Back Myology Flashcards
The 3 superficial layers of the back are extrinsic and innervated by…
Anterior rami or cranial nerves
The 3 deep layers of the back are intrinsic and innervated by…
Posterior rami
What is in the first muscle layer of the back?
Trapezius m.
Latissimus dorsi m.
What are the actions of the whole Trapezius m.?
- Rotation of point of shoulder (glenoid cavity)
- Retract scapula
- Rotate scapula
What are the actions of the upper fibers of the Trapezius m.?
– Elevate scapula
What are the actions of the lower fibers of the Trapezius m.?
– Depress scapula
What are the actions of the Trapezius m. when the scapula is fixed?
- Extend neck (bilaterally)
- Laterally flex neck (unilaterally)
- Rotate face away (unilaterally)
What is the innervation of the Trapezius m.?
Motor = Spinal accessory N. (CN XI) Sensory = C3, 4
What is the origin of the Trapezius m.?
- Medial 1/3 of the superior nuchal line
- External occipital protuberance
- Nuchal line
- Spinous processes of C7-T12
What is the insertion of the Trapezius m.?
- Lateral 1/3 of clavicle
- Acromion
- Scapular spine
What is the origin of the Latissimus Dorsi m.?
- Spinous processes of T6-L5
- Ribs 9-12
- Iliac crest
- Median sacral crest via thoracolumbar fascia
What is the insertion of the Latissimus Dorsi m.?
Floor of humeral intertubercular groove
What are the actions of the Latissimus Dorsi m.?
- Extend humerus
- Adduct humerus
- Medially rotate humerus
- Rotate point of shoulder down (glenoid cavity)
What innervates the Latissimus Dorsi m.?
Thoracodorsal n. (C6-8)
***Also supplied by Thoracodorsal artery
What is the 2nd layer of the back muscles?
Rhomboid major m.
Rhomboid minor m.
Levator scapulae m.
What is the origin of the rhomboid major m.?
Spinous processes of T2-T5
What is the insertion of the rhomboid major m.?
Medial border of scapula (inferior to scapular spine)
What are the actions of the rhomboid major m. and rhomboid minor m.?
- Retract scapula
- Elevate scapula
- Rotate point of shoulder down (glenoid cavity)
What is the origin of the rhomboid minor m.?
Spinous processes of C7-T1
What is the insertion of the rhomboid minor m.?
Medial border of the scapula (at scapular spine)
What is the origin of the Levator Scapulae m.?
Posterior tubercles of transverse processes C1-4
What is the insertion of the Levator Scapulae m.?
Medial border of the scapula (superior to scapular spine)
What actions does the Levator Scapulae m. perform?
- Retract scapula
- Elevate scapula
- Rotate point of shoulder down (glenoid cavity)
***Same as rhomboids
What actions does the Levator Scapulae m. do when the scapula is fixed?
- Extend neck (bilaterally)
- - Laterally flex neck (unilaterally)
What innervates the 2nd layer of back muscles?
Dorsal scapular N. (C4-5)
What is part of the 3rd layer of back muscles?
Serratus Posterior Superior m.
Serratus Posterior Inferior m.
What is the origin of the Serratus Posterior Superior m.?
- Nuchal L.
- - Spinous Processes C7-T3
What is the insertion of the Serratus Posterior Superior m.?
Superior surfaces of Ribs 2-4
What are the actions of the Serratus Posterior Superior m.?
Elevate ribs with forced inspiration (proprioceptive)
What is the origin of the Serratus Posterior Inferior m.?
Spinous Processes T11-L2
What is the insertion of the Serratus Posterior Inferior m.?
Inferior surface of Ribs 8-12
What are the actions of the Serratus Posterior Inferior m.?
Depress ribs with forced expiration (proprioceptive)
What innervates the Serratus Posterior Superior m.?
Intercostal N. (2-5)
What innervates the Serratus Posterior Inferior m.?
Anterior Rami T9-12
What is in the 4th layer of back muscles?
Splenius Capitis m.
Splenius Cervicis m.
What is the origin of the Splenius Capitis m.?
- Lower 1/2 of nuchal l.
- - Spinous processes C7-T3/T4
What is insertion of the Splenius Capitis m.?
- Mastoid process of Temporal B.
- Lateral 1/3 of superior nuchal line
- Occipital B.
What are the actions of the Splenius Capitis m. and Splenius Cervicis m.?
- Extend neck
- Laterally flex neck
- Rotate face toward muscle
What is the origin of the Splenius Cervicis m.?
Spinous processes T3-T6
What is the insertion of the Splenius Cervicis m.?
Transverse processes C1-C3/C4
What innervates layer 4 of the back muscles?
Posterior Rami (C3-5 for capitis, C5-7 for cervicis)
What is part of the 5th muscle layer in the back?
Erector Spinae Group
What actions do the Erector Spinae group perform?
- Maintain erect posture
- Extend vertebral column
- Extend head
- Laterally flex vertebral column
***Longissimus capitis can also rotate face toward muscle
What is the most lateral of the erector spinae group? What are its parts?
Iliocostalis m.
Iliocostalis Lumborum m.
Iliocostalis Thoracis m.
Iliocostalis Cervicis m.
***ONLY one with a Lumborum section
What is the origin and insertion for the Iliocostalis group of muscles?
Lumborum – Goes from Iliac/Sacral crests to the ribs
Thoracis – Goes from Ribs to Ribs and C7
Cervicis – Goes from Ribs to Posterior tubercles of C4-6
What is the intermediate part of the Erector Spinae group? What are its parts?
Longissimus m.
Longissimus thoracis m.
Longissimus cervicis m.
Longissimus capitis m.
What is the origin and insertion for the Longissimus group of muscles?
Thoracis – Lumbar vert. and sacral/iliac crests to Ribs
Cervicis – Thoracic vert. to Cervical vert.
Capitis – Thoracic and Cervical vert. to Mastoid process
What is most medial part of the Erector Spinae group? What are its parts?
Spinalis m.
Spinalis Thoracis m.
Spinalis Cervicis m.
Spinalis Capitis m.
***Cervicis and Capitis are usually absent, will not see in Lab
What are the origin and insertion for the Spinalis group of muscles?
Thoracis – Spinous processes T11-L2 to T1-T4
Cervicis – Spinous processes T1-6 to C2 (3,4)
Capitis – Usually blended with Semispinalis Capitis m.
A back (STRAIN/SPRAIN) is an injury to the ligamentous attachments between bone, usually the result of inadequate stretching before activity.
Sprain
A back (STRAIN/SPRAIN) involves excessive stretching and sometimes tearing of muscle fibers produced by an overly strong muscular contraction. Tissue will spasm, or involuntarily contract in response to injury and inflammation as a protective measure.
Strain
What is in the 6th layer of back muscles?
Transversospinalis group
What innervates the 5th layer of back muscles?
Posterior Rami
What are the actions of the Transversospinalis group?
- Extend spine
- Rotate spine away (from muscle)
***Only difference is Semispinalis capitis which extends HEAD and rotates FACE away from muscle
What innervates the Transversospinalis group?
Posterior rami
What are the origin and insertion for the Transversospinalis group?
Run from Transverse processes to Spinous processes on different vertebrae
***Except Semispinalis capitis which inserts b/w superior and inferior nuchal line
What are the parts of the Transversospinalis group? How many spinal segments do each stretch?
- Semispinalis group (extend 5 or more segments)
- Multifidus m. (extend 3 or 4 segments)
- Rotatores longus m. (extend 2 segments)
- Rotatores brevis m. (extend 1 segment)
What is in the Semispinalis group?
Semispinalis Thoracis m.
Semispinalis Cervicis m.
Semispinalis Capitis m. (Spinalis capitis blends with this)
These muscles stretch from one spinous process to the adjacent spinous process and extend the spine.
Interspinalis m.
These muscles stretch from one transverse process to the adjacent transverse process and laterally flex spine.
Intertransversarii m.
***Has an anterior and posterior portion. Anterior is innervated by Anterior Rami, posterior is Posterior Rami
This muscle stretches from transverse processes C7-T11 to the 2nd rib inferior to the origin. Elevates ribs.
Levator Costarum Longus m.
This muscle stretches from transverse processes C7-T11 to the adjacent rib inferior to origin. Elevates ribs.
Levator Costarum Brevis m.
What makes up the suboccipital region?
Rectus Capitis Posterior Minor m.
Rectus Capitis Posterior Major m.
Obliquus Capitis Superior m.
Obliquus Capitis Inferior m.
What are the actions of the sub occipital muscles?
- Extend head
- - Rotate face toward muscle
What innervates the sub occipital muscles?
Suboccipital n.
What are the boundaries of the sub occipital triangle?
Rectus Capitis Posterior Major m. – Medial border
Obliquus Capitis Superior m. – Lateral border
Obliquus Capitis Inferior m. – Inferior border
What is contained inside the sub occipital triangle?
Vertebral a. (travels through floor of triangle)
Suboccipital n. (posterior ramus of 1st cervical spine n.)