All muscles of the back including superficial, intermediate and deep; All layers of the neck muscles; blood supply and nerve innervation of the back and neck.
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
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