Muscles of the Back Flashcards
What 3 muscles is the Erector Spinae composed of?
Composed of three muscular columns (lateral to medial): iliocostalis, longissimus, and spinalis
(Erector spinae known as “antigravity” muscles)
Common origin for the Erector Spinae
dorsal sacrum, iliac crest, and spinous processes
Innervation of Erector Spinae
Dorsal rami of spinal nerves
Action of Erector Spinae
Unilateral: lateral flexion and rotation of vertebral column and head
Bilateral: extension of vertebral column and head
Origin of Iliocostalis
Common origin and ribs
Action of Iliocostalis
Unilateral: lateral flexion of vertebral column
Bilateral: extension of vertebral column
Depression of ribs
Insertion of Iliocostalis
Ribs Transverse processes (cervical)
Innervation of Iliocostalis
Dorsal rami of spinal nerves
Action of Latissimus Dorsi
Adduction of arm
Extension of arm
Medial rotation of arm
Origin of Latissimus Dorsi
Sacral and lumbar spines via thoracolumbar fascia
Ilium (iliac crest) via thoracolumbar fascia
Ribs (lower four)
Spinous processes of T6-12 vertebrae
Scapula (inferior angle)
Insertion of Latissimus Dorsi
Humerus (floor of intertubercular sulcus)
Innervation of Latissimus Dorsi
Thoracodorsal nerve
Action of Levator Scapulae
Elevation of scapula (e.g., shrugging shoulders)
Inferior rotation of scapula (directing glenoid fossa inferiorly)
Lateral flexion of neck (when scapula fixed)
Origin of Levator Scapulae
Transverse processes of C1-4 vertebrae
Insertion of Levator Scapulae
Scapula (superior angle and medial border)
Innervation of Levator Scapulae
Dorsal scapular nerve
Ventral rami of C3-4 spinal nerves
Action of Longissimus
Unilateral: lateral flexion of vertebral column and rotation of head to same side
Bilateral: extension of vertebral column and head
Depresses ribs
Origin of Longissimus
Iliac crest
Dorsal sacrum
Sacral and lumbar spinous processes
Supraspinous ligament
Insertion of Longissimus
Transverse processes (cervical and thoracic), ribs, and mastoid process
Innervation of Longissimus
Dorsal rami of spinal nerves
Action of Rhomboid Major
Retraction (adduction) of scapula
Elevation of scapula
Origin of Rhomboid Major
Spinous processes of T2-5 vertebrae
Insertion of Rhomboid Major
Scapula (medial border)
Innervation of Rhomboid Major
Dorsal scapular nerve
Action of Rhomboid Minor
Retraction (adduction) of scapula
Elevation of scapula
Origin of Rhomboid Minor
Spinous processes of C7-T1 vertebrae