Back muscles: Identification

Erector Spinae muscle actions

Acting bilaterall: the erector spinae muscles extend the vertebral column & head Acting unilaterally: they laterally flex the vertebral column During vertebral flexion: from the standing position, they control movement as their fibers are lengthened (eccentric muscle contraction)

Blood supply of Deep back Muscles

Blood supply is via the dorsal branch of posterior intercostal arteries

Erector Spinae- Iliocostalis (Attachments, innervation, blood supply)

Proximal- Arises by a broad tendon from posterior part of iliac crest, posterior surface of sacrum, sacro-iliac ligaments, sacral and inferior lumbar spinous processes, and supraspinous ligament Distal- lumborum, thoracis, cervicis; fibers run superiorly to angles of lower ribs and cervical transverse processes Action- Acting bilaterally: extend vertebral column and head; as back is fl exed, control movement via eccentric contraction Acting unilaterally: laterally flex vertebral column Innervation-posterior rami of spinal nerves

Erector Spinae- Longissimus (Attachments, innervation, blood supply)

Proximal- Arises by a broad tendon from posterior part of iliac crest, posterior surface of sacrum, sacro-iliac ligaments, sacral and inferior lumbar spinous processes, and supraspinous ligament Distal- thoracis, cervicis, 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 Action- Acting bilaterally: extend vertebral column and head; as back is fl exed, control movement via eccentric contraction Acting unilaterally: laterally flex vertebral column Innervation-posterior rami of spinal nerves

Spinalis (Attachments, innervation, blood supply)

Proximal- Arises by a broad tendon from posterior part of iliac crest, posterior surface of sacrum, sacro-iliac ligaments, sacral and inferior lumbar spinous processes, and supraspinous ligament Distal-thoracis, cervicis, capitis; fibers run superiorly to spinous processes in the upper thoracic region and to cranium Action- Acting bilaterally: extend vertebral column and head; as back is fl exed, control movement via eccentric contraction Acting unilaterally: laterally flex vertebral column Innervation- posterior rami of spinal nerves Blood-

Spinotransversales- splenius cervisis (Attachments, innervation, blood supply)

Proximal- Arises from spinous processes of T3 - T6 vertebrae Distal- transverse processes of C1 - C3 vertebrae Action- Extends neck, rotates head to same side Innervation- posterior rami of spinal nerves

Spinotransversales- splenius capitis (Attachments, innervation, blood supply)

Proximal- Arises from the nuchal ligament, spinous processes of C7 - T4 vertebrae, and the supraspinous ligament Distal- mastoid process and the occipital bone Action- Draws head back, extends neck, rotates head to same side Innervation- posterior rami of spinal nerves

Rectus capitis posterior major (Attachments, innervation, blood supply)

Proximal- Attaches to the spine of the second cervical vertebrae Distal- Attaches to the inferior nuchal line of the occiput. Action- Attaches to the inferior nuchal line of the occiput. Innervation-suboccipital nerve (DPR of C1)

Inferior oblique capitis (Attachments, innervation, blood supply)

Proximal- Attaches to the spine of the second cervical vertebrae. Distal- Attaches to the transverse process of C1. Action- Rotates C1 and cranium. Innervation-suboccipital nerve (DPR of C1)

Superior oblique capitis (Attachments, innervation, blood supply)

Proximal- Attaches to the transverse process of C1. Distal- Attaches to the occipital bone between the superior and the inferior nuchal lines. Action- Extends and laterally rotates the head. Innervation-suboccipital nerve (DPR of C1)

Levator Scapulae (Attachments, innervation, blood supply)

Proximal- C1-C4 transverse processes Distal-Medial border of scapula superior to scapular spine Action- Elevates scapula, draws it medially, and tilts glenoid fossa inferiorly. Extends or laterally flexes neck Innervation- C3,4 anterior rami (from cervical plexus). Lower portion receives dorsal scapular nerve (C4,5) Blood- Transverse cervical a. (deep branch)

Rhomboid minor (Attachments, innervation, blood supply)

Proximal- C7-T1 spinous processes Distal- Root of scapular spine Action- Retracts (adducts) scapula, and elevates scapula. With assistance of other muscles rotates the lateral aspect of the scapula inferiorly Innervation-Dorsal scapular nerve Blood-Deep branch of the transverse cervical artery

Serratus Posterior Superior (Attachments, innervation, blood supply)

Proximal- C7-T3 Distal- Upper Ribs Action- Raises Ribs Innervation- segmental intercostal nerves Blood- Posterior intercostal arteries

Trapezius (Attachments, innervation, blood supply)

Proximal- External occipital protuberance, superior nuchal line, ligamentum nuchae, C7-T12 spinous processes Distal- Spine of scapula, acromion, lateral 1/3 of clavicle Action- Adducts scapula, upward & outward scapular rotation, elevates scapula, depresses scapula Innervation-Spinal accessory nerve (CN XI). Propioception from C3 and C4 SN Blood-superficial branch of the transverse cervical artery

Interspinales (Attachments, innervation, blood supply)

Proximal- Spinous Processes Distal- Spinous Processes Action- Spinal Stability Innervation-posterior rami of spinal nerves

Serratus Posterior Inferior (Attachments, innervation, blood supply)

Proximal- T11-L3 Distal- Upper lumber to lower ribs Action- stabilizes & depresses ribs Innervation- segmental intercostal nerves Blood- Posterior intercostal arteries

Latissimus Dorsi (Attachments, innervation, blood supply)

Proximal- T7-12 & lumbar spinous processes, sacrum, iliac crest, ribs 10-12. Distal- Floor of bicipital groove (intertubercular groove) Action- Extends, adducts, medially rotates humerus Pulls body toward arm in climbing and chin up exercise Innervation- Thoracodorsal nerve (C6-8) Blood- thoracodorsal artery

Levatores costarum (Attachments, innervation, blood supply)

Proximal- Transverse Processes Distal- Ribs Action- Spinal Stability Innervation-posterior rami of spinal nerves

Intertransversarii (Attachments, innervation, blood supply)

Proximal- Transverse Processes Distal- Transverse Processes Action- Spinal Stability Innervation-posterior rami of spinal nerves

rotatores (Attachments, innervation, blood supply)

Proximal- Transverse processes Distal- Spinous Processes (1 segment=breves, 2 segments=longus) Action- Rotation to contralateral side Innervation-posterior rami of spinal nerves

Semispinalis capitis (Attachments, innervation, blood supply)

Proximal- Transverse processes of C7-T6 and. 4. articular process of C4-C6 Distal- Occipital bone b/w nuchal lines Action- Rotation to contralateral side Innervation-posterior rami of spinal nerves

Semispinalis Cervicis (Attachments, innervation, blood supply)

Proximal- Transverse processes of T1 - T6 Distal- Spinous processes of C2 - C5 Action- Rotation to contralateral side Innervation-posterior rami of spinal nerves

Multifidus (Attachments, innervation, blood supply)

Proximal- arises from the sacrum, ilium, and transverses processes of C4-C7 vertebrae Distal- spinous processes of all vertebra up to C2 Action- Rotation to contralateral side Innervation-posterior rami of spinal nerves

Rectus capitis posterior minor (Attachments, innervation, blood supply)

Proximal- posterior tubercle of atlas Distal- inferior nuchal line medially Action- extends the head Innervation-suboccipital nerve (DPR of C1)

Semispinalis Thoracis (Attachments, innervation, blood supply)

Proximal- the transverse process of the 6th to 10 Thoracic vertebrae Distal- the spinous process of the 1st to 4th thoracic and 6th-7th cervical vertebrae Action- Rotation to contralateral side Innervation-posterior rami of spinal nerves

Rhomboid Major (Attachments, innervation, blood supply)

Proximal-T2-T5 spinous processes Distal-Medial border of scapula Action-Retracts (adducts) scapula, and elevates scapula. With assistance of other muscles rotates the lateral aspect of the scapula inferiorly Innervation-Dorsal scapular nerve Blood- Deep branch of the transverse cervical artery

Dorsal rami of spinal nerves

Send branches that innervate deep back muscles, zygapophysial joints, posterior spinal ligaments, and the skin overlying the back

Deep (Extrinsic) Back Muscles

Spinotransversales (Superficial)- Splenius cervisis & capitis Erector Spinae (Intermediate)- Spinalis, longissimus, iliocostalis Transversopinales (Deep)- Semipinalis, multifidus, rotatores Segmental (Deepest)- Interspinales & intertransversarii Levatores costarum

Intertubercular (bicipital) groove

lies between the greater and lesser tubercles of the proximal humerus and is the site of the distal attachment of the latissimus dorsi muscle