Back Muscles Flashcards
Trapezius
Decided into parts: Superior fibers, Middle fibers, Inferior fibers
ORIGIN: Medial 1/3 superior nuchal line, external occipital protuberance, nuchal l., SPs of C7-T12
INSERTION: Lateral 1/3 clavicle, acromion and spine of scapula
ACTION:Superior - elevation of scapula
Middle - retraction of scapula
Inferior - depression of scapula
Superior and inferior fibers together - upward rotation of scapula
INNERVATION: Motor - CN XI (Spinal accessory n.) Sensory - C3, C4
BLOOD SUPPLY: Transverse cervical a.
Latissimus Dorsi
Covers wide area of back, passes from posterior trunk medially to anterior humerus
ORIGIN: SPs of T6-12, thoracolumbar fascia, iliac crest, inferior 3 or 4 ribs
INSERTION: Floor of intertubercular (IT) groove (sulcus) of humerus
ACTION: Extension, ADD, MR of humerus, downward rotation of scapula; raises body towards arms when climbing
N: Thoracodorsal N.
B: Thoracodorsal a.
Levator Sacpulae
Lies deep to sternocleidomastoid and trapezius mm.
Fibers pass inferiorly from origin to insertion
O: Posterior tubercles of TPs C1-4
I: Medial border of scapula, superior to root of scapular spine
A: Elevation and downward rotation of scapula; bilaterally, extension of neck
N: Dorsal scapular n.
B: Dorsal scapula a.
Rhomboid Major
Lies deep to trapezius, inferior to rhomboid minor m.
O:SPs T2-5
I: Medial border of scapula from level of spine to inferior angle
A: Retraction and downward rotation of scapula; fix scapula to thoracic wall
N: Dorsal scapular n.
B: Doral scapular a.
Rhomboid Minor
Lies deep to trapezius, superior to rhomboid major m.
O: Nuchal l. And SPs of C7 and T1
I: Smooth triangular area at base of scapular spine
A: Retraction and downward rotation of scapula; fix scapula to thoracic wall
N: Dorsal scapular n.
B: Dorsal scapular a.
Serratus Posterior Superior
O: Nuchal L., SPs (spinous process) C7-T3
I: Superior borders of 2nd to 4th ribs
A: Proprioception (elevation of ribs); considered accessory m. Of respiration.
N: 2nd-5th intercostal nn.
Serrated Posterior Inferior
O: SPs T11-L2
I: inferior borders of 8th-12th ribs near their angles.
A: Proprioception (depress ribs); considered accessory m. Of respiration.
N: Ventralrami of T9-T12 thoracic spinal nn.
Splenius Cervicis
O: SPs of T3-T6
I: Tubercles of TPs C1-C3
A: Ipsilateral rotation and lateral flexion; bilaterally extension of the neck.
N: Dorsal rami of spinal nn.
Splenius Capitis
O: Nuchal L. And SPs of C7-T3
I: Mastoid Process and lateral 1/3 of superior Nuchal line
A: Ipsilateral rotation and lateral flexion; bilaterally extension of neck.
N: Dorsal rami of spinal nn.
Iliocostalis
Forms the later column
O: Posterior part of iliac crest, post surface of sacrum, sacroiliac ligament, sacral & inferior lumbar SPs & supraspinous ligament
I:
Lumborum- angles of lower ribs
Thoracis- Angles of upper ribs
Cervicis- cervical TPs
A: Bilateral- extension of vertebral column, unilateral- flexion of vertebral column.
N: Dorsal rami of spinal nn.
Longissimus
Forms Intermediate Column
O: Posterior part of the iliac crest, posterior surface of sacrum, sacroiliac ll., sacral and inferior lumbar SPs and supra spinous I.
I:
Thoracis- ribs between tubercles and angles of TPs in thoracic region.
Cervicis- Cervical TPs
Capitals- Mastoid process
A: Bilateral- extension of vertebral column and head; unilateral- lateral flexion of vertebral column.
N: Dorsal rami of spinal nn.
Spinalis
Forms medial column
O: Posterior part of the iliac crest, posterior surface of sacrum, sacroiliac ll., sacral and inferior lumbar SPs and supra spinous l.
I:
Thoracis- SPs in thoracic region
Cervicis- SPs in cervical region (often absent)
Capitis- cranium (sometimes fuses with semispinalis capitis to form biventer capitis.)
A: Bilateral- extension of vertebral column and head; unilateral- lateral flexion of vertebral column.
N: Dorsal rami of spinal nn.
Semispinalis
Superficial layer of the group.
Divided into 3 parts based on superior attachments.
O: TPs of C4-T12 vertebrae
I:
Thoracic- SPs 4-6 vertebral segments superior.
Cervicis- SPs 4-6 vertebral segments superior.
Capitis- Occipital bone
A: Bilateral extension of all regions; contra lateral rotation of all regions.
N: Dorsal Rami of spinal nn.
Multifidus
Middle layer.
Best developed in the lumbar region
O: Posterior sacrum, PSIS, sacroiliac ligament, aponeurosis of erector spinae m, mamillary processes of lumbar vertebrae, TPs of T1-12 & articulate processes of C4-7
I: SPs 2-4 segments superior
A: Stabilize vertebrae during local movements of vertebral column
N: Dorsal rami of spinal nerve
Interspinalis
Connect SPs
O: Superior surfaces of SPs of cervical and lumbar vertebrae
I: inferior surfaces of SPs of vertebrae superior
A: Aid in extension and rotation of vertebral column.
N: Dorsal rami of spinal nn.
Intertransversarii
Connect TPs
O: TPs of cervical and lumbar vertebrae
I: TPs of adjacent vertebrae
A: Aid in lateral flexion of vertebral column; Bilaterally- stabilize vertebral column.
N: Dorsal and ventral rami (cervical region only) of spinal nn.
Levatores Costarum
O: Brevis and Longus - TPs of C7-T11
I: Rib between tubercle and angle
A: Elevates ribs in inspiration, assist with lateral flexion of vertebral column.
N: Dorsal Rami of C8-T11
Rectus Capitis Posterior Major
Located lateral to rectus capitis posterior minor m.
O: SP of C2
I: Lateral part inferior Nuchal line
A: Extension of head; rotation to same side
N: suboccipital n.
B: Vertebral and occipital aa.
Rectus Capitis Posterior Minor
Located medial to rectus capitis posterior major
O: Posterior tubercle of posterior arch of C1
I: Medial part of inferior nuchal line
A: Extension of head; rotation to same side
N: Suboccipital n.
B: Vertebral and occipital aa.
Obliquus Capitis Inferior
Only “capitis” muscle to have no attachment to cranium
Greater occipital n. Emerges inferior to this muscle
O: SP of C2
I: TPs of C1
A: Rotation of atlas and face to same side
N: Suboccipital n.
B: Vertebral and occipital aa.
Obliquus Capitis Superior
O: TPs of C1
I: Occipital bone between superior and inferior nuchal lines
A: Extension of head and lateral flexion of head and neck
N: Suboccipital n.
B: Vertebral and occipital aa.
Rotatores
- Deepest of 3 layers
- Best developed in thoracic region
O: TPs of vertebrae
I: Longus- SP 2 segments superior; brevis SP 1 segment superior.
A: Stabilize vertebrae and assist with extension and rotator you movements; Proprioception.
N: Dorsal rami of spinal nn. M
