The acromion that the scapula is a huge bony forecast on the superior finish of the scapula. It is vital landmark the the bones system and also a muscle attachment allude essential to the function of the shoulder joint. The acromion also forms the acromioclavicular (AC) joint v the clavicle.

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Anatomy

The pectoral girdle is crucial region the the skeletal device that attaches the upper limb to the axial skeleton. Proceed Scrolling to Read an ext Below...

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ongoing From Above... two bones, the scapula (shoulder blade) and clavicle (collarbone), form the pectoral girdle.

The scapula is a flat, triangular bone situated posterior come the ribcage. A bony ridge, recognized as the spine of the scapula, rises from the posterior surface of the scapula follow me its medial side. The spine grows taller and also thicker together it move laterally and superiorly toward the shoulder joint. In ~ the far finish of the spine, the acromion creates where the bone widens significantly and also extends anteriorly come cover the superior element of the shoulder joint.

The acromion is a level bony projection and has a rectangle-shaped shape through rounded corners. It is only around 1 customs (2.5 cm) vast and approximately 2 customs (5 cm) long. The anterior finish of the acromion is flat and also smooth to kind the acromioclavicular joint with the clavicle.

Physiology

The acromioclavicular joint, or AC joint, is an important part of the shoulder that develops a joint in between the acromion and the clavicle. It is a planar synovial joint the holds the scapula and clavicle with each other while allowing the scapula come glide in plenty of directions loved one to the rest of the body. The scapula’s motion at the AC joint greatly increases the mobility the the eight at the shoulder, especially when reaching throughout the human body or elevating the arm towards the head.

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Two significant muscles, the deltoid and trapezius, attach to the acromion. The deltoid, i m sorry abducts the eight at the shoulder, develops its beginning along the acromion, the spine of the scapula, and the clavicle. From these origins, it the cross the shoulder joint and also inserts ~ above the deltoid tuberosity the the humerus. The trapezius muscle arises from the spinous processes of the cervical and thoracic vertebrae and inserts on the acromion and also spine the the scapula. Contraction of the trapezius rotates and retracts the scapula or may assist to stabilize that is position.