The neck is divided into many triangles and sub-triangles in order to facilitate the description and localization of various structures located in the area. One such triangle is the omoclavicular, also called the subclavian triangle, which is part of the larger posterior triangle of the neck.
This article explains the contents and the borders of the subclavian triangle.
Triangles of the Neck
The neck is divisible into an anterior and a posterior triangle by the sternocleidomastoid muscle on the anterior and lateral aspects. Each of these triangles are composed of sub-triangles that are bounded or defined by structures that are both visible and palpable, and structures that are not palpable. The anterior triangle may be further subdivided into the following triangles:
- submental - apex at the chin, hyoid bone as base, anterior bellies of digastric muscles as sides
- carotid - posterior belly of digastric and stylohyoid as superior base, sternocleidomastoid as lateral side, superior belly of omohyoid as medial side
- muscular - median line of the neck as base, anterior margin of sternocleidomastoid as inferior side, superior belly of omohyoid as superior side
- digastric - anterior belly of digastric anteroinferiorly, posterior belly of digastric and stylohyoid as the base, mandible as lateral side, anterior belly of digastric as medial side
The posterior triangle includes the sub-triangles given below:
- occipital (posterior edge of sternocleidomastoid as anterior side, anterior edge of trapezius as posterior side and inferior belly of omohyoid as inferior base)
- supraclavicular (omoclavicular)
The omoclavicular triangle, which is also called the subclavian triangle because the third part of the subclavian artery is located in it, is indicated on the surface of the neck by the supraclavicular fossa which is also the lowest portion of the posterior triangle.
This triangle is clinically relevant. For example it is a common site for the palpation of pathologically enlarged lymph nodes, as well as a site where the pulsations of great veins may be seen. It contains:
The subclavian triangle is bounded by the:
- clavicle inferiorly
- posterior border of sternocleidomastoid anteriorly
- inferior belly of the omohyoid muscle superiorly
- first digitation of serratus anterior muscle and the first rib inferiorly, forming the floor of the triangle. This is owing to the fact that the posterior end of the first rib may be felt as fullness in the posterior aspect of the fossa.
Contents of the omoclavicular/subclavian triangle are as follows:
- the subclavian artery
- the inferior part of the external jugular vein,
- the investing layer of deep cervical fascia
- the trunks of the brachial plexus
The borders of the triangle are: