Tricep
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.
Origin and Insertion One of the points of attachment is the ORIGIN (typically the non-moving point of attachment). The other point of attachment is the INSERTION (typically the moving point of attachment). For example - when the brachialis muscle (located on the upper arm) contracts - it shortens the distance between the origin (on the humerus - the upper arm bone and the insertion (on the radius - the forearm bone). The humerus does not move, but the radius does move - it moves closer to the humerus.
Origin and Insertion One of the points of attachment is the ORIGIN (typically the non-moving point of attachment). The other point of attachment is the INSERTION (typically the moving point of attachment). For example - when the brachialis muscle (located on the upper arm) contracts - it shortens the distance between the origin (on the humerus - the upper arm bone and the insertion (on the radius - the forearm bone). The humerus does not move, but the radius does move - it moves closer to the humerus.
Reverse origin and insertion refers to the changing of the attachment points of a muscle. When the origin and insertion of a muscle are reversed, the muscle's previous insertion point now becomes the origin, and vice versa. This can have an impact on the muscle's function and movement.
The origin of a muscle is where the muscle starts ("the starting point"). The insertion of a muscle is where the muscle ends ("the ending point"). Also, the insertion of the muscle is what moves a lot (contrary of the origin where the muscle mostly stays stationary).
Insertion
yes
The "movable" end of a muscle is called the insertion. The "immobile" end is called the origin. Shortening, or contraction, of a muscle causes the origin and insertion to become closer to one another.
The origin attachments are on, or near, the medial epicondyle of the humerus.
Scapula is very interesting bone. It holds the upper limb, but have no bony attachment to your thorax. It is attached to thorax, through the collar bone or the clavicle. Lateral end of the clavicle is attached to the lateral end of the spine of the scapula. On the inside of the spine of the scapula and clavicle, you have insertion of the muscle called as trapezius. From out side of this, you have origin of the deltoid muscle. Technically and mechanically, the trapezius muscle continues as deltoid muscle.
There are two points of attachment for a (skeletal) muscle, the origin and the insertion. The origin is the immovable (or slightly movable) part. The insertion moves towards the origin.
Where a muscle attaches to a bone is at the origin and insertion points. The origin is the immovable (or slightly moveable) attachment point and the the insertion is the movable attachment point. During contraction the insertion moves towards the origin. HOW a muscle attaches to a bone is through tendons.