Back Myology Flashcards
Innervation for superficial 3 layers of back
Branch of an anterior ramus or cranial nerve
Innervation for deep three layers of back
Posterior rami
Trapezius OIN (origin, insertion, innervation)
O- spinous processes of C7-T12, ligamentum nuchae, external occipital protuberance and medial 1/3 of superior nuchal line
I- Lateral 1/3 of clavicle, acromion and scapular spine
N- Motor- CN XI
Sensory- C3, 4
Latissimus dorsi OIN
O- spinous processes of T6-12, L1-5, ribs 9-12, iliac crest and median sacral crest via thoracolumbar fascia
I- floor of the humeral intertubercular groove
N- Thoracodorsal N (C6-C8)
Trapezius action
Whole muscle- rotates point of the glenoid cavity superiorly, retracts scapula
Upper fibers- elevate scapula
Lower fibers- depress scapula
With scapula fixed, upper fibers will extend the neck bilaterally, laterally flex the neck and rotate the face away when working unilaterally
Latissimus dorsi action
Extend, adduct and medially rotate humerus, rotate glenoid cavity inferiorly
Layer 2 muscles include
Rhomboid major/minor
Levator scapulae
Rhomboid major OIN
O- Spinous processes of T2-T5
I- medial border of scapula (inferior to scapular spine)
N- Dorsal scapular nerve C4,5
Rhomboid major action
Retract and elevate scapula, rotate glenoid cavity inferiorly
Rhomboid minor OIN
O- spinous processes of C7-T1, lower part of ligamentum nuchae
I- medial border of scapula (at scapular spine)
N- Dorsal scapular nerve C4,5
Rhomboid minor action
Retract and elevate scapula, rotate glenoid cavity inferiorly
Levator scapulae OIN
O- posterior tubercles of transverse processes C1-4
I- medial border of scapula (superior to scapular spine)
N- C3,4 Dorsal scapular C5
Levator scapulae action
Elevate scapula, rotate glenoid cavity inferiorly, laterally flex neck when scapula is fixed
Layer 3 muscles include
Serratus posterior superior
Serratus posterior inferior
Serratus posterior superior OIN
Nuchal line and spinous processes C7-T3
I- superior surfaces of ribs 2-4
N- Intercostal nerve 2-5
Serratus posterior inferior OIN
O-Spinous processes T11-L2
I- superior surfaces of ribs 8-12
N- anterior rami T9-12
Serratus posterior superior/inferior action
Superior- elevate ribs with forced inspiration
Inferior- depress ribs with forced expiration
Layer 4 muscles include
Splenius capitis
Splenius cervicis
Splenius capitis OIN
O- Lower 1/2 nuchal line, spinous process C7-T3(4)
I- mastoid process of temporal bone, lateral 1/3 superior nuchal line of occipital bone
N- posterior rami C3-5
Splenius capitis/cervicis action
Extend neck when working bilaterally, laterally flex neck and rotate face toward when working unilaterally
Splenius cervicis OIN
O- spinous processes T3-6
I- Transverse processes C1-3(4)
N- Posterior rami C5-7
Layer 5 muscles
Erector spinae group:
Iliocostalis (lateral group)
Longissimus (intermediate group)
Spinalis (medial group)
Action and innervation of all erector spinae group muscles
A- maintain erect posture and extend the vertebral column and head when working bilaterally. Laterally flex the vertebral column when working unilaterally
N- Segmentally innervated by posterior rami of spinal nerves
Iliocostalis lumborum OI
O- posteromedial iliac crest, spinous processes T11-L5, median sacral crest, lateral sacral crest, sacrotuberous ligament and long posterior sacroiliac ligament
I- Costal angles of ribs 6-12
Iliocostalis thoracic OI
O- costal angles of ribs 6-12
I- costal angles of ribs 1-6 and transverse process C7
Iliocostalis cervicis OI
O- costal angles of ribs 3-6
I- posterior tubercles of transverse processes C4-6
Longissimus thoracis OI
O- common origin with iliocostalis lumborum, transverse and accessory processes L1-5
I- Transverse processes T1-L2, Ribs 3-12 b/w costal angle and costal tubercle
Longissimus cervicis OI
O- transverse processes T1-5
I- posterior tubercles of transverse processes and articular processes of C2-6
Longissimus capitis OI
O- transverse processes T1-5, articular processes C4-7
I- mastoid process of temporal bone
Spinalis thoracis OI
O- spinous processes T11-L2
I- spinous processes T1-4
Spinalis cervicis OI
O- Spinous processes T1-6
I- spinous processes C2 (3,4)
Spinalis capitis
Usually absent or blended with semispinalis capitis
Strain vs sprain
Strain involves excessive stretching or tearing of muscle fibers from overly strong contraction
Sprain is an injury to the ligamentous attachments between bone- due to inadequate stretching
Layer 6 muscles include, and what innervates them
Semispinalis group Multifidus Rotatores longus Rotatores brevis Innervated by posterior rami
Semispinalis thoracis OI
O- transverse processes T6-12
I- spinous processes C6-T4
Semispinalis cervicis OI
O- Transverse processes T1-6
I- Spinous processes C2-5
Semispinalis thoracis/cervicis action
Extend spine and rotate spine away
Semispinalis capitis OI
O- transverse proc. C7-T6, articular processes C4-6
I- b/w superior/inferior nuchal lines of occipital bone
Semispinalis capitis action
Extend head, rotate face away
Multifidus OI
O- mamillary processes of lumbar vertebrae, transverse processes of thoracic vertebrae and articular processes of C4-7
I- spinous processes three numeric segments superior, does not insert onto atlas
Multifidus action
Extend spine, rotate spine away
Rotatores longus OI and action
O- transverse processes
I- roots of spinous processes 2 segments superior
A- Extend spine, rotate spine away
Rotatores brevis OI and action
O- transverse processes
I- roots of spinous processes 1 segment superior
A- extend spine, rotate spine away
Interspinalis OIN and action
O- spinous process
I- adjacent spinous process
N- posterior rami
A- Extend spine
Intertransversarii OIN and action
O- transverse process
I- adjacent spinous process
N- posterior rami
A- extend spine
Levator costarum longus OIN and action
O- transverse processes C7-T11
I- 2nd rib inferior to origin
N- posterior rami
A- elevate ribs
Levator costarum brevis OIN and action
O- transverse processes C7-T11
I- adjacent rib inferior to origin
N- posterior rami
A- elevate ribs
Rectus capitis posterior major OIN and action
O- spinous process C2
I- lateral portion of inferior nuchal line
N- suboccipital nerve
A- extend head, rotate face toward
Rectus capitis posterior minor OIN and action
O- posterior tubercle of C1
I- below inferior nuchal line
N- suboccipital nerve
A- extend head
Obliquus capitis inferior OIN and action
O- spinous process C2
I- transverse process C1
N- suboccipital nerve
A- rotate face forward
Obliquus capitis superior OIN and action
O- transverse process C1
I- b/w superior and inferior nuchal lines
N- suboccipital nerve
A- extend and laterally flex head
Boundaries of suboccipital triangle include
Rectus capitis posterior major (medial), obliquus capitis inferior (inferior), obliquus capitis superior (lateral)
Contents of suboccipital triangle
Vertebral artery travels through the floor Suboccipital nerve (which is the posterior ramus of the 1st cervical spinal nerve) and innervates musculator of suboccipital region
Suboccipital muscles include
Rectus capitis posterior major/minor
Obliquus capitis inferior/superior
