Anatomy And Physiology

Muscles Attachment to the Human Scapula

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"Muscles Attachment to the Human Scapula"
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The human skeleton, consisting of 206 bones, is organized into two parties, the first being the axial skeleton, to which the appendicular skeleton, the second group, is attached. The axial skeleton comprises a whole set of bones that form the longitudinal axis.

The scapulae (singular: scapula), parts of the appendicular skeleton, help along with the clavicles in connecting the upper limbs to the axial skeleton. In order to do so, muscles originate from and are inserted into the scapula, connecting it to the humerus of the arm, the vertebral column of the axial skeleton and to other bones of the body, which helps the bone achieve its optimum function, in accordance with the structure it's connected to.

There is a total of 17 muscles connected to the scapula, 11 of which originate from it, whereas 6 others have it as a point of insertion. The muscles that originate from the vertebral column and are inserted into the scapula are the: Trapezius, Levator scapulae, Rhomboid major and Rhomboid minor.

The Trapezius is inserted into the spine of the scapula, wheras the other 3 are inserted into its medial border, which helps them achieve their function the best. Two more muscles that are inserted into the scapula are the Serratus anterior and the Pectoralis minor.

The Serratus anterior is inserted to the whole length of the medial border of the scapula, anterior to the three other muscles mentioned above. This is because its point of origin is the anterior chest wall, so the muscle itself extends around the thoracic cage in order to reach its designated point of insertion.

Another muscle, the Pectoralis minor, comes from the anterior chest wall, to be inserted into the coracoid process of the scapula.

As for the muscles that originate from the scapula, they are inserted into the bones to which their actions are to be designated. So, of all the 11 muscles originating from the scapula, only the Omohyoid is inserted into the hyoid bone (Notice how the prefix of the name of the muscle indicates its point of origin -omo means scapula in Latin- whereas its suffix indicates its point of insertion).

The other 10 muscles are all inserted into the humerus. This shows how the scapula is of an important role in the muscular function of the arm, as the muscles attached to the humerus connecting it to the scapula are capable of rotating, extending, abduction the arm as well as bringing about other types of movements.

Those muscles are the: Coracobrachialis, Triceps brachii (long head), Biceps brachii (short and long head), Subscapularis, Deltoid, Supraspinatous, Infraspinatous, Teres major, Teres minor and some few fibres from the Latissimus dorsi.

The Supraspinatous and Infraspinatous originate from the supraspinous and infraspinous fossae, respectively, while the Subscapularis originates from the subscapular fossa located on the other (anterior) side of the scapula. The Deltoid originates from both the scapula and the clavicle, so just like the Trapezius, it's attached to the spine of the scapula.

The Teres major, Teres minor and the long head of the Triceps brachii are attached to the lateral border of the scapula. Fibers from the Latissimus dorsi, a muscle that originates from the iliac crest and extends along the length of the vertebral column, ascending to the 7th thoracic vertebra, are attached to the inferior angle of the scapula.

The Coracobrachialis, along with the short head of the Biceps brachii, originate at the tip of the coracoid process. The long head of the Biceps originates from a point just a bit farther away from the point of attachment of its short head.

Thus it's seemingly obvious how the action of the muscles attached to the scapula is determined by their points of insertion or origin. Muscles inserted to the scapula act on it, moving it, whereas those originating from it act on parts to which they are inserted. This shows how the scapula plays an important role in movement.

More about this author: Ahmad Turk

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