Lecture 4: Back Myology Flashcards
What are the two Layer 1 muscles of the back and what are their innervations?
- Trapezius M. (Spinal Accessory Nerve XI)
2. Latissimus Dorsi M. (Thoracodorsal N.)
Trapezius M. action
- Whole muscle: rotate Glenoid Cavity superior/retract scapula
- upper fibers (elevate scapula), lower fibers (depress)
- laterally flex and rotate face away (unilateral)
Latissimus Dorsi M. action
- extend, ADduct, medially rotate humerus
- rotate Glenoid Cavity inferiorly
What are the 3 Layer 2 muscles of the back and what are their innervations?
- Levator Scapulae
- Rhomboid Minor
- Rhomboid Major
innervation: Dorsal Scapular N.
Rhomboid Minor and Major M. actions
- retract/elevate scapula
- rotate Glenoid Cavity Inferiorly
Levator Scapulae M. action
- elevate scapula, Rotate Glenoid Cavity inferiorly
- [fixed scap] –> extend, laterally flex neck
What are the 2 Layer 3 muscles of the back and what are their innervations?
- Serratus Posterior Superior M. (Intercostal N.)
2. Serratus Posterior Inferior M. (T9-T12)
Serratus Posterior Superior and Inferior M. actions
Superior: elevate ribs w/forced inspiration
Inferior: depress ribs w/forced expiration
What are the 2 Layer 4 muscles of the back and what are their innervations?
- Splenius Capitis M. (posterior rami)
2. Splenius Cervicis M. (posterior rami)
Splenius Capitis and Splenius Cervicis M. actions
- extend neck (bilaterally)
- laterally flex and rotate face toward (unilaterally)
What is the Layer 5 muscles and what is its innervation?
Erector Spinae Group (posterior rami)
What are the 3 groups that make up Erector Spinae group, and what are the 3 divisions of each of those groups? (I Love Spaghetti)
- Iliocostalis M. (lumborum, thoracis, cervicis)
- Longissimus M. (thoracis, cervicis, capitis)
- Spinalis (thoracis, cervicis, capitis)
Back Sprain vs Back Strain
Sprain: injury to ligamentous attachments between bones (inadequate stretching)
Strain: excessive stretch/tearing of muscle fibers (overly strong muscle contraction)
What are the 4 Layer 6 muscles of the back and what are their innervations/actions?
- Rotatores Brevis (extend to adjacent spinal segment)
- Rotatores Longus (extend 2 spinal segments)
- Mutifidus M. (extend 3/4 spinal segments)
- Semispinalis M. (extend 5/6 spinal segments)
innervation: posterior rami
action: extend spine, rotate spine away
What are the 3 divisions of the semispinalis M. and what are their actions?
- thoracis, cervicis, capitis
action: extend spine (neck), rotate spine (face) away
Interspinalis M. action and innervation
action: extend spine
innervation: posterior rami
Intertransversarii M. action and innervation
action: laterally flex spine
innervation: anterior AND posterior rami
Levator Costarum Longus and Brevis M. action and innervation
Longus: extend to 2nd rib inferior from origin
Brevis: extend to adjacent rib inferior from origin
action: elevate ribs
innervation: posterior rami
What are the 4 Suboccipital Region muscles and what are their innervation?
- Rectus Capitis Posterior Major M.
- Rectus Capitis Posterior Minor M.
- Obliquus Capitis Superior M.
- Obliquus Capitis Inferior M.
innervation: Suboccipital N.
Rectus Capitis Posterior Major M. action
extend head, rotate face toward
Rectus Capitis Posterior Minor M. action
extend head
Obliquus Capitis Superior M. action
extend, laterally flex neck
Obliquus Capitis Inferior M. action
rotate face toward
What are the two structures moving through the Suboccipital Triangle and what structure is present inferior to the Triangle?
- in triangle: Vertebral A. and Suboccipital N.
- below triangle: Greater Occipital N.
