Back muscles Flashcards
What are the 6 layers of muscles in the back, and their contents?
Extrinsic - superficial
(traps, lat dorsi, lev scap, rhomboids)
Extrinsic - intermediate
(serraturs posterior inferior & superior)
Intrinsic - superficial
(splenius cap & cerv)
Intrinsic - intermediate (erector spinae)
(iliocostalis, longissimus, spinalis)
Intrinsic - deep (transverspinalis)
(semispinalis, rotatores, multifidi)
Intrinsic - deep accessory (interspinalis)
(interspinalis, intertransversari, levator costarum)
Describe the anatomy of the extrinsic superficial muscle group
4 muscles - trapezius, levator scapulae, rhomboids, latissimus dorsi
Trapezius:
PA: EOP, superior nuchal line, nuchal ligament, C7-T12 SPs
DA: lateral 1/3 clavicle, acromion, spine of scap
NS: motor: CNXI accessory, sensory C3-4 spinal
Actions: elevates, retracts and depresses scap
Levator Scapulae:
PA: C1-4 TPs
DA: medial border of scap (superior to spine)
NS: Dorsal scapular, C3-4 spinal
Actions: rotates medial border of scap superiorly
Rhomboids:
PA: Nuchal ligament and C7-T1 SPs(minor); T2-5 SPs (major)
DA: medial border of scap - minor superior to spine, major inferioro to spine
NS: Dorsal scapular
Actions: retract & elevate scap, rotate medial border of scap superiorly
Latissimus Dorsi:
PA: iliac crest, thoracolumbar fascia, T6-12 TPs, ribs 9-12
DA: bicipital groove of humerus (floor)
NS: Thoracodorsal
Actions: extends, abducts and internally rotates humerus, draws body towards arms when arms overhead
Describe the anatomy of the extrinsic intermediate muscles
2 muscles - serratus posterior superior and inferior
Serratus Posterior Superior: PA: nuchal ligament, C7-T3 SPs DA: ribs 2-5 NS: ventral rami T2-5 Actions: elevates ribs, inspiration
Serratus Posterior Inferior: PA: T11-L2/3 DA: ribs 9-12 NS: ventral rami T9-12 Actions: depresses ribs, expiration
Describe the anatomy of the intrinsic superficial muscles
2 muscles - splenius capitis and cervicis
Splenius Capitis: PA: nuchal ligament & C7-T3 TPs DA: occiput laterally NS: dorsal rami C3-4 Actions: extends and laterally flexes head and neck
Splenius Cervicis:
PA: T3-6 (SPs & supraspinous ligaments)
DA: C1-3 TPs
NS: dorsal rami C5-7
Actions: extends, rotates and laterally flexes neck
Describe the anatomy of the intrinsic intermediate muscles (erector spinae)
3 muscles - iliocostalis, longissimus & spinalis
Common actions: bilaterally extend vertebrae, and unilalterally side bend vertebrae
Common nerve supply: segmental spinal nerves
Segments:
Iliocostalis - Lx, Tx, Cx (SIJ to C4)
Longissimus - Tx, Cx, Cap (sacrum to mastoid process)
Spinalis - Tx, Cx, Cap (L3 to EOP)
Iliocostalis - from common tendon at sacroiliac joint, to all ribs, and C4-6 TPs
Longissimus -from sacrum and Lx SPs to TPs Tx, Cx, and mastoid process
Spinalis - from C2-L3 SPs to SPs in same segment, EOP
Describe the anatomy of the intrinsic deep (transversospinales) group
3 muscles - semispinalis, multifidis, rotatores (brevis and longus)
Common nerve supply: segmental spinal nerves
Common anatomy: all originate from TPs and move superomedially to SPs
Common actions: extension and stabilization of vertebrae
Orientation:
- semispinalis: most superficial, Tx to skull, span 4-6
- Multifidis: mostly in Lx, span 2-4
- Rotatores: mostly in Tx, span 1-2
Semispinalis:
- from TPs to SP 2-4 segments above
- anchors sacrum & occiput
Multifidis:
- from TPs to SP 1-2 segments above (brevis or longus)
Describe the anatomy of the intrinsic minor deep / accessory group (interspinalis)
3 muscles - interspinous, intertransversari, levator costarum
- only span 1 segment
- no independent movement: stabilize spine and assist other movements
- innervated by segmental spinal nerves
Segments:
- interspinous: Cx, Lx
- intertransversari - mostly Tx
- levator costarum - only Tx
Interspinous - between adjacent SPs
Intertransversari - between adjacent TPs
Levator costarum - between TPs & ribs
