ILS-4: Back, Shoulder, Axilla

Extrinsic back muscle functions

Upper limb movement

Respiration

Intrinsic back muscle functions

Vertebral column movement and posture

Superficial (extrinsic muscles)

• 1st layer: trapezius, latissimus dorsi

• 2nd layer: rhomboids (minor & major), levator scapulae

Function: upper extremity movement

Intermediate (extrinsic muscles)

• 3rd layer: serratus posterior (superior & inferior)

Function: breathing

Deep (intrinsic muscles)

• Superficial: splenius capitis, splenius cervicis

• Intermediate: erector spinae (iliocostalis), longissimus, spinalis

• Deep: semispinalis (transversospinalis), multifidus, rotatores (brevis, longus)

• Minor: interspinales, intertransversarii, levatores costarum

Trapezius (origin)

• medial occipital (nuchal line)

• external occipital protuberance

• spinous processes of C7-T12

Trapezius (insertion)

Lateral 1/3 of clavicle, acromion, scapula spine

Trapezius (actions)

• Descending part: elevate scapula

• Transverse part: pull scapula medially

• Ascending part: pull medial border of scapula downward

Trapezius (innervation)

• CN XI

• C3 and C4 sensory

Trapezius (spinal movements)

Co-contraction of both scapulae > Neck extension

Trapezius (exercises)

• Upper: elevate shoulders

• Middle: pull bar horizontally

• Lower: torso elevation on parallel bars (drawing shoulder blades downward)

Latissimus Dorsi (origin)

• spinous process T7-T12

• thoracolumbar fascia

• posterior iliac crest

• inferior 3-4 ribs

• inferior angle of scapula

Latissimus Dorsi (insertion)

Floor of intertubercular (bicipital) groove of humerus

Latissimus Dorsi (action)

Extend, adduct, medial rotation of humerus, raise body during climbing

Latissimus Dorsi (innervation)

Thoracordorsal nerve (C6-C8)

Latissimus Dorsi (exercise)

• Vertical: pull-down, pull-up, chin-up

• Horizontal: Bent-over row, T-bar row

Levator Scapulae (origin)

Transverse processes of upper four cervical

Levator Scapulae (insertion)

Medial border of scapula

Levator Scapulae (action)

Stabilize, elevate, and inferiorly rotate scapula

Levator Scapulae (innervation)

C3 and C4 (dorsal scapular nerve)

Rhomboids minor (origin)

Lower nuchal ligament and spinous processes of C7 and T1

Rhomboids minor (insertion)

Inferior-medial scapula

Rhomboids minor (innervation)

Dorsal scapular nerveR

Rhomboids minor (action)

Stabilize, retract, inferiorly rotate scapula

Rhomboids major (origin)

Spinous processes of T2-T5

Rhomboids major (insertion)

Medial scapula

Rhomboids major (action)

Stabilize, retract, inferiorly rotate scapula

Rhomboids major (innervation)

Dorsal scapular nerve

Scapula Rotators (upward rotators)

Overhead reach

• Upper/lower trapezius

• Serratus anterior

Scapula Rotators (downward rotators)

Lower arm

• Rhomboids

• Levator scapulae

• Pectoralis minor

Serratus Posterior Superior (origin)

Ligamentum nuchae

Spinous C7-T3

Serratus Posterior Superior (insertion)

2nd to 5th ribs

Serratus Posterior Superior (action)

Elevates ribs

Serratus Posterior Superior (innervation)

Intercostal nerves

Serratus Posterior Inferior (origin)

Spinous T11 to L2/L3

Serratus Posterior Inferior (insertion)

Low 4 ribs

Serratus Posterior Inferior (action)

Lower ribs

Serratus Posterior Inferior (innervation)

Intercostal