Latissimus Dorsi
The lastisimus dorsi originates on the dorsal, lateral and ventral sides of the pig. It inserts on the proximal end of the humerus (funny bone) on its medial surface. The action of the lastissimus dorsi is moving the fore leg caudally and dorsally. To reach the latissimus dorsi one must reflect the pectoralis major and follow the muscle down, along the side of the pig.
Trapezius
The trapezius originates from the occipital (eye) bone, as well as the cervical and thoracic vertebrae (back bone). It inserts in the spine of the scapula (shoulder blade). The trapezius retracts the scapula towards the spine and helps to stabilize the scapula during forelimb movement. To get to the trapezius pull the skin of the fetal pig over the back of it and break through the connective tissue to get down to the muscle.
Brachiocephalic
The brachiocephalic originates from the back of the neck, head and mastoid process, and inserts in the humerus (funny bone). The action of this muscle is to move the forelimb anteriorly. To reach the brachiocephalic first skin both sides of the neck then located the two sternohyiod muscles and move further down to and towards the outside of the pig, where the brachiocephalic runs to the humerus.
Rhomboideus cervicis
The rhomboideus cervicis originates from the cervical neck bone and inserts on the medial border of the scapula (shoulder blade). It retracts the scapula and rotates it to depress the glenoid cavity. To observe this muscle transect the trapezius muscle near where it inserts on the spine of the scapula. Reflect the trapezius towards the back.
Rhomboideus capitus
The rhomboideus capitus originates at the occipital area of the cranium. It inserts at the scapula at the vertebrae boarder. THe action of the rhomboideus capitus is to draw the scapula forward. To observe this muscle follow the same steps as you would to find the rhomboideus cervicis.
Deltoid (Spinodeltoid)
The deltoid origin is on the spine of the scapula and its insertion is on the proximal end of the humerus. It raises the humerus. Carefully remove the skin from on top of the shoulder where it is located, so as not to damage or completely tear this muscle, as it is quite easy to.
Splenius
The splenius originates from the 1st and 2nd thoracic vertebrae and inserts on the occipital bone of the cranium. Its action is to extend the head and flexes the head from side to side. To observe the splenius move the rhomboideus capitus to one side and the rhomboideus cervicis in the other direction and the splenius will lie underneath.