Anatomy 8/24/2023

Shoulder flexion

Shoulder extension

Shoulder abduction

Shoulder adduction

Shoulder horizontal abduction

Shoulder horizontal adduction

Shoulder internal rotation

Shoulder lateral rotation

What four joint articulations add to shoulder motion?

1. Glenohumeral

2. Acromioclavicular

3. Sternoclavicular

4. Scapulothoracic

Pectoralis major proximal attachment (clavicular head)

Clavicular head: anterior surface of medial half of clavicle

Pectoralis major proximal attachment (sternocostal head) (3)

1. anterior surface of sternum

2. superior six costal cartilages

3. aponeurosis of external oblique muscle

Pectoralis major distal attachment

Lateral lip of intertubercular groove of humerus

Pectoralis major action (clavicular head) (2)

1. Flexion of humerus

2. Adduction of humerus across midline

Pectoralis major action (sternocostal head) (2)

1. Adduct humerus

2. Internally rotate humerus

Pectoralis major action (reverse)

Elevate thorax

Pectoralis major nerve innervation (2)

Medial pectoral (C8-T1)

Lateral pectoral (C5, C6, C7)

Pectoralis minor proximal attachment

Anterior and exterior surface of ribs 3-5

Pectoralis minor distal attachment

Upper surface of coracoid process

Pectoralis minor action (2)

1) Stabilizes scapula by drawing it inferiorly and anteriorly against thoracic wall

2) Depresses tip of the shoulder

Pectoralis minor nerve innervation (2)

Medial pectoral nerve (C8, T1)

Lateral pectoral nerve

Subclavius proximal attachment

Junction of 1st rib and its costal cartilage

Subclavius distal attachment

Inferior surface of the middle 1/3 of the clavicle

Subclavius action (2)

1. Depresses clavicle

2. Anchors clavicle

Subclavius nerve innervation

Nerve to subclavius (C5, C6)

Scapular elevation

Upward (superior) motion of the scapula.

Scapular depression

Downward (inferior) motion of the scapula.

Scapular retraction

Adduction of scapula; shoulder blades move toward the midline.

Scapular protraction

Abduction of scapula; scapula moves anteriorly along the chest wall

Upward rotation of scapula

glenoid cavity of scapula faces upward, inferior angle of scapula moves laterally

Downward rotation of scapula

glenoid cavity moves in a downward direction

Serratus anterior proximal attachment

Slips from external surfaces of upper 8 ribs

Serratus anterior distal attachment

Costal surface of scapula at superior angle, medial border, and inferior angle

Serratus anterior action (3)

1) Protracts the scapula

2) Upwardly rotates the scapula

3) Stabilizes the scapula against thorax so deltoid can act on the humerus

Serratus anterior nerve innervation

Long thoracic nerve (C5, C6, C7)

Rhomboid major proximal attachment

Spines and supraspinous ligaments of TV2-5

Rhomboid major distal attachment

Medial border of scapula from level of spine to inferior angle

Rhomboid major action (3)

1) Retracts the scapula

2) Downward rotation of scapula

3) Elevation of scapula

Rhomboid major nerve innervation

Dorsal scapular nerve (C4, C5)

Rhomboid minor proximal attachment (2)

1. Lower portion of ligamentum nuchae,

2. CV7 and TV1 spines

Rhomboid minor distal attachment

medial border of the scapula at the root of the spine of the scapula

Rhomboid minor nerve innervation

Dorsal scapular (C4, C5)

Levator scapulae proximal attachment

Post tubercules of transverse processes of CV1-CV4

Levator scapulae distal attachment

Medial border of scapula, at and above spine of scapula

Levator scapulae action (2)

1) Elevation of scapula

2) Downward rotation of scapula

Subscapularis proximal attachment

Subscapular fossa

Subscapularis distal attachment (2)

1. Lesser tubercule of humerus and its crest

2. Anterior aspect of glenohumeral capsule

Subscapularis action

1) Internal rotation of humerus

2) Stabilizes the head of humerus in the glenoid cavity

Subscapularis nerve innervation (2)

1. Upper subscapular (C5, C6, C7)

2. Lower subscapular (C5, C6, C7)

Supraspinatus proximal attachment

Medial 2/3 of supraspinous fossa and fascia

Supraspinatus distal attachment

Superior facet of greater tubercle of humerus (blends with capsule)

Supraspinatus action

1) Abducts the humerus (empty can)

2) Stabilizes the head of humerus in the glenoid cavity

Supraspinatus nerve innervation

Suprascapular (C4, C5, C6)

Infraspinatus proximal attachment (2)

1) Medial 2/3 of infraspinous fossa

2) Lower surface of scapular spine

Infraspinatus distal attachment

Middle facet of greater tubercle of humerus (blends with capsule)

Infraspinatus action (2)

1. External rotation of humerus

2. Stabilizes the head of the humerus in the glenoid cavity

Infraspinatus nerve innervation

Suprascapular (C5, C6)

Teres minor proximal attachment

Lateral margin of infraspinous fossa

Teres minor distal attachment (2)

1. Lowest facet on the greater tubercle of the humerus

2. Area just distal (tendon fused to lower articular capsule and sometimes infraspinatus)

Teres minor action (2)

1. External rotation of humerus

2. Stabilizes head of the humerus in the glenoid cavity

Teres minor nerve innervation

Axillary nerve (C5, C6)