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Serratus posterior inferior
Origin: spinous processes of T11-L2
Insertion: inferior aspect of ribs 9-12
Innervation: ventral rami of lower thoracic nerves
Actions: depress ribs
Blood supply: posterior intercostal arteries
Muscle group: intermediate back
Serratus posterior superior
Origin: nuchal ligament, spinous processes of C7-T3
Insertion: superior aspect of ribs 2-4
Innervation: ventral rami of upper thoracic nerves
Actions: elevates ribs
Blood supply: posterior intercostal arteries
Muscle group: intermediate back
Splenius capitis
Origin: nuchal ligament, spinous process of C7-T3
Insertion: mastoid process of temporal bone, lateral third of superior nuchal line
Innervation: dorsal rami of middle cervical nerves
Actions:
- bilaterally: extends head
- unilaterally: laterally bends and rotates face to same side
Blood supply: descending branch of occipital artery, deep cervical artery
Muscle group: spinotransverse
Splenius cervicis
Origin: spinous process of T3-T6
Insertion: transverse processes of C1-C3
Innervation: dorsal rami of lower cervical nerves
Actions:
- bilaterally: extends neck
- unilaterally: laterally bends and rotates neck toward the same side
Blood supply: descending branch of occipital artery, deep cervical artery
Muscle group: spinotransverse
Obliquus capitis inferior
Origin: spine of axis
Insertion: transverse process of atlas
Innervation: suboccipital nerve
Actions: rotates atlas to turn face to same side
Blood supply: vertebral artery, descending branch of occipital artery
Muscle group: suboccipital
Obliquus capitis superior
Origin: transverse process of atlas
Insertion: occipital bone
Innervation: suboccipital nerve
Actions: extends and bends head laterally
Blood supply: vertebral artery, descending branch of occipital artery
Muscle group: suboccipital
Rectus capitis posterior major
Origin: spine of axis
Insertion: inferior nuchal line
Innervation: suboccipital nerve
Actions: extends and rotates head to same side
Blood supply: vertebral artery, descending branch of occipital artery
Muscle group: suboccipital
Rectus capitis posterior minor
Origin: tubercle of posterior arch of atlas
Insertion: median inferior nuchal line
Innervation: suboccipital nerve
Actions: extends head
Blood supply: vertebral artery, descending branch of occipital artery
Muscle group: suboccipital
Latissimus dorsi
Origin: spinous processes of T7-L5, thoracolumbar fascia, iliac crest, last three ribs
Insertion: humerus (intertubecular sulcus)
Innervation: thoracodorsal nerve
Actions: extends, adducts, and medially rotates humerus
Blood supply: thoracodorsal artery, dorsal perforating branches of 9th, 10th, and 11th posterior intercostal, subcostal, and first three lumbar arteries
Muscle group: superficial back
Levator scapulae
Origin: posterior tubercle of transverse processes of C1-C4
Insertion: medial border of scapula from superior angle to spine
Innervation: ventral rami of C3-C4 and dorsal scapular nerve
Actions: elevates scapula medially, inferiorly, rotates glenoid cavity
Blood supply: dorsal scapular artery, transverse cervical artery, ascending cervical artery
Muscle group: superficial back
Rhomboid major
Origin: spinous processes of T2-T5 vertebrae
Insertion: medial border of scapula below base of spine of scapula
Innervation: dorsal scapular nerve
Actions: fixes scapula to thoracic wall and retracts and rotates it to depress glenoid cavity
Blood supply: dorsal scapular artery or deep branch of transverse cervical artery, dorsal perforating branches of the upper five or six posterior intercostal arteries
Muscle group: superficial back
Rhomboid minor
Origin: nuchal ligament, spines of C7-T1 vertebrae
Insertion: medial border of scapula at spine of scapula
Innervation: dorsal scapular nerve
Actions: fixes scapula to thoracic wall and retracts and rotates it to depress glenoid cavity
Blood supply: dorsal scapular artery or deep branch of transverse cervical artery, dorsal perforating branches of the upper five or six posterior intercostal arteries
Muscle group: superficial back
Trapezius
Origin: superior nuchal line, external occipital protuberance, nuchal ligament, spinous processes of C7-T12
Insertion: lateral third of clavicle, acromion, spine of scapula
Innervation: accessory nerve (XI)
Actions: elevates, retracts, and rotates scapula, lower fibers depress scapula
Blood supply: transverse cervical artery, dorsal perforating branches of posterior intercostal arteries
Muscle group: superficial back
Multifidus
Origin: sacrum, ilium, transverse processes of T1-T12 and articular processes of C4-C7
Insertion: spinous processes of vertebrae above, spinning two or four segments
Innervation: dorsal rami of each region
Actions: stabilizes spine
Blood supply:
- cervical: occipital, deep cervical, and vertebral arteries
- thoracic: dorsal branches of posterior, intercostal, subcostal, and lumbar arteries
- sacral: dorsal branches of lateral sacral arteries
Muscle group: transversospinalis
Semispinalis
Origin: transverse processes of C4-T12
Insertion: spinous processes of cervical and thoracic regions
Innervation: dorsal rami of spinal nerves
Actions: extends head, neck, and thorax, and rotates them to opposite sides
Blood supply:
- cervical: occipital, deep cervical, and vertebral arteries
- thoracic: dorsal branches of posterior intercostal arteries
Muscle group: transversospinalis
