Muscles of the Trunk

Question 1

What is the name, origin, insertion, innervation, and action of this muscle?

Answer 1

Name: Latissimus dorsi

Origin: via lumbodorsal fascia into spines of T7-L5, lower 4 ribs, and iliac crest.

Insertion: floor of intertubercular groove of humerus.

Innervation: Thoracodorsal nerve

Action: (1) agonist of arm extension, (2) powerful arm adductor, (3) medially rotates arm and shoulder, (4) depresses scapula, (5) pulls body upwward and forward with arms fixed overhead

Question 2

What is the name, origin, insertion, innervation, and action of this muscle?

Answer 2

Name: Levator scapulae

Origin: Transverse processes of C1-C4

Insertion: medial border of scapula, superior to spine

Innervation: (1) cervical spinal nerves and (2) dorsal scapular nerve

Action: (1) elevates and adducts scapula and (2) tilts glenoid cavity down, flexes neck to same side

Question 3

What is the name, origin, insertion, innervation, and action of this muscle?

Answer 3

Name: Pectoralis major

Origin: sternal end of clavicle, sternum, cartilage of ribs 1-6, and aponeurosis of external oblique muscle.

Insertion: by a short tendon into intertuberculuar groove of humerus

Innervation: Lateral & medial pectoral nerves

Action: Agonist of arm extension, rotates are medially, adducts arg against resistance, and pulls rib cage upward with scapula flexed.

Question 4

What is the name, origin, insertion, innervation, and action of this muscle?

Answer 4

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Question 5

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Question 6

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Question 7

What is the name, origin, insertion, innervation, and action of this muscle?

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Question 8

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Question 9

What is the name, origin, insertion, innervation, and action of this muscle?

Answer 9

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