Summary The anatomy of the neck & back

BACK MUSCLES
ORIGIN → site of tendinous attachment that is stationary during contraction
 Where muscle starts
INSERTION → site of tendinous attachment that moves during contraction
 Where muscle ends
BELLY → portion of muscle between origin & insertion




 Muscles only pull, they don’t push
 Muscles of back and neck are complex detailed arrangement
 General pattern simple

3 layers:
 Superficial
 Intermediate
 Deep

SUPERFICIAL MUSCLES
 Involved in movements of shoulder
 2 layers
 Trapezius & latissimus dorsi → 1st layer
 Rhomboid minor & major and levator scapulae → 2nd layer

,TRAPEZIUS
 Origin
o Superior nuchal line on skull
o Ligamentum nuchae
o Spines of vertebrae C7 - T12
 Insertion
o Lateral 1/3 clavicle
o Acromion process
o Superior border scapula spine
 Action
o Lifts shoulders up and down (elevation & depression)
o Retraction (pulling scapula together)
o Lateral rotation of glenohumeral joint

, LATISSIMUS DORSI
 Origin
o Spines of vertebrae T7-L5
o Lumbar vertebrae
o Sacral & iliac crests
o Inferior 4 ribs (via thoracolumbar fascia)
 Insertion
o Intertubercular sulcus of humerus
 Action
o Extension, adduction & medial rotation of arm at shoulder
o Draws arms inferiorly & posteriorly