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Triceps Brachii

As the name suggests, it has three heads. Triceps brachii is a large muscle, which creates the majority of (nearly 70%) of the matter on the back of arm.

Triceps Brachii

Triceps Brachii

Origin

Lateral Head

Starting simply under the head of the humerus and ending nearly midway down the bone, and the surrounding lateral intermuscular septum, a perpendicular line on the outward back corner of the shaft of the humerus.

Medial Head

It originates via the posterior sides of part of the lateral intermuscular septum and all of the medial intermuscular septum and a large, extended, triangular area inhabiting the lower section of the back side of the humerus that expands up on the medial side of the back side of the shaft.

Long Head

Emerges at Infraglenoid tubercle below the socket of the scapula and a small area under it around the lateral (axillary) border of the scapula, it does not emerge via the humerus

Insertion

Lateral Head

Upper two-thirds of the lateral edge and deep part of the upper section of the triceps tendon

Medial Head

The triceps tendon inserts into the horizontal posterior edge of the top of the olecranon procedure of the ulna. Lower third of both the medial and lateral edges and the lower section of the deep part of the triceps tendon

Long Head

Upper two-thirds of the medial edge of the tendon of insertion of the triceps, which in turn inserts into the horizontal posterior edge of the top of the olecranon procedure of the ulna.

 Structure

Long Head

The volume of the long head protrude rather far forward, getting to nearly three-fourths of the route towards the front of the arm, at the upper section of the within the arm. This flattened, teardrop-shaped head lies on the inner back corner of the upper arm and is the biggest of the three heads of the triceps. It comes down three-fourths of the method down the arm ,the head is pointed at the inferior end.

The upper end of the long head towards its connection on the scapula dives in between the teres major and teres minor muscles, maintaining a broad, fleshy density. With the arm down by the side, the upper section of the long head, right before it vanishes in between the teres muscles, is crossed by a nearly vertical skin fold running perpendicular to the long head muscle fibers.

Lateral Head

Most of the superficial section of the lateral head situated on the middle third of the outer back corner of the upper arm looks elliptical or teardrop-shaped, more lateral than posterior. From the bottom of the teardrop, as a descending end, the staying fibers of the lateral head continue down the lateral edge of the triceps tendon. These fibers place into the edge of the tendon in an irregular style.

The extended muscular ridge of the tail looks like a narrow inverted cone, when the triceps extends the elbow joint. The lateral head can quickly be seen from the front view.

Medial Head

The medial head by itself is a flattened teardrop shape, directed superiorly, that arcs around the behind the lower half of the humerus. It is seen on the side as a long, narrow, cylindrical shape on the lower half of the inner back corner of the upper arm since it is primarily concealed by the long head and the triceps tendon.

Superiorly, to reach the upper degree of its connection on the humerus this shape travels down deeply in the middle of the long head of the triceps and the biceps. It never ever appears on the side on the upper half of the within the upper arm.

Actions

  • The triceps brachii is the powerful extensor of the elbow joint.
  • The long head reinforces the head of humerus throughout hyperabduction of the arm.

Nerve Supply

By radial nerve (C7, C8). Every head gets a different subdivision via radial nerve in the following way:

  • Nerve to long head emerges via the radial nerve in axilla.
  • Nerve to lateral head emerges via the radial nerve in the radial groove.
  • Nerve to medial head emerges via the radial nerve in the radial groove.
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By Dr. Joseph H Volker | 2018-08-30T09:20:33+00:00 August 8th, 2018|Anatomy, Muscles, Upper Limb|0 Comments