muscles of the chest shoulder and upper limb Let us know

muscles of the chest shoulder and upper limb ، By presenting insertions in the bones of the upper limb, some are described that are studied in other muscle groups: subclavian, pectoral minor and major, serratus anterior, trapezius, rhomboid major and minor, levator scapula and latissimus dorsi. (SEE TABLE)

muscles of the chest shoulder and upper limb

Subclavian:

It is located below the clavicle, covered by the pectoralis major, and is small and fusiform. It is located in the deep plane of the anterior wall of the armpit; it is surrounded by the subclavian fascia, which depends on the clavipectoral fascia, fixed by the clavicle. It delimits the first digitation of the serratus anterior muscle and separates the clavicle from the subclavian artery.

Insertions: originates in the superior aspect medially and below the first costal cartilage; it is directed up, back and laterally until inserted into the subclavian sulcus in the middle third, inferior aspect of the clavicle.

Actions: stabilizes the clavicle during the movements of the shoulder girdle, tracing it medially. The text of Latarjet states that the clavicle descends but its paralysis does not cause any significant consequence.

Innervation and vascularization : it is innervated by the subclavian nerve. It comes from the upper trunk of the brachial plexus with branches of C5 and C6 that descend in front of the subclavian vessels. It is irrigated by the clavicular artery, branch of the thoracoacromial from the axillary.

Pectoralis major:

It is a wide, flattened, triangular, fan-shaped muscle that covers the entire anterolateral part of the thorax. It has three portions: abdominal, sternocostal and clavicular, which converge in the humerus. The deep face of this muscle forms the foreground of the anterior wall of the axillary fossa, in addition, it crosses the axis of the vessels and nerves. It is separated from the deltoid thanks to the deltopectoral groove through which the cephalic vein circulates. In its lower edge it is related to the serratus anterior, with the rectus abdominis and with the external oblique of the abdomen.

Insertions: it originates in the middle two thirds of the anterior border of the clavicle; it is on the anterior side of the handlebar and sternal body; it is the anterior face of the first seven ribs, and its cartilages and third portion are on the anterior aspect of the rectus abdominis sheath. The direction of the fibers has opposite direction because the upper ones are inserted in a lower portion; the inferior ones are inserted in an upper portion in the humerus, in the lateral lip of the intertubercular sulcus in front of the tendons of the greater round, latissimus dorsi and that of the long head of the biceps brachii.

Actions: Globally it is approximation and internal rotator of the humerus. When its fixed point is the thorax, it approximates the arm; At the same time, it carries forward the shoulder. When the arm is in lateral rotation, rotate it medially and when its fixed point is the humerus, raise the trunk to climb. When the humerus is immobile it helps in breathing as an inspiration.

Innervation and vascularization: the pectoral nerve that comes from the brachial plexus -ramas of C5, C6 and C7-; with two branches, one superior for the clavicular portion and one inferior for the deep face of the muscle. Also for sternocostal and abdominal portions of C7, C8 and T1. It is irrigated by the thoracoacromial artery, branch of the axillary; in addition, by perforators coming from the intercostals.

Pectoral minor :

It is located in the upper lateral region of the thorax and joins it with the coracoid; It is behind the pectoralis major, it is flattened and triangular.

Insertions: through three tabs on the lateral side and upper edge of ribs 3, 4 and 5, close to the costal cartilage. These fibers converge on a tendon that is directed towards the coracoid process in the anterior medial border.

Actions : descends the scapula and participates in the internal rotation of the same; If the fixed point is the coracoid, it behaves as an inspirer when raising the ribs.

Innervation and vascularization: medial pectoral nerve of the brachial plexus C8 and T1. It also receives branches of the lateral pectoral nerve fibers from C6, C7 and C8. It is irrigated by the thoracoacromial branch of the axillary.

Serrato anterior:

Click here to view serrato anterior

Muscle wide, flattened, quadrilateral and with multiple tabs. On the anterior side it joins the scapula, at its medial edge, to the ribs, and forms the lateral wall of the axilla on the superficial plane.

Insertions: intercostal fascia and first nine ribs through tabs or fingerings; the latter mesh with those of the external oblique muscle of the abdomen. All the muscle fibers are directed back until they reach the medial border and the inferior angle of the scapula.

Actions: when the fixed point is the scapula, lift the ribs for forced inspiration. When its fixed point is in the thorax it is protractor of the scapula, it participates in the external rotation of the scapula, and the scapula oscillates in the abduction of the humerus. Accompanies the elevation of the humerus above the horizontal.

Innervation and vascularization : long thoracic nerve (nerve of Charles Bell) C5, C6 and C7. It is irrigated by the lateral thoracic artery, by perforators coming from the intercostals, and by the thoracodorsal from the subscapularis.

Trapeze:

Wide, flattened and triangular muscle found in the cervicodorsal region. Along with the collateral forms a trapeze, that’s why its name. It limits the posterior triangle of the neck. It has three parts according to the arrangement of the fibers: ascending, transverse and descending.

Insertions: above, in the inner third of the nuchal line and the external occipital protuberance. It is fixed medially in the spinous processes of the cervical and thoracic vertebrae, in addition, in the corresponding interspinous ligaments and in the posterior nuchal or cervical ligament. Lateral is fixed on the lateral third of the superior aspect and posterior margin of the clavicle, on the inner border of the acromion, and on the upper lip of the posterior border of the scapular spine.

Actions : if the fixed point is medial, the superior fibers elevate the scapula and are superior rotators. If the fixed point is lateral, they help to lateralize the neck unilaterally, and bilaterally in the extension. The sustained contracture of this produces torticollis. The transverse fibers are retractors of the scapula, the inferior fibers descend and are inferior rotators.

Innervation and vascularization: cranial nerve XI spinal or accessory, and sensitively by fibers of the brachial plexus. It is irrigated by the dorsal artery of the scapula, branch of the subclavian.