Muscles Of Head And Neck
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.
- 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.
- 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.
- 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.
- 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.
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