Learn about the anatomy of your hand .

1. HAND
DR. G. KAMAU

2. • Objectives:-1)Hand spaces & their clinical
significance.
2) Revise neurovascular supply to
the hand & intrinsic muscles of the hand

3. • The hand is a chief tactile & sensory organ,capable of fine
dexterous precision grip movements ,strong grasping power grip
movements, hook grip as lifting an object ,or combination of the
movements. It is the terminal working tool of upper limb.
• The thumb is most important digit with a lot of free mobility > loss
of thumb is about 50% loss of hand function.Thumb movements are
adduction/abduction, flexion /extension ,rotation &opposition.
• For adduction/abduction of the fingers, the middle finger & its
metacarpal act as imaginary reference line .The dorsal interrossei
are abdutors (DAB),& palmar interossei adductors (PAD)
• It has intrinsic hand muscles supplied by ulnar &median nerves
&extrinsic long tendon muscles from the forearm. Radial nerve
does not supply the intrinsics

4. • Homunculus is topographical arrangement of
body areas on the brain precentral motor
gyrus & postcentral gyrus sensory of cerebral
cortex. Note the hand occupies a very large
area on the brain especially its thumb. Note
the body is inverted, except the face, the toes
being on medial surface of the cerebral cortex.

7. Tissues of the hand
• The tissues of the hand from the palm consists of:-1)
Palmar skin is of thick similar to the sole with little mobility
because of numerous interlocking fibrous septa enclosing
fat.
-2)Palmar aponeurosis arising from terminal end of
palmaris longus.
-3)Thenar/Hypothenar muscles
-4)Long flexor tendons & associated lumbricals
-5)Adductor Pollicis arising as transverse & oblique heads
from 3rd metacarpal.
-6)The interossei ,palmer & dorsal arising from the
metacarpals.

10. Nail &pulp spaces infection infections
• Paronychia is soft tissue adjacent to the nail
infection. May be acute due to bacteria eg
staphylococcus aureas but occassionally due
Herpes simplex virus. Chronic may be fungal
eg candida or mycobacteria.
• Pulp space infection or felon is very painful
because the pus forms in inter-septal spaces
where it becomes enclosed.It may lead to
osteomyelitis of distal phalange.

14. • Palmar Aponeurosis:- It is a continuation of
palmaris longus. It extends, from distal border
of flexor retinaculum , fanning out in a
triangular fashion towards the bases of the
fingers sending to each a slip.Each slip further
subdivides into two bands that are attached to
deep transverse ligament. Dupuytren’s
contracture of palmar aponeurosis >fixed
flexion contractures of fingers.

17. • Thenar muscles:- They arise from flexor retinaculum:-Abductor
pollicis brevis attached to radial side of base of 1st phalange is the
most prominent & radial.It abducts the thumb at the MP joint.
Flexor pollicis brevis is attached via a radial sesamoid to radial
border of 1st phalange as its flexor at MP joint.Opponens pollicis is
inserted to radial border of 1st MC. All are supplied by median nerve
• In relaxed position of the hand, the thumb is at right angle to the
palm plane./In apposition of the thumb, its MC &phalanges are
rotated so that the thumb lies parallel to palm plane,Apposition
mainly occur at Trapezial-metacarpal joint.
In relaxed hand position also,the other fingers become
progressively more flexed becoming most flexed at little finger &
least at index finger. A pointing finger is a sign of long flexor
tendons not working.

18. • Hypothenar muscles:-All arise from flexor
retinaculum. Abductor digiti minimi attached
to ulnar side of base of proximal phalange>
abduction of little finger to ulnar side. Flexor
digiti minimi Inserted to base of proximal
phalange.Opponens digiti minimi inserted to
ulnar border of 5th MC.All hypothenar muscles
are supplied by deep branch of ulnar nerve.

19. • Lumbricals:-Arise from the four profundus
tendons passing at the radial side of MP joints.
Their tendons passing through fibrous
lumbrical canals reach the extensor expansion
on the dorsum of proximal phalange. The two
ulnar lumbricals are innervated by ulnar nerve
& the two radial by median nerve. They flex
the MP joints.

20. • Adductor pollicis:-Transverse head arises from 3rd MC,
oblique head also from 2nd MC to be attached via ulna
sesamoid to ulna side of base of proximal phalange.It
approximates the thumb to index finger.It is supplied
by deep branch of ulnar nerve.
• Interossei:-Palmar are smaller and arise from their own
MC.They adduct (PAD). Middle finger & thumb have no
palmar interossei. Dorsal are larger & arise from both
adjacent MC,They abduct(DAB).Supplied by deep
branch of ulnar nerve,They are inserted to the proximal
phalange via the extensor expansion hood.

22. • Fibrous flexor sheath:-For the long flexor tendons over
the metacarpal heads & phalanges. They prevent
bowstringing of the long flexor tendons. FDS &FDP
tendons pass through them,.The FDS tendon splits to
spiral &decussate around FDP to be attached to middle
phalange &FDP to distal phalange.
The zones of long flexor tendons are :-Zone1 distally
containing profundus. Zone2 (No man’s land)
containing both FDS & FDP. Zone3 FDP where the
lumbricals arise.Zone4 At carpal tunnel.Zone5 above
carpal tunnel at forearm.

25. Synovial flexor sheaths:-In the carpal tunnel, the long flexor tendons
are invested with a synovial sheath of parietal & visceral layers. The
visceral layer sends double folds of synovium called vincula that
contain blood supply to the tendon. They extend proximally into
the forearm as space of Parona, anterior to pronator quadratus &
distally into the fingers.FPL of the thumb & flexors of little fingers
have continous synovial flexor sheaths through out ,hence their
great mobility & extend 2.5 cm above the wrist in the forearm as
Radial (smaller) & Ulnar bursae (larger)The synovial sheaths for
index ,middle & ring fingers have interruptions where the tendons
are bare &where the lumbricals arise in the palm. >Synovial sheath
infection at 2nd ,3rd & 4th fingers may be restricted to the fingers,but
that of thumb & little fingers can spread into the wrist & distal
forearm.
-Space of Parona-may in infection & abscesses as proximal extension of
the synovial sheath infection

29. • PALMAR SPACES:- The palmer aponeurosis sends
from its side fibrous septa into the :-
-1)5th MC > hypothenar space with hypothenar
muscles.
-2)Middle MC > midpalmar space& thenar space
The midpalmar space floor is 3rd & 4th MC with their
interossei & distally continue as lumbrical canals
in the three web spaces. Infection in web spaces
>to lumbrical canals > to midpalmar space. The
thenar space always contain the 1st lumbrical. Its
floor is adductor pollicis.

34. • Arterial arcades in the hand:-
• Superficial palmar arch:-This is an arterial arcade that lie below the
palmar aponeurosis as a direct continuation of ulnar artery beyond
the flexor retinaculum. It is completed on radial side by superficial
branch of radial artery. It gives common palmar digital arteries
>digital arteries at the web to adjacent fingers surfaces ulna surface
of little finger,except the radial side of index finger & entire thumb.
• Deep palmar arch:-This is an arterial arcade mainly by the deep
terminal branch of radial artery after passing between the two
heads of 1st dorsal interrossei, then between oblique & transverse
heads of adductor pollicis in the palm. It gives palmar metacarpal
arteries(3) which anastomose with palmar digital arteries of
superficial arch; arteria radialis indicis &arteria princeps pollicis.

36. • Digital nerves:- The palmar surfaces of the
hand & fingers are supplied by ulna & median
nerves only. Radial nerve does not supply the
palm.The digital nerves accompany & are deep
to digital arteries. The thumb, index ,midddle
fingers & radial ½ of ring fingers are supplied
entirely by digital nerves from median nerve.
The little finger & ulnar ½ of ring fingers are
supplied by digital nerves from the superficial
branch of ulnar nerve.

39. Anatomical snuff box
• It is visible especially when the thumb is fully
extended on the radial side of wrist & thumb. It
lies between EPL & EPB together with APL. It
contains superficial branch of radial nerve &
radial artery ,whose pulse is palpable at the box.
Cephalic vein branches also. On its base ,the
scaphoid can be felt together with radial styloid
process , base of thumb metacarpal & trapezium.
Tenderness in the snuff box could be due to # 0f
waist of scaphoid , a notorious # because of AVN
of proximal # fragment >causing OA of the wrist
joint; delayed or non-union of the #.

44. s