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Questions and Answers
What is the primary functional role of the superficial muscles of the back, as a collective group?
What is the primary functional role of the superficial muscles of the back, as a collective group?
- To act as the primary respiratory muscles.
- To exclusively control movements of the vertebral column.
- Primarily facilitate movements of the lower limbs.
- Connect the spine, external occipital protuberance, and superior nuchal line to the upper limb girdle or humerus. (correct)
Which of the following is NOT a typical action of the latissimus dorsi muscle?
Which of the following is NOT a typical action of the latissimus dorsi muscle?
- Upward rotation of the scapula. (correct)
- Internal (medial) rotation of the arm at the shoulder joint.
- Adduction of the arm at the shoulder joint.
- Extension of the arm at the shoulder joint.
The trapezius muscle is divided into three parts. Which of the following describes the insertion point of the middle fibers?
The trapezius muscle is divided into three parts. Which of the following describes the insertion point of the middle fibers?
- Superior nuchal line
- Posteromedial part of the spine of the scapula
- Lateral third of the clavicle
- The acromion (correct)
What would be the most likely observable outcome of paralysis of the trapezius muscle?
What would be the most likely observable outcome of paralysis of the trapezius muscle?
What nerve innervates both rhomboid major and rhomboid minor?
What nerve innervates both rhomboid major and rhomboid minor?
Which of the following describes the combined action of the upper and lower fibers of the trapezius muscle?
Which of the following describes the combined action of the upper and lower fibers of the trapezius muscle?
What muscles cause retraction of the scapula?
What muscles cause retraction of the scapula?
Where does the latissimus dorsi insert?
Where does the latissimus dorsi insert?
Damage to the spinal accessory nerve (cranial nerve XI) would most directly affect the function of which muscle?
Damage to the spinal accessory nerve (cranial nerve XI) would most directly affect the function of which muscle?
Which structure serves as a key connective tissue that allows forces from the upper limb to be transmitted to the lower limb?
Which structure serves as a key connective tissue that allows forces from the upper limb to be transmitted to the lower limb?
In which specific movement is the latissimus dorsi primarily involved, based on its adduction and extension capabilities?
In which specific movement is the latissimus dorsi primarily involved, based on its adduction and extension capabilities?
What is a key function of the thoracolumbar fascia in relation to the back muscles?
What is a key function of the thoracolumbar fascia in relation to the back muscles?
Which of the following is NOT a vertebral level of origin for the latissimus dorsi?
Which of the following is NOT a vertebral level of origin for the latissimus dorsi?
Levator scapulae, when working with the trapezius, has what net effect on scapular rotation?
Levator scapulae, when working with the trapezius, has what net effect on scapular rotation?
Which of the muscles of the back, when acting unilaterally (one side only) with the scapula and clavicle fixed, can cause lateral bending of the neck?
Which of the muscles of the back, when acting unilaterally (one side only) with the scapula and clavicle fixed, can cause lateral bending of the neck?
Flashcards
Superficial back muscles
Superficial back muscles
The superficial muscles linking spine, external occipital protuberance, and superior nuchal line to upper limb girdle or humerus.
Latissimus dorsi
Latissimus dorsi
Broadest muscle of the back; causes adduction, extension, and downward rotation of the scapula.
Trapezius
Trapezius
Muscle with upper, middle, and lower parts; rotates scapula upwards.
Levator scapulae
Levator scapulae
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Rhomboid muscles
Rhomboid muscles
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Spinal accessory nerve (CN XI)
Spinal accessory nerve (CN XI)
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Linking Function
Linking Function
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Latissimus Dorsi Translation
Latissimus Dorsi Translation
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Thoracolumbar Fascia
Thoracolumbar Fascia
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Latissimus Dorsi Action
Latissimus Dorsi Action
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Study Notes
- Superficial muscles of the back connect the spine, external occipital protuberance, and superior nuchal line to the upper limb girdle or humerus.
- The superficial back muscles include latissimus dorsi, trapezius, levator scapulae, rhomboid major, and rhomboid minor.
- These muscles move the arm, shoulder, and vertebral column.
- They help maintain posture and suspend the scapula.
Muscle Name Meanings
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Latissimus dorsi means the broadest muscle of the back
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Trapezius and rhomboids are named for their shapes
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Levator scapulae's name reflects its function of scapula elevation
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The trapezius and latissimus dorsi are located close to the skin.
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Lower fibers of the trapezius overlap the upper fibers of the latissimus dorsi.
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The levator scapulae and rhomboids become visible when the trapezius is cut and turned away.
Trapezius Muscle Details
- The trapezius has upper, middle, and lower parts.
- It originates from the external occipital protuberance, superior nuchal line, ligamentum nuchae, and all 12 thoracic spines.
- Upper fibers insert anterolaterally on the lateral third of the clavicle.
- Middle fibers are horizontally oriented and pass to the acromion.
- The remaining muscle inserts on the posteromedial spine of the scapula.
- The upper and lower fibers combine with the serratus anterior to rotate the scapula upwards, facilitating full abduction of the upper limb.
- The middle and lower fibers retract the scapula.
- When the scapula/clavicle are fixed, unilateral trapezius action causes lateral neck bending, while bilateral contraction extends the neck.
- Trapezius otherwise stabilizes the scapula.
- The spinal accessory nerve (cranial nerve XI) innervates the trapezius.
- Paralysis of the trapezius shows its supportive action, resulting in shoulder drooping.
Latissimus Dorsi Muscle Details
- The latissimus dorsi originates from spinous processes of T6-T12, L1-5, crests of ilium and sacrum, lower 4 ribs, thoracolumbar fascia, and the inferior angle of the scapula.
- It inserts into the floor of the intertubercular sulcus.
- Function: adduction, extension, and downward rotation of the scapula at the shoulder joint.
- It enables rowing and wide grip pull ups.
- It passes from posterior to anterior to reach the intertubercular sulcus, causing internal (medial) rotation at the shoulder joint.
- The thoracolumbar fascia supports the back and its tension is maintained by latissimus dorsi.
- Forces from the upper limb can be transmitted to the lower limb via the thoracolumbar fascia.
- The thoracodorsal nerve supplies the latissimus dorsi.
Levator Scapulae
- Originates from the posterior tubercles of the transverse processes C1-C4.
- Inserts on the superior part of the medial border of the scapula.
- Actions include elevation and downward rotation of the scapula.
- When acting with trapezius the upward and downward scapula rotations are nullified, resulting in just elevation.
- Innervated by the dorsal scapular nerve.
Rhomboid Muscles
- Rhomboid minor inserts onto the medial border of the scapula at the root of the spine.
- Actions: retraction, elevation, and downward rotation of the scapula.
- Both rhomboids are also supplied by the dorsal scapular nerve.
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