1. Wrist & Hand
Long Nguyen

2. Past exam q’s
Diagram of a cross section of Radius, Ulna and tubes provided with the caption: “At the lower end of the forearm there is an extensor retinaculum. Septa attach the retinaculum to the radius and ulna forming six osseofascial tunnels for the extensor tendons”. List the tendons corresponding to each of the numbered tunnels above. (Oct 00)
What is the arrangement of structures passing from the forearm to the wrist at the level of the carpal tunnel within the flexor retinaculum.
Write short notes on the anatomy of the lunate bone. (Sept 04)
Draw a clear diagram and anatomical relations of the scaphoid bone. (April 04)
Write notes on the supernumerary bones of the hand. (?)
In the embryological development of the hand and foot, many of the bones are homologous (for example the radius is a homologue of the tibia and the ulna is homologous to the fibula). Which carpal bones and tarsal bones are homologues? (Sept 02)
Regarding the thumb: (Oct 01) a what muscles are responsible for thumb flexion? b extension? c abduction? d adduction? e what is the nerve supply of each of these muscles
Write short notes on the arterial supply to the hand. (April 04)

3. Bones of the hand 8 carpal bones, 5 metacarpal bones, 14 phalanges
8 carpal bones lie in two semicircular rows separated by S-shaped midcarpal joint
Prox row – S, L, Tqm, P
Distal row – Tpzm, Tpzd, C, H
Carpal bones articulate with each other by intercarpal joints

4. Carpal bones Scaphoid bone (boat shaped) Lunate
Most commonly fractured carpal bone
Convex articular proximal surface for radius
Flat surface medially for lunate
Concave distomedially for capitate
Convex distal articulation with trapezium & trapezoid
Tubercle on the volar aspect of distal lateral surface
Narrow waist perforated by vascular foramina more numerous distally
In 15%, blood supply to scaphoid is solely supplied from nutrient arteries which pass distal to proximal
Fracture trhough the waist can produce avascular necrosis of proximal portion
Lunate
Most commonly dislocated carpal bone (displaced anteriorly)
Convex proximal facet for radius
Concave distally for capitate
Facet for adjoining bones on either side

5. Carpal bones Triquetral Pisiform Trapezium Trapezoid Capitate Hamate
Oval fact on distal palmar surface for pisiform
Pisiform
Flat surface for articulation with triquetral
Trapezium
Saddle-shaped distal articular surface with 1st MC
Tendon of flexor carpi ulnaris lies in a vertical groove on the palmar surface
Trapezoid
Capitate
Convex proximal surface for lunate articulation
Articulates with 3rd MC and small facet for 4th MC
Hamate
hook projects from the distal part of the palmar surface, and is directed laterally

6. Metacarpals & phalanges
1st MC (saddle joint) articulates solely with trapezium
Remaining MC’s had expanded bases and articulate with each other and the distal row of carpal bones
Middle MC has prominent styloid process projecting dorsally into angle between trapezoid and capititate
MCJ and IPJ are hinged synovial joints

7. Ossification Carpus cartilagenous at birth
Ossification in a clockwise direction from capitate
Capitate & hamate 1 year
Triquetral 2-3 year
Lunate 3-5 year
Scaphoid, trapezium, trapezoid: 6 year
Pisiform year
MC & phalangeal shafts ossify in utero
Radiographs of the left hand are obtained for bone age assessment by comparing features such as epiphyseal appearance and fusion

8. 18m
3y 9m
5y 4m
7y 1m
13y

9. Ossification - variable timing
2y 11m
5y 4m
6y 11m
7y 1m

10. Supernumery bones
Sesamoid in the tendon of the flexor pollicis brevis near MC head of thumb
Os centrale found between scaphoid, trapezoid and capitate. May represent tubercle of scaphoid that has not fused with upper pole
Os radiale externum immediately distal to radial styloid

11. Wrist Joint Condyloid/ellipsoid synovial joint
Radius articulates with scaphoid and lunate. Articulation with triquetral only on ulnar deviation
Ulna shorter than distal radius. Fibrocartilaginous disc projects laterally from ulna styloid to the radius. It articulates with lunate and triquetral
Fibrous capsule lined by synovium incloses the joint
Strengthened by dorsal and palmar radiocarpal ligaments which run distally and medially from radius
Radial and ulnar collateral ligaments

12. Wrist Joint

13. Wrist Movements Flexion (80º) Extension (60º) Abduction (15º radial)
Flexor carpi radialis & flexor carpi ulnaris
Palmaris longus, flexors of fingers and thumb, abductor pollicis longus
Extension (60º)
Extensor carpi radialis longus, extensor carpi radialus brevis, extensor carpi ulnaris
Extensors of fingers and thumb
Abduction (15º radial)
FCR, ECRL, ECRB
APL
Adduction (45º ulna)
FCU, ECU

14. Extensor retinaculum
Antebrachial fascia thickened posteriorly at the wrist to form a transverse 2.5cm band
Proximal attachment: anterolateral border of radius above styloid process
Distal attachment: pisiform & triquetral
6 shealths containing 9 tendons occupy the six osseofibrous tunnels deep to the extensor retinaculum
A) 3 for thumb in 2 shealths (EPL) (EPB,APL)
B) 3 for extensors of the wrist in 2 sheaths (ECU) (ECRL,ECRB)
C) 3 for extensors of the digits in 2 sheaths (EDigitorum, E Indicis) (Extensor digiti minimi)

15. Extensor retinaculum

16. Anatomical snuff box

17. Palmar Aponeurosis
Fascia of the forearm continues distally as the deep fascia of the palm
Fascia is thickened in the palm (thin over the thenar and hypothenar eminences)
Overlies long flexor tendons of the palm
Proximal end continuous with flexor retinaculum
Distal ends of the aponeurosis divides at the roots of the digits into four longitudinal bands which attaches to base of prox phalanx

18. Fascial compartments Central compartment
Flexor tendons and shealths
Superficial palmar arch
Branches of median and ulnar nerves
Superior boundary: palmar aponurosis
Inferior boundary: deep muscles of palm (adductor pollicis)
Bounded on either side by septa passing from medial and lateral edges of aponeurosis to 1st and 5th MC bones
Medial/hypothenar compartment
Lateral thenar compartment

19. Potential space between central compartment and the deep muscles of the palm: midpalmar space
Retroadductor space between adductor pollicis and 1st dorsal interosseous muscle

20. Carpal tunnel Carpal bones angled producing anterior concavity
Hollow formed by these bones is bounded anteriorly by flexor retinaculum
Flexor retinaculum attachments
Medially: hook of hamate & pisiform
Laterally: ridge of trapezium & scaphoid tubercle
Contents:
Median nerve immediately deep to retinaculum
Flexor pollicis longus tendon
Tendons of flexor digitorum superficialis (x4) and flexor digitorum profundus (x4)
Tendon of flexor carpi radialis grooves the trapezium and lies in separate compartment of tunnel
Relations
Ulnar artery superficial to flexor retinaculum, lateral to ulnar nerve

21. Intrinsic hand muscles
Palmar aspect
3 groups
Thenar muscles
Hypothenar muscles
Lumbricals and interossei

22. Thenar muscles Produce thenar eminence Oppose thumb
Supplied by recurrent branch of median nerve
Muscle
Prox attachment
Distal attachment
Innervation
Action
Abductor pollicis brevis
Flex retinaculum, tubercles of scaphoid & trapezium
Lateral aspect base of prox 1st phalanx
Median n. recurrent branch
Abduction
Opposition
Flexor pollicis brevis
Flex retinaculum, tubercle of trapezium
Flexion
Oppones pollicis
Lateral aspect 1st MC
Medial rotation
Adductor pollicis
Oblique: base or 2nd & 3rd MC, capitate
Transverse: anterior body of 3rd MC
Medial aspect base of prox 1st phalanx
Ulnar n. deep branch
Adduction (grasp)

23. Movements of the thumb Movement Muscles Innervation Flexion at MCP/IPJ
Flexor pollicis longus
Flexor pollicis brevis
Median (anterior interosseous n)
Median (recurrent branch)
Extension at MCP/IPJ
Extensor pollicis longus
Extensor pollicis brevis
Radial (posterior interosseous)
Flexion (flexion/transpalmar adduction)
Flexor pollicis brevis Adductor pollicis
Ulnar (deep branch)
Extension (radial abduction)
Abductor pollicis longus
Abduction (palmar)
Abductor pollicis brevis
Adduction (ulnar adduction)
Adductor pollicis
Opposition
Oppones pollicis

24. Hypothenar muscles Muscle Prox attachment Distal attachment
Innervation
Action
Abductor digiti minimi
Pisiform bone
Medial aspect base of 5th prox phalanx
Ulnar n. deep branch
Abduction
Flexor digiti minimi brevis
Hook of hamate and flex retinaculum
Flexion
Opponens digiti minimi
Medial border of 5th MC
Opposition (towards thumb)

25. Short muscles in the hand
4 Lumbricals
act on medial 4 digits
Flex digits at the MCPJ and extend IPJ
7 Interossei
3 palmar adduct (PAD)
4 dorsal abduct (DAB)

26. Muscle
Prox attachment
Distal attachment
Innervation
Action
Lumbricals 1 & 2
Lateral 2 tendons of flexor digitorum profundus
Lateral aspect of extensor expansion of digits 2-5
Median n.
Flex digits at the MCPJ and extend IPJ
Lumbricals 3 & 4
Medial 3 tendons of FDP
Ulnar n. deep branch
Palmar interossei
Palmar surface of 2nd, 4th, 5th MC
Extensor expansions & bases of prox phalanges of digits 2, 4, 5
Adduct digits & assist lumbricals
Dorsal interossei
Adjacent sides of two MC bones
Extensor expansions & bases of prox phalanges of digits 2-4
Abduct digits & assist lumbricals

27. Long flexor tendons Flexor digitorum superficialis tendon
Enters the fibrous flexor shealth on the palmar surface of the flexor digitorum profundus
Splits into 2 and wraps around the profundus and meets on deep surface in a chiasma
Distal to chiasma, superficialis tendon is attached to margins of the front of middle phalanx
Profundus tendon
enters fibrous sheath deep to the superficialis
then lies superficial distal to the split of the superficialis tendon
attaches to base of terminal phalanx
Each tendon receives blood vessels invested in synovial membrane called vincula

28. Long extensor tendons
Extensor tendon blends in with a triangular fibrous expansion on the dorsum of the proximal phalanx
Margins of expansion thickened by attachments of the tendons of lumbrical and interossei
Extensor tendon splits into middle and two collateral slips as it approaches PIPJ
Middle slip attached to base of middle phalanx
Collateral slips joined by thickened margins of expansion and converge to insert into base of distal phalanx

29. Arterial supply Ulnar artery continues as superficial palmar “arch”
Usually not complete arch
Continuous with superficial palmar branch of radial artery if complete
Gives rise to 3 common palmar digital arteries which run distally to the webs between the fingers and divides into proper palmar digital arteries (run alongside 2nd-4th digits)
Radial artery
Princeps pollicis artery (thumb)
Radialis indicis artery (lateral side of 2nd digit)
Joins deep branch of ulnar artery to form deep palmar arterial arch
Arch gives rise to 3 palmar metacarpal arteries which run distally and join the common palmar digital arteries

30. Cutaneous nerves of the hand