Subclavian Triangle
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Subclavian Triangle

Muscles Of Head And Neck

General Anatomy

Subclavian Triangle

The subclavian triangle is a small lower part of posterior triangle of neck. The posterior triangle is a space on the side of the neck situated behind the sternocleidomastoid muscle. The posterior triangle of neck is subdivided by the inferior belly of the omohyoid into:

1. A large upper part, called occipital triangle.

2. A smaller lower part, called the supraclavicular or the subclavian triangle.


Anterior: posterior border of sternocleidomastoid

Posterior: anterior border of trapezius

Inferior of base: middle one-third of clavicle.

Apex: lies on the superior nuchal line where the trapezius and sternocleidomastoid meet.


The roof is formed by the investing layer of deep cervical fascia.


The floor of the posterior triangle is formed by the prevertebral layer of deep cervical fascia, covering the following muscles:

  1. Splenius capitis
  2. Levator scapulae
  3. Scalenus medius and occasionally scalenus posterior

The content of Subclavian triangle are:

a. Three trunks of brachial plexus
b. Nerves to serratus anterior (long thoracic, C5, C6, C7)
c. Nerves to subclavius (C5, C6)
d. Suprascapular nerves (C5, C6)
Lymph Nodes
A few members of the supraclavicular chain


  1. Three trunks of the brachial plexus emerge between the scalenus anterior and medius, and carry the axillary sheath around them. The sheath contains the brachial plexus and the subclavian artery.
  2. The nerves to serratus anterior (long thoracic, C5, C6, C7) arise by three roots. The roots from C5 and C6 pierce the scalenus medius and join the root C7. The nerve passes over the serratus anterior in the medial wall of the axilla and gives branches to the digitations of muscle.
  3. The nerve to the subclavius (C5, C6) descends in front of the brachial plexus and the subclavian vessels, to reach the deep surface of the subclavius muscle. As it runs near the lateral margin of the scalenus anterior, sometimes it gives off the accessory phrenic nerve, which joins the phrenic nerve in front of the scalenus anterior.
  4. The suprascapular nerve (C5, C6) arises from the upper trunk of the brachial plexus and crosses the lower part of the posterior triangle. It passes backwards over the shoulder to reach the scapula. It supplies the suprasintaus and infraspinatus muscles.


  1. The subclavian artery passes behind the tendon of the scalenus anterior and the subclavian vein passes in front of the tendon
  2. The suprascapular artery is a branch of the thyrocervical trunk which passes laterally and backwards behind the clavicle.
  3. The transverse cervical artery is also a branch of the thyrocervical trunk. It crosses the scalenus anterior, th phrenic nerve, and the upper trunks of the brachial plexus, the nerve to the subclavius, the suprascapular nerve and the scalenus medius. At the anterior border of the levator scapulae it divides into superficial and deep branches.


A few members of the supraclavicular chain.


Image Source:-  WIKIPEDIA

External Links:-

Posterior Triangle of Neck

Brachial Plexus

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