Q: Which equation best represents the force required to abduct the arm at the shoulder, considering the torque generated by the deltoid muscle?

$$F_{deltoid} \times d_{deltoid} = F_{arm} \times d_{arm}$$

Question 1

Which muscle is primarily responsible for protracting and stabilizing the scapula, and what is its innervation?

Accepted Answer

Serratus anterior; long thoracic nerve

Question 2

A patient presents with winged scapula after trauma. Which nerve is most likely injured, and which muscle is affected?

Accepted Answer

Long thoracic nerve; serratus anterior

Question 3

Which muscles are involved in the superior rotation of the scapula during arm abduction?

Accepted Answer

Trapezius (upper and lower fibers) and serratus anterior

Question 4

What is the origin and insertion of the trapezius muscle?

Accepted Answer

Origin: Occipital bone, spines of C1-7 and T1-12; Insertion: Acromion, spine of scapula, lateral third of clavicle

Question 5

Which muscle is NOT part of the rotator cuff?

Accepted Answer

Teres major

Question 6

Simultaneous contraction of the rotator cuff muscles stabilizes the humerus in the glenoid cavity. What is the main function of sequential contraction of these muscles?

Accepted Answer

Causes rotation of the humerus in the glenoid cavity

Question 7

Which muscle is responsible for elevating the scapula and what is its origin?

Accepted Answer

Levator scapulae; transverse processes of C1-4

Question 8

Which equation best represents the force required to abduct the arm at the shoulder, considering the torque generated by the deltoid muscle?

Accepted Answer

$$F_{deltoid} 	imes d_{deltoid} = F_{arm} 	imes d_{arm}$$

Question 9

Which muscle is innervated by the axillary nerve and is responsible for abduction of the humerus?

Accepted Answer

Deltoid

Question 10

A baseball pitcher develops pain and weakness in lateral rotation of the humerus. Which rotator cuff muscle and nerve are most likely involved?

Accepted Answer

Infraspinatus; suprascapular nerve

Question 11

Which muscles are synergists in adduction of the humerus?

Accepted Answer

Latissimus dorsi, pectoralis major, teres major

Question 12

Which muscle originates from the sternal end of the clavicle, sternum, and costal cartilages 1-6, and what is its main function?

Accepted Answer

Pectoralis major; adducts the humerus

Question 13

Which muscle is responsible for depression of the scapula and is innervated by the medial and lateral pectoral nerves?

Accepted Answer

Pectoralis minor

Question 14

Which muscle is most likely to be torn in repetitive overhead activities, such as throwing, and what is its function?

Accepted Answer

Supraspinatus; initiates abduction of the humerus

Question 15

Which muscle inserts on the lesser tubercle of the humerus and medially rotates the humerus?

Accepted Answer

Subscapularis

Question 16

Which nerve innervates the trapezius muscle, and what is one of its major actions?

Accepted Answer

Spinal accessory nerve (CN XI); elevates the scapula

Question 17

Which muscle is responsible for retraction of the scapula and is innervated by the dorsal scapular nerve?

Accepted Answer

Rhomboid major

Question 18

Which muscle originates from the spinous processes of T2-T5 and inserts on the medial edge of the scapula?

Accepted Answer

Rhomboid major

Question 19

Which muscle is a synergist in medial rotation and extension of the humerus, but is NOT part of the rotator cuff?

Accepted Answer

Teres major

Question 20

Which equation best describes the relationship between muscle force and lever arm length in shoulder abduction?

Accepted Answer

$$F_{muscle} 	imes r_{muscle} = F_{load} 	imes r_{load}$$

Muscles that Move the Shoulder and Upper Limb: Scapula and Humerus Musculature 10.1

Guida di studio - Domande di pratica

Study guide - Flashcard