Forearm Anatomy

Front 1

What type of curvature does the radius have from proximal to distal?

Back 1

It has a gradual bend that is convex lateral, this must be restored when repairing radius fractures.

Front 2

What is the bony process found proximally on the radius and what attaches here?

Back 2

The adial tuberosity is found medially on the proximal radius and is the site for the biceps attachment

Front 3

Lister's tubercle is at the level of what joint?

Back 3

Scapholunate joint

Front 4

In what position is the DRUJ most stable?

Back 4

In supination

Front 5

What bones make up the radiocarpal joint?

Back 5

Radius, scaphoid, lunate, triquetrium

Front 6

Which ligaments of the wrist, volar or dorsal, are most important for stability?

Back 6

Volar are most important

Front 7

The Triangular Fibrocartilage Complex (TFCC) originates from the most ulnar portion of the radius and extends into the caput ulnae and the wrist aspect of the ulna to the base of the fifth metacarpal. What are the 5 components of the TFCC, where does each originate and insert?

Back 7

Dorsal and volar radioulnar ligament
-Origin: Ulnar radius; Insertion: Caput ulnae
Articular disc
-Origin: Radius/ulna; Insertion: Triquetrum
Prestyloid recess
-Origin: Disc; Insertion: Meniscus homolog
Meniscus homolog
-Origin: Ulna/disc; Insertion: Triquetrum/uln coll lig.
Ulnar collateral ligament
-Origin: Ulna; Insertion: Fifth metacarpal

Front 8

What makes up the mobile wad?

Back 8

Brachioradialis, ECRB, ECRL

Front 9

What muscle is primarily involved in lateral epicondylitis?

Back 9

ECRB

Front 10

What is the origin, insertion, action, and innervation of the following muscle?
Pronator Teres

Back 10

Origin: Medial epicondyle and coronoid
Insertion: Mid-lateral radius
Action: Pronating & flexing forearm
Innervation: Median

Front 11

What is the origin, insertion, action, and innervation of the following muscle?
Flexor Carpi Radialis

Back 11

Origin: Medial Epicondyle
Insertion: Second and Third metacarpal bases
Action: Flexing wrist
Innervation: Median

Front 12

What is the origin, insertion, action, and innervation of the following muscle?
Palmaris Longus

Back 12

Origin: Medial epicondyle
Insertion: Palmar aponeurosis
Action: Flexes wrist
Innervation: Median

Front 13

What is the origin, insertion, action, and innervation of the following muscle?
Flexor carpi ulnaris

Back 13

Origin: Medial epicondyle and posterior ulna
Insertion: Pisiform
Action: Flexes wrist
Innervation: Ulnar

Front 14

What is the origin, insertion, action, and innervation of the following muscle?
Flexor digitorum superficialis

Back 14

Origin: Medial epicondyle, anterior ulna & radius
Insertion: Base of middle phalanges
Action: Flexes PIP joint digits 2-5
Innervation: Median nerve

Front 15

What is the origin, insertion, action, and innervation of the following muscle?
Flexor digitorum profundus

Back 15

Origin: Anterior and medial ulna
Insertion: Base of distal phalanges
Action: Flexes DIP joints
Innervation: AIN: 2&3; Ulnar: 4&5

Front 16

What is the origin, insertion, action, and innervation of the following muscle?
Flexor pollicis longus

Back 16

Origin: Anterior and lateral radius
Insertion: Base of distal phalanges
Action: Flexes IP joint, thumb
Innervation: AIN

Front 17

What is the origin, insertion, action, and innervation of the following muscle?
Pronator quadratus

Back 17

Origin: Distal ulna
Insertion: Volar radius
Action: Pronates hand
Innervation: AIN

Front 18

What is the origin, insertion, action, and innervation of the following muscle?
Brachioradialis

Back 18

Origin: Lateral supracondylar humerus
Insertion: Lateral distal radius
Action: Flexes forearm
Innervation: Radial (m. in extensor compartment)

Front 19

What is the origin, insertion, action, and innervation of the following muscle?
Extensor Carpi Radialis Longus

Back 19

Origin: Lateral supracondylar humerus
Insertion: Second metacarpal base
Action: Extends wrist
Innervation: Radial nerve
--"Long to short and short to long"

Front 20

What is the origin, insertion, action, and innervation of the following muscle?
Extensor Carpi Radialis Brevis

Back 20

Origin: Lateral epicondyle of humerus
Insertion: Third metacarpal base
Action: Extends wrist
Innervation: Radial nerve

Front 21

What is the origin, insertion, action, and innervation of the following muscle?
Anconeus

Back 21

Origin: Lateral epicondyle of humerus
Insertion: Proximal dorsal ulna
Action: Extends forearm
Innervation: Radial

Front 22

What is the origin, insertion, action, and innervation of the following muscle?
Extensor Digitorum Communis

Back 22

Origin: Lateral epicondyle of humerus
Insertion: Extensor aponeurosis ulnar 4 digits
Action: Extends digits at MCP, extends hand at wrist
Innervation: PIN (from radial nerve)

Front 23

What is the origin, insertion, action, and innervation of the following muscle?
Extensor digiti minimi

Back 23

Origin: Common extensor tendon lateral epicondyle of humerus
Insertion: Small finger extensor expansion over P1
Action: Extends small finger
Innervation: PIN

Front 24

What is the origin, insertion, action, and innervation of the following muscle?
Extensor Carpi Ulnaris

Back 24

Origin: Lateral Epicondyle of Humerus
Insertion: Fifth Metacarpal Base
Action: Extends/Adducts hand
Innervation: PIN

Front 25

What is the origin, insertion, action, and innervation of the following muscle?
Supinator

Back 25

Origin: Lateral epicondyle of humerus, radial collateral and annular ligaments, supinator crest of ulna
Insertion: Lateral, posterior and anterior surfaces of proximal 1/3 of radius
Action: Supinates forearm
Innervation: PIN

Front 26

What is the origin, insertion, action, and innervation of the following muscle?
Abductor Pollicis Longus

Back 26

Origin: Dorsal Ulna/Radius
Insertion: First metacarpal base
Action: Abducts/Extends thumb @ CMC
Innervation: PIN

Front 27

What is the origin, insertion, action, and innervation of the following muscle?
Extensor pollicis brevis

Back 27

Origin: Dorsal radius
Insertion: Thumb proximal phalanx base
Action: Extends thumb MCP
Innervation: PIN

Front 28

What is the origin, insertion, action, and innervation of the following muscle?
Extensor Pollicis Longus

Back 28

Origin: Posterior surface of middle 1/3 of ulna and interosseous membranee
Insertion: Thumb dorsal phalanx base
Action: Extends thumb IP & CMC joint
Innervation: PIN

Front 29

What is the origin, insertion, action, and innervation of the following muscle?
Extensor Indicis Proprius

Back 29

Origin: Dorsolateral Ulna
Insertion: Index finger extensor apparatus (ulnarly)
Action: Extends index finger
Innervation: PIN

Front 30

Name the 4 muscles innervated by the radial nerve and the 8 muscles innervated by the PIN.

Back 30

Radial Nerve: Triceps, brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis

PIN: Supinator, extensor carpi ulnaris, extensor digitorum communis, extensor digiti minimi, abductor pollicis longus, extensor pollicis longus, extensor pollicis brevis, extensor indicis proprius

NOTE: Be able to name them in this order as this is the order of innervation and in a compressive neuropathy, the EIP would be last to regain function

Front 31

Name the 8 muscles innervated by the median nerve (lumbricals and FDP count as 1) and the 3 muscles innervated by the AIN.

Back 31

Median nerve: Pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis, abductor pollicis brevis, superficial head of flexor pollicis brevis, opponens pollicis, first and second lumbrical muscles

AIN: Flexor digitorum profundus (first and second), flexor pollicis longus, pronator quadratus

Front 32

Name the 10 muscles innervated by the ulnar nerve (lumbricals and FDP count as 1)

Back 32

Flexor carpi ulnaris, flexor digitorum profundus (third and fourth), pollicis brevis, abductor digiti minimi, opponens digiti minimi, flexor digiti minimi, third and fourth lumbrical muscles, interossei, adductor pollicis, deep head of flexor pollicis brevis

Front 33

Describe the course of the radial nerve starting at the plexus

Back 33

The radial nerve is the largest branch of the brachial plexus and arises from the posterior cord and courses posterior to the axillary and brachial arteries and enters the radial groove on the posterior humerus and travels with the deep artery of the arm. It descends between the long and medial heads of the triceps muscle. It pierces the lateral intermuscular septum to enter the anterior compartment and descends anterior to the lateral epicondyle BETWEEN THE BRACHIALIS AND BRACHIORADIALIS to enter the cubital fossa where it splits into a superficial branch and the Posterior Interosseous Nerve (PIN). The PIN SPLITS THE SUPINATOR and runs posteriorly along the interosseous septum with the posterior interosseous artery. The superficial branch runs between the brachioradialis and extensor carpi radialis longus then passes dorsally around the radius and runs to the distal dorsal hand where it innervates the skin of the radial side of the hand and the radial two and a half digits over the proximal phalanges, it does not supply the skin over the distal phalanges

Front 34

Describe the course of the median nerve starting at the plexus

Back 34

The median nerve is formed from heads of both the medial and lateral cords. The nerve runs down the anteriomedial aspect of the arm with the brachial artery along the brachialis. It passes through the cubital fossa deep to the bicipital aponeurosis and MEDIAL TO THE BRACHIAL ARTERY. Branches into the anterior interosseous nerve which SPLITS PRONATOR TERES AND RUNS BETWEEN FLEXOR DIGITORUM SUPERFICIALIS AND FLEXOR DIGITORUM PROFUNDUS then splits pronator quadratus and ends in sensory "twigs" to the wrist joint and capsule. After splitting into AIN, the median nerve continues between the flexor digitorum superficialis and flexor digitorum profundus muscles then goes superficial by passing between the tendons of the flexor digitorum superficialis and flexor carpi radialis near the wrist. It enters the palm through the carpal tunnel, gives off a muscular recurrent branch and terminates by dividing into three common palmar digital nerves

Front 35

Describe the course of the ulnar nerve starting at the plexus

Back 35

Terminal branch from the medial cord, runs down the medial aspect of the arm, pierces the medial intermuscular septum at the middle of the arm, and descends together with the superior ulnar collateral branch of the brachial artery. Descends behind the medial epicondyle. It enters the forearm between flexor carpi ulnaris and flexor digitorum profundus. It enters the hand superficial to the flexor retinaculum and lateral to the pisiform bone. It terminates by dividing into superficial and deep branches at the root of the hypothenar eminence. The superficial branch innervates the palmaris brevis and the skin over the palmar and dorsal surfaces of the medial one third of the hand, including the hypothenar eminence and then terminates in the palm by dividing into three palmar digital branches which supply the skin of the little finger and the medial side of the ring finger.
The deep branch arises at about the level of the pisiform and passes between the pisiform and the hook of the hamate, between the origins of the abductor and flexor digiti minimi brevis muscles, and then deep to the opponens digiti minimi. It curves around the hook and then turns laterally to follow the course of the deep palmar arterial arch across the interossei. It innervates the hypothenar muscles, the medial two lumbricals, all ter interossei, the adductor pollicis, and usually the deep head of the flexor pollicis brevis

Front 36

What is the interval for the anterior (Henry's) approach to the forearm? What 2 structures are at risk during this approach?

Back 36

Interval: Brachioradialis (radial nerve) and pronator teres (median nerve). Distally: flexor carpi radialis (median nerve)

Structures at risk: Must ligate the leash of Henry (radial artery branches)
Superficial branch of the radial nerve

Front 37

What is the interval for the Dorsal Posterior (Thompson's) approach to the forearm? What structure is at risk?

Back 37

Extensor Carpi Radialis Brevis (radial nerve) and Extensor Digitorum Communis (PIN).
Distally: Extensor pollicis longus

Structures at risk: PIN, you must avoid excessive retraction of the supinator

Front 38

What is the interval for the ulnar approach to the forearm?

Back 38

Extensor carpi ulnaris (PIN) and flexor carpi ulnaris (ulnar nerve)

Front 39

Proximal forearm

Back 39

yep

Front 40

Mid forearm

Back 40

yep

Front 41

Distal forearm

Back 41

yep

Front 42

Briefly describe a proximal Henry's approach to the forearm. Why is supination of the forearm important?

Back 42

Proximally: Isolate and ligate the leash of Henry (radial artery branches) proximally, and strip the supinator from its insertion subperiosteally; supination of the forearm displaces the PIN ulnarly (ie, laterally and posteriorly).

Front 43

Briefly describe a middle third Henry's approach to the forearm. Why is supination of the forearm important?

Back 43

Middle third: Pronate the forearm and incise the insertion of the pronator teres subperiosteally

Front 44

Briefly describe a distal Henry's approach to the forearm. Why is supination of the forearm important?

Back 44

Distally: Dissect off the FPL and pronator quadratus.

Front 45

As it enters the forearm, what structure does the ulnar nerve run between?

Back 45

The ulnar nerve splits the two heads of the FCU as it enters the forearm

Front 46

As it enters the forearm, what structure does the median nerve run between?

Back 46

As it enters the forearm, the median nerve splits the two heads of the pronator teres.