The back is comprised of the biggest muscles after legs. The muscles of your back stabilize your spine. This entire group covers around 2/3rd of the upper body. They support different sections of the spine which house the spinal cord and also maintain the right posture of the body. The back contains many more muscles that lie underneath the major three discussed below. But, these muscles are not directly hit with an exercise. The exercises for the three major groups involve and provide breakdown to these deep muscles. The back can be divided into three major groups of muscles.
1. The Latissimus Dorsi
3. Erector Spinae
LATISIMUS DORSI -
The word itself means “broadest of the back”. It is the major pulling muscle of the torso. It originates from the iliac crest, spinous process of the thoracic vertebrae T7 to T12 and the last three ribs via the thoracolumbar fascia. It inserts into the bicipital groove of the humerus. The anatomical shape of the latissimus dorsi is in the form of a V. From an aesthetic stand point, the only muscle that contributes to the coveted V taper is the latissimus dorsi. The function of latissimus dorsi are shoulder extensions as we perform in bent over rows, shoulder adduction as performed in lat pull downs and Broad Grip Chin-Ups.
In day-to-day life, the latissimus dorsi helps us with many things – to pull things that are placed anteriorly, towards us, we use its extension function; to climb a wall, we use the adduction function of latissimus dorsi.
Trapezius is a part of the back. The trapezius is a big trapezoid muscle covering the entire cervical region. It is a superficial muscle that covers most of the upper area of the back and the posterior of the neck. The function of the trapezius muscle is to move the scapula. This movement of the scapulae is done in 3 different directions to hit the 3 segments of the trapezius that have different fibres. The trapezius muscle is divided into 3 heads. The significance of this division lies in the variety of functions performed by this muscle. Different fibers of the trapezius muscle perform different types of movements at the scapula.
Upper fibres of the trapezius- The primary function of this head is to elevate the scapula. It runs from the occipital and nuchal ligament to the lateral third of the clavicle. The movement in which the upper fibres is highly involved is shrugs. Another muscle that gets trained while performing shrugs is the levator scapulae, which is a deep muscle and performs the same function as the upper fibers.
Middle fibers of the trapezius- The primary function of this head is to retract the scapula. It originates from the spinal processes of the first to fourth thoracic vertebrae and inserts at the acromion. The exercise to work this muscle is prone shrugs. But we do include this exercise separately in our workouts as the breakdown of this muscle occurs in all horizontal pulling movements e.g. the bent over rows, if done with correct form and technique. While retracting the scapula in pulling movements, we engage one more muscle – the rhomboids. It has the same function as the middle head of trapezius.
Lower fibers of the trapezius- The function of this muscle is to depress the scapula. Extends from the spinal processes of the fifth to twelfth thoracic vertebrae to the scapular spine. The exercise for this muscle is reverse shrugs. We do not add this movement in our workout because the breakdown of lower fibers of the trapezius occurs while doing vertically pulling movements as in the case of lat pull down.
ERECTOR SPINAE -
Erector spinae is a group of back muscles which span the entire vertebral column, from the hip, right up to the skull.
It is also known as Sacrospinalis, since it starts from the sacrum & spans the entire spine.
It originates from the posterior iliac crest and sacrum and inserts into the transverse processes of all the vertebrae, all the way to the nuchal lines of the occipital bone to the posterior aspect of the mastoid processes of the temporal bone.
Thus, the Erector Spinae play a significant role in the development of a stronger back and thus are extremely crucial to a stronger core.
Strengthening your erector spinae is a major part of building a strong core.
Though their specific function is stated as Trunk Extension, they are actually used in an Isometric manner to resist Trunk Flexion under load.
The spine with all its physiological curvatures (Lordotic Cervical, Kyphotic Thorax & Lordotic Lumbar) is referred to as the NEUTRAL spine. In simple words when a person maintains an erect posture, the spine is said to be Neutral. When a person lifts a load in an unsupported manner, there is a huge flexion load on the spine. If a person is successful in maintaining a Neutral spine while under load, then it is only with the recruitment of the ERECTOR SPINAE that the Neutral Spine is maintained, despite the load pushing down on the trunk towards flexion.
In even more simpler terms, the ERECTOR SPINAE, prevents our trunk from bending while doing important lifts such as the deadlift and the squats.