Muscles connecting the upper limb to the vertebral column – these muscles are extrinsic muscles of the back. They are supplied by the ventral rami of cervical nerves, not by the dorsal rami as one would expect. This is due to the posterior migration of the superficial back muscles during embryonic development. The dorsal primary rami supply sensory innervation to the skin overlying the intrinsic muscles of the back, the medial two thirds of the back.
Add the Rhomboid Major and Minor muscles. There is a rhomboid major and minor and sometimes they are indistinguishable from each other. Typically, the rhomboid major is about two times wider than the rhomboid minor. Their separation is based on their attachment either above or below the medial end of the scapular spine. The rhomboid muscles assist upper extremity function by positioning the scapula. Refer to your assigned textbook for the Origin, Insertion, Innervation, Action, and Blood supply.
Rotate - the cadaver to visualize this muscle.
Add the Levator Scapulae muscle. Superior to the Rhomboids and lies deep to the Trapezius. This muscle moves the scapula. Refer to your assigned textbook for the Origin, Insertion, Innervation, Action, and Blood supply.
Rotate - the cadaver to visualize this muscle.
Add the Lattimus Dorsi muscle. A large fan shaped muscle that fills the lower half of the back. This muscle has an important attachment to the thoracolumbar fascia and the humerus. It functions to move the humerus on the axial skeleton. Refer to your assigned textbook for the Origin, Insertion, Innervation, Action, and Blood supply.
Rotate - the cadaver to visualize this muscle.
The Trapezius Muscle is a large diamond shape muscle of the superficial back that has three sections; Upper, Middle, Lower. Each section of the trapezius muscle generates individual motions of the scapula on the rib cage, but together the each assist with upward rotation of the scapula on the thorax. Refer to your assigned textbook for the Origin, Insertion, Innervation, Action, and Blood supply.
Rotate - the cadaver to visualize this muscle.
Now study some of the muscles indicated above by viewing them on cross-section in the image below, and then go to the VH Dissector model at Step 10 and add in the Cross Sections Panel. Put your mouse on the sagital cross-section and move this cross section up or down to change the transverse cross-section view and study how a muscles shape and position changes and how it is oriented to the surrounding structures. From this point you can use the highlighter tool and look at other muscles in relation to the superficial back muscles.
Figure 1. Transverse (Axial) Plane Cross-Section at T7 vertebral level
Figure 2. Transverse (Axial) Plane Cross-Section at T4 vertebral level
Figure 3. Transverse (Axial) Plane Cross-Section at C6 vertebral level
VH Dissector steps modified for Drexel Dissector by Haviva Goldman, PhD, Noel Goodstadt, DPT and Sophie Geagan (MD student) from original website activity created by Jeffrey Fahl, MD, Kyle Petersen, PhD, Richard Drake, PhD, Alesha Petitt, MA, Claira Ralston, MS and Kim Price, MA and modified by Jeffrey Fahl, MD, Michael Smith, PhD, Albany Medical College.