1. LUMC 2020
Hand
Robert J. Frysztak, Ph.D.

2. Objectives
Identify and be able to diagram the bones of the wrist and hand, as well as their articulations.
Identify the intrinsic muscles of the hand, their actions, attachments and innervation.
Understand the arterial supply of the hand, including the origins of the deep and superficial palmar arterial arches and the branches of the arches; also understand the dorsal venous arch.
Name and demonstrate the movements of the fingers and thumb.
Describe the fascial spaces in the hand and their significance. Describe the components of an osseofibrous tunnel and the origin and treatment of carpal tunnel syndrome.
Describe and identify the recurrent median nerve and understand it’s significance.
Describe and identify the palmar aponeurosis; the extensor expansion.
Understand transmission of forces through the hand.
Describe the structures that form the "cup" of the hand, and the significance of these as shock absorbers.
Describe the functional consequences of injuries to the axillary, radial, median, ulnar, and musculocutaneous nerves.

3. * So Long To Pinky, Here Comes The Thumb Bones of the Hand and Wrist
Palmar View
So Long To Pinky,
Here Comes The Thumb
Dorsal View
Proximal Row: Scaphoid, Lunate, Triquetrum, Pisiform
Distal Row: Hamate, Capitate, Trapezoid, Trapezium *

4. Carpal Bones Proximal row
Scaphoid: boat-shaped; most frequently fractured carpal bone; has tubercle for attachment of the flexor retinaculum.
Lunate: crescent-shaped; most frequently dislocated carpal bone.
Triquetrum: pyramidal-shaped; has oval articular facet on the palmar surface for the pisiform bone.
Pisiform: small, pea-shaped; sesamoid bone within the tendon of the flexor carpi ulnaris.
Distal row
Hamate: a hook-like process (hamulus) from the palmar surface
Capitate: the largest carpal bone; first to ossify
Trapezoid: wedge-shaped
Trapezium: has saddle-shaped facet for the 1st metacarpal and tubercle for attachment of the flexor retinaculum
Interesting notes:
Most common fracture is the scaphoid, due to falls on base of palm forcing capitate into scaphoid.
Capitate is the keystone of the carpal tunnel.
Only scaphoid and lunate articulate with the radius.

5. * Metacarpals & Phalanges Metacarpals:
5 bones numbered from lateral (thumb) to medial
Common characteristics: base articulates with the carpal bones; linear shaft; rounded head
Phalanges:
14 bones
2 in thumb (proximal and distal)
3 in digits 2 to 5 (proximal, middle, and distal)
Each bone has a base (proximal), shaft and head (distal) *

6. Cutaneous Innervation
Palmar
Dorsum

7. Dermatomes
Leonard Nimoy C7 C8 C6
“Live long and prosper”

8. Deep Palmar Fascia
Palmaris longus tendon
Continuous proximally with the antebrachial fascia and at the borders of the palm with the fascia on the dorsum of the hand.
Thin over the thenar and hypothenar eminences, but thick in the palm, where it forms the palmar aponeurosis.
Continues distally onto the fingers by helping to form the fibrous digital sheaths.
Palmar aponeurosis: Strong, heavy, dense, well-defined triangular layer of the deep fascia in the middle of the palm.
Palmaris brevis
Palmar aponeurosis
Palmar aponeurosis
Palmar Aponeurosis
Covers the long tendons of the digital muscles as they pass through the hand and also covers the arteries and nerves destined for the fingers: vessels and nerves escape from the aponeurosis to proceed to the web between each 2 digits before dividing to reach contiguous sides of the 2 digits.
Septa extend from the deep aspect of the palmar aponeurosis in the distal part of the palm. They form the sides of the anular fibrous canals for passage of the ensheathed flexor tendons and lumbrical muscles as well as the blood vessels and nerves.
Fibrous digital sheaths

9. Dupuytren’s Contracture
Manifests as a progressive fibrosus, which typically produces abnormal bands of fibrous tissue that extend from the aponeurosis to the bases of the phalanges, pulling one or more digits into marked flexion at the metacarpophalangeal joints so they can not be straightened.

10. Synovial Sheaths
Allows free movement of tendons into hand and fingers

11. Carpal Tunnel
The posterior boundary of the carpal tunnel is formed by the carpal bones.
The anterior boundary is formed by the flexor retinaculum.
There are 10 structures that pass through the carpal tunnel:
Flexor digitorum superficialis (4 tendons)
Flexor digitorum profundus (4 tendons)
Flexor pollicis longus (1 tendon)
Median Nerve
Radial a. & n.
Flexor retinaculum
Median n.
Canal of Guyon
Ulnar a. & n.
Flexor carpi radialis tendon
Flexor digitorum superficialis tendons
Flexor pollicis longus tendon
Flexor digitorum profundus tendons *

12. Carpal Tunnel Syndrome
Results from any lesion that will decrease the size of the carpal tunnel.
Possible Causes:
Fluid retention
Infection
Excessive exercise
The median nerve is the softest structure in the tunnel and is the most effected by an increase in pressure.
Paresthesia, hypoesthesia, anesthesia of the lateral 3 ½ fingers
• The palmar cutaneous branch comes off the median nerve BEFORE it enters the carpal tunnel so sensation to the central palm should be spared
The median nerve innervates the thenar muscles, so there may be thenar wasting, and/or weakness of most thumb movements
• Thumb adduction is spared because adductor pollicis is innervated by ulnar nerve
Note wasting of thenar muscles

13. * Thenar Compartment of Hand Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis
Opponens pollicis m.
Abductor pollicis brevis m.
Flexor pollicis brevis m.
Palmaris brevis
O: Fascia overlying the hypothenar eminence
I: Skin of the palm near the ulnar border of the hand
A: Draws the skin of the ulnar side of the hand toward the center of the palm
N: Superficial ulnar (C8, T1
THENAR MUSCLES:
Abductor pollicis brevis
O: Flexor retinaculum, scaphoid, trapezium
I: Base of the proximal phalanx of the 1st digit
A: Abducts thumb
N: Recurrent branch of the median (C8, T1)
Flexor pollicis brevis
O: Flexor retinaculum, trapezium
I: Proximal phalanx of the 1st digit
A: Flexes the carpometacarpal and metacarpophalangeal joints of the thumb
Opponens pollicis
I: Shaft of the 1st metacarpal
A: Opposes the thumb
Flexor pollicis brevis
Abductor pollicis brevis
Opponens pollicis
ALL innervated by Recurrent branch of Median nerve *

14. “O A F” – Opponens, Abductor & Flexor
Thenar Compartment of Hand
“O A F” – Opponens, Abductor & Flexor
Flexor pollicis brevis m.
Flexor pollicis brevis m.
Abductor pollicis brevis m.
Palmaris brevis: draws skin of hypothenar area towards center of palm; Ulnar n.
Abductor pollicis brevis: abduct thumb; Recurrent median n.
Flexor pollicis brevis: flex thumb at carpometacarpal & metacarpophalangeal joints; Recurrent median n.
Opponens pollicis: opposes thumb; Recurrent median n.
Abductor pollicis brevis m.
Opponens pollicis m.
Opponens pollicis m. *

15. * Movements of the Thumb Flexion Extension Resting ABduction ADduction
Opposition

16. * Hypothenar Compartment Opponens digiti minimi Abductor digiti minimi
Flexor digiti minimi brevis
Abductor digiti minimi brevis m.
Flexor digiti minimi brevis m.
Opponens digiti minimi m.
Abductor digiti minimi
O: Pisiform
I: Base of the proximal phalanx of the 5th digit on its ulnar side
A: Abducts the 5th digit
N: Deep ulnar (C8, T1)
Flexor digiti minimi brevis
O: Hook of the hamate and the flexor retinaculum
I: Proximal phalanx of the 5th digit
A: Flexes the carpometacarpal and metacarpophalangeal joints of the 5th digit
Opponens digiti minimi
I: Shaft of the 5th metacarpal
A: Opposes the 5th digit
Abductor digiti minimi
Opponens digiti minimi
Flexor digiti minimi brevis *

17. “O A F” – Opponens, Abductor & Flexor
Hypothenar Compartment of Hand
“O A F” – Opponens, Abductor & Flexor
Flexor digiti minimi brevis m.
Abductor digiti minimi brevis m.
Abductor digiti minimi: abducts pinky; Ulnar n.
Flexor digiti minimi brevis: flexes carpometacarpal & metacarpophalangeal joints of pinky; Ulnar n.
Opponens digiti minimi: opposes pinky; Ulnar n.
Opponens digiti minimi m. *
Opponens Digiti Minimi

18. Flexor digitorum profundus tendons
Lumbricals
Originate from FDP tendons
extend the proximal and distal interphalangeal joints
1st Lumbrical
Lumbricals
2nd Lumbrical
3rd Lumbrical
Lumbricals 1 & 2: Flex the metacarpophalangeal joints; extend the proximal and distal interphalangeal joints of digits 2–3; Recurrent median n.
Lumbricals 3 & 4: Flex the metacarpophalangeal joints; extend the proximal and distal interphalangeal joints of digits 4–5; Ulnar n.
Lumbricals 1 and 2
O: Radial side of flexor digitorum profundus tendons of digits 2–3
I: Extensor expansion on the radial side of the proximal phalanx of digits 2–3
A: Flex the metacarpophalangeal joints; extend the proximal and distal interphalangeal joints of digits 2–3
N: Median (C8, T1)
Lumbricals 3 and 4
O: Adjoining sides of flexor digitorum profundus tendons of digits 4–5
I: Extensor expansion on the radial side of the proximal phalanx of digits 4–5
A: Flex the metacarpophalangeal joints; extend the proximal and distal interphalangeal joints of digits 4–5
N: Deep ulnar (C8, T1)
4th Lumbrical
1 & 2 by Median n.
3 & 4 by Ulnar n.
Flex the Metacarpophalangeal joints *
Flexor digitorum profundus tendons

19. Lumbricals
The lumbricals will help extend a flexed finger – Due to the insertion on the EXTENSOR expansion.
• This allows pinching on the pulp of the fingers (not the tips).
Flexors only
Flexors + Lumbrical *

20. Extensor Expansion Common “hood” which aids in extension of fingers.
Receives extensor digitorum, interossei, and lumbrical tendons.
On the dorsum of the fingers, the long extensor tendons flatten to form a dorsal digital expansion, a triangular tendinous aponeurosis. This forms a “hood” that wraps around the sides of the distal metacarpus and proximal phalanx and holds the extensor tendon in place. It inserts onto the middle and distal phalanges via a central slip and paired lateral heads. It is reinforced by the lumbricals and interossei muscles of the palm, which attach to the lateral bands and assist in extension of the interphalangeal joints in the fingers.

21. * Dorsal Interossei – DABS (4)
Bipennate muscle (2 heads)
Extension of proximal and distal IP joints
Dorsal interossei ABduct the digits at the MCP joint
2nd dorsal interosseous
3rd dorsal interosseous
Dorsal interossei
O: 4 muscles, each arising from 2 adjacent metacarpal shafts
I: Base of the proximal phalanx and the extensor expansion on lateral side of the 2nd digit, lateral and medial sides of the 3rd digit, and medial side of the 4th digit
A: Flex the metacarpophalangeal joint, extend the proximal and distal interphalangeal joints of digits 2–4; abduct digits 2–4 (abduction of digits in the hand is defined as movement away from the midline of the 3rd digit)
N: Deep ulnar (C8, T1)
1st dorsal interosseous
4th dorsal interosseous
Flex the Metacarpophalangeal joint
Do NOT confuse with adductor pollicis m.
Radial a.
Central Axis of Hand *

22. * Palmar Interossei – PAD (3)
Unipennate muscle (1 head)
Deep to Lumbricals and Adductor pollicis
Extension of proximal and distal IP joints
2nd palmar interosseous
Palmer interossei ADduct the digits at the MCP joint
3rd palmar interosseous
1st palmar interosseous
Palmar interossei
O: 3 muscles, arising from the palmar surface of the shafts of metacarpals 2, 4, and 5 (the palmar interosseous of the thumb is usually fused with the adductor pollicis muscle)
I: Base of the proximal phalanx and extensor expansion of the medial side of digit 2 and lateral side of digits 4 and 5
A: Flexes the metacarpophalangeal; extends proximal and distal interphalangeal joints and adducts digits 2, 4, and 5 (adduction of the digits of the hand is in reference to the midline of the 3rd digit)
N: Deep ulnar (C8, T1)
1st dorsal interosseous
Flex the Fingers *
Central Axis of Hand

23. * Adductor Pollicis Muscle
Flexor pollicis longus tendon
Adductor pollicis (transverse head)
Adductor pollicis (Oblique head)
Adductor pollicis – fan-shaped muscle with 2 heads
O: Oblique head: the capitate and the base of the 2nd and 3rd metacarpals; Transverse head: the shaft of the 3rd metacarpal
I: Base of the proximal phalanx of the thumb
A: Adducts the thumb
N: Deep ulnar (C8, T1) *

24. * *

25. * Arterial Supply “U S R D” - Ulnar Superficial, Radial Deep
Deep palmar arch
Superf. palmar arch *
Grant’s Atlas of Anatomy, 8th ed., LWW

26. * Ulnar Artery Superficial branch becomes the superficial palmar arch.
Anastamoses with superficial branch of radial artery
As it extends across the palm, it gives off digital branches to fingers
Ulnar a. and n.
Deep palmar branch of Ulnar a. and deep branch of ulnar n.
Superficial palmar arch
Common palmar digital aa. & nn.
Proper palmar digital aa. & nn.
Deep branch of the ulnar artery passes between abductor digiti minimi and flexor digiti minimi, and anastomoses with deep palmar arch *

27. Deep palmar (arterial) arch and deep branch of ulnar n.
Radial Artery
Radial artery continues around lateral carpal bones (dorsally) and extends across floor of snuff box, then pierces the 1st dorsal interosseous muscle to enter palmar areas of hand:
Gives off princeps pollicis artery to supply medial side of thumb
Gives off radialis indicis artery to supply lateral side of 2nd digit.
Continues through palm as the deep palmar arch, which eventually will anastamose with the deep branch of the ulnar a.
Radial a.
Superficial palmar branch of radial a.
Deep palmar (arterial) arch and deep branch of ulnar n.
Princeps pollicis a.
Superficial Palmar Branch – branches off of radial before it wraps around the lateral carpals, then passes through thenar muscles to anastamose with superficial palmar arch.
Radialis indicis a.
Common palmar digital aa.
Proper palmar digital aa. *

28. * Nerves of the Hand Median: ½ LOAF Ulnar:
All other intrinsic muscles of the hand
1st / 2nd Lumbricals
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis *
Grant’s Atlas of Anatomy, 8th ed., LWW

29. * Nerves of the Hand: Median Median (C5-C8, T1):
Will enter the hand under the flexor retinaculum through the carpal tunnel
Recurrent (Thenar) Branch:
First branch distal to the flexor retinaculum
Enters the thenar eminence
Innervates OAF:
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis
Palmar Surface
Continues on to innervate 1st & 2nd Lumbricals.
Palmar Cutaneous Branch
Will branch just proximal to the carpal tunnel (does not run through the carpal tunnel!)
Provides cutaneous sensation to the skin of the central palm
Will become common palmar digital nerves and then proper palmar digital nerves
Provide cutaneous sensation to the palmar aspect of the lateral 3 ½ fingers AND the dorsal aspect of the same fingers distally (in the area of the nail bed) *

30. * Nerves of the Arm: Ulnar Ulnar (C8, T1):
Enters hand via canal of Guyon (ulnar canal).
Palmar cutaneous branch to medial side of palm.
Dorsal cutaneuous branch passes under FCU tendon and extends distally across dorsum of hand, including dorsal surfaces of the medial 1 ½ digits.
Distal to the flexor retinaculum, gives off 2 branches
Superficial branch – becomes common palmar digital nerves and then proper palmar digital nerves
Deep branch – passes between AbdDM and FDMB tendons, passes deep to the flexor tendons along the path of the deep palmar arch, and innervates:
Palmaris Brevis
Hypothenar muscles (OAF)
3rd and 4th Lumbricals
Dorsal Interossei
Palmar Interossei
Adductor Pollicis
Palmar Surface *
Clinically Oriented Atantomy, 5th ed., Moore & Dalley, LWW

31. * Nerves of the Arm: Radial Radial (C5-C8, T1):
Superficial branch enters dorsum of hand by passing over anatomical snuff box.
Continues as dorsal digital nerves to the dorsal aspect of the lateral hand, including cutaneous sensation to the dorsal aspect of the lateral 2 ½ digits proximal to the DIP joint.
NO MOTOR BRANCHES in hand.
Proper palmar digital branches of median nerve *

32. Nerve – Muscle Relationships
MUSCLE NERVE *

33. Claw Hand (Ulnar Claw) Due to ulnar nerve palsy Usually at the wrist
Will lead to weakness of the most of the intrinsic muscles of the hand
Especially important is the weakness of the lumbricals
Deformity occurs because of unopposed activity of the extensor digitorum muscle
Leads to hyperextension of the 4th and 5th metacarpophalangeal joints and flexion of the PIPs and DIPs
Will also lose ability to spread the fingers due to loss of interossei

34. Ape Hand Due to median nerve palsy Wasting of the thenar muscles
Inability to oppose the thumb
The thumb is pulled posteriorly and lines up with the other digits
It can occur with an injury of the median nerve either at the elbow or the wrist, impairing the thenar muscles including the opponens pollicis muscle.

35. Hand of Benediction Due to median nerve palsy
Will see the deformity while trying to make a fist
Results from prolonged compression or injury of the Median nerve at the level of the elbow or upper arm.
Deformity caused by inability to flex the lateral 3 ½ fingers
Are still able to flex the DIP of the 4th and 5th digits
Due to loss of innervation of the lateral 2 lumbricals of the hand and the lateral half of the flexor digitorum profundus which are supplied by the median nerve. Flexion at the proximal interphalangeal joints of digits 4–5 is weakened, but flexion at the metocarpophalangeal joints and distal interphalangeal joints remains intact. The extensor digitorum is left unopposed and the metacarpophalangeal joints of digits 2–3 remain extended while attempting to make a fist.

36. Wrist Drop Palsy of the radial nerve
Loss of motor innervation to the wrist extensors in the forearm
Also no opposition to the wrist flexors
Usually damaged proximal to the elbow joint

37. Final Thoughts
Have a seat, Kermit. What I’m about to tell you might come as a big shock . . .

38. Shocking new imagery of the Hamburger Helper mascot:

39. Flashback . . .
Family Photo – First trip to the Vet with her brothers & sisters.