Superficial Back Muscles

Question 0

Latissimus Dorsi

Answer 0

Origin: Spinous processes of inferior six thoracic vertebrae, iliac crest, thoracolumbar fascia, and inferior 3 and 4 ribs

Insertion: floor of intertubercular sulcus of the humerus

Innervation: thoracodorsal nerve (C6, C7, C8)

Action: extend, adduct, and internally rotate humerus, and pull body towards arms when climbing

Question 1

Trapezius

Answer 1

Origin: medial third of the superior nuchal line, EOP, nuchal ligament, spinous processes of C7 to T12

Insertion: lateral third of the clavicle, acromion, and spine of the scapula

Innervation: spinal accessory nerve (CN XI) and C3,C4

Action: elevate scapula, retract scapula, depress scapula, and raise glenoid cavity superiorly

Question 2

Rhomboid Minor

Answer 2

Origin: nuchal ligament, spinous processes of C7-T1

Insertion: triangular area at the medial end of the scapular spine

Innervation: dorsalscapular nerve (C4,C5)

Action: retract scapula, fix scapula to thoracic wall, downward rotation of the glenoid cavity

Question 3

Rhomboid Major

Answer 3

Origin: spinous processes of T2-T5

Insertion: Medial border of the scapula from the level of the spine to the inferior angle

Innervation: dorsalscapular nerve (C4,C5)

Action: retract scapula, fix scapula to thoracic wall, downward rotation of the glenoid cavity

Question 4

Levator Scapulae

Answer 4

Origin: posterior tubercles of transverse processes C1-C4

Insertion: medial border of the scapula superior to root of spine

Innervation: dorsal scapular nerve (C5) and C3,C4

Action: elevate the scapula and downward rotation of the glenoid cavity

Question 5

Erector Spinae - Iliocostalis

Answer 5

Origin: posterior iliac crest, posterior surface of sacrum, sacroiliac ligament, spinous processes of inferior lumbar and sacral vertebrae, and supraspinous ligament

Insertion: inferior angles of ribs and transverse processes of cervical vertebrae

Innervation: posterior rami of the spinal nerve

Action: bilaterally extend the vertebral column and when neck is flexed, lengthen fibers to control movement and unilaterally lateral

Question 6

Erector Spinae - Longissimus

Answer 6

Origin: posterior iliac crest, posterior surface of sacrum, sacroiliac ligament, spinous processes of inferior lumbar and sacral vertebrae, and supraspinous ligament

Insertion: transverse processes of thoracic and cervical vertebrae and mastoid process

Innervation: posterior rami of the spinal nerve

Action: bilaterally extend the vertebral column and when neck is flexed, lengthens fibers to control movement and unilaterally lateral

Question 7

Erector Spinae - Spinalis

Answer 7

Origin: posterior iliac crest, posterior surface of sacrum, sacroiliac ligament, spinous processes of inferior lumbar and sacral vertebrae, and supraspinous ligament

Insertion: spinous processes of upper thoracic vertebrae up to the cranium

Innervation: posterior rami of the spinal nerve

Action: bilaterally extend the vertebral column and when neck is flexed, lengthens fibers to control movement and unilaterally lateral