The Anatomy Of The Back Muscles

Welcome to the brief overview of the anatomy of back muscles. The human back isn’t just one large slab of muscle – it’s a complex network that’s divided into three specific regions: upper, middle, and lower back. Each of these regions houses certain muscles which perform unique functions. These muscles work both individually and collectively to support movement and provide strength. To fully understand how your back works and how to train it effectively, it’s essential to grasp the intricate makeup of these distinctive areas and the muscles they encompass. 

Knowing the functional anatomy of back muscles holds many benefits. For starters, it can provide you with an understanding of what each muscle does, where it is located, and how it contributes to the overall functioning of your back and entire body. This knowledge can guide you in your workout routines, ensuring you target the correct muscles and avoid injuries. Not only this, but it can also be a valuable tool in managing and preventing back pain. For instance, if you are aware that the erector spinae muscles are responsible for maintaining a stable posture while standing or sitting, you can ensure to strengthen these muscles in your fitness regimen, ultimately improving your posture and mitigating back discomfort. 

The functional anatomy of back muscles

Dividing the back into distinct regions

The human back isn’t just one large slab of muscle – it’s a complex network that’s subdivided into three specific regions: upper, middle, and lower back. Each of these regions houses certain muscles which perform unique functions. These muscles work both individually and collectively to support movement and provide strength. To fully understand how your back works and how to train it effectively, it’s essential to grasp the intricate makeup of these distinctive areas and the muscles they encompass. 

1. UPPER BACK
2. MIDDLE BACK
3. LOWER BACK

To build the back optimally, you should be familiar with all the major muscles that make up each of those three specific back regions, their actions, and which exercises build those individual muscles best. Fortunately, you don’t have to guess. Scientific studies using sophisticated tools such as electromyography (EMG) and magnetic resonance imaging (MRI) show us how these muscles work and which exercises work best for building them.

Upper back muscles

The surface muscles of the upper back include the trapezius muscles (traps) and posterior (rear) deltoids. These muscles give height and breadth to back development. However, even though the rear deltoids are one of the three muscle heads that make up your shoulders, along with your side and front delts, their primary action is moving our shoulder blades back (they play a key part in pulling movements) so it is somewhat justified to mention them here also.

#1 Trapezius muscle (traps)

The trapezius is a large, superficial (and most visible) muscle that extends downward from the back of the skull and neck to the upper spine, and laterally toward each shoulder blade. Its appearance resembles a trapezoid (or diamond-like shape), thus the name ‘trapezius’. The trapezius muscle, from an anatomical perspective, divides into three distinct regions – upper, middle, and lower. Each region performs separate functions.

The upper trapezius originates from the base of the skull and the cervical vertebrae, inserting into the outer part of the clavicle. Its function is to elevate the scapula (shoulder blade) and extend the neck. It is exactly the upper trapezius that contributes to movements such as shrugging the shoulders.

In contrast, the middle trapezius originates from the cervical and thoracic vertebrae, inserting into the acromion process of the scapula. This part of the muscle primarily retracts the scapula, leading to a ‘shoulders back’ posture. 

The lower trapezius starts from the thoracic vertebrae and inserts onto the spine of the scapula. This section draws the scapula downward. To keep this muscle healthy and strong, you might consider exercises like shrugs and upright rows for the upper trapezius, seated or bent-over rows for the middle trapezius, and pull-downs or decline dumbbell pullovers for the lower trapezius. 

#2 Rear deltoids

The posterior divisions, also known as the posterior deltoids, are located on the backside of the shoulder joint. This posterior term just denotes its location towards the body’s back. It’s crucial not to confuse them with your rhomboids, which are situated between the two scapula bones. Regrettably, for a lot of people, the posterior deltoids (the ones that aren’t visible in the mirror like the front or middle delts), are typically so underdeveloped in many people that you’d need a microscope to spot them. As the image reflects, these deltoid heads also bear a somewhat triangular shape, much like the other two heads of the deltoid, which display an even more pronounced triangular appearance.

Since the fibers of the rear deltoids begin where the fibers of the upper and middle trapezius end, on the scapula, many of the rear delt’s movements are “married” to those of the trapezius and the other scapular muscles involved in the “horizontal pull” exercises, such as rows.

Many consider your rear deltoids as shoulder muscles, however, various exercises that work your upper back also emphasize them. That’s because their job is to pull your upper arm backward, a movement that you perform whenever you do a rowing exercise.

Mid-back muscles

The mid-back muscles include the latissimi dorsi (lats), rhomboids, and teres major.

#1 Latissimus dorsi

The latissimus dorsi muscles, affectionately known as ‘lats’ or ‘wings,’ undoubtedly rank among the most prominent back muscles. Lats are definitely the widest (broadest) muscles in the human body and also the largest and most powerful muscles in the entire back region. Once well-developed, they make a significant contribution to the coveted “V-taper” physique, creating an impressive silhouette. Thanks to their broad shape and location, stretching below the armpits and across the back of the ribcage, they capably transform the contour of the upper body into a symbol of strength and fitness. Therefore, building back width (broader, wider back) primarily involves targeting the latissimus dorsi. It comes as no surprise that these are the back muscles most commonly targeted by fitness enthusiasts hitting the gym.

The lats are attached to the upper end of the arm bones (humeri) at one end and fan out down the length of the spine to the pelvis. The latissimus dorsi extends the shoulder, which means that it pulls the arm downward toward the hips. During pull-ups, the lats raise the body toward the arms when the arms are fixed. These muscles also stabilize the trunk during multiple-joint, large-muscle lifts, such as squats and bench presses. Good exercises for the lats include pull-ups (using a wide and neutral grip), lat pull-downs, and pullovers. Rowing exercises also target lats if you are pulling the bar up higher toward the chest. 

#2 Rhomboids (rhomboid major and minor)

The rhomboid muscles lie deep beneath the trapezius and descend diagonally from the thoracic vertebrae. These muscles make their home right between your shoulder blades. They start at your spine and attach to your shoulder blade. To be more specific, the rhomboid minor is found towards the upper back part of the torso, just below the trapezius muscle, and right above its sibling, the rhomboid major. The latter sits just below the rhomboid minor and it’s at a further distance from the trapezius. The trapezius fully conceals these muscles, so unfortunately, catching a glimpse of them in the mirror is a no-go. They are two hidden gems within your body. 

The names of the rhomboid muscles suggest their diamond (rhombus) shape.  Sometimes we call them “Christmas three muscles“.  When you look at the rhomboids bilaterally with the spinal column between them, they look exactly like a Christmas tree in shape.  The term major signifies that the rhomboid major is the bigger sibling of the pair. Conversely, the term minor denotes the rhomboid minor as the tinier muscle of the two. There might be a fractional area separating these two, but more often, they are found blending seamlessly together, forming a beautiful combination of strength and structure within your back.

When the rhomboids on both sides work together, the muscles squeeze the shoulder blades together. The rhomboids draw the scapulae toward the spinal column. That’s the main reason why we call them scapular retractor muscles. 

Considering you are retracted during any rowing motion exercise or pull-down, the rhomboids generally work with the lats. In most back exercises, separating the rhomboids and the lats is difficult. The lats are normally the agonists because they are large and strong, and the rhomboids are synergists, much like the teres major. 

Considering the above, the most effective back workouts for engaging the rhomboids include exercises such as barbell rows, seated rows, t-bar rows, one-arm rows, as well as pull-ups and chin-ups.

#3 Teres major

Now, you might be questioning, is it a back or shoulder muscle? Well, it’s both! Its role in anatomy truly blurs the lines between our back and shoulder muscular systems. We can say it’s like a bridge – connecting the shoulder and back, enhancing the functional synergy of these two areas.   

The teres major is a thick, flattened, elongated cone or a narrow, upside-down triangle that tapers as it finds its way to its insertion point. It’s located exactly on the underside of the shoulder (connecting the scapula to the humerus bone) or just above the latissimus dorsi, forming part of what we often refer to as our “wing” muscles. That’s why people often refer to it as a “little lat” muscle.

Compared to other back muscles, like the trapezius and latissimus dorsi, its size is relatively small. Though not entirely visible to the naked eye in all individuals, it subtly contributes to the sculpted appearance of an athletic back.  

It mirrors the functionality of the larger latissimus dorsi muscle but it also works with the rotator cuff muscles. Its functions include pulling the arms (humerus) downwards and rotating them inwards. The rhomboids and teres major work together to move the arms backward during movements such as rowing. 

You can effectively engage the teres major muscle by performing specific exercises such as straight-arm lat pulldowns and dumbbell pullovers. Nonetheless, it’s not a necessity to solely focus on these isolation exercises, as there are numerous compound back exercises – such as different types of pull-ups, row movements, and rear deltoid raises – that can offer sufficient training for this muscle group. In short, exercises that target the latissimus dorsi also engage the teres major muscle.  

Low-back muscles

Your lower back is perhaps among the most critical areas of your body that require attention. Strong lower back muscles support your spine, improve posture, and provide a foundation for your power exercises. The most notable muscles in this region are the spinal erectors or erector spinae.

#1 Erector spinae (spinal erectors)

As you can see from the picture, the lower back is made up of the erector spinae muscles (also known as extensor spinae) that run alongside the entire length of the spinal column (from the base of the spine all the way to the neck bones). This muscle group can also be referred to as the lower back, even though it extends above that area. Well-developed spinal muscles make you look as if you have two boa constrictors running up your back. Having a strong lower back can have a significant improvement in lower back strength, pains, and aches. Since you use your lower back on a daily basis, having strength in that muscle will greatly improve everyday tasks such as lifting or bending over. 

The muscles of the erector spinae attach to the vertebrae, the ribs, and the pelvis. In the lumbar region, the erector spinae splits into 3 columns: the iliocostalis, the longissimus, and the spinalis. 

All these muscles do is support the spine and allow it to extend, help hold the body upright, and allow the trunk of the body to move, twist, and bend in many directions. These muscles collaborate with abdominal muscles in supporting the torso, and you should strengthen them simultaneously with ab exercises. 

When it comes to strength training, many people don’t pay enough attention to the erector spinae back muscles.  Good exercises for developing these muscles include back hyperextensions, bird dogs, deadlifts, and good mornings. But remember, any exercises to strengthen the erector spinae muscles should be performed carefully. Employing the right technique is vital to avoiding lower back injury. 

Conclusion: The importance of knowing the anatomy of the back muscles

Strive to build all three parts of the back (upper, middle, and lower) if you want to develop a superior physique and well-balanced muscles. Strong, symmetrical back muscles give balance to the shoulder joint by maintaining uniform tension on the front and back of the shoulder. This promotes joint health and prevents shoulder pain stemming from abnormal stresses on the joint.

Moreover, identifying the muscle groups in your back and understanding their relative functions can significantly aid in the prevention and treatment of back pain.

In addition, identifying back muscles also assists in optimizing your workouts to ensure a fully balanced and comprehensive training of your whole back. This prevents the overworking of certain muscle groups and the neglect of others, leading to a more harmonious distribution of muscle development. Also, trained back muscles can considerably amplify your performance on other lifts like the bench press or squat, acting as stabilizers.