Anterior Arm and Forearm

Question 1

Which arm is fractured more often and why?

Answer 1

Radius because it is the bone primarily in contact with carpals

Question 2

When are ulnar fractures seen?

Answer 2

In defensive injuries (holding arm in front of face)

Question 3

Ulnar pseudoarthrosis

Answer 3

Joint in the middle of the bone with formation of cartilage and synovial capsule – causes swelling but no functional deficit

Question 4

Elbow joints (2)

Answer 4

Humeroradial and humeroulnar joints – both functional and morphological hinge joints (radioulnar joint not part of elbow but promotes function)

Question 5

What ligament joins the radius and ulna?

Answer 5

Annular ligament – strongest proximal connection (radial head can dislodge without this)

Question 6

Important elbow ligaments on medial side

Answer 6

Ulnar collateral ligaments (posterior, anterior, transverse)

Question 7

What fracture is usually caused by posterior dislocation of the ulna?

Answer 7

Fracture of coronoid process of ulna (in this dislocation trochlear notch sits next to medial epicondyle)

Question 8

“Nursemaid’s elbow” causing dislocated radius is a tearing of which ligament?

Answer 8

Annular ligament (dislocates to be superior to capitulum and anterior to ulnar coronoid process)

Question 9

Anterior compartment of arm (general action, innervation)

Answer 9

All are FLEXORS, innervated by MUSCULOCUTANEOUS N

Question 10

Biceps brachii: action

Answer 10

Flexion of shoulder, elbow, and supination

Question 11

Biceps brachii: attachments

Answer 11

Proximal attachment – NO attachment to humerus, attaches to coracoid process and supraglenoid tubercle of scapula
Distal attachment – radial tuberosity (and bicipital aponeurosis)

Question 12

Brachialis: action

Answer 12

Flexion of elbow

Question 13

Brachialis: innervation

Answer 13

Dual innervation: musculocutaneous AND radial!!

Question 14

Brachialis: attachments

Answer 14

Proximal attachment – distal half of anterior humeral shaft

Distal attachment – ulnar tuberosity

Question 15

Coracobrachialis: action

Answer 15

Flexion of shoulder, adduction of arm

Question 16

Coracobrachialis: attachments

Answer 16

Proximal attachment – coracoid process

Distal attachment – medial humerus

Question 17

Anterior compartment of forearm (general action, innervation)

Answer 17

Most are flexors of wrist/digits and two are pronators of forearm, all innervated by MEDIAN N except flexor carpi ulnaris and medial half of flexor digitorum profundus (both innervated by ulnar n)

Question 18

Superficial group of anterior compartment of forearm

Answer 18

Pronator teres (humeral head), palmaris longus, flexor carpi ulnaris and radialis

Question 19

Pronator teres (humeral head): attachments

Answer 19

Proximal attachment – medial epicondyle of humerus

Distal attachment – midshaft of radius

Question 20

Palmaris longus: atachments

Answer 20

Proximal attachment – medial epicondyle of humerus

Distal attachment – palmar aponeurosis

Question 21

Palmaris longus: action

Answer 21

Flex wrist, tense palmar aponeurosis

Question 22

Flexor carpi radialis: attachments

Answer 22

Proximal attachment – medial epicondyle of humerus

Distal attachment – base of metacarpal II

Question 23

Flexor carpi radialis: action

Answer 23

Flexion and ABDUCTION of wrist

Question 24

Flexor carpi ulnaris: attachments

Answer 24

Proximal attachment – medial epicondyle of humerus and olecranon
Distal attachment – hook of hamate, pisiform, and base of metacarpal V

Question 25

Flexor carpi ulnaris: innervation

Answer 25

ULNAR N

Question 26

Flexor carpi ulnaris: action

Answer 26

Flexion and ADDUCTION of wrist

Question 27

Intermediate group of anterior compartment of forearm

Answer 27

Pronator teres (ulnar head), flexor digitorum superficialis

Question 28

Pronator teres (ulnar head): attachments

Answer 28

Proximal attachment -- proximal head of ulna | Distal attachment -- midshaft of radius

Question 29

Flexor digitorum superficialis: attachments

Answer 29

Proximal attachment -- medial epicondyle, proximal radius | Distal attachment -- base of intermediate phalanges of digits 2-5

Question 30

Flexor digitorum superficialis: action

Answer 30

Flex proximal interphalangeal joints (PIP), metacarpophalangeal joints (MCP), and wrist

Question 31

Deep group of anterior compartment of forearm

Answer 31

Flexor digitorum profundus, flexor pollicis longus, pronator quadratus

Question 32

Innervation of deep group of anterior compartment forearm muscles

Answer 32

Anterior interosseous n EXCEPT medial half of flexor digitorum profundus

Question 33

Flexor digitorum profundus: attachments

Answer 33

Proximal attachment -- ulnar shaft, interosseous membrane | Distal attachment -- base of distal phalanges of digits 2-5

Question 34

Flexor digitorum profundus: action

Answer 34

Flex proximal interphalangeal (PIP) joints, distal interphalangeal (DIP) joints, metacarpophalangeal (MCP) joints, and wrist

Question 35

Flexor digitorum profundus: innervation

Answer 35

DUAL innervation -- lateral half = anterior interosseous n, medial half = ulnar n

Question 36

Flexor pollicis longus: attachments

Answer 36

Proximal attachment -- radial shaft, interosseous membrane | Distal attachment -- base of distal phalanx of digit 1

Question 37

Flexor pollicis longus: action

Answer 37

Flex carpometacarpal (CMC) joint, MCP, IP of digit 1, wrist

Question 38

Pronator quadratus: attachments

Answer 38

Proximal attachment -- distal ulnar shaft | Distal attachment -- distal radial shaft

Question 39

Radial artery anastomosis

Answer 39

Radial > radial recurrent > radial collateral > profunda brachii

Question 40

Ulnar artery anastomoses (3)

Answer 40

Ulnar > anterior ulnar recurrent > inferior ulnar collateral > brachial Ulnar > posterior ulnar recurrent > superior ulnar collateral > brachial Ulnar > common interosseous > posterior interosseous > recurrent interosseous > middle collateral > profunda brachii

Question 41

Cubital fossa borders

Answer 41

Medial: pronator teres Lateral: brachioradialis Superior: line between medial and lateral epicondyles

Question 42

Contents of cubital fossa

Answer 42

Superficial veins; brachial, ulnar, and radial arteries; median and radial nerves; biceps brachii tendon; bicipital aponeurosis

Question 43

Supra-epicondylar fracture

Answer 43

Damage to cubital fossa including BRACHIAL A (called Volkmann's ischemic contracture), brachialis pulls lower fragment superiorly and triceps pulls lower fragment posteriorly -- causes muscles in forearm to atrophy or die

Question 44

Median nerve injury in cubital fossa or more proximal

Answer 44

All muscles innervated by nerve will be de-innervated, clinical sign is Hand of Benediction (looks like blessing someone, can only flex two medial digits) -- can be caused by supracondylar fracture or anything that injures brachial a

Question 45

Pronator syndrome

Answer 45

Pronator teres compresses median nerve -- less severe injury than complete de-innervation -- pain in proximal forearm during pronation, weakness in finger flexion/wrist along with decreased sensation in lateral palm and digits

Question 46

Anterior interosseous syndrome

Answer 46

Damage to only the anterior interosseous nerve in forearm usually due to trauma, deep compartment muscles are de-innervated, can't make OK sign and difficulty with fine movement

Question 47

Ulnar nerve injury at elbow or more proximal

Answer 47

Clinical sign is ulnar claw (and inability to make tight fist) -- extension at MCP and joint flexion at IP, wasting of first dorsal interosseous, numbness of medial 1.5 digits

Question 48

Cubital tunnel syndrome

Answer 48

Compression of ulnar nerve as it passes through cubital tunnel (where humeral and ulnar heads of flexor carpi ulnaris meet), numbness and tingling of medial palm and 1.5 digits