We usually forget that lats belong to another muscle group, the superficial back muscles. They originate from the vertebral column and attach to the bones of the shoulder – the clavicle, scapula, and humerus. All these muscles are therefore associated with movements of the upper limb.
The muscles in this group are the latissimus dorsi, trapezius, levator scapulae and the rhomboids.
The latissimus dorsi is the larger, flat, dorsolateral muscle on the trunk, posterior to the arm, and partly covered by the trapezius on its median dorsal region.
Origin:
- Spinous process of T7-L5.
- Upper 2-3 sacral segments.
- Iliac crest.
- Lower 3 or 4 ribs.
Insertion:
Lateral lip of the intertubercular groove.
It is responsible for extension, adduction, horizontal abduction, flexion from an extended position, and (medial) internal rotation of the shoulder joint. It also has a synergistic role in extension and lateral flexion of the lumbar spine.
Pain and symptoms associated with the Latissimus Dorsi muscle
– Pain is felt in the mid-back especially below the bottom of the shoulder blade.
– Pain is felt in the front of the shoulder.
– Pain in the side and or mid-back similar to a side stitch.
– Numbness, tingling and/or aching that extends down the arm to the little finger and often the ring finger.
– Pain while reaching forward with the arms
– Pain when lifting arms overhead
– Can contribute to breathing difficulty.
– Pain does not worsen with activity nor does it ease at rest, it is steady and constant.
Activities that can cause latissimus dorsi pain
– Activities that require continuously or repeatedly raising the shoulders
– Gymnastics
– Rowing
– Throwing or pitching a ball
– Swimming
– Swinging a baseball bat
– Swinging a tennis racket
– Shoveling dirt or snow
– Chopping wood
– Exercise that requires pulling up (chin up) or pushing down (push-ups) with the arms
– Reaching forward or overhead repetitiously
The trapezius is a broad, flat and triangular muscle. The muscles on each side form a trapezoid shape. It is the most superficial of all the back muscles.
Origin:
- External occipital protuberance.
- Along the medial sides of the superior nuchal line.
- Ligamentum nuchae (surrounding the cervical spinous processes).
- Spinous processes of C1-T12.
Insertion:
- Posterior, lateral 1/3 of clavicle.
- Acromion.
- The superior spine of the scapula.
It has three functional regions:
- Superior (descending part), which supports the weight of the arm.
- Intermediate (transverse part), which retracts the scapulae.
- Inferior (ascending part), which medially rotates and depresses the scapulae.
Contraction of the trapezius muscle can have two effects:
- Movement of the scapulae when the spinal origins are stable.
- Movement of the spine when the scapulae are stable. Its main function is to stabilize and move the scapula.
Pain and symptoms associated with the Trapezius muscle
– Headache in the temple area
– Pain in the jaw that travels down into the neck and over behind the ear
– Pain behind one eye
– Tension headache
– Contributes to dizziness
– Pain at the base of the skull
– Stiff neck
– Ache or burning sensation in the middle of the back
– Pain or tingling during raising or lowering the arms
Activities that cause pain and symptoms in the trapezius
– Whiplash
– Lifting heavy objects
– Working with your arms out in front of you (computer, playing the piano, driving)
– Keeping your shoulders rolled forward or pulled up
– Carrying a heavy purse or backpack on one shoulder
– Large breasts
The levator scapulae is a small strap-like muscle. It elevates the scapula.
Origin:
Transverse processes of C1-C3 or C4.
Insertion:
The superior angle of scapula toward the scapular spine.
Pain and symptoms associated with the Levator Scapulae muscle
– Pain at the slope of the neck and shoulder
– Stiff neck, difficulty turning head to look over the shoulder
– Headaches at the base of the skull
– Occasionally pain from the top of the shoulder blade extending to the middle of the shoulder blade
Activities that cause pain or symptoms of the levator scapulae muscle
– Keeping head turned to one side ie. Sleeping on stomach, holding phone to ear with shoulder
– Sleeping without proper head support
– Acute upper respiratory infection will cause the levator scapulae to shorten and become stiff and painful
– Painting overhead for extended periods
– Carrying heavy backpacks or purses
– Whiplash
– Forward head posture
There are two rhomboid muscles, major and minor. The rhomboid major helps to hold the scapula (and thus the upper limb) onto the ribcage. Together with the rhomboid major, the rhomboid minor retracts the scapula when trapezius is contracted. Acting as an antagonist to the trapezius, the rhomboid major and minor elevate the scapula medially and upward, working in tandem with the levator scapulae muscle to rotate the scapulae downward. While other shoulder muscles are active, the rhomboid major and minor stabilize the scapula.
Rhomboid major:
Origin:
- Spinous processes of T2-T5.
- Supraspinous ligament.
Insertion:
Medial scapula from the scapular spine to the inferior angle
Rhomboid minor:
Origin:
- Spinous process of C7 & T1.
- Ligamentum nuchae.
- Supraspinous ligament.
Insertion:
Medial margin of the scapula at the medial angle
Pain and symptoms associated with the Rhomboid Major and Minor muscles
– Pain along the inside of the shoulder blade especially noticeable at rest.
– Popping and/or grinding noise when moving the shoulder blade
– Inability to straighten the upper body out of a slumped position
Activities that can cause rhomboid muscle pain
– Activities that require continuously or repeatedly raising the shoulders
– Hanging wallpaper
– Rowing
– Throwing a ball
– Pull Ups
– Extended work at the computer
– Military posture: standing with extremely straight posture with shoulders pulled back, chest thrust forward.
