The Forearm, Wrist & Hand

Question 1

Describe position of ulna and radius with respect to the body. Which bone has the bigger head at the superior part (at the olecrenon)? Describe job of membrane between the 2 bones.

Answer 1

Radius: lateral (Bigger head at carpi…wrist)
Ulna: medial (bigger head at olecrenon). Therefore has the most articulation with the humerus.
Membrane (Interosseous membrane) dissipates force upon impact.

Question 2

What is a styloid? Which styloid has a tendon that passes between it?

Answer 2

A superior peak that connects to the carpi bones. Both the radius and the ulna have one (Radial styloid, ulnar styloid.). Ulna styloid has tendon passing through it.

Question 3

Sam Likes To Push The Toy Truck Hard (Carpal bones, in order from radial to ulnar. Every 4 bone, move down one row distally)

Answer 3

Scaphoid (Makes contact with Radisu and Ulna)
Lunate (Makes contact with Radius and Ulna)
Triquetrum
Pisiform
Trapezium
Trapezoid
Capitate
Hamate

Question 4

Difference between metacarpals and phalanges

Answer 4

All fingers have metacarpals. First period outside of the wrist. The phalanges are broken into Proximal, middle, and distal, but only the thumb is the only finger without a middle phalanges.

Question 5

Colles’ Fracture, What is damaged?

Answer 5

“FOOSH” injury (Fall On an OutStretched Hand). Distal radius. Creates a “dinner fork concavity”

Question 6

Scaphoid fracture

Answer 6

Note swelling in anatomical snuffbox. Also note osteonecrosis of the proximal fragments of the wrist since the DISTAL wrist bones is where the blood supply of the wrist bones lands. The fracture will appear on the x ray as2 carpi bones appearing as one fused bone instead of 2.

Question 7

Joints of forearm, Wrist, Hand

Answer 7

Forearm: Radioulnar and Radiocarpal
Wrist and Hand: Carpometacarpal, Metacarpophalangeal (MP), INterphalangeal (IP) –> Proximal interphalangeal (PIP), Distal Interphalangeal (DIP)

Question 8

Radioulnar Joint

Actions

Answer 8

Action: Pronation and Supination

Question 9

Radiocarpal joint

Answer 9

COMPOSED of only scaphoid and lunate bones and it ONLY CONTACTS FAT HEAD OF RADIUS (Ulna is not touched). Allows for flextion/extension, abduction/adduction, circumduction

Question 10

Thumb carpometacarpal joint

Answer 10

Flex/extend, abduct/adduct, opposition/reposition, circumduction. Note that the joint sits at a 90 degree angle

Question 11

Metacarpophalangeal joint

Answer 11

Knuckle joint Flexion/extension, abduction/adduction, circumduction. Middle finger = midline. Middle finger can only abduct

Question 12

Interphalangeal joint

Answer 12

Both PIP (proximal) and DIP (distal) flex and extend

Question 13

Nerve that governs the posterior side of hand? The Anterior side of hand?

Answer 13

Anterior: Median nerve (flex, pronate)
Posterior: Radial nerve (extend, supinate)

Question 14

Pronator muscles…and WHAT NERVE?! What connections?

Answer 14

Pronator teres (Medial epicondyle is proximal connection) and Pronator quadratus (connects the distal part of the ulna and radius, proximal to the radioulnar joint)
Median nerve...remember, pronators are from median.)

Question 15

Wrist flexors (Most superficial level)

Answer 15

From RADIAL to ULNAR: Flexar carpi radialis, Palmaris Longus (15% of population), Flexor carpi ulnaris. All by median nerve (they are flexors). In order, PFPF (first P is pronator teres). All of these muscles start at medial epicondyle

Question 16

Digit flexors (Median level)

Answer 16

Flexor digitorum superficialis, flexor digitorum profundus. both are straddling the ulna. Both Start at the medial epicondyle. Note: Profundus (deeper) flexes the finger TIPS. Superficialis DOES NOT.
Flexor pollicis lungus (straddles radius). All = median nerve

Question 17

Describe scope of median nerve. What does the nerve change its name to, and when does it do this??

Answer 17

Superficial and intermediate muscles. Anterior Interosseeous nerve = new name when it reaches DEEP MUSCLES

Question 18

Describe location and job of ulnar nerve

Answer 18

Works for ANTERIOR musles. Lines Ulna next to flexor digitorum superficialis (underneath flexor carpi ulnaris). Specifically innervates Flexor Carpi Ulnaris and FIRST HALF, from more medial side, of ring finger. “You will be tested on this”

Question 19

Is the brachioradialis a posterior forearm muscle or an anterior forearm muscle? What does it do?

Answer 19

Posterior forearm muscle, even though it lies on the anterior side. FLexes forearm at elbow. Beer drinking muscle. Note that this is a posterior muscle because it works best when PRONATED

Question 20

Wrist extensors. Innervation

Answer 20

I order from Ulna to radius: Extensor carpi ulnaris, extensor carpiradialis brevis, extensor carpi radialis longus, Innervated by radial nerve. The brevis and longus skip pass 2 smuscle inbetween them. They are the Extensor digiti minimi (ulnar side) and extensor digitorum (radial side)

Question 21

Intermediate level posterior muscle

Answer 21

Supinator (the actual name of the muscle). Straddles proximal end of radius and ulna

Question 22

Deep extensors

Answer 22

From radial to ulnar: Extensor indicis, extensor pollicis longus, extensor pollicis brevis, abductor pollicis longus

Question 23

Main nerves of the posterior forearm and their innervations

Answer 23

Radial nerve: Innervates brachioradialis and EXTENSOR caccrpi radialis longus
Deep Radial Nerve: All of the remaining muscles (in other words, only memorize the muscles of the radialis…)

Question 24

Where do radial and ulnar artery come from?

Answer 24

Splits from brachial artery

Question 25

Job of ulnar artery:

Answer 25

Supplies blood to deep muscles. More important than radial artery since radial artery can be used for grafts.. Ulnar = dominant blood supply to hand. it also supplies blood to the anterior and posterior interosseous

Question 26

How to check viability of ulnar and radial artery

Answer 26

Allen test

Question 27

What gives hand sensation? What gives hand mobility

Answer 27

Sensation: Median nerve
Mobility: Ulnar nerve

Question 28

Name of thiccc fascia of wrist

Answer 28

Retinacula. Both a flexor (anterior…forms carpal tunnel) and extensor (posterior…has blue, bursa sacs) version present

Question 29

Contents of carpal tunnel

Answer 29

9 flexor tendons (1 flexor pollicies longus
4 flexor digitorum profundus
4 flexordigitorum superficialis
), and the median nerve

Question 30

What keeps skin of palm tightly attached in order to facilitate grip?

Answer 30

Palmar Aponeurosis

Question 31

Intrinsic hand muscles (18 of them)

Answer 31

3 thenar msucels + 1 abductor pollices brevis, 1 flexor poollices brevis, 1 opponens pollices brevis, 1 adductor pollicis (not a thenar muscle, and innervated by deep ulnar nerve)
3 hyothenar muscles (abductor digiti minimi, flexor digit minimi, opponens digiti minimi)

Question 32

Lumbrical muscles

Answer 32

FLexes at metcarpalphalagel joint and simultaneously causes extension at interphalanges joint. Injure this = clawed hand

Question 33

The 7 interossei

Answer 33

3 palmar interossei adduct (PAD) and 4 Dorsal Interossei Abduct (DAB), all innervated by ulnar nerve

Question 34

Innervation of hand

Answer 34

Motor: C8 and T1. COmes from median (the 2 lumbercals and the thenar muscles) and the deep ulnar nerve (responsible for adductor pollicis, ulnar 2 lumbricals, hypothenar muscles, interossei)
Sensory: C6, C7, C8. Stems from median nerve (radial 3.5 digits) and ulnar nerve (1.5 digits)

Question 35

Median nerve in hand innervation

Answer 35

2 LOAF = 2 lumbrical s + opponens, abduction, flection (for thenar muscle). All else = radial

Question 36

Note slide 57.

Answer 36

T1 does not ever make it into the hand Also, pink + 0.5 ring = C8, C6 and C7 = the rest of the hand for sensory

Question 37

Arterial supply to hand

Answer 37

Ulnar artery (superfical palmar arch) amd Radial artery (Deep palmar arch). Note that the vessles run on the SIDES of the fingers, not the tops and bottoms