Triceps Brachi

Authors
Affiliations

Nate Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

Figure 1: Muscles that move the humerus
Figure 2: Muscles that move the Forearm
Figure 3: Left Scapula (Lateral view)
Figure 4: Left Humerus (Posterior view)
Reading list
  • Triceps and Anconeus Muscle
  • Long head MMT
  • Middle head MMT
  • Lateral head MMT

Long Head

Origin

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

There is also attachments to the glenohumeral capsule.

Figure 5: Left Scapula (Anterior view)

Insertion

Olecranon process of Ulna

Innervation

Radial N. (C6, C7, C8)

Action

  • Elbow: Extension
  • Shoulder: Extension, Assists in Adduction

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

Adductor force couple

The triceps brachii long head and latissimus dorsi form a “force adductor couple”. 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 glide. 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)
  • Medial intermuscular septum

Insertion

Olecranon process

Innervation

Radial N. (C6, C7, C8)

Action

Elbow: Extension

Lateral Head

Origin

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

Insertion

Olecranon process

Innervation

Radial N. (C6, C7, C8)

Action

Elbow: Extension

Notes

Triceps Reflex

Triceps reflex can be used to assess C7 nerve root

References

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