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Trapezius
- Origin: Occipital bone, ligamentum nuchae, spinous processes of C7, T1-T6
- Insertion: Lateral 1/3 of clavicle, acromion and spine of scapula
- Nerve Supply: Spinal Part of Accessory Never (motor) and C3 and 4 (sensory)
- Action:
- Upper fibers: elevates scapula
- Middle fibers: draws scapula medially
- Lower fibers: pulls medial border of scapula downward
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Latissimus Dorsi
- Origin: Iliac crests, lumbar fascia, spines of lower six thoracic vertebra, inferior angle of scapula, lower three or four ribs
- Insertion: Floor of the bicipital groove of humerus
- Nerve: Thoracodorsal nerve (C6-C8)
- Action: Extends, Adducts, Medially Rotates arm
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Levator Scapulae
- Origin: Transverse processes of first four cervical vertebra
- Insertion: Medial border of scapula
- Nerve Supply: C3, C4, dorsal scapular nerve
- Action: Raises medial border of scapula
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Rhomboid Major
- Origin: 2nd to 5th thoracic spines
- Insertion: Medial border of scapula
- Nerve Supply: dorsal scapular nerve
- Action: Raises medial border of scapula upward and medially
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Rhomboid Minor
- Origin: Ligamentum nuchae, spines of C7 and T1
- Insertion: Medial border of scapula
- Nerve Supply: dorsal scapular nerve
- Action: Raises medial border of scapula upward and medially
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What are the superficial muscles?
- Trapezius
- Latissimus Dorsi
- Levator Scapulae
- Rhomboid Major
- Rhomboid Minor
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Serratus Posterior Superior
- Origin: Upper cervical and lower thoracic spines
- Insertion: Upper ribs
- Nerve Supply: Intercostal Nerves
- Action: Raises ribs therefore inspiratory muscle
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Serratus Posterior Inferior
- Origin: Lower thoracic and upper lumbar spines
- Insertion: Lower ribs
- Nerve Supply: Intercostal nerves
- Action: Depresses ribs therefore expiratory
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What are the intermediate muscles of the back?
- Serratus Posterior Superior
- Serratus Posterior Inferior
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What comprise the Erector Spinae Muscles?
- Iliocostalis
- Longissimus
- Spinalis
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What comprise the Transversospinalis muscles?
- Semispinalis
- Multifidus
- Rotatores
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Erector Spinae
- Origin: Posterior sacrum, iliac crest, sacrospinous and supraspinous ligament, spinous processes of lower lumbar and sacral vertebra
- Insertion:
- Iliocostalis: angles of lower ribs, cervical tranverse processes
- Longissimus: between tubercles and angles of ribs, transverse processes of thoracic and cervical vertebra, mastoid process
- Spinalis: spinous process of upper thoracic and midcervical vertebrae
- Nerve Supply: Dorsal rami of each region
- Action: Extend and laterally bend vertebral column and head
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Multifidus
- Origin: sacrum, ilium, transverse processes of T1-T12, articular processes of C4-C7
- Insertion: spinous processes of vertebra above, spanning two to four segments
- Nerve Supply: Dorsal rami of each region
- Action: bilaterally extends vertebral column; unilaterally laterally flexes; contralaterally rotates vertebral column; stabilizes spine
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Rotatores (Longus and Brevis)
- Origin: Transverse processes of cervical, thoracic, and lumbar vertebra
- Insertion: Lamina (brevis) and transverse processes (longus) of vertebra above, spanning one to two segments
- Nerve Supply: Dorsal rami of spinal nerves
- Action: Bilaterally extends vertebral column; Unilaterally rotates vertebral column to opposite side; stabilizes spine
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Semispinalis
- Origin: Transverse process of C4-T12
- Insertion: Spinous process of cervical and thoracic vertebrae
- Nerve Supply: Dorsal rami of spinal nerves
- Action: Extends head, neck, and thorax; rotates VC to opposite side
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Interspinales
- Origin: Spinous processes
- Insertion: Adjacent spinous processes
- Nerve Supply: Dorsal rami of spinal nerves
- Action: Aid in the extension of VC
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Intertransversarii
- Origin: Extend between adjacent transverse processes of vertebrae
- Insertion: Extend between adjacent transverse processes of vertebrae
- Nerve Supply: Dorsal rami of spinal nerves
- Action: Assist in the lateral flexion of vertebral column
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Quadratus Lumborum
- Origin: Iliolumbar ligament, iliac crest, tips of transverse processes of lower lumbar vertebrae
- Insertion: 12th rib
- Nerve Supply: Lumbar plexus
- Action: Fixes 12th rib during inspiration; depresses 12th rib during forced expiration; laterally fixes vertebral column to same side
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Rectus Abdominis
- Origin: Symphysis pubis and pubic crest
- Insertion: 5th, 6th, 7th costal cartilages and xiphoid process
- Nerve Supply: Lower six thoracic nerves
- Action: Supports and compresses abdominal contents, flexes the vertebral column, accessory muscle for expiration
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External Oblique
- Origin: Lower eight ribs
- Insertion: Xiphoid process, linea alba, pubic crest, pubic tubercle, iliac crest
- Nerve Supply: Lower six thoracic nerve, ilioinguinal and iliohypoglossal nerves
- Action: Supports and compresses abdominal contents; assists in flexion and rotation of trunk; assists in forced expiration, defecation, micturition, vomiting, and parturition.
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Internal Oblique
- Origin: Lumbar fascia, iliac crest, lateral 2/3 of inguinal ligament
- Insertion: Lower three costal cartilages and ribs, xiphoid process, linea alba, symphysis pubis
- Nerve Supply: Lower six thoracic nerve, ilioinguinal and iliohypoglossal nerves
- Action: Supports and compresses abdominal contents; assists in flexion and rotation of trunk; assists in forced expiration, defecation, micturition, vomiting, and parturition.
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Transversus
- Origin: Lumbar fascia, lower six costal cartilages, iliac crest, lateral 2/3 of inguinal ligament
- Insertion: xiphoid process, linea alba, pubis symphysis
- Nerve Supply: Lower six thoracic nerve, ilioinguinal and iliohypoglossal nerves
- Action: Compression of abdominal contents
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Diaphragm
- Origin: Xiphoid process, lower six costal cartilages, first three lumbar vertebrae
- Insertion: Central Tendon
- Nerve Supply: Phrenic Nerve
- Action: Very important muscle for inspiration: increases the vertical diameter of thorax by pulling the central tendon downward, assists the raising of the ribs
used in weight training and abdominal straining
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External Intercostals
- Origin: Inferior border of rib
- Insertion: Superior border of rib below
- Nerve Supply: Intercostal nerves
- Action: when the 1st rib is fixed, it raises the ribs for inspiration
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Internal Intercostals
- Origin: Inferior border of rib
- Insertion: Superior border of rib below
- Nerve Supply: Intercostal nerves
- Action: with the last rib fixed by abdominal musculature, it depresses the ribs during expiration
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Levatores Costarum
- Origin: Tips of transverse processes of C7 to T1
- Insertion: Rib below
- Nerve Supply: Posterior rami of thoracic spinal nerve
- Action: Raises rib
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Splenius Capitis
- Origin: Ligamentum nuchae, spinous processes of C7 to T6
- Insertion: Mastoid process and lateral end of superior nuchal line
- Nerve Supply: Dorsal primary rami of spinal nerves C2 to C6
- Action: Capital flexion; Extends and laterally bends head and neck and rotates head to axis to same sime
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Splenius Cervicis
- Origin: Ligamentum nuchae, Spinous processes of C7 to T6
- Insertion: Posterior tubercles of the transverse processes of C1-C3
- Nerve Supply: Dorsal primary rami of spinal nerves of C2-C6
- Action: Capital flexion; extends and laterally bends head and neck and rotates head on axis to the same side
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Rectus Capitis Posterior Minor
- Origin: Posterior tubercle of atlas
- Insertion: Inferior nuchal line
- Nerve Supply: Suboccipital nerve
- Action: Bilaterally extend head
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Rectus Capitis Posterior Major
- Origin: spinous process of neck
- Insertion: inferior nuchal line
- Nerve Supply: suboccipital nerve
- Action: bilaterally extends head and neck and unilaterally rotates head to same side
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Obliquus Capitis Inferior
- Origin: Spinous process of axis
- Insertion: Transverse process of atlas
- Nerve Supply: Occipital Nerve
- Action: Rotates head to turn face to same side
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Obliquus Capitis major
- Origin: transverse process of atlas
- Insertion: Occipital bone
- Nerve Supply: Suboccipital nerve
- Action: Extends and laterally bends head
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