Triceps Brachii Muscle Anatomy

Overview
Origin Long head: infraglenoid tubercle of scapula
Lateral head: above the radial groove
Medial head: below the radial groove
Insertion Olecranon process of ulna
Action All heads: extension of elbow.
Long head: adduction and extension of the arm at the shoulder joint
Nerve Radial nerve (C6, C7, C8)
Artery Deep brachial artery
Long head: posterior circumflex humeral artery

Location & Overview

The triceps brachii is a three headed muscle of the arm. It is a relatively large muscle which is located posterior to the humerus and is primarily responsible for flexion of the elbow. It often has a horseshoe like appearance. The Latin word ‘brachii’ is a reference to the muscle being located in the arm. The ‘tri’ in the word triceps is a reference to its three muscle heads (or points of origin). The word ‘ceps’ means head. The three heads of the triceps are: a long head, a lateral head, and a medial head [1] [2].

three heads of the biceps brachii

Pictured here we can see all three heads of the triceps brachii muscle as well as their common tendon.

Origin & Insertion

The long head originates from the infraglenoid tubercle of the scapula. The medial head originates just inferior to the radial groove, whereas the lateral head originates superior to the radial groove. The medial head of the triceps is mostly covered by the lateral and long heads. The fibres of the three heads then converge to a single tendon which then inserts onto the olecranon process of the ulna (a bony prominence of the elbow which is located on the upper portion of the ulna) [3] [4] [5].

origin of the long head of the triceps brachii

Pictured here we can see the origin of the long head of the triceps brachii at the infraglenoid tubercle of scapula (origin highlighted in red).

origin of the triceps lateral head

Pictured here we can see the origin of the lateral head which originates above the radial groove (origin highlighted in red).

origin of the triceps medial head

Pictured here we can see the origin of the medial head of the triceps brachii which is below the radial groove (origin highlighted in red).

the insertion of the triceps brachii

Pictured here we can see the insertion of the triceps brachii at the olecranon process of ulna.

Actions

All the heads of the triceps brachii can assist in extension of elbow. However, because the long head crosses the shoulder joint; the long head can also assist in adduction and extension of the arm at the shoulder joint [6] [7].

Innervation

The heads of the triceps brachii muscle are innervated by the radial nerve (C6, C7, C8) [8] [9].

Blood Supply

Blood is supplied by the deep brachial artery and the long head also gets a blood supply from the posterior circumflex humeral artery [10] [11].

Want some flashcards to help you remember this information? Then click the link below:
Triceps Brachii Flashcards

References

References
1, 4, 7 Madsen M, Marx RG, Millett PJ, Rodeo SA, Sperling JW, Warren RF. Surgical anatomy of the triceps brachii tendon: anatomical study and clinical correlation. Am J Sports Med. 2006 Nov;34(11):1839-43. doi: 10.1177/0363546506288752. Epub 2006 May 30. PMID: 16735585.
2, 5 Moore KL, Agur AMR, Dalley AF. Clinically Oriented Anatomy. 8th ed. Philadelphia: Lippincot Williams & Wilkins; 2017.
3, 8 Tiwana MS, Sinkler MA, Bordoni B. Anatomy, Shoulder and Upper Limb, Triceps Muscle. [Updated 2021 Aug 6]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK536996/
6 Kholinne E, Zulkarnain RF, Sun YC, Lim S, Chun JM, Jeon IH. The different role of each head of the triceps brachii muscle in elbow extension. Acta Orthop Traumatol Turc. 2018 May;52(3):201-205. doi: 10.1016/j.aott.2018.02.005. Epub 2018 Mar 2. PMID: 29503079; PMCID: PMC6136322.
9 Glover NM, Murphy PB. Anatomy, Shoulder and Upper Limb, Radial Nerve. 2021 Jul 27. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan–. PMID: 30521261.
10 Tang A, Varacallo M. Anatomy, Head and Neck, Posterior Humeral Circumflex Artery. [Updated 2021 Aug 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK538283/
11 Dankel SJ, Jessee MB, Abe T, Loenneke JP. The Effects of Blood Flow Restriction on Upper-Body Musculature Located Distal and Proximal to Applied Pressure. Sports Med. 2016 Jan;46(1):23-33. doi: 10.1007/s40279-015-0407-7. PMID: 26446893.