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MUSCLES OF BACK.pdf
1. MUSCLES OF BACK
There are two major groups of muscles in the back.
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1) The extrinsic back muscles.
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A) Superficial extrinsic back muscles: ÖMER ASLANKAN
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B) Intermediate extrinsic back muscles;
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2) The intrinsic (deep) back muscles.
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superficial extrinsic back muscles
1) upper trapezius
Origin; superior nuchal line & external occipital protrudence
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Insertion; lateral 1/3 of clavicle
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Action; elevation of scapula
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Innervation; spinal accessory nerve (X1)
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2) Middle Trapezius;
Origin; ligamentum nuchae & C7
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Insertion; acromion
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Action; retraction of scapula
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Innervation; Spinal Accessory Nerve (XI)
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3) Lower Trapezius;
Origin; 12 thoracic vertebrae
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Insertion; spine of scapula
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Action; depression and rotation of the scapula
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Innervation; Spinal Accessory Nerve (XI)
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4) Latissimus Dorsi
Origin; spinous process of inferior 6 thoracic vertebrae, all lumbar vertebrae and posterior aspect of iliac crest
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Insertion; floor of biciptal groove
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Action; adduction, extension, IR of humerus
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Innervation; thoracodorsal nerve (C6,C7,C8)
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Blood Supply; thoracodorsal artery
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5) Levator Scapulae
Origin; transverse processes of the upper 4 cervical vertebrae
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Insertion; superior angle of scapula superior portion of medial border
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Action; elevation of scapula plays a role in head posture
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Innervation; Dorsal Scapular Nerve (C5)
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Blood Supply; thoracodorsal artery
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6) Rhomboid Major
Origin; spinous processes of T2-T5
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Insertion; Inferior aspect of the medial border of scapula
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Action; retract and stabilize scapula inferior rotation of scapula (glenoid faces caudal)
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Innervation; Dorsal Scapular Nerve (C5)
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Blood Supply; Dorsal Scapular Artery
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7) Rhomboid Minor
Origin; lower part of ligamentum nuchae spinous processes of C7 & T1
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Insertion; superior to the rhomboid major on the medial border of the scapula
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Action; retract and stabilize scapula inferior rotation of scapula ( glenoid faces caudal)
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Innervation; Dorsal Scapular Nerve (C5)
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2. Blood Supply; Dorsal Scapular Artery
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intermediate extrinsic muscles
1. serratus posterior superior
Origin; ligamentum nuchae spinous process of C7 and upper 2 or 3 thoracic vertebrae
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Insertion; Upper ribs 2-5
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Action; elevation of ribs
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Innervation; Ventral rami of upper 3 or 4 thoracic spinal nerves
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2. serratus posterior inferior
Origin; spinous process of lower 2 thoracic and upper 2 lumbar vertebrae
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Insertion; lower three or four ribs
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Action; pulls lower ribs inferiorly
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Innervation; Ventral rami of lower thoracic (9-12) spinal nerves
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Intrinsic Back Muscles
A) Superficial Layer
1) Splenius
Origin: Nuchal ligament and spinous processes of C7-T6
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Insertion: varies with capitus or cervisus
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Innervation Posterior rami
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Action: Extend head and neck
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Nerve supply; posterior rami of spinal nerves
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2) Splenius capitus
Origin: Nuchal ligament and spinous processes of C3-C7
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Insertion: Superolaterally to mastoid process and lateral third of superior nuchal line
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Innervation: Posterior rami
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Action: laterally flex neck and rotate head
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Nerve supply; posterior rami of spinal nerves
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3) Splenius cervicis
Origin: T3-T6 spinous processes
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Insertion: tubercles of transverse processes of C1-C3 or C4
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Innervation: Posterior rami
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Action: laterally flex neck and rotate head
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Nerve supply; posterior rami of spinal nerves
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B) Intermediate layer
4) Erector spinae group
Origin: Broad ligament from posterior iliac crest, posterior sacrum, sacro-iliac ligament, sacral and inferior
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lumbar spinous processes, supraspinous ligament
Innervation: Posterior rami
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Action bilaterally: extends vertebral column and head, controls movement of back flexion
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Nerve supply; posterior rami of spinal nerves
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5) Iliocostalis
Origin: Broad tendon from posterior part of iliac crest, posterior surface of sacrum, sacro-iliac ligaments, sacral
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and inferior lumbar spinous processes, supraspinous ligament
Insertion: Fibers run superiorly to angles of lower ribs and cervical transverse processes
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Innervation: Lateral branches of posterior rami
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Action: Extends spine and head, control movement of eccentric contraction, laterally flex spine
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3. Nerve supply; posterior rami of spinal nerves
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6) Longissimus
Origin: Broad tendon from posterior part of iliac crest, posterior surface of sacrum, sacro-iliac ligaments, sacral
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and inferior lumbar spinous processes, supraspinous ligaments
Insertion: Superiorly to ribs between tubercles and angles to transverse processes in thoracic and cervical
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regions, to mastoid process of temporal bone
Innervation: lateral branches of posterior rami
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Action: Extends spine and controls movement via eccentric contraction, laterally flex vertebral column
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Nerve supply; posterior rami of spinal nerves
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7) Spinalis
Origin: Broad tendon from posterior part of iliac crest, posterior surface of sacrum, sacro-iliac ligaments, sacral
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and inferior lumbar spinous processes, supraspinous ligament
Insertion: Fibers superiorly to spinous processes in the upper thoracic region and to cranium
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Innervation: posterior rami
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Nerve supply; posterior rami of spinal nerves
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C) Deep Layer:
8) Transversospinalis
Origin: transverse processes
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Insertion: spinous processes of more superior vertebrae
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Innervation: posterior rami
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Action: externsion
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Nerve supply; posterior rami of spinal nerves
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9) Semispinalis
Origin: transverse porcesses of C4-T12
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Insertion: Supermedial to occipital bone and spinous processes in thoracic and cervical region; spans 4-6
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segments
Innervation: Posterior rami
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Action: extends head, thoracic and cervical vertebrae, contralateral rotation
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Nerve supply; posterior rami of spinal nerves
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10) Multifidus
Origin: posterior sacrum, posterior superior iliac spine, aponeurosis of erector spinae, sacro-iliac ligaments,
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mammillary processes of lumbar vertebrae, transverse processes of T1-T3, articular processes of C4-C7
Insertion: Thickest in lumbar region; fibers obliquely superomedially to entire length of spinous processes, 2-4
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segments superior to proximal attachment
Innervation: posterior rami
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Action: stabilizes vertebrae during local movements
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Nerve supply; posterior rami of spinal nerves
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11) Rotatores (breves/longi)
Origin: transverse processes of T1-T12 best developed in thoracic region
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Insertion: Supramedially to junction of lamina and transverse or spinous process of superior vertebra: breves 1
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vertebra, longus 2 vertebrae
Innervation: posterior rami
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Action: Stabilize vertebrae, assist with local extension and rotation, possibly proprioception
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Minor Deep layer;
12) Interspinales
Origin: Superior surfaces of spinous processes of cervical and lumbar vertebrae
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Insertion: Inferior surfaces of spinous processes of vertebra superior to vertebra of proximal attachment
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4. Innervation: Posterior rami
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Action: Aid in extension and rotation of vertebral column
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Nerve supply; posterior rami of spinal nerves
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13) Intertransversarii
Origin: Transverse processes of cervical and lumbar ribs
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Insertion: Transverse processes of adjacent vertebrae
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Innervation: Posterior and anterior (cervical) rami
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Action: Aid in lateral flexion of vertebral column, stabilize vertebral column.
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Nerve supply; posterior rami of spinal nerves
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14) Levatores costarum
Origin: Tips of transverse processes of C7 and T1-T11
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Insertion: Inferolaterally to next rib (breves) or rib two vertebrae below (longi)
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Innervation: Posterior rami of C8-T11 nerves
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Action: elevates ribs to assist with respiration; lateral flexion of vertebral column
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Nerve supply; posterior rami of spinal nerves
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Principle muscles producing movement of cervical intervertebral joints
Flexion;
Bilateral action of: Longus coli, Sternocleidomastoid, Scalene
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Extension;
Deep neck muscles:
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1 Semispinalis cervicis, iliocostalis cervicis > 2 Splenius cervicis, levator scapulae
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3 Splenius capitis > 4 Multifidus > 5 Longissimus capitis > 6 Semispinalis capitis T, Trapezius (?)
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Lateral Bending;
Unilateral action of: Iliocostalis cervicis, Longissimus capitis and cervicis
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Splenius capitis and cervicis , Intertransversarii and scalenes
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Rotation;
Unilateral action of: Rotatores , Semispinalis capitis and cervicis
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Multifidus, Splenius cervicis
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Principle muscles producing movement of thoracic and lumbar intervertebral joints
FLEXION;
Bilateral action of; Rectus abdominis, Psoas major, Gravity
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EXTENSION;
Bilateral action of; Erector spinae, Multifidus, Semispinalis thoracis
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LATERAL BENDING
Unilateral action of ; Iliocostalis thoracis and lumborum, Longissimus thoracis, Multifidus
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External and internal oblique! Quadratus lumborum, Rhomboids, Serratus anterior
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ROTATION;
Unilateral action of; Rotatores, Multifidus, Iliocostalis, Longissimus
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External oblique acting synchronously with opposite internal oblique
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Splenius thoracis
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Principle muscles producing movement of atlanto-occipital intervertebral joints
Flexion;
longus capitis, rectus capitis anterior, anterior fibers of sternocleidomastid,
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suprahyoid and infrahyoid muscle
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Extension;
rectus capitis posterior, (major and minor), obliquus capitis superior, splenius capitis
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Longissimus capitis, trapezius
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Lateral flexion;
5. Sternocleidomastoid, obliquus capitis superior, rectus capitis laterals,
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Longissimus capitis, splenius capitis
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Surface Anatomy of Back Muscles
posterior median furrow = midline of back; continuous with nuchal groove of neck
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erector spinae muscles produce vertical bulges on each side of furrow
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Suboccipital and Deep Neck Muscles
Suboccipital Region; muscle compartment deep to superior part of posterior cervical region
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1) Rectus Capitis Posterior Major
origin; C2 (spinous process)
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insertion; Occipital bone (middle third of inferior nuchal line)
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innervation; Posterior ramus of C1 (Suboccipital nerve
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action; Unilateral: Rotates head to same side
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Bilateral: Extends head
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2) Rectus Capitis Posterior minor
origin; C1 (posterior tubercle)
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insertion; Occipital bone (inner third of inferior nuchal line)
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innervation; Posterior ramus of C1 (Suboccipital nerve)
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action; Unilateral: Rotates head to same side
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Bilateral: Extends head
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3) Obliquus capitis superior
origin; C1 (transverse process )
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insertion; Occipital bone (above insertion of rectus capitis)
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innervation; Posterior ramus of C1 (Suboccipital nerve)
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action; Unilateral: tilts head to same side, rotates it to opposite side
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Bilateral: Extends head
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4) Obliquus capitis inferior
origin; C2 (Spinous process )
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insertion; C1 transverse process
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innervation; Posterior ramus of C1 (Suboccipital nerve)
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action; Unilateral: tilts head to same side, rotates it to opposite side
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Bilateral: Extends head
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Suboccipital Triangle
Superomedial boundary; Rectus capitis posterior major
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SuperoLateral boundary; Obliquus capitis superior
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Inferiolateral boundary; Obliquus capitis inferior
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Floor; Posterior Atlanto occipital membrane and posterior arch of vertebrae C1
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Roof; Semispinalls capitis
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Contents; vertebral artery and suboccipital nerve
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Disorders of Back
back sprain;
It is Injury caused by ligamentous tissue without dislocation or fracture.
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caused by excessively strong contractions, for example as excessive extension or rotation.
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Back strain;
it results from overly strong muscular contraction.
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