Anatomy OINAS (Unit 3)

Trapezius (Upper) Origin

External occipital protuberance; medial superior nuchal line; nuchal ligament; SP C7

Trapezius (Upper) Insertion

Lateral clavicale; acromion process of scapula

Trapezius (Upper) Innervation

Motor: Spinal accessory nerve (CN XI)

Sensory: C3 and C4 APRs

Trapezius (Upper) Action

Elevates scapula; upward rotation (when working with lower trapezius)

Trapezius (Middle) Origin

SP upper T/S

Trapezius (Middle) Insertion

Medial acromion process; superior lip of scapular spine

Trapezius (Middle) Innervation

Motor: Spinal accessory nerve (CN XI)

Sensory: C3 and C4 APRs

Trapezius (Middle) Action

Retracts scapula

Trapezius (Lower) Origin

SP lower T/S

Trapezius (Lower) Insertion

Tubercle at the apex of scapular spine

Trapezius (Lower) Innervation

Motor: Spinal accessory nerve (CN XI)

Sensory: C3 and C4 APRs

Trapezius (Lower) Action

Depresses scapula; upward rotation (when working with lower trapezius)

Latissimus dorsi Origin

SP lower T/S; thoracolumbar fascia; iliac crest

Latissimus dorsi Insertion

Floor of intertubercular groove of humerus

Latissimus dorsi Innervation

Thoracodorsal nerve (C6-C8)

Latissimus dorsi Action

Extends + adducts + internally rotates humerus; raises body toward arms during climbing

Levator scapulae Origin

Posterior tubercles TP C1-C4

Levator scapulae Insertion

Medial border of scapula

Levator scapulae Innervation

Dorsal scapular nerve (C5) + Cervical nerves (C3-C4)

Levator scapulae Action

Elevates scapula: downward rotation

Rhomboid major Origin

SP upper T/S

Rhomboid major Insertion

Medial border of scapula (from spine to inferior angle)

Rhomboid major Innervation

Dorsal scapular nerve (C4-C5)

Rhomboid major Action

Retracts scapula; downward rotation; fixes scapula to thoracic wall

Rhomboid minor Origin

Nuchal ligament; SP C7-T1

Rhomboid minor Insertion

Medial border of scapular spine

Rhomboid minor Innervation

Dorsal scapular nerve (C4-C5)

Rhomboid minor Action

Retracts scapula; downward rotation; fixes scapula to thoracic wall

Pectoralis major Origin

Clavicular head: Anterior medial clavicle

Sternocostal head: Anterior sternum; superior 6 costal cartilages; aponeurosis of external oblique

Pectoralis major Insertion

Lateral lip of intertubercular groove of humerus

Pectoralis major Innervation

Clavicular head: Lateral pectoral nerve (C5-C6)

Sternocostal head: Medial pectoral nerve (C7-T1)

Pectoralis major Action

Adducts + internally rotates humerus; draws scapula inferio-anteriorly

Clavicular head: Flexes humerus

Sternoclostal head: Extends humerus (from flexed position)

Pectoralis minor Origin

Ribs 3-5 near costal cartilages

Pectoralis minor Insertion

Coracoid process

Pectoralis minor Innervation

Medial pectoral nerve (C8-T1)

Pectoralis minor Action

Stabilizes scapula by drawing it inferio-anteriorly against thoracic wall

Serratus anterior Origin

External lateral surfaces of ribs 1-8

Serratus anterior Insertion

Anterior medial border of scapula

Serratus anterior Innervation

Long thoracic nerve (C5-C7)

Serratus anterior Action

Protracts scapula; holds it against thoracic wall; upwardly rotates scapula

Deltoid (Anterior) Origin

Lateral clavicle

Deltoid (Anterior) Insertion

Deltoid tuberosity

Deltoid (Anterior) Innervation

Axillary nerve (C5-C6)

Deltoid (Anterior) Action

Flexes + internally rotates arm

Deltoid (Middle) Origin

Acromion

Deltoid (Middle) Insertion

Deltoid tuberosity

Deltoid (Middle) Innervation

Axillary nerve (C5-C6)

Deltoid (Middle) Action

Abducts arm

Deltoid (Posterior) Origin

Spine of scapula

Deltoid (Posterior) Insertion

Deltoid tuberosity

Deltoid (Posterior) Innervation

Axillary nerve (C5-C6)

Deltoid (Posterior) Action

Extends + externally rotates arm

Teres major Origin

Inferior angle of scapula

Teres major Insertion

Medial lip of intertubercular groove of humerus

Teres major Innervation

Lower subscapular nerve (C5-C6)

Teres major Action

Adducts + internally rotates arm

Supraspinatus Origin

Supraspinous fossa of scapula

Supraspinatus Insertion

Superior facet of greater tubercule of humerus

Supraspinatus Innervation

Suprascapular nerve (C5-C6)

Supraspinatus Action

Initiates + assists deltoid in abduction of arm; stabilizes humeral head within glenoid cavity

Infraspinatus Origin

Infraspinous fossa of scapula

Infraspinatus Insertion

Middle facet of greater tubercle of humerus

Infraspinatus Innervation

Suprascapular nerve (C5-C6)

Infraspinatus Action

Externally rotates arm; stabilizes humeral head within glenoid cavity

Teres minor Origin

Middle lateral border of scapula

Teres minor Insertion

Inferior facet of greater tuibercle of humerus

Teres minor Innervation

Axillary nerve (C5-C6)

Teres minor Action

Externally rotates arm; stabilizes humeral head within glenoid cavity

Subscapularis Origin

Subscapular fossa

Subscapularis Insertion

Lesser tubercle of humerus

Subscapularis Innervation

Upper and lower subscapular nerves (C5-C7)

Subscapularis Action

Internally rotates arm; stabilizes humeral head within glenoid cavity

Biceps brachii Origin

Short head: coracoid process of scapula

Long head: supraglenoid tubercle of scapula

Biceps brachii Insertion

Radial tuberosity; fascia of forearm via bicipital aponeurosis

Biceps brachii Innervation

Musculocutaneous nerve (C5-C7)

Biceps brachii Action

Flexes humerus; supinates forearm; flexes forearm (when supinated)

Brachialis Origin

Distal half of anterior humerus

Brachialis Insertion

Ulnar tuberosity + coronoid process of ulna

Brachialis Innervation

Musculocutaneous nerve (C5-C6); radial nerve (C5-C7)

Brachialis Action

Flexes forearm in all positions

Coracobrachialis Origin

Coracoid process of scapula

Coracobrachialis Insertion

Middle 1/3 of medial humerus

Coracobrachialis Innervation

Musculocutaneous nerve (C5-C7)

Coracobrachialis Action

Helps flex + adduct humerus; resists anterior dislocation of shoulder

Triceps brachii (long head) Origin

Infraglenoid tubercle of scapula

Triceps brachii (long head) Insertion

Olecranon of ulna; fascia of forearm

Triceps brachii (long head) Innervation

Radial nerve (C6-C8)

Triceps brachii (long head) Action

Extends forearm; long head assists in adduction and extension of humerus

Triceps brachii (lateral head) Origin

Posterior humerus superior to radial groove

Triceps brachii (lateral head) Insertion

Olecranon of ulna; fascia of forearm

Triceps brachii (lateral head) Innervation

Radial nerve (C6-C8)

Triceps brachii (lateral head) Action

Extends forearm; long head assists in adduction and extension of humerus

Triceps brachii (medial head) Origin

Posterior humerus inferior to radial groove

Triceps brachii (medial head) Insertion

Olecranon of ulna; fascia of forearm

Triceps brachii (medial head) Innervation

Radial nerve (C6-C8)

Triceps brachii (medial head) Action

Extends forearm; long head assists in adduction and extension of humerus

Anconeus Origin

Lateral epicondyle of humerus

Anconeus Insertion

Lateral olecranon; superior posterior ulnar

Anconeus Innervation

Radial nerve (C7-T1)

Anconeus Action

Assist in extension of forearm; stabilizes elbow joint