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

omohyoideus The omohyoid muscle is a muscle that depresses the hyoid. It is located in the front of the neck, and consists of two bellies separated by an intermediate tendon. The omohyoid muscle is proximally attached to the scapula and distally attached to t ...

; below, by the

clavicle The clavicle, or collarbone, is a slender, S-shaped long bone approximately 6 inches (15 cm) long that serves as a strut between the shoulder blade and the sternum (breastbone). There are two clavicles, one on the left and one on the rig ...

; its base is formed by the posterior border of the

sternocleidomastoideus The sternocleidomastoid muscle is one of the largest and most superficial cervical muscles. The primary actions of the muscle are rotation of the head to the opposite side and flexion of the neck. The sternocleidomastoid is innervated by the access ...

. Its floor is formed by the first rib with the first digitation of the

serratus anterior The serratus anterior is a muscle that originates on the surface of the 1st to 8th ribs at the side of the chest and inserts along the entire anterior length of the medial border of the scapula. The serratus anterior acts to pull the scapula fo ...

. The size of the subclavian triangle varies with the extent of attachment of the clavicular portions of the

Sternocleidomastoideus The sternocleidomastoid muscle is one of the largest and most superficial cervical muscles. The primary actions of the muscle are rotation of the head to the opposite side and flexion of the neck. The sternocleidomastoid is innervated by the access ...

and

Trapezius The trapezius is a large paired trapezoid-shaped surface muscle that extends longitudinally from the occipital bone to the lower thoracic vertebrae of the spine and laterally to the spine of the scapula. It moves the scapula and supports the ...

, and also with the height at which the

Omohyoideus The omohyoid muscle is a muscle that depresses the hyoid. It is located in the front of the neck, and consists of two bellies separated by an intermediate tendon. The omohyoid muscle is proximally attached to the scapula and distally attached to t ...

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

platysma The platysma muscle is a superficial muscle of the human neck that overlaps the sternocleidomastoid. It covers the anterior surface of the neck superficially. When it contracts, it produces a slight wrinkling of the neck, and a "bowstring" effect ...

, and crossed by the supraclavicular nerves. Just above the level of the clavicle, the third portion of the

subclavian artery In human anatomy, the subclavian arteries are paired major arteries of the upper thorax, below the clavicle. They receive blood from the aortic arch. The left subclavian artery supplies blood to the left arm and the right subclavian artery supplie ...

curves lateralward and downward from the lateral margin of the

scalenus anterior The scalene muscles are a group of three pairs of muscles in the lateral neck, namely the anterior scalene, middle scalene, and posterior scalene. They are innervated by the third to the eight cervical spinal nerves (C3-C8). The anterior and m ...

, across the first

rib In vertebrate anatomy, ribs ( la, costae) are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the ches ...

, to the

axilla The axilla (also, armpit, underarm or oxter) is the area on the human body directly under the shoulder joint. It includes the axillary space, an anatomical space within the shoulder girdle between the arm and the thoracic cage, bounded superior ...

, and this is the situation most commonly chosen for ligaturing 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

brachial plexus The brachial plexus is a network () of nerves formed by the anterior rami of the lower four cervical nerves and first thoracic nerve ( C5, C6, C7, C8, and T1). This plexus extends from the spinal cord, through the cervicoaxillary canal in th ...

of nerves lies above the artery, and in close contact with it. Passing transversely behind the clavicle are the

transverse scapular vessels The suprascapular artery is a branch of the thyrocervical trunk on the neck. Structure At first, it passes downward and laterally across the scalenus anterior and phrenic nerve, being covered by the sternocleidomastoid muscle; it then crosses ...

; and traversing its upper angle in the same direction, the

transverse cervical artery The transverse cervical artery (transverse artery of neck or transversa colli artery) is an artery in the neck and a branch of the thyrocervical trunk, running at a higher level than the suprascapular artery. Structure It passes transversely b ...

and vein. The

external jugular vein The external jugular vein receives the greater part of the blood from the exterior of the cranium and the deep parts of the face, being formed by the junction of the posterior division of the retromandibular vein with the posterior auricular vein ...

runs vertically downward behind the posterior border of the Sternocleidomastoideus, to terminate in the

subclavian vein The subclavian vein is a paired large vein, one on either side of the body, that is responsible for draining blood from the upper extremities, allowing this blood to return to the heart. The left subclavian vein plays a key role in the absorption ...

; 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

from the

cephalic A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may ...

. The small nerve to the subclavius also crosses this triangle about its middle, and some

lymph glands A lymph node, or lymph gland, is a kidney-shaped organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphocytes that include ...

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.

Gallery

File:Musculussternocleidomastodieus.png,

Sternocleidomastoid muscle The sternocleidomastoid muscle is one of the largest and most superficial cervical muscles. The primary actions of the muscle are rotation of the head to the opposite side and flexion of the neck. The sternocleidomastoid is innervated by the access ...

File:Gray386.png, Muscles of the neck. Anterior view. File:Posterior triangle of the neck.PNG, Posterior triangle of the neck labeled. (Anterior triangles to the left. Occipital triangle labeled at center left.) )

References

External links

* {{Authority control Human head and neck Triangles of the neck

Gallery

See also

References

External links