Back Muscles Flashcards
Supericial Layer of Intrinsic Back Muscles
Splenius Cervicis
Origin: Arises from nuchal ligament and spinous processes of C7-T6 vertebrae
Insertion:
tubercles of transverse processes of C1-C3 or C4
Innervation- Posterior Rami of Spinal Nerves
Action-
Acting Alone-lateral flexion and ipsilateral rotation(rotate/tilt head to the side of the active muscles
Acting Together- extend head and neck
Supericial Layer of Intrinsic Back Muscles
Splenius Capitis
Origin: Arises from nuchal ligament and spinous processes of C7-T6 vertebrae
Insertion:
fibers run superolaterally to mastoid process of temporal bone and lateral third of superior nuchal line of occipital bone
Innervation- Posterior Rami of Spinal Nerves
Action-
Acting Alone-laterally flex head and rotate head to side of active muscles
Acting Together- extend head and neck
Intermediate Layer of Intrinsic Back Muscles
Iliocostalis (lumborum, thoracis, and cervicis)
Origin: Arises by broad tendon from: 1) posterior part of iliac crest 2) posterior surface of sacrum 3) sacro-iliac ligaments 4) sacral and inferior lumbar spinous processes 5) supra-spinous ligament
Insertion:
fibers run superiorly to angles of lower ribs and cervical transverse processes
Innvervation: Posterior Rami of Spinal Nerves
Action:
Acting bilaterally: extend vertebral column and head as back is flexed,control movement by gradually lengthening their fibers
Acting Unilaterally: laterally flex vertebral column
Intermediate Layer of Intrinsic Back Muscles (erector spinae)
Longissimus
Origin: Arises by broad tendon from: 1) posterior part of iliac crest 2) posterior surface of sacrum 3) sacro-iliac ligaments 4) sacral and inferior lumbar spinous processes 5) supra-spinous ligament
Insertion:
(throacis, cervicis, and capitis): fibers run superiorly to ribs between tubercles and angles to transverse processes in thoracic and cervical regions and to mastoid process of temporal bone
Innervation: Posterior Rami of Spinal Nerves
Action:
Acting bilaterally: extend vertebral column and head as back is flexed,control movement by gradually lengthening their fibers
Acting Unilaterally: laterally flex vertebral column
Intermediate Layer of Intrinsic Back Muscles (erector spinae)
Spinalis (thoracis, cervicis, and capitis)
Origin: Arises by broad tendon from: 1) posterior part of iliac crest 2) posterior surface of sacrum 3) sacro-iliac ligaments 4) sacral and inferior lumbar spinous processes 5) supra-spinous ligament
Insertion: fibers run superiorly to spinous processes in upper thoracic region to cranium
Innvervation: Posterior Rami of Spinal Nerves
Action:
Acting bilaterally: extend vertebral column and head as back is flexed,control movement by gradually lengthening their fibers
Acting Unilaterally: laterally flex vertebral column
Deep Layer of intrinsic back muscles (transversospinales)
Semispinalis (throacis, cervicis, and capitis)
Origin: Arises from the transverse processes of C4-T10 vertebrae
Insertion: 1)Fibers run superomedially to occipital bone
2) spinous processes in upper thoracic and cervical regions spanning 4 to six segments
Nerve Supply: Posterior Rami of Spinal Nerves
Action: Extend head, Thoracic and Cervical regions of vertebral columns and rotates them contra-laterally
Deep Layer of intrinsic back muscles (transversospinales)
Multifidus
Origin: Arises from 1) posterior sacrum 2) posterior superior iliac spine 3) aponeurosis of erector spinae 4) sacro-iliac ligaments 5) mamillary processes of lumbar vertebrae 6) transverse processes of thoracic vertebrae 7) articular processes of C4-C7
Insertion: Thickest in Lumbar Region, Fibers run superomedially of spinous process of vertebrae located two to four segments superior to origin
Innervation: Posterior Rami of Spinal Nerves
Action: 1) unilateral contraction rotates to contralateral side 2) stabilizes vertebrae during localized movements of vertebral column
Deep Layer of intrinsic back muscles (transversospinales)
Rotatores (brevis and longus)
Origin: Arise from transverse processes of vertebrae; are best developed in thoracic region
Insertion: Fibers pass superomedially to attach to junction of lamina and transverse process or spinous process of vertebra immediately (brevis) or two segments (longus) superior to vertebra of origin
Innervation: Posterior Rami of Spinal Nerves
Action: may function as organs of proprioception; possibly stabilize vertebrae and assist with local extension and rotary movements of vertebral column
Rectus Capitis Posterior Major
Origin: spinous process of the C2 vertebrae
Insertion: lateral part of inferior nuchal line of the occipital bone
Innervation: Posterior Ramus of C1 aka Suboccipital Nerve
Rectus Capitis Posterior Minor
Origin: posterior tubercle on the posterior arch of the C1 vertebrae
Insertion: medial third of the inferior nuchal line
Innervation: posterior ramus of C1, suboccipital nerve
Obliquus Capitis Inferior
Origin: spinous process of the C2 vertebrae
Insertion: transverse process of the C1 vertebrae
Innervation: posterior ramus of C1, suboccipital nerve
Obliquus Capitis Superior
Origin: transverse processes of C1 vertebrae
Insertion: occipital bone between the superior and inferior nuchal lines
Innvervation: Posterior Rami of C1, Suboccipital Nerve
Trapezius
Origin: 1) medial third of nuchal line 2) external occipital protuberance 3) nuchal ligament 4) spinous processes of C7-T12
Insertion: Lateral third of the clavicle, acromion, and spine of scapula
Innervation: CN 11 spinal accessory nerve,(motor fibers) C3, C4 spinal nerves (pain and proprioceptive fibers)
Action: Descending(superior): elevates, ascending (inferior): depresses and transverse (middle) retracts the scapula; ascending and descending parts act together to rotate the glenoid cavity superiorly
Latissimus Dorsi
Origin: Spinous Processes of T7-T12, thoracolumbar fascia, inferior three or four ribs, iliac crest
Insertion: Floor of intertubercular sulcus (groove) of humerus
Innervation: Thoracodorsal Nerve (C6, C7, C8) “C6 C7 C8 make the lats great”
Action: extends, adducts, medially rotates shoulder joint; raises body towards arm when climbing
Levator Scapulae
Origin: Posterior Tubercles of Transverse Processes of C1-C4 vertebrae
Insertion: Medial border of scapula superior to root of spine
Innervation: Dorsal Scapular C5 and Cervical (C3,C4) spinal nerves
Action: Elevate Scapula and tilt its glenoid cavity inferiorly by rotating scapula
