Shoulder & Arm Muscles Flashcards
Deltoid (Origin/Insertion)
Origin:
- Lateral one-third of clavicle
- Acromion
- Spine of scapula
Insertion:
- Deltoid tuberosity
Deltoid (Action/Innervation)
Action:
1. All fibers:
- Abduct the shoulder (glenohumeral joint)
2. Anterior fibers:
- Flex the shoulder
- Medially rotate the shoulder
- Horizontally adduct the shoulder.
3. Posterior fibers:
- Extend the shoulder
- Laterally rotate the shoulder
- Horizontally ABduct the shoulder
Innervation:
- Axillary (C5,6)
Trapezius (Origin/Insertion)
Origin:
- External occipital protuberance
- Medial portion of superior nuchal line of the occiput
- Ligamentum nuchae
- Spinous processes of C7 thru T12
Insertion:
- Lateral one-third of clavicle
- Acromion
- Spine of the scapula
Trapezius (Action/Innervation)
Action:
1. Upper Fibers:
- Bilaterally: Extend the head and neck
- Unilaterally: Laterally flex the head and neck to the same side; Rotate the head and neck to the opposite side; Elevate the scapula (scapulothoracic joint); Upwardly rotate the scapula (S/T joint)
2. Middle fibers:
- Adduct the scapula (S/T joint)
- Stabilize the scapula (S/T joint)
3. Lower fibers:
- Depress the scapula (S/T joint)
- Upwardly rotate the scapula (S/T joint)
Innervation:
- Spinal portion of cranial nerve XI (accessory) and ventral ramus (C2,3,4)
Latissimus Dorsi (Origin/Insertion)
Origin:
- Inferior angle of scapula
- Spinous processes of last six thoracic vertebrae
- Last three or four ribs
- Thoracolumbar fascia
- Posterior iliac crest
Insertion:
- Intertubercular groove of the humerus
Latissimus Dorsi (Action/Innervation)
** Handcuff muscle!
Action:
- Extend the shoulder (Glenohumeral joint)
- Adduct the shoulder (G/H joint)
- Medially rotate the shoulder (G/H joint)
Innervation:
- Thoracodorsal (C6,7,8)
Teres Major (Origin/Insertion)
Origin:
- Inferior angle and lower one-third of lateral border of the scapula
Insertion:
- Crest of the lesser tubercle of the humerus
Teres Major (Action/Innervation)
** Handcuff muscle!
Action:
- Extend the shoulder (G/H joint)
- Adduct the shoulder (G/H joint)
- Medially rotate the shoulder (G/H joint)
Innervation:
- Lower subscapular (C5,6,7)
Supraspinatus (Origin/Insertion)
** Rotator Cuff Muscle
Origin:
- Supraspinous fossa of the scapula
Insertion:
- Greater tubercle of the humerus
Supraspinatus (Action/Innervation)
** Rotator Cuff Muscle
Action:
- ABduct the shoulder
- Stabilize the head of the humerus in glenoid cavity
Innervation:
- Suprascapular (C4,5,6)
Infraspinatus (Origin/Insertion)
** Rotator Cuff Muscle
Origin:
- Infraspinous fossa of the scapula
Insertion:
- Greater tubercle of the humerus
Infraspinatus (Action/Innervation)
** Rotator Cuff Muscle
Action:
- Laterally rotate the shoulder (G/H joint)
- Adduct the shoulder (G/H joint)
- Stabilize the head of the humerus in glenoid cavity
Innervation:
- Suprascapular (C4,5,6)
Teres Minor (Origin/Insertion)
** Rotator Cuff Muscle
Origin:
- Upper two-thirds of lateral border of the scapula
Insertion:
- Greater tubercle of the humerus
Teres Minor (Action/Innervation)
** Rotator Cuff Muscle
Action:
- Laterally rotate the shoulder (G/H joint)
- Adduct the shoulder (G/H joint)
- Stabilize the head of the humerus in the glenoid cavity
Innervation:
- Axillary (C5,6)
Subscapularis (Origin/Insertion)
** Rotator Cuff Muscle
Origin:
- Subscapular fossa of the scapula
Insertion:
- Lesser tubercle of the humerus
Subscapularis (Action/Innervation)
** Rotator Cuff Muscle
Action:
- Medially rotate the shoulder (G/H joint)
- Stabilize the head of the humerus in the glenoid cavity
Innervation:
- Upper and lower subscapular (C5,6,7)
Rhomboid Major & Minor (Origin/Insertion)
Origin:
- Major: Spinous processes of T2 to T5
- Minor: Spinous processes of C7 to T1
Insertion:
- Major: Medial border of the scapula between the spine of the scapula and inferior angle
- Minor: Upper portion of medial border of the scapula, across from the spine of the scapula
Rhomboid Major & Minor (Action/Innervation)
Action:
- Adduct the scapula (Scapulothoracic joint)
- Elevate the scapula (S/T joint)
- Downwardly rotate the scapula (S/T joint)
Innervation:
- Dorsal Scapular (C4,5)
Levator Scapula (Origin/Insertion)
Origin:
- Transverse processes of first through fourth cervical vertebrae
Insertion:
- Medial border of scapula, between the superior angle and the superior portion of spine of scapula
Levator Scapula (Action/Innervation)
Action:
1. Unilaterally:
- Elevate the scapula (Scapulothoracic joint)
- Downwardly rotate the scapula (S/T joint)
- Laterally flex the head and neck
- Rotate the head and neck to the same side
2. Bilaterally:
- Extend the head and neck
Innervation:
- Cervical (3,4)
- Dorsal Scapular (C4,5)
Serratus Anterior (Origin/Insertion)
Origin:
- External surfaces of the upper eight or nine ribs
Insertion:
- Anterior surface of the medial border of the scapula
Serratus Anterior (Action/Innervation)
Action:
1. With the origin fixed:
- ABduct the scapula (Scapulothoracic joint)
- Upwardly rotate the scapula (S/T joint)
- Depress the scapula (S/T joint)
- Hold the medial border of the scapula against the rib cage
2. With the scapula fixed:
- May act to elevate the thorax during forced inhalation
Innervation:
- Long Thoracic (C5,6,7,8)
Pectoralis Major (Origin/Insertion)
Origin:
- Medial half of clavicle
- Sternum
- Cartilage of first through sixth ribs
Insertion:
- Crest of greater tubercle of humerus
Pectoralis Major (Action/Innervation)
Action:
1. All Fibers:
- Adduct the shoulder (Glenohumeral joint)
- Medially rotate the shoulder (G/H joint)
2. Upper Fibers:
- Flex the shoulder (G/H joint)
- Horizontally adduct the shoulder (G/H joint)
3. Lower Fibers:
- Extend the shoulder (G/H joint)
Innervation:
1. Upper Fibers:
- Lateral Pectoral (C5,6,7)
2. Lower Fibers:
- Lateral and Medial Pectoral (C6,7,8 & T1)
