Injury to the latissimus dorsi and/or teres major muscles are infrequent but can be debilitating.
These 2 muscles affect the shoulder's:
(1) extension
(2) adduction
(3) internal rotation
People at risk of injury:
(1) pitcher or other thrower
(2) eccentric contraction of the muscles by sudden forced extension or hyperadduction
Injuries may affect:
(1) a tendon including its insertion
(2) the musculotendinous junction
(3) the muscle body (strains, tears)
Usually only one of the muscles is affected but rarely both may be.
Clinical features:
(1) shoulder pain, often of sudden onset but sometimes preceded by aching
(2) burning sensation
(3) weakness in extension, adduction and internal rotation
(4) reduced active range of motion
Diagnosis is typically confirmed by imaging studies (MRI, ultrasound).
Differential diagnosis:
(1) damage to the rotator cuff
