Anatomy of the Triceps Muscle

Courtesy: Prof Nabil Ebraheim, University of Toledo, Ohio, USA

Triceps muscle is a powerful extensor of the elbow joint

-has 3 heads
. Long head
. Lateral head
. Medial head

Long and lateral head forms superficial part of triceps

Medial head forms deep part of triceps

Long head

• Arise from the scapula and stretches across the shoulder and elbow joint
• Origin – infraglenoid tubercle of scapula
• Insertion- proximal end of the olecranon process of ulna

Lateral head

• Origin – posterior aspect of humerus Superior to spiral groove
• Insertion- proximal end of the olecranon process of the ulna

Medial head

• Origin – posterior aspect of the humerus inferior to the spiral groove and stretches across the elbow joint
• Insertion-. Proximal end of the olecranon process of ulna

Insertion of triceps
– all the three heads inserted to OLECRANON PROCESS
– 12mm distal to the tip of olecranon

ARTERIAL SUPPLY
– branches of deep brachial artery

NERVE SUPPLY

– Radial nerve
Innervation – >comes from the posterior cord of brachial plexus -> run through the spiral groove between the lateral head and medial head of triceps -> 13cm above the trochlea , the radial nerve pierce the lateral intermuscular septum approximately 7.5cm above the trochlea .

RELATIONSHIP BETWEEN RADIAL NERVE AND TRICEPS

3 anatomical spaces

I. Quadrangular space
Superiorly- teres minor
Inferiorly – teres major
Medially – long head triceps
Laterally – surgical neck humerus

Contents
1. Axillary nerve
2. Posterior circumflex

II Triangular interval
Bounded by
Teres major ,Humerus shaft , Long head triceps
Contents
1. Deep branch of brachial
2. Radial nerve

III . Triangular space
Boundaries – teres minor , teres minor , long head of triceps
Contents
1. Circumflex scapular artery

Rupture of triceps can occur
A) DISTAL TRICEPS TENDON rupture can occur

• Result from sports such as weight lifting and body building (seen in middle aged men )
• steroid injection at insertion can lead to rupture

B) INSERTION SITE
– may be partial or complete
– patient may hear a painful pop with rupture of tendon

FLAKE SIGN
an avulsion of a small piece of bone from the elbow sometime is seen on lateral xray

MRI – best study

REPAIR
A)primary surgical repair of the tendon for acute complete tear or partial tear more than 50%
B)Reconstruction of the tendon by tendon graft in chronic, neglected cases especially if the patient has a major disability in elbow extension

Risk factors for rupture
-Local injection of steroid
-Taking antibiotics (Ciprofloxacin )
-general system disease like rheumatoid arthritis , hyperparathyroidism, diabetes , renal disease

Note – excision of comminuted olecranon fracture fragment with reattached of the triceps tendon in the elderly patients can be done with a reasonable result of the fragment size is less than 50%