Back Muscles Flashcards
Trapezius
O: External occipital protuberance, superior nuchal line, ligamentum nuchae, spinous processes of C7 and thoracic vertebrae
INS: Lateral 1/3 of clavicle, acromion, spine of scapula
INN: Accessory nerve (CN XI)
A: Superior fibers elevate and laterally rotate scapula; middle fibers retract scapula; inferior fibers depress and laterally rotate scapula
Latissimus dorsi
O: Spinous processes of lower thoracic and lumbar vertebrae, iliac crest, sacrum
INS: Intertubercular groove of humerus
INN: Thoracodorsal nerve
A: Extends, adducts and medially rotates humerus
Levator scapulae
O: Transverse processes of upper cervical vertebrae
INS: Superior angle of scapula
INN: Dorsal scapular nerve
A: Elevates scapula
Rhomboid major
O: Spinous processes of lower cervical and upper thoracic vertebrae
INS: Medial border of scapula inferior to the spine
INN: Dorsal scapular nerve
A: Retracts and medially rotates scapula
Rhomboid minor
O: Spinous processes of lower cervical and upper thoracic vertebrae
INS: Medial border of scapula superior to the spine
INN: Dorsal scapular nerve
A: Retracts and medially rotates scapula
Splenius capitis
O: Ligamentum nuchae, spinous processes of C7 and upper thoracic vertebrae
INS: mastoid process and superior nuchal line
INN: Dorsal rami of spinal nerves
A: Acting bilaterally, they extend the head and neck; acting unilaterally, they rotate the head to one side
Splenius cervicis
O: Ligamentum nuchae, spinous processes of C7 and upper thoracic vertebrae
INS: transverse processes of upper cervical vertebrae
INN: Dorsal rami of spinal nerves
A: Acting bilaterally, they extend the head and neck; acting unilaterally, they rotate the head to one side
Erector spinae
O: Sacrum, iliac crest, ribs, spinous and transverse processes of vertebrae
INS: Spinous and transverse processes of vertebrae, ribs, skull
INN: Dorsal rami of spinal nerves
A: Acting bilaterally, they extend the head and trunk; acting unilaterally, they bend the trunk laterally; they are also important for “controlling” flexion
Semispinalis capitis
O: Transverse processes of lower cervical and upper thoracic vertebrae
INS: Occipital bone near nuchal lines
INN: Dorsal rami of spinal nerves
A: Acting bilaterally, they extend the head; acting unilaterally, they rotate the head to one side
