A Look at the Major Shoulder Muscles
Serratus and subclavius shoulder muscles
The serratus muscles anterior muscles trace their origin at the eighth upper rib which is located at the side region of the chest. They terminate by inserting along the medial border related to the scapula.
The subclavius muscles are traced to be placed at a region inferior to the clavicle. They originate from the first position rib and inserts at the subclavian groove.
Pectoralis minor and the sternocleidomastoid shoulder muscles
Pectoralis minor muscles are found to attach to the upper region of caracoid process found on the scapula. It originates from the three regions. These are the third, fifth and fourth rib position especially around their constituent cartilage.
Sternocleidomastoid muscles are traced to attach to three regions which are the sternum, mastoid process and the clavicle bone.
Rhomboid (Major& Minor) and Deltoid Shoulder Muscles are another group of shoulder muscles. The rhomboid group is found to originate from the spinous processes associated with thoracic vertebrae. They terminate by inserting at the medial border at the scapula. Deltoid muscles are studied in three categories based on the location of the fibers. The anterior fibers originate from anterior border and the upper surface of the clavicle bone. The middle fibers originate at the lateral margin surface of the acromion. Posterior fibers are traced to originate from the lower region posterior to the border of the scapular spine.
Trapezius shoulder muscles are traced to originate from the occipital bone and the spinous processes of the entire thoracic vertebrae.
The lavatory scapulae muscles originate from first four position cervical vertebrae and at their transverse processes and terminate at the scapula along the medial border.
Functions of the various shoulder muscles
Serratus anterior muscles attach the scapula to the thoracic wall and helps in abduction and rotation movements of the scapula.
Subclavius muscles are responsible for stabilization of clavicle and functions to depress the lateral clavicle.
Pectoralis minor plays a role in respiration. They also involved in rotation and protraction of the scapula.
Sernocleidomastoid muscles play a role in flexion and rotation of the head. They also play a role in respiration mechanism.
The levator scapulae muscles functions to bring about the rotation of the scapula in a downward direction and also in the elevation of the scapula.
The rhomboid group muscles are responsible for downward rotation as well as adduction of the scapula. They work closely with their counterpart levator scapulae muscles.
Trapezius muscles facilitate upward rotation of the scapula, depression movements, adduction and elevation of the scapula.
Functioning of shoulder muscles will have an impact on the joints available to trigger the resulting movements.