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Muscles of shoulder and upper arm

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Deltoid muscle. In human anatomy, the deltoid muscle is the muscle forming the rounded contour of the shoulder.

Deltoid muscle

Anatomically, it appears to be made up of three distinct sets of fibers though electromyography suggests that it consists of at least seven groups that can be independently coordinated by the central nervous system.[1] A study of 30 shoulders revealed an average mass of 191.9 grams (6.77 oz) (range 84 grams (3.0 oz)–366 grams (12.9 oz)) in humans.[2] Structure[edit] The deltoid originates in three distinct sets of fibers, often referred to as "heads":[3] Fick[14] divided these three groups of fibers, often referred to as parts (Latin: pars) or bands, into seven functional components:[15] the anterior part has two components (I and II); the lateral one (III); and the posterior four (IV, V, VI, and VII) components.

Side. Front. Back. Animation. Deltoid muscle. Origin, insertion, and function of the deltoid muscle. Rhomboid major muscle. The rhomboid major is a skeletal muscle on the back that connects the scapula with the vertebrae of the spinal column.

Rhomboid major muscle

In human anatomy, it acts together with the rhomboid minor to keep the scapula pressed against thoracic wall and to retract the scapula toward the vertebral column.[1] Human anatomy[edit] Structure[edit] Origin, insertion, and function of Rhomboid major. Rhomboid minor muscle. In human anatomy, the rhomboid minor is a small skeletal muscle on the back that connects the scapula with the vertebrae of the spinal column.

Rhomboid minor muscle

Located inferior to levator scapulae and superior to rhomboid major, it acts together with the latter to keep the scapula pressed against the thoracic wall. It lies deep to trapezius but superficial to the long spinal muscles.[1] Origin, insertion, and functio of Rhomboid minor. Coracobrachialis muscle. The coracobrachialis is the smallest of the three muscles that attach to the coracoid process of the scapula.

Coracobrachialis muscle

(The other two muscles are pectoralis minor and biceps brachii.) It is situated at the upper and medial part of the arm. Structure[edit] Origin, insertion, and function of coracobrachialis. Teres major muscle. The teres major muscle (Latin teres meaning 'rounded') is a muscle of the upper limb and one of seven scapulohumeral muscles.

Teres major muscle

It is a thick but somewhat flattened muscle, innervated by the lower subscapular nerve (C5 and C6). Structure[edit] It arises from the oval area on the dorsal surface of the inferior angle of the scapula, and from the fibrous septa interposed between this muscle and the rotator cuff lateral rotator pair of the teres minor and infraspinatus. Teres Major origin, insertion, and function. Pectoralis major muscle. The pectoralis major (/ˌpɛktəˈreɪlɨs ˈmeɪdʒər/) (from Latin: pectus, breast) is a thick, fan-shaped muscle, situated at the chest (anterior) of the human body.

Pectoralis major muscle

It makes up the bulk of the chest muscles in the male and lies under the breast in the female. Origin, insertion, and function of Pectoralis major. Trapezius muscle. In human anatomy, the trapezius (/trəˈpiːzi.əs/) is a large superficial muscle that extends longitudinally from the occipital bone to the lower thoracic vertebrae and laterally to the spine of the scapula (shoulder blade).

Trapezius muscle

Its functions are to move the scapulae and support the arm. Origin, insertion and function of trapezius. Latissimus dorsi muscle. The latissimus dorsi (/ˌləˈtɪsɨməs ˈdɒrsaɪ/) (plural: latissimi dorsi), meaning 'broadest [muscle] of the back' (Latin latus meaning 'broad', latissimus meaning 'broadest' and dorsum meaning the back), is the larger, flat, dorso-lateral muscle on the trunk, posterior to the arm, and partly covered by the trapezius on its median dorsal region.

Latissimus dorsi muscle

Latissimi dorsi are commonly known as "lats", especially among bodybuilders. Structure[edit] Variations[edit] Axillary arches shown from two different angles. The number of dorsal vertebra to which it is attached varies from four to eight; the number of costal attachments varies; muscle fibers may or may not reach the crest of the ilium. Latissimus dorsi.