Triceps Brachi

Authors
Affiliations

Doctor of Physical Therapy

B.S. in Kinesiology

Doctor of Physical Therapy

B.A. in Neuroscience

Figure 1: Muscles that move the humerus1
Figure 2: Muscles that move the Forearm1
Figure 3: Left Scapula (Lateral view)2
Figure 4: Left Humerus (Posterior view)2
Reading list
  • Triceps and Anconeus Muscle3
  • 4
  • Long head MMT5
  • Middle head MMT5
  • Lateral head MMT5

Long Head

Origin

The triceps long head as a proximal origin on the Infraglenoid tubercle of scapula6.

There is also attachments to the glenohumeral capsule.

Figure 5: Left Scapula (Anterior view)2

Insertion

Olecranon process of Ulna6

Innervation

Radial N. (C6, C7, C8)6

Action

  • Elbow: Extension6
  • Shoulder: Extension, Assists in Adduction6

When looking at the long head’s origin and insertion, it is lengthened by shoulder flexion, as a result it optimizes the length-tension curve7. The Long head can produce the most force when the shoulder is flexed7.

Adductor force couple

The triceps brachii long head and latissimus dorsi form a “force adductor couple”7. The adduction and extension moment created by the latissimus dorsi results in inferior displacement of the humeral head, the triceps long head contracts and its abductive component counteracts the latissimus dorsi creating a superior glide7. This results in no net vertical translation of the humeral head and keeping its optimal position in the glenoid.

Thus although the triceps long head has an “abductive” component, we consider it to function as an “adductive assist.”

Medial Head

Origin

  • Posterior surface of humerus (distal to radial groove)6
  • Medial intermuscular septum6

Insertion

Olecranon process6

Innervation

Radial N. (C6, C7, C8)6

Action

Elbow: Extension6

Lateral Head

Origin

  • Posterior surface of humerus (prox to radial groove)6
  • Lateral intermuscular septum6

Insertion

Olecranon process6

Innervation

Radial N. (C6, C7, C8)6

Action

Elbow: Extension6

Notes

Triceps Reflex

Triceps reflex can be used to assess C7 nerve root8

References

1.
Betts JG, Blaker W. Anatomy and Physiology. 2nd ed. OpenStax; 2022. https://openstax.org/details/books/anatomy-and-physiology-2e/?Book%20details
2.
Gray H. Anatomy of the Human Body. 20th ed. (Lewis WH, ed.). Lea & Febiger; 1918. https://www.bartleby.com/107/
3.
Donnelly JM, Simons DG, eds. Travell, Simons & Simons’ Myofascial Pain and Dysfunction: The Trigger Point Manual. Third edition. Wolters Kluwer Health; 2019.
4.
Neumann DA, Kelly ER, Kiefer CL, Martens K, Grosz CM. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. 3rd ed. Elsevier; 2017.
5.
Weinstock D. NeuroKinetic Therapy: An Innovative Approach to Manual Muscle Testing. North Atlantic Books; 2010.
6.
Gilroy AM, MacPherson BR, Wikenheiser JC, Voll MM, Wesker K, Schünke M, eds. Atlas of Anatomy. 4th ed. Thieme; 2020.
7.
Jones B. B Project Foundations. b Project; 2025.
8.
Hong CG, Nam WD. Reliability and Diagnostic Accuracy of Standard Dermatomes and Myotomes for Determining the Pathologic Level in Surgically Verified Patients With Cervical Radiculopathy. Neurospine. 2022;19(4):1006-1012. doi:10.14245/ns.2244194.097

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