Origins, Insertions, Actions, Innervation and Blood Supply

Question 1

What is the origin, insertion, action, innervation and blood supply of the pectoralis major m.?

Answer 1

O: Clavicular head - anterior surface of medial half of clavicle
Sternal head - anterior surface of sternum, superior 6 costal cartilages and aponeurosis of external oblique m.

I: Lateral lip of IT groove of humerus

A: Adduction and MR of humerus

N: Medial and lateral pectoral nn.

B: Pectoral branches of thoracoacromial trunk

Question 2

What is the origin, insertion, action, innervation and blood supply of the pectoralis minor m.?

Answer 2

O: Ribs 3- 5 (sometimes 6) @ costochondral junction

I: Medial border and superior surface of coracoid process of scapula

A: Stabilizes scapula by drawing it anterior and inferior against thoracic wall

N: Medial pectoral n. (C8, T1)

B: Pectoral branches from thoracoacromial trunk

Question 3

What is the origin, insertion, action, innervation and blood supply of the subclavius m.?

Answer 3

O: Junction of 1st rib and its costal cartilage

I: Inferior surface of the middle third of clavicle

A: Anchors and depresses clavicle

N: Nerve to subclavius (C5, C6)

B: Clavicular branches from thoracoacromial trunk

Question 4

What is the origin, insertion, action, innervation and blood supply of the serratus anterior m.?

Answer 4

O: External surfaces of lateral parts of ribs 1-8 (sometimes 9)

I: Anterior surface of medial border of scapula

A: Scapular protraction and upward rotation; fixes scapula against thoracic wall

N: Long thoracic n. (C5, C6, C7)

B: Superior and lateral thoracic aa.

Question 5

What is the origin, insertion, action, innervation and blood supply of the biceps brachii m.?

Answer 5

O: Short head - tip of coracoid process
Long head - supraglenoid tubercle and glenoid labrum

I: Tuberosity of the radius and bicipital aponeurosis

A: Supination of forearm; when supine flexes forearm; short head resists shoulder dislocation; slight flexion @ shoulder joint

N: Musculocutaneus n. (C5, C6, C7)

B: Brachial a. & anterior humeral circumflex a.

Question 6

What is the origin, insertion, action, innervation and blood supply of the deltoid?

Answer 6

O: lateral third of the clavicle; acromion and spine of scapula.

I: Deltoid tuberosity of humerus

A: Anterior (clavicular) fibers - flexion and MR of humerus
Middle (acromial) fibers - abduction 15 - 90 degrees
Posterior (spinal) fibers - extension and LR/ER of humerus

N: Axillary n. (C5, C6)

B: Anterior and posterior humeral circumflex aa.; acromial and deltoid branches of thoracoacromial trunk

Question 7

What is the origin, insertion, action, innervation and blood supply of the teres major?

Answer 7

O: Posterior surface of inferior angle of scapula

I: Medial lip of the IT groove of humerus

A: Adduction and MR of humerus

N: Lower subscapular n. (C5, C6)

B: Thoracodorsal a. and posterior humeral circumflex a.

Question 8

What is the origin, insertion, action, innervation and blood supply of the supraspinatus?

Answer 8

O: Supraspinatus fossa of scapula

I: Superior facet of the greater tubercle of the humerus

A: First 15 degrees of abduction of the humerus.

N: Suprascapular n. (C4, C5, C6)

B: Suprascapular and dorsal scapular aa.

Question 9

What is the origin, insertion, action, innervation and blood supply of the infraspinatus?

Answer 9

O: Infraspinous fossa of scapula

I: middle facet of the greater tubercle of the humerus

A: LR of humerus

N: Suprascapular n. (C5, C6)

B: Suprascapular and circumflex scapular aa.

Question 10

What is the origin, insertion, action, innervation and blood supply of the teres minor?

Answer 10

O: Middle part of the lateral border of scapula

I: Inferior facet of the greater tubercle of humerus

A: LR of humerus (assists in adduction)

N: Axillary n. (C5, C6)

B: Posterior humeral circumflex & circumflex scapular aa.

Question 11

What is the origin, insertion, action, innervation and blood supply of the subscapularis?

Answer 11

O: Subscapular fossa (most of anterior surface of scapula - only anterior rotator cuff m.)

I: Lesser tubercle of humerus

N: Upper and lower subscapular nn. (C5, C6, C7)

B: Subscapular a.

Question 12

What is the origin, insertion, action, innervation and blood supply of the serratus anterior?

Answer 12

O: External surfaces of lateral parts of R 1-8

I: Anterior surface of medial border of scapula

A: Scapular protraction and upward rotation; fixes scapula against thoracic wall

N: Long thoracic n. (C5, C6,C7)

B: Superior and lateral thoracic aa.

Question 13

What is the origin, insertion, action, innervation and blood supply of the biceps brachii?

Answer 13

O: Short head - Tip of coracoid process
Long head - Supraglenoid tubercle and glenoid labrum

I: Tuberosity of the radius and fascia of forearm via bicipital aponeurosis

A: Supination of forearm; when supine, flexes forearm; short head resists shoulder dislocation; slight flexion @ shoulder joint

N: Musculocutaneous n. (C5, C6, C7)

B: Brachial a. and anterior humeral circumflex a.

Question 14

What is the origin, insertion, action, innervation and blood supply of the brachialis m.?

Answer 14

O: Distal half of anterior surface of humerus.

I: Coronoid process and tuberosity of ulna.

A: Flexion of forearm in all positions

N: Musculocutaneous n. (C5, C6)

B: Brachial a.

Question 15

What is the origin, insertion, action, innervation and blood supply of the coracobrachialis m.?

Answer 15

O: Tip of the coracoid process.

I: Middle third of medial surface of humerus.

A: Flexion and adduction of arm; resists shoulder dislocation.

N: Musculocutaneous n. (C5, C6, C7)

B: Axillary a.

Question 16

What is the origin, insertion, action, innervation and blood supply of the triceps brachii?

Answer 16

O: Long head - Infraglenoid tubercle
Lateral head - Posterior surface of humerus superior to radial groove
Medial head - Posterior surface of humerus inferior to radial groove

I: Proximal end of olecranon of ulna and fascia of forearm

A: Main extensor of forearm

N: Radial n. (C6, C7, C8)

B: Profunda brachii a.

Question 17

What is the origin, insertion, action, innervation and blood supply of the anconeus?

Answer 17

O: Lateral epicondyle of humerus

I: Lateral surface of olecranon and superior part of posterior surface of ulna

A: Assists with forearm extension

N: Radial n. (C7, C8, T1)

B: Brachial a.

Question 18

What is the origin, insertion, action and innervation of the pronator teres?

Answer 18

O: Ulnar head - Coronoid process of ulna
Humeral head - Medial epicondyle via common flexor tendon.

I: Middle of convexity of lateral surface of radius.

A: Fast and powerful pronation; flexion for forearm.

N: Median n. (C6, 67)

Question 19

What is the origin, insertion, action and innervation of the flexor carpi radialis?

Answer 19

O: Medial epicondyle via common flexor tendon.

I: Base of 2nd metacarpal.

A: Flexion and radial deviation of hand.

N: Median n. (C6, C7)

Question 20

What is the origin, insertion, action and innervation of the palmaris longus?

Answer 20

O: Medial epicondyle via common flexor tendon.

I: Distal half of flexor retinaculum and apex of palmar aponeurosis.

A: Flexion of hand @ wrist; tenses palmar aponeurosis.

N: Median n. (C7, C8)

Question 21

What is the origin, insertion, action and innervation of the flexor carpi ulnaris?

Answer 21

O: Humeral head - Medial epicondyle via common flexor tendon.
Ulnar head - Olecranon and posterior border via aponeurosis.

I: Pisiform, hook of hamate and 5th metacarpal.

A: Flexion and ulnar deviation of hand.

N: Ulnar n. (C7, C8)

Question 22

What is the origin, insertion, action and innervation of the flexor digitorum superficialis?

Answer 22

O: Humeroulnar head - Medial epicondyle via common flexor tendon.
Radial head - Superior half of anterior border.

I: Shafts of middle phalanges of digits 2-5.

A: Flexion of proximal interphalangeal joint; strong flexion of metacarpophalangeal joint.

N: Medial n. (C7, C8, T1)