Subclavian triangle

The subclavian triangle (or supraclavicular triangle, omoclavicular triangle, Ho's triangle), the smaller division of the posterior triangle, is bounded, above, by the inferior belly of the <a href="/facts/Omohyoideus/Wu1M7zIC">omohyoideus</a>; below, by the <a href="/facts/Clavicle/YWNjLv6s">clavicle</a>; its base is formed by the posterior border of the <a href="/facts/Sternocleidomastoideus/fmo4FYaH">sternocleidomastoideus</a>.
Its floor is formed by the first rib with the first digitation of the <a href="/facts/Serratus_anterior/wlY4Uz9L">serratus anterior</a>.
The size of the subclavian triangle varies with the extent of attachment of the clavicular portions of the <a href="/facts/Sternocleidomastoideus/fmo4FYaH">Sternocleidomastoideus</a> and <a href="/facts/Trapezius/67PxLb8e">Trapezius</a>, and also with the height at which the <a href="/facts/Omohyoideus/Wu1M7zIC">Omohyoideus</a> crosses the neck.
Its height also varies according to the position of the arm, being diminished by raising the limb, on account of the ascent of the clavicle, and increased by drawing the arm downward, when that bone is depressed.
This space is covered by the integument, the superficial and deep fasciæ and the <a href="/facts/Platysma/FRTGEJzD">platysma</a>, and crossed by the supraclavicular nerves.
Just above the level of the clavicle, the third portion of the <a href="/facts/Subclavian_artery/FFBqPyLm">subclavian artery</a> curves lateralward and downward from the lateral margin of the <a href="/facts/Scalenus_anterior/gaKFtIWy">scalenus anterior</a>, across the first <a href="/facts/Rib/qM1ggSsE">rib</a>, to the <a href="/facts/Axilla/Q0EaYG2p">axilla</a>, and this is the situation most commonly chosen for <a href="/facts/Ligature_(medicine)/p7CYDSWv">ligaturing</a> the vessel.
Sometimes this vessel rises as high as 4 cm. above the clavicle; occasionally, it passes in front of the Scalenus anterior, or pierces the fibers of that muscle.
The subclavian vein lies behind the clavicle, and is not usually seen in this space; but in some cases it rises as high as the artery, and has even been seen to pass with that vessel behind the Scalenus anterior.
The <a href="/facts/Brachial_plexus/3kmp3Mwj">brachial plexus</a> of nerves lies above the artery, and in close contact with it. Passing transversely behind the clavicle are the <a href="/facts/Transverse_scapular_vessels/VLayvQzg">transverse scapular vessels</a>; and traversing its upper angle in the same direction, the <a href="/facts/Transverse_cervical_artery/NVCgDoLC">transverse cervical artery</a> and vein.
The <a href="/facts/External_jugular_vein/5daXs7NB">external jugular vein</a> runs vertically downward behind the posterior border of the Sternocleidomastoideus, to terminate in the <a href="/facts/Subclavian_vein/SKSKEjRy">subclavian vein</a>; it receives the transverse cervical and transverse scapular veins, which form a plexus in front of the artery, and occasionally a small vein which crosses the <a href="/facts/Clavicle/YWNjLv6s">clavicle</a> from the <a href="/facts/Cephalic/cyGI6o4p">cephalic</a>.
The small nerve to the subclavius also crosses this triangle about its middle, and some <a href="/facts/Lymph_glands/vkwfcQjH">lymph glands</a> are usually found in the space.
Enlarged nodes in this triangle irrespective of size are categorized at N3 in the TNM classification for nasopharyngeal carcinoma.

Subclavian triangle open-in-new

Subclavian triangle