Back Myology Flashcards
(72 cards)
What is the relation of Six Layer model of back muscles to Extrinsic/Intrinsic catergories?
- The superficial 3 layers are extrinsic (innervated by a branch of an Anterior Ramus or Cranial nerve)
- The deep 3 layers are intrinsic (innervated by Posterior Rami)
What are the muscles present in layer 1 of the back?
- Trapezius M.
- Latissimus Dorsi M.
What muscle is this?

Trapezius M.
What muscle is this?

Lattisimus Dorsi M.
Trapezius M.
Origin:
Insertion:
Action:
Innervation:
Origin: Spinous processes of C7-T12, Ligamentum Nuchae, External Occipital Protuberance and medial 1/3 of Superior Nuchael Line of Occipital B.
Insertion: Lateral 1/3 of the Clavicle, Acromion and Scapular Spine
Action: Whole muscle (rotate point of the Glenoid Clavity superiorly, retract the Scapula); upper fibers (elevate Scapula); lower fibers (depress Scapula); with the Scapula fixed the upper fibers with extend the Neck working bilaterally, laterally flex the Neck and rotate the Face away when working unilaterally
Innervation: Motor: Spinal Accessory N. (CN XI); Sensory: C3,4
Lattisimus Dorsi M.
Origin:
Insertion:
Action:
Innervation:
Origin: Spinous Processes of T6-12, Ribs 9-12, Iliac Crest and Spinous Processes of L1-5, and Median Sacral Crest via Thoracolumbar Fascia
Insertion: Floor of the Humeral Intertubercular Groove
Action: extend, abduct, and medially rorate the Humerus; rotate the Glenoid Cavity inferiorly
Innervation: Thoracodorsal N. (C6-8)
What muscles are present in layer 2 of the back?
- Rhomboid Major M.
- Rhomboid Minor M.
- Levator Sapulae M.
What muscle is this?

Rhomboid Major M.
What muscle is this?

Rhomboid Minor M.
What muscle is this?

Levator Scapulae M.
Rhomboid Major M.
Origin:
Insertion:
Action:
Innervation:
Origin: Spinous Processes of T2-5
Insertion: Medial border of Scapula (inferior to Scapular Spine)
Action: Retract and elevate Scapula, rotate the Glenoid Cavity inferiorly
Innervation: Doral Scapular N. (C4, 5)
Rhomboid Minor M.
Origin:
Insertion:
Action:
Innervation:
Origin: Spinous Processes of C7-T1, lower part of the Ligamentum Nuchae
Insertion: Medial border of Scapula (at Scapular Spine)
Action: Retract and elevate Scapula, rotate the Glenoid Cavity inferiorly
Innervation: Dorsal Scapular N. (C4, 5)
Levator Scapulae M.
Origin:
Insertion:
Action:
Innervation:
Origin: Posterior Tubercles of Transverse Processes C1-4
Insertion: Medial border of Scapula (superior to Scapular Spine)
Action: Elevate Scapula, rotate the Glenoid Cavity inferiorly; when the Scapula is fixed, extend and laterally flex the Neck
Innervation: C3, 4, Dorsal Scapular N. (C5)
What muscles are present in layer 3 of the back?
- Serratus Posterior Superior M.
- Serratus Posterior Inferior M.
What muscle is this?

Serratus Posterior Superior M.
What muscle is this?

Serratus Posterior Inferior M.
Serratus Posterior Superior M.
Origin:
Insertion:
Action:
Innervation:
Origin: Nuchal L. and Spinous Processes C7-T3
Insertion: Superior surfaces of Ribs 2-4
Action: Elevate Ribs with forced inspiration (primarily proprioceptive)
Innervation: Intercostal N. (2-5)
Serratus Posterior Inferior M.
Origin:
Insertion:
Action:
Innervation:
Origin: Spinous Processes T11-L2
Insertion: Inferior surface of Ribs 8-12
Action: Depress Ribs with forced expiration (primarily proprioceptive)
Innervation: Anterior Rami T9-12
What muscles are present in layer 4 of the back?
- Splenius Capitis M.
- Splenius Cervicis M.
What muscle is this?

Splenius Capitis M.
What muscle is this?

Splenius Cervicis M.
Splenius Capitis M.
Origin:
Insertion:
Action:
Innervation:
Origin: Lower 1/2 Nuchal L., Spinous Processes C7-T3(4)
Insertion: Mastoid Process of Temporal B., lateral 1/3 Superior Nuchal Line of the Occipital B.
Action: Extend the Neck when working bilaterally; laterally flex the Neck and rotate Face toward when working unilaterally
Innervation: Posterior Rami C3-5
Splenius Cervicis M.
Origin:
Insertion:
Action:
Innervation:
Origin: Spinous Processes T3-6
Insertion: Transverse Processes C1-3(4)
Action: Extend the Neck when working bilaterally; laterally flex the Neck and rotate Face toward when working unilaterally
Innervation: Posterior Rami C5-7
What muscles are present in layer 5 of the back?
(intrinsic, largest layer)
- Iliocostalis (lateral group): Iliocostalis Lumborum M., Iliocostalis Thoracis M., Iliocostalis Cervicis M.
- Longissimus (intermediate group): Longissimus Thoracis M., Longissinus Cervicis M., Longissimus Capitis M.
- Spinalis (medial group): Spinalis Thoracis M. (often blends with Longissimus Thoracis M.), Spinal Cervicis M. (usually absent), Spinalis Capitis M. (usually absent or blended with Semispinalis Capitis M.)




























