shoulder symptoms[27] [28][29]

3. Other Relationships

  • Sympathetic nerve blocks at the thoracic spine can improve chronic upper extremity neuropathic pain[30]
  • 70 percent of patients with lateral elbow pain have co-existing thoracic pain (compared to 16 percent of the control group)[31]

Postural and Positional Implications

Certain postural dysfunctions could result in compensatory thoracic dysfunction (i.e. ‘gives’):[1]

  • 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[32]
Figure 1. Forward head position.


Poor cervico-thoracic postures such as[1]:


Can cause[1]:

  • Muscle imbalances
  • Joint incongruity
  • Ligament laxity
  • Altered neurodynamics


Thoracic scoliosis[1]:

  • Even minor curves cause wedging of the vertebrae and discs[33]
  • 80 percent of athletes who experience asymmetrical loading on their trunk and shoulders (e.g. javelin throwers, tennis players) have thoracic scoliosis[34]
  • It could, therefore, be proposed that scoliosis provides a mechanical advantage in asymmetrical sports[1]

Summary

  • Patients presenting for physiotherapy with back or neck pain will have an associated thoracic spine dysfunction which needs to be assessed and managed[35]
  • 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

  1. ↑ 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. ↑ 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).
  3. ↑ 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.
  4. ↑ 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]
  5. ↑ 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.
  6. ↑ 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. ↑ 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/
  8. ↑ 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.
  9. ↑ 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.
  10. ↑ 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. ↑ 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).
  12. ↑ McConnell J. Recalcitrant chronic low back and leg pain--a new theory and different approach to management. Man Ther. 2002;7(4):183-92.
  13. ↑ Mohanty PP, Pattnaik M. Mobilisation of the thoracic spine in the management of spondylolisthesis. J Bodyw Mov Ther. 2016;20(3):598-603.
  14. ↑ 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.
  15. ↑ Edmondston SJ, Singer KP. Thoracic spine: anatomical and biomechanical considerations for manual therapy. Man Ther. 1997;2(3):132-43.
  16. ↑ Kudzinskas A, Callahan AL. Anatomy, Thorax. [Updated 2023 Jul 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-.
  17. ↑ 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.
  18. ↑ 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.
  19. ↑ 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.
  20. ↑ 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.
  21. ↑ 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. ↑ 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.
  23. ↑ 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.
  24. ↑ Cevik R, Pala OO. Effects of upper thoracic Mulligan mobilization on pain, range of motion and function in patients with mechanical neck pain: A randomized placebo-controlled trial. Plos one. 2024 Oct 28;19(10):e0311206.
  25. ↑ 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.
  26. ↑ Manoso-Hernando D, Bailón-Cerezo J, Angulo-Díaz-Parreño S, Reina-Varona Á, Elizagaray-García I, Gil-Martínez A. Shoulder mobility and strength impairments in patients with rotator cuff related shoulder pain: a systematic review and meta analysis. PeerJ. 2024 Jun 26;12:e17604.
  27. ↑ 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.
  28. ↑ 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.
  29. ↑ Manoso-Hernando D, Bailón-Cerezo J, Elizagaray-García I, Achútegui-García-Matres P, Suárez-Díez G, Gil-Martínez A. Cervical and thoracic spine mobility in rotator cuff related shoulder pain: A comparative analysis with asymptomatic controls. Journal of Functional Morphology and Kinesiology. 2024 Jul 24;9(3):128.
  30. ↑ 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.
  31. ↑ 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.
  32. ↑ Xi F, Xue X, Ji E, Zhang Q, Zhao S, Li K, Li Y. Relationship between leg length discrepancy and functional scoliosis in children and adolescents. BMC Musculoskeletal Disorders. 2025 Apr 30;26(1):428.
  33. ↑ Stokes IA, Aronsson DD. Disc and vertebral wedging in patients with progressive scoliosis. J Spinal Disord. 2001;14(4):317-22.
  34. ↑ Swärd L. The thoracolumbar spine in young elite athletes. Current concepts on the effects of physical training. Sports Med. 1992;13(5):357-64.
  35. ↑ Reynolds B, McDevitt A, Kelly J, Mintken P, Clewley D. Manual physical therapy for neck disorders: an umbrella review. Journal of Manual & Manipulative Therapy. 2025 Jan 2;33(1):18-35.
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