L4 - MSK Back Myology Flashcards
Muscle:
Layer #:
Layer Classification:

Trapezius M.
Layer 1
Superficial/Extrinsic
Trapezius M.
Origin:

Spinous processes of C7-T12,
Ligamentum Nuchae,
External Occipital Protuberance,
Medial 1/3 of Superior Nuchal Line of Occipital B.
Trapezius M.
Insertion:

Lateral 1/3 of the Clavicle, Acromion and Scapular Spine

Trapezius M.
Action:
Whole muscle: Rotate point of the Glenoid Cavity superiorly / Retract the Scapula
Upper fibers: Elevate Scapula
Lower fibers: Depress Scapula
Upper fibers, with the Scapula fixed:
Extend the Neck working bilaterally
Laterally Flex the Neck & Rotate the Face away when working unilaterally
Trapezius M.
Innervation:
Motor: Spinal Accessory N. (CN XI/11)
Sensory: C3, 4
Muscle:
Layer #:
Layer Classification:

Latissimus Dorsi M.
Layer 1
Superficial/Extrinsic

Latissimus Dorsi M.
Origin:

Spinous processes of T6-T12
Ribs 9-12
Iliac Crest and Spinous Processes of L1-5
Median Sacral Crest via Thoracolumbar Fascia

Latissimus Dorsi M.
Insertion:

Floor of the Humeral Intertubercular Groove

Latissimus Dorsi M.
Action:

Extend, ADduct and Medially Rotate the Humerus
Rotate the Glenoid Cavity inferiorly

Latissimus Dorsi M.
Innervation:
Thoracodorsal N. (C6-8)
Layer 2 muscles

- Rhomboid Major M.
- Rhomboid Minor M.
- Levator Scapulae M.
Rhomboid Major M.
Origin:

Spinous processes of T2-T5

Rhomboid Major M.
Insertion:

Medial border of scapula (Inferior to scapular spine)

Rhomboid Major M.
Action:

Retract and Elevate scapula
Rotate Glenoid Cavity inferiorly

Rhomboid Major M.
Innervation:
Dorsal Scapular N. (C4, 5)
Rhomboid Minor M.
Origin:

Spinous processes of C7-T1
Lower part of the Ligamentum Nuchae

Rhomboid Minor M.
Insertion:
Medial border of scapula (at scapular spine)

Rhomboid Minor M.
Action:

Retract and Elevate scapula
Rotate the Glenoid Cavity inferiorly

Rhomboid Minor M.
Innervation:
Dorsal Scapular N. (C4, 5)
Levator Scapulae M.
Origin:

O: Posterior Tubercles of Transverse processes C1-4

Levator Scapulae M.
Insertion:
I: Medial border of scapula (superior to scapular spine)

Levator Scapulae M.
Action:

Elevate scapula
Rotate the Glenoid Cavity inferiorly
When the Scapula is fixed: Extend and Laterally Flex the Neck

Levator Scapulae M.
Innervation:
N: C3, 4, Dorsal Scapular N. (C5)
Layer 3 Muscles
1.
2.

- Serratus Posterior Superior M.
- Serratus Posterior Inferior M.




























































