Muscles that attach to the scapula are:
The rhomboid major originates on the spinous processes of the second to fifth thoracic border and inserts on the medial border of the scapula. It retracts the scapula.
Center of the shoulderblade and attaches to the spine.
Posterioly there are the Rhomboideus major and minor and levator scapula. While anteriorly is the upper three digitations of serratus anterior.
Rhomboideus Major The rhomboid major helps to hold the scapula (and thus the upper limb) onto the ribcage. It also acts to retract the scapula, pulling it towards the vertebral column, and downwardly rotates the scapula with respect to the glenohumeral joint. It works collectively with the levator scapulae to elevate the medial border of the scapula.
The strongest protractor of the scapula is the serratus anterior muscle. It originates from the upper ribs and inserts along the medial border of the scapula. Contraction of the serratus anterior muscle pulls the scapula forward around the rib cage.
The serratus anterior muscle protracts and depresses the scapula. It originates on the upper ribs and inserts along the medial border of the scapula. This muscle is important for stabilizing the scapula during movements like pushing and reaching overhead.
The scapula is not a muscle; it is a bone.
injections are normally given in the deltoid muscle which attaches to itself to the scapula and acromion
The primary muscle responsible for moving the scapula forward and downward is the serratus anterior. This muscle originates along the upper eight or nine ribs and inserts along the inner border of the scapula. Contraction of the serratus anterior pulls the scapula forward and downward along the ribcage.
The deltoid is very interesting muscle. It arise from the outer and lateral border of the clavicle and outer and lateral border of the spine of the scapula. From the corresponding inner border, you have insertion of the trapezius muscle. The deltoid muscle is inserted on the deltoid tuberosity on the lateral and middle part of the humerus bone. So it looks that the trapezius muscle continue as the deltoid muscle.
Many muscles are attached to shoulder girdle. You have trapezius, deltoid muscles attached to spine of the scapula and clavicle. Rhomboid major and minor muscles and serratus anterior muscle attached to the medial border of the scapula. You have subscapularis, supraspinatus, infraspinatus muscles attached to the inner and outer surfaces of the scapula. You have teres minor and major muscles attached to lateral border of the scapula. You have pectoralis major muscle (clavicular head) attached to clavicle. You have biceps muscle attached to coracoid process and supraglenoid tubercle of the scapula. you have long head of triceps attached to infraglenoid tubercle of the scapula. you have pectoralis major muscle attached to coracoid process of the scapula.You have subclavius muscle attached to clavicle.
The supraspinatus muscle originates from the supraspinous fossa of the scapula.