[4.0] UL 2: Pectoral, Back, Scapular, and Shoulder Muscles

Pectoralis Major, Pectoralis Minor, Subclavius, Serratus Anterior

What are the pectoral muscles?

Pectoralis Major

What is the muscle shown in the photo?

Sternum, Clavicle

Origin of the pectoralis major

Bicipital groove of the humerus

Insertion of the pectoralis major

Adduction, internal (medial rotation), shoulder flexion

Action of the pectoral muscles

Deltopectoral groove

• Line between the superior border of the pectoralis major and medial border of the deltoid

• Location of the cephalic vein

Pectoralis minor

What is the muscle shown in the photo?

Pectoralis minor

Small triangular muscle lying under pectoralis major that:

1. pulls the scapula downward

2. cannot move the shoulder joint

Subcoracoid space

Space behind (deep to) the Pectoralis minor; part of the axillary cavity

Axillary artery and vein; Cords of the Brachial Plexus

Neurovascular structures that pass through the subcoracoid space:

3rd to 5th ribs

Origin of the pectoralis minor

Coracoid process

Insertion of the pectoralis minor

Scapular depression, protraction, and stabilization

Action of the pectoralis minor

Subclavius

What is the muscle shown in the photo?

Subclavius

Which muscle serves as an accessory respiratory muscle during labored breathing?

By elevating the 1st rib

How does the subclavius assist in respiration?

1st rib

Origin of the subclavius

Inferior border of clavicle

Insertion of the subclavius

Depression and stabilization of the clavicle; Elevation of the 1st rib

Action of the subclavius

Serratus Anterior

What is the muscle shown in the photo?

Serratus Anterior

Which muscle holds the scapula close to the rib cage?

Winged scapula (bulging of the vertebral border)

Caused by injury or paralysis of the serratus anterior

Lateral ribs

Origin of the serratus anterior

Vertebral border of the scapula

Insertion of the serratus anterior

Scapular protraction and stabilization

Action of the serratus anterior

Trapezius, Latissimus Dorsi, Levator Scapulae, Rhomboid Major and Minor

What are the back muscles?

Trapezius

What is the muscle shown in the photo?

Superior descending fiber

Which fiber of the trapezius muscle elevates the scapula?

Middle transverse fiber

Which fiber of the trapezius muscle retracts the scapula?

Inferior ascending fiber

Which fiber of the trapezius muscle depresses the scapula?

Latissimus dorsi

What is the muscle shown in the photo?

Vertebrae, Thoracolumbar/Lumbosacral fascia, Pelvis (iliac crest)

Origin of the latissimus dorsi

Bicipital groove of the humerus

Insertion of the latissimus dorsi

Arm extension, adduction, medial rotation

Action of the latissimus dorsi

Trapezius, Latissimus dorsi, Medial border of the scapula

What muscles compose the Triangle of Auscultation medially, inferiorly, and laterally?

Levator Scapulae

What is the muscle shown in the photo?

Transverse processes of C1-C4

Origin of the levator scapulae

Superior medial border of scapula

Insertion of the levator scapulae

Scapular elevation

Action of the levator scapulae

Rhomboid Major

What is the muscle shown in the photo?

Rhomboid Major

Which back muscle is located adjacent to the infraspinous fossa?

T2-T5

Origin of the rhomboid major

T2-T5

Origin of the rhomboid major

Retract and elevate the scapula (stabilizing it against the ribcage)

Action of the rhomboid major

Rhomboid Minor

What is the muscle shown in the photo?

Nuchal ligament, Spinous processes of C7 and T1

Origin of the rhomboid minor

Medial border of scapula, adjacent to the scapular spine

Insertion of the rhomboid minor

Retract and elevate the scapula (stabilizing it against the ribcage)

Action of the rhomboid minor

Deltoid, Rotator Cuff Muscles, Teres Major

What are the deltoid and scapular muscles?

Anterior deltoid, shoulder flexion

What is the muscle shown in the photo, and what is its action?

Middle deltoid, shoulder abduction

What is the muscle shown in the photo, and what is its action?

Posterior deltoid, shoulder extension/hyperextension

What is the muscle shown in the photo, and what is its action?

Pure shoulder abduction

What is the collective action of the deltoid muscles?

15–100°

The deltoid is the primary shoulder abductor at what angle?

Insertion of trapezius

Origin of deltoid muscles

Deltoid tuberosity of the humerus

Insertion of deltoid muscles

Adduction, Internal (medial) rotation, flexion of the shoulder

Action of deltoid muscles

Rotator Cuff

Which muscle/s improve shoulder joint stability by pulling on the humeral head?

Supraspinatus, Infraspinatus, Teres Minor, Subscapularis

What are the muscles of the rotator cuff?

Supraspinatus, Infraspinatus, Teres Minor

Which muscle/s of the rotator cuff is/are responsible for the external rotation of the humerus?

Supraspinatus, Infraspinatus, Teres Minor

Which muscle/s of the rotator cuff is/are responsible for the external rotation of the humerus?

Supraspinatus

What is the muscle shown in the photo?

Supraspinatus

What muscle initiates shoulder abduction below below 15°?

Supraspinous fossa

Origin of the supraspinatus

Greater tuberosity of the humerus, Shoulder joint capsule

Insertion of the supraspinatus

Initiates abduction, External rotation of the humerus

Action of the supraspinatus

Infraspinatus

What is the muscle shown in the photo?

Infraspinous fossa

Origin of the infraspinatus

Greater tuberosity of the humerus, Shoulder joint capsule

Insertion of the infraspinatus

External rotation of the humerus

Action of the infraspinatus

Teres Minor

What is the muscle shown in the photo?

Infraspinous fossa

Origin of the infraspinatus

Greater tuberosity of the humerus, Shoulder joint capsule

Insertion of the infraspinatus

External rotation of the humerus

Action of the infraspinatus

Subscapularis

What is the muscle shown in the photo?

Subscapular fossa

Origin of the subscapularis

Lesser tuberosity of the humerus

Insertion of the subscapularis

Internal rotation of the humerus

Action of the subscapularis

Teres Major

What muscle is shown in the photo?

Teres Major

Which muscle serves as the anatomical landmark for the posterior circumflex humeral artery and circumflex scapular artery?

Lower third of lateral border of scapula

Origin of the teres major

Medial lip of bicipital groove of humerus

Insertion of the teres major

Adduction and medial rotation of the shoulder

Action of the teres major