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Upper Trapezius
- Origin: Occipital protuberance, superior nuchal line, ligamentum nuchae, spinous process C7
- Insertion: lateral 1/3 of clavicle and acromion process of scapula
- peripheral nerve: spinal portion of cranial nerve XI (accessory) and ventral ramus
- nerve roots: C3, C4
- Function: Origin fixed: elevation of scapula; upward rotation of the scapula, stabilize scapula in scapular adduction; insertion fixed: acting unilaterally: extend, laterally flex, and rotate the head and cervical vertebrae to turn face toward opposite side; acting bilaterally: neck extension and assists in forced inspiration
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Middle Trapezius
- Origin: spinous processes of 1st-5th thoracic vertebrae
- Insertion: medial margin of acromion and superior lipe of spine of scapula
- Peripheral nerve: spinal portion on cranial nerve XI (accessory) and ventral ramus
- Nerve roots: C3, C4
- Function: Origin fixed: adduction of scapula and horizontal fibers stabilize scapula during upward rotation of the scapula
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Lower Trapezius
- Origin: spinous processes of 6th-12th thoracic vertebrae
- Insertion: tubercle at apex of spine of scapula
- Peripheral nerve: spinal portion on cranial nerve XI (accessory) and ventral ramus
- Nerve roots: C3, C4
- Function: Origin fixed: upward rotation of the scapula, depression of scapula, and stabilizes the scapula during adduction of scapula
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Rhomboid major
- Origin: spinous processes of 2nd-5th thoracic vertebrae
- Insertion: medial border of scapula between the spine and inferior angle
- Peripheral nerve: dorsal scapular
- Nerve roots: C4, C5
- Function: adduct and elevates the scapula and downward rotation of scapula
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Rhomboid minor
- Origin: ligamentum nuchae, spinous processes of 7th cervical, and 1st thoracic vertebrae
- Insertion: medial border at root of spine of scapula
- Peripheral nerve: dorsal scapular
- Nerve roots: C4, C5
- Function: adduct and elevates the scapula and downward rotation of scapula
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Levator scapulae
- Origin: transverse processes of first 4 cervical vertebrae
- Insertion: medial border of scapula between superior angle and root of the spine
- Peripheral nerve: dorsal scapular and cervical
- Nerve roots: [cervical] - C3, C4 & [dorsal scapular] - C4, C5
- Function: fixed origin: elevates the scapula and downward rotation of scapula; fixed insertion: unilaterally: ipsilateral cervical lateral bend, and ipsilateral cervical rotation; bilaterally: cervical extension
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Pectoralis minor
- Origin: superior margins, anterior surface of 3rd, 4th, and 5th ribs
- Insertion: medial border, coracoid process of scapula
- Peripheral nerve: medial pectoral with fibers from the communicating branch of the lateral pectoral
- Nerve roots: C7, C8
- Function: Origin fixed: tilts scapula anteriorly; insertion fixed: assists in forced inspiration
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Serratus Anterior
- Origin: superior borders of upper eight or nine ribs
- Insertion: medial border of scapula
- Peripheral nerve: long thoracic
- Nerve roots: C5, C6, C7
- Function: abducts the scapula, upper fibers elevate the scapula and lower fibers depress the scapula; holds the medial border of the scapula firmly against the rib cage (push or pull)
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Latissimus dorsi
- Origin: spinous processes of lower 6 thoracic vertebrae, last 3-4 ribs, thoracolumbar fascia, posterior external lip of iliac crest, and inferior angle of the scapula
- Insertion: intertubercular groove of humerus
- Peripheral nerve: thoracodorsal
- Nerve roots: C6, C7, C8
- Function: Origin fixed: medially rotates, adducts, and extends shoulder joint; depresses shoulder girdle; assists in lateral flexion of the trunk; insertion fixed: assists in tilting the pelvis anteriorly and laterally; bilaterally assists in hyperextending the spine and anteriorly tilting the pelvis or in flexing the spine; acts as accessory muscle of respiration
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Teres major
- Origin: dorsal surfaces of the inferior angle and lateral border of the scapula
- insertion: medial lip of the intertubercular groove of the humerus
- Peripheral nerve: lower subscapular
- Nerve root: C6
- Function: medially rotates, adducts & extends the shoulder
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Pectoralis major (clavicular fibers)
- origin: anterior surface of clavicle
- insertion: lateral lip of intertubercular groove of humerus
- peripheral nerve: lateral pectoral
- nerve roots: C5, C6, C7
- Function: origin fixed (as a whole): adducts and medially rotates the humerus;insertion fixed (as a whole): elevates thorax as in forced inspiration; using assistant devices assists in supporting weight of body; upper fibers: flex and medially rotates the shoulder joint and horizontally adducts the humerus to the opposite shoulder
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Pectoralis major (sternal fibers)
- Origin: (sternocostal portion) anterior surface of sternum; cartilages of first 6 or 7 ribs; aponeurosis of external oblique
- Insertion: lateral lip of intertubercular groove of humerus
- Peripheral nerve: lateral and medial pectoral
- Nerve roots: C6, C7, C8, T1
- Function: origin fixed (as a whole): adducts and medially rotates the humerus;insertion fixed (as a whole): elevates thorax as in forced inspiration; using assistant devices assists in supporting weight of body; lower fibers: depress shoulder girdle; obliquely adduct the humerus toward the opposite iliac crest
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Infraspinatus
- Origin: medial 2/3 of infraspinous fossa of scapula
- Insertion: middle facet of greater tubercle of humerus and shoulder joint capsule
- peripheral nerve: suprascapular
- Nerve root: C5, C6
- Function: laterally rotates the shoulder joint; stabilizes the head of the humerus in the glenoid cavity during shoulder movement
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Teres minor
- Origin: upper dorsal surface lateral border of scapula
- Insertion: lowest facet of greater tubercle of humerus and shoulder joint capsule
- Peripheral nerve: axillary
- Nerve root: C5, C6
- Function: laterally rotates the shoulder joint; stabilizes the head of the humerus in the glenoid cavity during movements
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Subscapularis
- Origin: subscapular fossa of scapula
- Insertion: lesser tubercle of the humerus and shoulder joint capsule
- Peripheral neve: upper and lower subscapular
- Nerve roots: C5, C6
- Function: medially rotates the shoulder joints; stabilizes the head of the humerus in the glenoid cavity during movements
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supraspinatus
- Origin: medial supraspinous fossa of scapula
- Insertion: superior facet of rearer tubercle of humerus; shoulder joint capsule
- Peripheral nerve: suprascapular
- Nerve roots: C5, C6
- Function: stabilizes head of humerus; initiates abduction of the humerus; laterally rotates the shoulder joint
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Middle Deltoid and Supraspinatus
- Origin: lateral margin and superior surface of acromion
- Insertion: deltoid tuberosity of the humerus
- Peripheral nerve: axillary
- Nerve root: C5. C6
- Function: middle deltoid: abduction of glenohumeral joint
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Anterior deltiod
- Origin: lateral 1/3 of clavicle
- Insertion: deltoid tuberosity of humerus
- Peripheral nerve: axillary
- Nerve Roots: C5, C6
- Function: shoulder flexion; when in supine-medially rotate the humerus; stabilize to assist middle deltoid with abduction of the glenohumeral joint
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Posterior deltiod
- Origin: posterior border of spine of scapula
- Insertion: deltoid tuberosity of humerus
- Peripheral nerve: axillary
- Nerve roots: C5. C6
- Function: shoulder extension; in prone - lateral rotation of the shoulder joint; stabilize the humerus to assist the middle fibers in abduction of the glenohumeral joint
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