11. Shoulder muscles Flashcards
Identify
- Trapezius muscle
- Deltoid muscle
- Latissimus dorsi muscle
Identify 1. O & I
Insertion (distal): Superior fibers of the trapezius muscle insert into ___
Middle fibers insert into the medial margin of the acromion and posterior border of the scapular spine.
Inferior fibers converge to end in an aponeurosis inserted into the scapular spine.
- Trapezius muscle
→ the posterior border of the lateral third of the clavicle
Identify 1. O & I
Insertion (distal): Superior fibers of the trapezius muscle insert into the posterior border of the lateral third of the clavicle.
Middle fibers insert into (1)____ & (2) ____
Inferior fibers converge to end in an aponeurosis inserted into the scapular spine.
Trapezius muscle
- the medial margin of the acromion
- posterior border of the scapular spine.
Identify 1. O & I
Insertion (distal): Superior fibers of the trapezius muscle insert into the posterior border of the lateral third of the clavicle.
Middle fibers insert into the medial margin of the acromion and posterior border of the scapular spine.
Inferior fibers converge to end in an aponeurosis inserted into ____
Trapezius muscle
→ the scapular spine.
Identify 1. Action
The upper and lower fibers of the trapezius muscle → rotate the scapula for full abduction of the upper extremity.
The upper fibers → (1)____ and (2)____ when a weight is being carried by the shoulder or hand.
Central fibers → run horizontally and (3)____
Lower fibers → draw the scapula downward
-
Trapezius muscle
(1) elevate the shoulder
(2) brace the shoulder girdle
(3) retract the shoulder.
Identify 1. Action
The upper and lower fibers of the trapezius muscle → ___
The upper fibers → elevate the shoulder and brace the shoulder girdle when a weight is being carried by the shoulder or hand.
Central fibers → run horizontally and ____
Lower fibers → draw the scapula downward.
- Trapezius muscle
→ retract the shoulder.
Identify 1. Innervation
- Trapezius muscle
Motor supply is from the accessory nerve (CN XI).
Proprioceptive fibers are from the 3rd and 4th cervical nerves.
Identify 1. Does this muscle receive innervation from brachial plexus?
The trapezius, in contrast to the other shoulder muscles, does not receive nerve fibers from the brachial plexus.
→ Motor supply is from the accessory nerve (CN XI). Proprioceptive fibers are from the 3rd and 4th cervical nerves.
The trapezius can be tested by having a patient elevate the shoulder against resistance (the upper portion of the contracting muscle can be felt).
→ This tests the integrity of ____ innervating this muscle.
the accessory nerve (CN XI)
Identify
- Latissimus dorsi muscle
- Teres major muscle
- Thoracolumbar fascia
Identify
- Levator scapulae muscle
- Splenius capitis muscle
Identify 1. O & I
Origin (proximal): Latissimus dorsi muscle spinous processes of the lower 6 thoracic vertebrae
Insertion (distal): the intertubercular groove of the humerus.
Identify 1.
Insertion (distal): The fibers of the latissimus dorsi muscle converge as the muscle curves around the lower border of the teres major and twists on itself.
→ They end as a tendon that inserts into the ___
- Latissimus dorsi muscle
→ intertubercular groove of the humerus.
Identify 1. Action?
- Latissimus dorsi muscle
→ Extends, adducts, and medially rotates the humerus (arm).
Identify 1. Innervation?
- Latissimus dorsi muscle
→ Thoracodorsal nerve (C6-C8).
With the upper extremity fixed, the latissimus dorsi ____ when the arms are stretched above the head, as when reaching up while climbing.
elevates the trunk
Latissimus dorsi muscle
→ The blood supply is by (1)____, a branch of (2)___
- the thoracodorsal artery
- the subscapular artery (which arises from the axillary artery).
Identify
- Levator scapulae muscle
- Splenius capitis muscle
Identify 1. O & I
Origin (proximal): Levator scapulae muscle arises from the transverse processes of the first 4 cervical vertebrae.
Insertion (distal): Inserts into the superior portion of the medial (vertebral) border of the scapula.
Identify 1. Action
- Levator scapulae muscle
→ Action:
- Elevates the superior angle of the scapula and tends to draw it medially.
- Rotates the scapula so that the glenoid cavity is tilted inferioly.
- When the scapula is held in a fixed position, the levator scapulae bends the neck laterally and rotates it slightly toward the same side.
Identify 1. Direct actions with scapula?
- Levator scapulae muscle
Elevates the superior angle of the scapula and tends to draw it medially.
→ Also rotates the scapula so that the glenoid cavity is tilted inferioly
Identify 1. Action with neck?
- Levator scapulae muscle
→ When the scapula is held in a fixed position, the levator scapulae bends the neck laterally and rotates it slightly toward the same side.
Identify 1. Innervation?
- Levator scapulae muscle
Innervation: By the 3rd and 4th cervical nerves from the cervical plexus and by a branch from the dorsal scapular nerve (C5) to the muscle’s lower fibers.
Contraction of the levator scapulae helps shrug the shoulders.
→ The blood supply to the muscle comes largely from (1)____ of the (2)___
- the transverse cervical artery
- thyrocervical trunk.
Identify 1. O & I
Deltoid muscle
Origin (proximal): Arises from the lateral third of the clavicle, the superior surface of the acromion, and the spine of the scapula.
Insertion (distal): The deltoid tuberosity on the lateral aspect of the shaft of the humerus.
The blood supply is largely via the thoracoacromial artery and also via the anterior and posterior humeral circumflex arteries, which arise from the ____
Axillary artery
Identify 1. Action
Deltoid muscle
- Abduction of the arm at the shoulder in a movement initiated together with the supraspinatus muscle.
- The clavicular portion of the muscle rotates the arm medially and helps the pectoralis major flex the arm at the shoulder.
- The spinous portion rotates the arm laterally and helps the latissimus dorsi extend the arm at the shoulder.
Identify 1. Innervation
Deltoid muscle
- Axillary nerve (C5 and C6).
The blood supply of deltoid muscle is largely via the (1)___ (3 arteries), which arise from the axillary artery.
thoracoacromial artery; the anterior and posterior humeral circumflex arteries
Identify
- Supraspinatus muscle
- Infraspinatus muscle
- Rhomboid minor muscle
- Rhomboid major muscle
- Teres major muscle
Identify 1. O & I
- supraspinatus muscle
Origin (proximal): the supraspinous fossa
Insertion (distal): superior facet on the greater tubercle of the humerus.
Identify 1. Action
- supraspinatus muscle
Action: The supraspinatus strengthens the shoulder joint by drawing the humerus toward the glenoid fossa.
Identify 1. Innervation
- supraspinatus muscle
the suprascapular nerve (C5 and C6).
Identify 2. O & I
- Supraspinatus muscle
- Infraspinatus muscle
Origin (proximal): the infraspinous fossa
Insertion (distal): middle facet on the greater tubercle of the humerus
Identify 2. Action
- Supraspinatus muscle
- Infraspinatus muscle
Action: The infraspinatus strengthens the shoulder joint by bracing the head of the humerus in the glenoid fossa. It is also a lateral rotator of the humerus.
Identify 2. Innervation
- Supraspinatus muscle
- Infraspinatus muscle
Innervation: The suprascapular nerve (C5 and C6).
Identify 1 & 2. Do the tendons of these 2 muscles adhere to each other?
- Supraspinatus muscle
- Infraspinatus muscle
→ YES!!!
Identify
- Teres minor muscle
- Teres major muscle
Identify 1. O & I
- Teres minor muscle
- Teres major muscle
Origin (proximal): The teres minor originates from the lateral border of the scapula.
Insertion (distal): The teres minor inserts into the inferior facet on the greater tubercle of the humerus.
Identify 1. Action
- Teres minor muscle
- Teres major muscle
ACTION:
- The teres minor rotates the arm laterally and weakly adducts the arm at the shoulder.
- Draws the humerus toward the glenoid fossa, strengthening the shoulder joint.
Identify 1. Innervation
- Teres minor muscle
- Teres major muscle
→ The teres minor is supplied by the axillary nerve (C5 and C6)
Identify 2. O & I
- Teres minor muscle
- Teres major muscle
Origin (proximal): The teres major arises from the dorsal surface of the inferior angle of the scapula.
Insertion (distal): The teres major inserts into the medial lip of the intertubercular groove of the humerus.
Identify 2. Action
- Teres minor muscle
- Teres major muscle
→ Action: the teres major helps extend the arm from the flexed position, and it adducts and medially rotates the arm at the shoulder.
Identify 2. Innervation
- Teres minor muscle
- Teres major muscle
→ the teres major is innervated by the lower subscapular nerve (C6 and C7).
The teres minor is 1 of the 4 ___, and it helps stabilize the shoulder joint. Often, it is inseparable from the infraspinatus muscle.
rotator cuff muscles
The teres minor is 1 of the 4 rotator cuff muscles, and it helps stabilize the shoulder joint. Often, it is inseparable from the ___ muscle.
infraspinatus
Identify 1. O & I
- Subscapularis muscle
Origin (proximal): The subscapular fossa and from the lower two-thirds of the lateral border of the scapula.
Insertion (distal): The lesser tubercle of the humerus
Identify 1. Action
- Subscapularis muscle
Action: As a rotator cuff muscle, the subscapularis helps
- stabilize the shoulder joint → prevents anterior displacement of the humerus
- medially rotates and adducts the humerus (arm) at the shoulder.
Identify 1. Innervation
- Subscapularis muscle
Innervation: Upper and lower subscapular nerves (C5 and C6).
The tendon of the muscle is separated from __ by the subscapular bursa.
the neck of the scapula
What is scapulothoracic joint?
a functional (physiological) articulation of the shoulder formed by the subscapularis and serratus anterior muscles
Function of scapulothoracic joint?
It permits a gliding movement of the scapula on the chest wall.
→ Scapular movements at this joint include elevation, depression, protraction, retraction, and rotation.
The blood supply to the Subscapularis muscle is by (1)____, a branch of (2)____.
- the subscapular artery
- the axillary artery
Identify 1. O & I
- Pectoralis major muscle
Origin (proximal): Arises from the sternal half of the clavicle, the upper half of the sternum
Insertion (distal): the intertubercular groove of the humerus.
1. Pectoralis major muscle
Action: The primary action is adduction of the arm at the shoulder. The pectoralis major is also a medial rotator of the humerus
- its clavicular portion helps ____ (2 ACTIONS)
- The sternocostal portion, along with the latissimus dorsi and teres major muscles, can extend—against resistance—the flexed humerus to the side of the trunk.
flex the shoulder and adduct the humerus medially across the midline.
1. Pectoralis major muscle
Action: The primary action is adduction of the arm at the shoulder. The pectoralis major is also a medial rotator of the humerus
- its clavicular portion helps flex the shoulder and adduct the humerus medially across the midline
- The sternocostal portion, along with the latissimus dorsi and teres major muscles, can ___
extend—against resistance—the flexed humerus to the side of the trunk.
Identify 1. Innervation
- Pectoralis major muscle
Innervation: Medial and lateral pectoral nerves (C5-C8 and T1).
The converging fibers of Pectoralis major muscle course toward the insertion on the humerus, forming the anterior boundary of the ___.
axilla
2 arteries that supply the pectoralis major.
The thoracoacromial and lateral thoracic arteries
