The document provides an in-depth summary of the anatomy of the hand. It discusses the extensor mechanism including the extrinsic muscles, intrinsic muscles, and fibrous structures. It describes the anatomy of the extensor tendons including the juncturae tendinae, sagittal bands, central slip, lateral bands, and terminal tendon. It also discusses the lumbrical and interosseous muscles and their functions. Finally, it covers the embryology, nerves, and clinical implications of hand anatomy.

1. Anatomy of The Hand
Prepared by
Mahmoud Elsayed Gouda Mohamed
Plastic Surgery Unit – Zagazig University

2. Agenda
Part 1 Part 2
• Terminology & Hand Motion
• Skin
• Fascia
• Musclo-Tendious Unit
• Embryology
• Bones & joints
• Neurovascular Unit
• Carpal tunnel
• Nail bed

3. Extensor Mechanism
The anatomy of the extensor mechanism is an intricate and layered
system that changes geometry as the finger flexes and extends

4. The extensor mechanism consists of
• extrinsic muscles, which are located on the forearm
(extensor communis, extensor indicis, extensor digiti minimi
(EDM)),
• intrinsic muscles, which are located at the level of the
metacarpals (interosseous and lumbrical muscles), and
• fibrous structures.

6. ECU lies in a separate fibro-osseous tunnel or subsheath. The
extensor retinaculum lies superficial and does not attach the
ulna, but swings around and attaches to the pisiform and
triquetrum.

8. Juncturae Tendinae
• On the dorsal hand, proximal to the metacarpophalangeal
(MP) joint level, stout interconnecting bands exist between the
ring EDC to the small and middle fingers, and there is a less
substantial band from the middle to the index finger.
• The importance of these juncturae tendinae is that finger
extension can be preserved if the EDC is lacerated proximal to
the juncturae tendinae connecting that finger to an intact
extensor tendon. The juncturae tendinae also restrict
independent extension of the ring and middle fingers when the
other digits are flexed at the MP joints.

9. EDC tendons insert onto extensor aponeurosis over the MP joint, and
continue distally as central slip
DTML

11. • Sagittal bands arise from volar plate and help stabilize the
extensor tendon over the MP joint.
• Central slip inserts on the base of middle phalanx and contributes
to PIP joint extension (along with the intrinsics)
• Two lateral slips arise from the central slip and join the intrinsics
to become conjoined lateral bands, inserting on the base of distal
phalanx as the terminal tendon and causing DIP joint extension.

12. Sagittal Bands
• The extensor tendon at the MP joint level is maintained in a central position
by the sagittal bands, which arise from the volar plate of the MP joint and the
intermetacarpal ligaments, to insert on the extensor hood.
• The mechanism by which extension of the MP joint is achieved by the pull of
EDC tendons is not related to a direct insertion of the tendon on the base of
the proximal phalanx but it is transmitted by the pull of the EDC tendon
through the sagittal bands.
• When the sagittal band system is damaged, and the EDC tendon subluxates
or dislocates off the central axis of the finger, MP joint extension is
compromised.

13. The lateral bands
• There is a normal dorsal-palmar translation of the lateral bands
with respect to the PIP joint axis of rotation during flexion and
extension, which must be preserved to retain normal extensor
function.
• the lateral bands displace volarly in flexion, and to return to the
dorsum of the finger in extension.

14. The lateral bands are maintained in position by :
• the triangular ligament, which unites them dorsal and distal to the PIP joint,
and the transverse retinacular ligaments, which stabilize them to the flexor
tendon sheath.
• The primary function of the triangular ligament is to prevent palmar
subluxation of the lateral bands during PIP joint flexion, which can occur in
the boutonniýre deformity as a result of triangular ligament incompetence.
• The primary function of the transverse retinacular ligament is to prevent
dorsal subluxation of the lateral bands during extension, as can occur in a
swan neck deformity.

15. The central slip insertion on the base of the middle phalanx helps
to initiate extension of the PIP joint; however, PIP joint extension
is possible even in the absence of the central slip, provided that
the triangular ligament, lateral bands, and transverse retinacular
ligaments are functioning normally.
Distal to the triangular ligament, the lateral bands converge to
form the terminal tendon, which inserts onto the base of the distal
phalanx. The germinal nail matrix, which creates the nail plate,
arises approximately 1.2 mm distal to the terminal

16. Elson test for central slip rupture:
• the examiner passively flexes the PIP
joint to 90 degrees over the edge of a
table and asks the patient to attempt
active extension of the PIP joint while
the examiner resists PIP joint extension.
• Acute rupture of the central slip results
in no extension power being felt at the
PIP joint, and significant extension
power, or hyperextension, produced at
the DIP joint.

19. The lumbrical muscles
lumbricals to the index and middle fingers arise from the radial side of
the FDP tendons to these fingers while that of the ring and little fingers
arise from the FDP tendons of adjacent fingers. The tendon of each
lumbrical passes volar to the deep TMCL (IVPL) and joins the radial
lateral band at the middle of the proximal phalanx.
▪ Function primarily as IP extenders
♦ Proximal migration of the FDP after injury leads to lumbrical
contracture and paradoxical extension of the PIP joint when
attempting to flex the MCP joint (“lumbrical plus” deformity

20. Lumbrical function is best reflected by having the
patient fully flex the finger (extrinsic flexor
function), then move the finger smoothly into
extension at the interphalangeal joints while
holding active flexion at the metacarpophalangeal
joint.

21. The palmar interossei arise from the medial side of the 2nd, 4th,
and 5thmetacarpal, cross volar to the MCP joint, and join the
extensor apparatus at the level of the proximal phalanx after
crossing palmar to the axis of the MP joint
▪ Function to adduct the fingers, flex the MCP joint.
• The dorsal interossei arise from the adjacent sides of the 5
metacarpal bones and join the extensor apparatus.
▪ Function to abduct the fingers, flex the MCP joint, and extend the
IP joints

23. The first two interosseous muscles approach the index
and middle finger from the radial side; the third and fourth
approach the middle and ring finger from the ulnar side.

24. • The ability to flex the metacarpophalangeal joints with the
interphalangeal joints extended (“intrinsic plus” posture)
confirms interosseous function.
• Paralysis is reflected by clawing of the fingers with
hyperextension of the metacarpophalangeal joints and flexion
of the interphalangeal joints on attempts actively to extend
the fingers (“intrinsic minus”)

25. • When MP joint hyperextension is prevented, EDC is capable of extending MP,
PIP, and DIP joints even in the absence of intrinsic muscle function
• Without intrinsic muscle function the long extensors exhaust their potential at the
level of the proximal phalanx. Anatomical studies have demonstrated that
isolated contraction of the extrinsic extensors results in hyperextended, claw like
position of the MP joints, but not complete finger extension

26. • The interossei function is dependent on the position of the MP joint
• In MP flexion --> the interossei lose its extensor function on IP
joints
• The lumbricals are not position dependent as they extend the IP
joints while MPJ is flexed or Extended

27. Lumbricals and FDP
• Reciprocal relationship
• Contratcted -- relaxef

28. • Biomechanically, the finger can be compared to a multiarticular
chain comprised of the three phalangeal bones For the proximal
phalanx, these are the extrinsic extensor and flexor muscles and the
diagonal intrinsic system (lumbrical and interosseous muscles).
• In the middle phalanx there is no diagonal muscle system; instead
the third component is made up of the oblique retinacular ligament
(Landsmeer’s ligament)
• Dissection of the ligament results in lack of extension of the DIP
Linked Chains

29. Hand elements
1-The fixed unit of the hand, consisting of the second and third
metacarpals and the distal carpal row.
2. The thumb and its metacarpal with a wide range of
motion at the carpometacarpal joint.
3. The index digit with independence of action within the
range of motion allowed by its joints and ligaments.
4. The third, fourth, and fifth digits with the fourth and
fifth metacarpals. This unit functions as a stabilizing vise
to grasp objects for manipulation by the thumb and
index finger, or in concert with the other hand units in
powerful grasp

30. • When the head of the first metacarpal is palmar-
abducted by thenar muscles innervated by the
median nerve, and the fourth and fifth metacarpals
are palmar-abducted by the hypothenar muscles
innervated by the ulnar nerve, a volar, concave,
transverse metacarpal arch is created,
approximating a semicircle. The mobile metacarpal
heads are pulled dorsally by extrinsic extensor
tendons when the thenar and hypothenar muscles
relax

31. • The active production of
a semicircular transverse
arch by the thenar and
hypothenar muscles
creates the proper
circumferential
arrangement of the
metacarpophalangeal
joints for convergence of
the fingers in flexion.

32. The proximal and distal interphalangeal joints are hinge
joints: any lateral motion is limited in all phases of flexion and
extension by radially oriented collateral ligaments, which are
tight at any angle.
The metacarpophalangeal joints, in contrast, allow motion through
several axes. The capsule, including the collateral ligaments and volar
plate, is quite lax, allowing medial and lateral deviation, flexion,
extension, and
thereby circumduction and a small degree of distraction. In the absence
of other sources of stabilization, upon cutting
of the collateral ligaments the metacarpophalangeal joint becomes a
flail, unstable mechanism.

33. Allah, fortunately, has
created another source of lateral stability – the interosseous
muscles. By virtue of the selective variable pull, the interossei
normally influence lateral motion in the metacarpophalangeal
joint to the extent allowed by the unyielding collateral
ligaments. If the collateral ligaments are sacrifced, the
interossei remain the sole source of lateral stability. When
there is intrinsic (ulnar) paralysis, if the collateral ligaments
are sacrifced, all lateral stability is lost and disastrous ulnar
deviation
occurs.

35. The frst carpometacarpal joint is
best described as a double
saddle where one saddle sits atop
another, allowing three
degrees of motion: (1) flexion-
extension; (2) abductionadduction;
and (3) medial rotation-lateral
rotation

36. Embryology

37. • The limb bud, appears at 26 days after
fertilization, represents an outgrowth of
the mesoderm into the overlying
ectoderm. Two sources of cells migrate
from their origins into the limb bud.
• The cells from the lateral plate
mesoderm become bone, cartilage,
and tendon.
• The cells from the somatic mesoderm
form the muscle, nerve, and vascular
elements of the limb bud

40. Signaling Centers :
That control the three spatial axes of limb development: proximal-
distal, anterior-posterior, and dorsal-ventral. :
• the apical ectodermal ridge (AER), the zone of polarizing
activity (ZPA), and the Wnt (Wingless type) signaling centers
• A coordinated effort between the AER, ZPA, and Wnt
pathways is necessary for proper limb patterning and axial
development.
• The three signaling centers are interdependent such that loss
of one signal results in compromise of the entire system.

41. 'morphogen' diffusible protein factors.

43. • Proximal to distal axis
• The key organizer is the apical ectodermal ridge (AER), a thickening of the ectoderm running
around the rim of the limb bud, in an anterior to posterior direction.
• Undifferentiated mesenchymal cells lie beneath the AER at the apex of the limb bud, in an area
known as the progress zone (PZ)
• The AER produces FGF-4 (under the influence of the HOX gene), and this controls proximal to
distal differentiation of the undifferentiated mesenchyme in the PZ.
• • Short time in PZ produces proximal structure.
• Long time in PZ produces distal structure.
• Removal of the AER causes limb truncation

45. Radial or ulnar
• This axis is controlled by an area of mesenchyme on the posterior part of the limb known as the zone of polarizing
activity (ZPA).
• The ZPA expresses a factor which controls differentiation into anterior and posterior structures.
• The cells of the ZPA express the sonic hedgehog gene, and produce the sonic hedgehog protein, which may
influence the morphogen factor.

46. Dorsal to ventral axis
Flexor or extensor
• This axis is controlled by the dorsal ectoderm, which produces a morphogen factor controlled by the
wnt7a gene.
• High concentration produces ventral structures.
Low concentration produces dorsal structures

47. • Programmed cell death plays an important role in limb
development. It is an active process that is genetically controlled
to eliminate unwanted cells during embryogenesis. Apoptotic
cells undergo a degenerative process consisting of DNA
fragmentation and are eventually engulfed by phagocytic cells.
Genetic control of cell death is necessary during limb bud
formation.
• For example, interdigital necrosis is necessary for finger
separation. Failure of interdigital apoptosis results in syndactyly

48. C:UsersmahDocumentsSnagit2017-
03-03_10-54-34.mp4
• Rotation of the limb

49. Genetic mutations can disrupt the molecular function of a
number of proteins orchestrating limb development, including
secreted proteins (ligands), ligand receptors, and transcription
factors.
The mutation may be inherited or may arise spontaneously.
Environmental factors, including mechanisms such as
1. thalidomide, which resulted in an epidemic of limb
malformations during the 1960s,
2. radiation,
3. nutritional defects,and infections
may affect the molecular pathways of development or be responsible
for a more gross insult resulting in
tissue hemorrhage and/or necrosis.

50. Associated anomalies
• For instance, thrombocytopenic absent radius, Fanconi’s
anemia, Holt–Oram syndrome and the VACTERLS association
may accompany a longitudinal radial defciency.
• A cardiac echogram, renal ultrasound, and blood examinations
are routine

52. Nerve Supply
• Median
• Ulnar
• Radial

53. Median nerve
• The median nerve is a mixed motor and
sensory nerve that is derived from C5, C6,
C7, C8, and T1.
• It forms a coalescence of the lateral and
medial cord just above the axilla and runs in
the medial aspect of the upper arm
• There are no branches in the arm as the
nerve courses lateral to the brachial artery
and then passes over brachialis in the
antecubital fossa.

54. • In the forearm, the median nerve proper supplies
1. pronator teres (PT) (from the anterior side),
2. FCR,
3. palmaris longus,
4. and FDS.
• It gives AIN from the lateral side at the level of radius
tuberosity then passes between the heads of pronator
teres.
• The anterior interosseous nerve (C8, T1) innervates
1. flexor pollicus longus,
2. flexor digitorum profundus (FDP) to the index
finger and sometimes long finger,
3. and pronator quadratus (PQ).
From the medial side

55. Anterior interosseous nerve (AIN) to deep motor branch
of ulnar nerve
• A schematic of the distal AIN to deep motor branch transfer.
The donor AIN (green) is seen divided under the pronator
quadratus muscle and transposed over to the recipient
deep motor branch of the ulnar nerve.
• At this level, distal to the take off the dorsal cutaneous
ulnar branch, the motor fascicles are ulnar and the main
sensory component of the nerve is radial. The coaptation is
performed in an end-to-end manner. FDS, flexor digitorum
superfcialis; FDP, flexor digitorum profundus.

56. • The median nerve lies between the flexor digitorum superficialis
and the flexor digitorum profundus in the proximal forearm and
adherent to the undersurface of FDS.
• As it travels distally, it becomes more superficial and 5 cm above
the wrist it becomes superficial and is located just deep to palmaris
longus at the wrist crease.
• At the wrist it has ̴̴ 30 fascicles. It has average diameter of 4-6mm
(The motor recurrent often consists of 2 fascicles)
• The nerve then enters into the carpal tunnel and travels distally into
the hand

57. The remainder of the nerve is largely sensory, with a
small motor component contributing to
• the recurrent motor branch, which innervates the
thenar muscles (abductor pollicus brevis,
opponens pollicus, and the superfcial head of
flexor pollicus brevis) and the two radial lumbricals.

58. The sensory contribution is to the volar surface of the thumb, index,
long, and radial half of the ring and to the dorsal aspect of those digits
distal to the distal interphalangeal joint

59. Mediannervetopography
The nerve bundles destined for the thenar branch are located radially to the
median nerve in 60% of the cases, anteriorly in 20% and centrally in 18%

60. Median nerve injury
• Low and High according to the injury below or above AIN
• Loss of flexion in the thumb, index finger and middle finger
due to paralysis of the following muscles:
FDS of the fingers, FDP of the index and middle finger
(AIN), superficial head of the FPB, abductor policis brevis
and opponens polices
• Thenar atrophy with reduced opposition and abduction
• Sensory loss over the palm and palmar surface of the
radial 3 and half fingers and dorsal surface up to DIP

61. • Look: wasting of the thenar musculature and sudomotor changes in the
nerve distribution.
• Motor:
• * Median nerve at the elbow: palpate tendon of FCR
with resisted wrist flexion.
• Anterior interosseus nerve sign: inability to make an ‘O’ sign due to
denervation of FDP to the index finger and flexor pollicis longus (FPL).
• Pronation of the forearm (quadratus) with elbow extended to
neutralize pronator teres.
• Motor branch of median nerve:
• Weakness in abduction of the thumb (APB).
• Opposition to the little finger (true pulp to pulp – opponens pollicis).
• Sensory: pulp of index
* Moving two-point discrimination.
* Sharp/blunt sensation

63. • Compression of the AIN or dysfunction of this nerve from viral
disease can result in an AIN palsy
• OK sign: Patients are unable to make an OK sign when asked by the
examiner to flex the thumb IP joint and index finger DIP joint

64. • Paper pinch sign: Asking patients with weak FPL and FDP (but not
palsy) to pinch a sheet of paper between the thumb and index finger
using only the fingertips and then trying to pull the paper away can
determine subtle weakness of the FPL and index finger FDP. The
patient will be unable to hold on to the sheet of paper with just the
fingertips and may compensate by using a more adaptive grip in which
the IP joint of the thumb and DIP joint of the index finger remain
extended.

65. • PQ assessment: The PQ is tested by checking the ability of the patient
to pronate the forearm with the elbow in maximal flexion. Maintaining
the elbow in flexion minimizes the contribution of the pronator teres.

66. Median nerve blood supply
• the median nerve below the
elbow was supplied by :
1. the superficial palmar arch,
2. by the ulnar artery just proximal
to the flexor retinaculum,
3. and by the median artery more
proximally in the forearm

67. Median nerve & ulnar interconnections
Martin-Grüber median ulnar anastomosis in the forearm
• Anastomoses of the median nerve to the ulnar nerve in the
forearm were described by Martin and Grüber.
• Their incidence ranges from 5 to 40%.
• The anastomosis comes from the median nerve or anterior
interosseous nerve, or is situated between the branches that
innervate the deep flexors of the fingers. It contains fibers that
innervate the deep flexors of the fingers and the intrinsic
muscles.

68. Riche and Cannieu's motor anastomosis
This anastomosis, which is observed very frequently (77% to 100%), is responsible
for the distribution of the innervation of the thenar muscles between the median
and ulnar nerves and takes on a variety of forms:
• The most classical form is a communicating branch between the thenar
branch of the median nerve and the deep branch of the ulnar nerve.
• Anastomosis at the level of the adductor muscle of the thumb.
• Anastomosis between the thenar branch and the deep branch of the ulnar
nerve at the level of the first lumbrical muscle.
• Anastomosis between a collateral nerve of the thumb and the deep branch
of the ulnar nerve.
It should be noted that the innervation of the lumbrical muscles is superimposed on

69. The carpal tunnel is a fibro-osseous tunnel that
• contains the median nerve and the nine flexor tendons to the
thumb and the fingers.
• The roof of the carpal tunnel is formed by the flexor retinaculum,
which extends between four bony prominences (proximally:
pisiform and tubercle of scaphoid, distally: hook of the hamate and
tubercle of trapezium)
Carpal tunnel syndrome

71. The flexor retinaculum can be divided into three components
• Proximal: Direct continuation of the deep antebrachial fascia
• Middle: Transverse carpal ligament (TCL)
• Distal: Aponeurosis between the thenar and hypothenar muscles

72. • The recurrent motor branch typically arises from the volar-radial aspect of
the median nerve at the distal end of the transverse carpal ligament and
turns proximally and radially to innervate the thenar muscles
• The origin of the recurrent motor branch is surface-marked at the intersection
of a vertical line from the radial border of the long finger and KCL. nerve ,
and three courses of this branch have been described.
• Extraligamentous (46%)
• Subligamentous (31%)
• Transligamentous (23%)

73. Variation of symptoms
• Variation of recurrent motor
• Ulnar – median interconnection

74. The following provocative tests have been used in the diagnosis of
CTS.
• Phalen test: This is done by holding the wrist in maximal flexion for 60
seconds. It is believed to compress the median nerve between the
proximal edge of the TCL and the underlying flexor tendons and should
elicit a pins and needles sensation in the median nerve sensory
distribution. A modifcation of this test has been described, in which the
wrist is held in maximal extension (reverse Phalen test)
Carpal tunnel pressure
Lowest at rest with wrist in neutral (2.5mmHg). Rises to 30mmHg in
full wrist flexion. In CTS pressures rise to 30mmHg and 90mmHg
respectively (Phalen's test provokes this rise in pressure).

75. Tinel sign: This is done by applying repeated digital percussion
over the median nerve at the level of the proximal edge of the
transverse carpal ligament (TCL) (in line with the pisiform)
medial to the FCR tendon (over the PL tendon if present) (Fig.
1-44). This should elicit the sensation of pins and needles in the
cutaneous distribution of the median nerve

76. • Carpal compression test (Durkan test): This is done by
applying direct digital pressure over the median nerve for 30
seconds (at the same site as described for the Tinel sign) and is
considered positive when symptoms are reproduced. It has also
been combined with the Phalen and reverse Phalen test.

77. Ulnar nerve
• the ulnar nerve enters the upper extremity as
a terminal branch of the medial cord of the
brachial plexus (C8–T1) .
• It travels medial to axillary and brachial a and
posterior to basilic v in the anterior
compartment of the upper arm.
• It pierces the medial intermuscular septum
and runs in the posterior compartment along
with the medial head of triceps together with
superior ulnar collateral a.

78. Approximately 8 cm proximal to
medial epicondyle the nerve
passes under the arcade of
Struthers, a thin band extend
from the medial intermuscular
septum to the medial epicondyle

79. • At the elbow , the nerve passes through
the cubital tunnel, where the articular
branch of the elbow is the 1st branch to
leave the nerve behind the medial
epicondyle.
• After the cubital tunnel , the nerve enters
the flexor tendon compartment of the
forearm between the two heads of flexor
carpi ulnaris , where it gives off motor
branches to the two heads.

80. • In the flexor compartment, the ulnar nerve lies on the medial
side of the FDP together with the ulnar a underneath the
FCU, which protects the nerve along most of the forearm.
The nerve supplies the FDP via muscular branches, which it
gives off a few cm below the elbow. Most commonly, the
ulnar nerve supplies the ulnar two slips.

81. • Midway to distal third along the forearm, the ulnar n may
give off the ( nerve of Henle), containing sympathetic
innervation to the ulnar a or a palmar cutaneous branch,
which is inconsistent and clinically less famous than its
median counterpart. When present, the branch continues
distally on the ulnar a, pierces the antebrachial fascia, and
provides sensory innervation to the ulnar part of the palm
over the area of pisiform.

82. • Reaching the distal fourth of the forearm, the dorsal cutaneous
branch of the ulnar n originates and pierces the antebrachial
fascia at 5 Cm from the pisiform.
• The dorsal cutaneous branch the travels subcutaneously and
crosses from volar to dorsal at the level of the ulnar head to
provide sensation to the ulnar half of the dorsal hand

83. • At the level of the wrist, the ulnar n becomes
superficial again, lying only slightly dorsal and radial
to the tendon of the FCU muscle and ulnarly to ulnar
a.
• It continues distally superficial to the flexor
retinaculum through the Guyon canal to divide into
superficial terminal and deep motor branches.
• The superficial terminal branch continues distally
deep to the palmaris brevis muscle, which it
innervates.
• It then divides into two palmar digital nerves: one to
ulnar half of the little finger and one ( a common
palmar digital nerve) to adjacent sides of the little and
ring fingers.

85. • The deep motor branch passes between the abductor digiti
minimi and the flexor digiti minimi muscles together with the
deep branch of ulnar artery.
• It pierces the opponens digiti minimi muscle before coming to lie
deep to the flexor tendons together with the deep palmar arterial
arch. It gives motor branches to
1. the hypothenar muscles,
2. the ulnar two ( or more ) lumbricals,
3. all palmar and dorsal interossei,
4. the adductor pollicis and variably to the deep head of FPB.
5. It also provides articular braches to the wrist and possibly
to the carpus and CMC joints.

86. Ulnarntopography

87. • At the level of the mid forearm, 50 mm from the ulnar styloid the motor
fascicles lie dorsal to the sensory fascicles
• The ulnar nerve has 15 to 25 fascicles at the wrist. It can be clearly
divided into volarly sensory component and a dorsal motor component
• The motor fascicle lie dorsal and slightly ulnarly to the sensory
fascicles at the wrist level and usually maintain a dorsal relationship as
one moves proximally. The motor component remains as a distinct
entity up to 90 mm proximal to the styloid, the dorsal sensory branch
joins the other groups.
• At the elbow, the ulnar contains 20 fascicles, including motor branches
to the forearm muscles. The motor fascicles to the FCU and intrinsic are
centrally located, whereas the sensory fascicles lies superficially
• The proximal motor branches to FCU and FDP can often be traced up
to 6 cm prior to interfasicular connections.

88. • The ulnar nerve has an extrinsic blood
supply consisting of multiple dominant
systems:
1. the SUCA,
2. the IUCA,
3. the posterior ulnar recurrent artery
4. and the ulnar artery. However, the entire
length of the ulnar nerve can survive
based on the SUCA and its venae
comitantes.
• Taylor’s group examined the blood supply of
the upper limb and classified peripheral
nerves according to their suitability for
microvascular free transfer, with type A
Ulnar n blood supply

89. • The ulnar n is supplied by the brachial and the
ulnar angiosomes. In the arm, the ulnar nerve is
type C as it courses distally with the SUCA on its
surface.
• As it passes behind the medial epicondyle , the
ulnar nerve is nourished by the anastomotic
system formed by the superior ulnar collateral
and posterior ulnar recurrent arteries and the
blood supply is a type E pattern.
• In the forearm, the ulnar nerve, receives a type A
supply as it accompanies the ulnar a, receiving
many characteristic Y- shaped arteriae nervorum.
• In the hand the ulnar n has type E blood supply
pattern again.

90. Ulnar nerve injury
• Low injuries occur distal to the origins of the motor branches to
the FCU and ring and little finger flexor digitorum profundus
(FDP) muscles. Strength of the extrinsic hand muscles is
unaffected, but sensation is lost on the ulnar border of the hand
and in the ring and little fingers, and the ulnar-innervated intrinsic
muscles are paralyzed. This results in weakness of thumb pinch,
claw deformity, loss of the normal pattern of finger flexion, and
significant loss of hand dexterity and strength
• High injuries occur above the origins of the motor branches to
the FCU and ring and little finger FDP muscles. In this situation,
loss of active ring and little DIP joint flexion and wrist flexion
compound the aforementioned findings, although paradoxically,
the claw deformity tends to be less severe

91. Claw deformity (Duchenne sign):
• This is the characteristic resting posture
of the ring and small fingers with
hyperextension of the MCP joint and
flexion of the IP joint.
• It results from the unopposed action of the
radial nerve–innervated long extensors at
the MCP joint (hyperextension) and
median nerve–innervated FDS at the PIP
joint (flexion) in the presence of the
paralyzed ulnar nerve–innervated
interosseous and the third and fourth
lumbricals that normally flex the MCP joint
and extend the PIP joint.

92. • Cross-your-fingers test: The patient is asked to cross the long
finger dorsally over the index finger or the index finger over the
long finger. In ulnar nerve palsy, the patient will be unable to do
so because of paralysis of the interossei.
• Middle finger abduction (Pitres-Testut sign): This is inability to
abduct the long finger from side to side.

93. Wartenberg sign:
The small finger is abducted at rest.
• This deformity results from unopposed
action of the radial nerve–innervated
EDM in the presence of the paralyzed
ulnar nerve–innervated third
palmar interosseous that normally
adducts the small finger.
• The EDM causes abduction of the
small finger in addition to extension
because it
has an insertion on the ulnar aspect of
the base of the proximal phalanx.

94. Froment sign:
• The patient is asked to pinch
sheets of paper between the
thumb and index finger of both
hands.
• A positive Froment sign is
indicated by marked thumb IP
joint flexion in the affected hand
as a result of the patient using his
median nerve–innervated FPL to
hold the sheet of paper, rather
than using the adductor pollicis

95. • The radial nerve arises from the
posterior cord of the brachial plexus
(C6–8) (all roots of the plexus
contribute to the various radially
innervated muscles)
• passes through a triangular space
that is bordered superiorly by the
teres major muscle, laterally by the
humerus, and medially by the long
head of the triceps muscle.
Accompanied by the profunda brachii
artery to enter the spiral groove
Radial n

96. • Throughout its course posterior to the
humerus, the nerve gives off branches
to the lateral and medial heads of the
triceps and to the lower lateral brachial
cutaneous nerve
• After passing around the lateral aspect
of the humerus and piercing the lateral
intermuscular septum, the radial nerve
enters the interval between the
brachialis and brachioradialis muscles.
The brachialis muscle is usually dually
innervated and receives motor supply
from the musculocutaneous and radial
n.

97. • the nerve passes along the anterior
surface of the joint capsule and
crosses into the forearm
• In the proximal arm, the radial nerve
gives off branches to the triceps,
anconeus epitrochlearis,
brachioradialis and extensor carpi
radialis longus ( ECRL).
• Anterior to the radial head, the nerve
branches into :
1. the posterior interosseous nerve
2. and the radial sensory branch.
• The supinator and ECRB branches
can depart from the main nerve, from
the proximal PIN or the same level
as the radial sensory branch.

98. • The radial sensory branch lies just
superficial to the antebrachial
fascia.
• Once identified, the radial sensory
branch is the most raidial/ volar,
followed by the ECRB and then by
the PIN which is the largest and
most dorsal and travels
underneath the superficial portion
of the supinator.

99. • The PIN continues between the superficial and deep
heads of supinator muscle, to exit on the dorsal
forearm.
• The PIN also has a short distance to travel to
reinnervate the motor end plates, which accounts for
generally favorable results after repair.
• After it emerges from the distal supinator, the PIN
sends branches to the : EDC, ECU, extensor digiti
minimi, EPL, EPB and extensor indicis in descending
order although there may be considerable variations.
• Finally, the deep posterior interosseous nerve
terminates to supply carpal joint sensation

100. • The dorsal or superfcial branch of the
radial nerve courses through the forearm
in relationship to the brachioradialis
muscle on the radial side of the forearm.
• The nerve crosses the “anatomic
snuffbox” between the EBB and the EPL
in the loose subcutaneous tissue.
• approximately 9 cm proximal to the
radial styloid. Distally, it arborizes
• It divides into multiple branches, which
give sensibility to the dorsum of the
hand over the radial two-thirds, the
dorsum of the thumb, and the index,
long, and half of the ring finger proximal
to the DIPJ.

101. Loss of radial nerve function in the hand creates a significant
disability. The patient cannot extend the fingers and thumb and has
great difficulty in grasping objects. Perhaps more importantly, the
loss of active wrist extension robs the patient of the mechanical
advantage that wrist extension provides for grasp and power grip.
It is imperative that the surgeon makes the important distinction
between complete radial nerve palsy (excluding the triceps) and
posterior interosseous nerve palsy.
The radial nerve innervates the brachioradialis (BR) and extensor carpi
radialis longus (ECRL) before it divides into its two terminal branches,
the posterior interosseous (motor) and superficial (sensory) branches.
Radial nerve injuries

102. In a patient with posterior interosseous nerve palsy, ECRL is intact,
resulting in radial deviation of wrist in extension.

103. Vascular

104. • Arterial
• Venous & Lymphatics

105. Arterial
The vascular inflow to the upper arm and hand
is a continuation of the axillary artery to the
brachial artery.
The brachial artery is palpable just medial to
the biceps tendon at the level of the elbow.
The brachial artery branches into the radial and
ulnar arteries at the bicipital aponeurosis of the
elbow.
Supplementary arteries in the forearm include
the anterior interosseous artery, the posterior
interosseous artery, and
the median artery

106. • the radial artery appears as a longitudinal continuation of the
brachial artery, (with the ulnar artery coming off perpendicularly
runs medial to the biceps tendon, deep to brachiradialis), and gives
off the radial recurrent artery.
• runs across supinator, over the tendon of pronator teres, the radial
origin of FDS, the origin of FPL. the insertion of pronator quadratus.
• At the forearm it lies beneath brachioradialis, between it and
FCR,where it runs alongside the superficial branch of the radial
nerve.
• gives off 9 to 17 fasciocutaneous branches perforator arteries
which anastomose with the ulnar, anterior and posterior
interosseous arteries and form a rich vascular network in the
subcutaneous layer.
• A superficial branch of the radial artery arises at the level of
the distal radius before the artery enters the “snuffbox” and
courses over or through the APB to contribute to the superficial
palmar arch. This branch contributes blood supply to the skin over
the thenar area and the underlying intrinsic muscles of the thumb

107. • then disappears below the tendons of APL and EPB to
cross the anatomical snuffbox.
• It passes deep to the tendon of EPL. and then between the
2 heads of 1st dorsal interosseous muscle, to emerge in the
palm between oblique and transverse heads of the
adductor pollicis to form the deep palmar arch
• At the base of the fifth metacarpal, it anastomoses
with the deep palmar branch of the ulnar artery (6) to
form the deep palmar arch (3), which lies on the bases
of the metacarpal bones and the interossei and is covered
by the oblique head of the adductor pollicis, the flexor
tendons of the fingers, and the lumbricals.
• The three palmar metacarpal arteries (9) arise from
the deep palmar arch and join the common digital arteries
of the superficial palmar arch at the web of the finger

108. The first dorsal metacarpal
artery (FDMA) has been
found to originate from the
dorsal radial artery, just distal
to the extensor pollicis longus
tendon

109. • The princeps pollicis artery (11) is given off from the
radial artery just as it curves medially into the palm.
It runs under the oblique head of the adductor
pollicis (4) and lateral to the first palmar interosseous
muscle. At the base of the proximal phalanx of the
thumb, it lies deep to the FPL tendon and divides
into a pair of digital arteries running along the radial
and ulnar sides of the tendon.
• The radialis indicis artery (12) usually springs from
the proximal part of the princeps pollicis artery (11),
passing between the first dorsal interosseous and
transverse head of the adductor pollicis and running
along the radial side of the index.

110. A. Typical radioulnar communication of deep palmar
arch (35% of cases)
B. The deep palmar arch is complete, and it also supplies
the ulnar side of the hand (13% of cases).
C. The deep palmar branch of the ulnar artery does
not join the deep palmar arch, but the radioulnar
communication is still complete, with connections
between the palmar metacarpal arteries and the
common palmar digital arteries (49% of cases).
D. The radial and ulnar arteries supply each side in the
deep system; there may be poor communication if
the superficial palmar arch is incomplete (3% of
cases)

111. Radial forearm flap

112. • The ulnar artery is the other major branch of the brachial artery.
It passes distally and medially across and under the pronator
teres (7), the median nerve, the flexor carpi radialis (8), and the
flexor digitorum superficialis (10).
• It reaches the medial side of the forearm at about midway
between the elbow and the wrist. It then runs between the flexor
carpi ulnaris (12) and the flexor digitorum superficialis (10)
muscles or tendons. The ulnar nerve is adjacent and medial to
the lower two thirds of the artery.
• At the wrist, the ulnar artery crosses the flexor
retinaculum lateral to the pisiform bone, and ends by
dividing into the deep palmar branch and the superficial
palmar branch.

113. Becker Rap perforator
A cutaneous perforator arises 3-5cm proximal to
the pisiform. This is the basis of the Becker ulnar
artery perforator flap.
Distal to the common interosseous artery, the ulnar
artery gives off three to five fasciocutaneous
branches between the FCU and the FDS that join
the rich subcutaneous vascular network already
described.
Ulnar forearm flap

114. • The AIA runs downward between the flexor digitorum profundus (4)
and flexor pollicis longus (5) with the anterior interosseous nerve
(10), along the anterior surface of the interosseous membrane.
• It gives off the median artery which accompanies the median nerve
At the proximal border of the pronator quadratus (8), the artery
divides into two terminal branches.
1. The anterior branch continuously runs distally between the
pronator quadratus muscle and interosseous membrane to join
the palmar carpal network;
2. the posterior branch penetrates the interosseous membrane to
anastomose with the PIA and then descends to join the dorsal
carpal network.
• After its penetration, it also gives off a dorsal cutaneous
branch, which runs between the extensor digitorum
tendons and the extensor pollicis longus tendon onto
the extensor retinaculum near Lister’s tubercle to
supply the dorsal skin of the wrist.

115. • The PIA, with a diameter of 1.2 to 1.5 mm, smaller
than the AIA, passes between the oblique cord and
the
upper border of the interosseous membrane and
emerges at the lower border of the supinator at about
the level between the upper and middle thirds of the
forearm.
• It then descends in the intermuscular septum
between the ECU and EDM. It gives muscular and
fasciocutaneous perforators. These provide the blood
supply for the posterior interosseous artery flap
• In its proximal third, the PIA lies deep in the septum on
the APL muscle, accompanied by the posterior
interosseous nerve.
• After that, it becomes more superficial on the EPL and
extensor indicis muscles, almost immediately beneath
the deep fascia in its middle and distal thirds.

116. The Posterior Interosseous Artery Flap

117. • The ulnar artery goes into the hand with the
ulnar nerve superficial to the flexor retinaculum
and lateral to the pisiform bone.
• It then runs medial to the hook of the hamate
and curves in the palm at the level of the
palmar midpoint to form the superficial palmar
arch anastomosing with the superficial palmar
branch of the radial artery.

118. • The palmaris brevis muscle (5) and the
superficial part of the flexor retinaculum (4)
are divided lateral to the pisiform bone (3).
• Then, the ulnar artery (8) can be identified
lateral to the ulnar nerve (9) between the
pisiform bone and the flexor retinaculum.
• Retracting the flexor carpi ulnaris tendon (1)
medially, the dissection proceeds proximally
to expose the ulnar artery and nerve.
• Although the ulnar nerve needs to be
mobilized, care should be taken not to injure
the deep branch of the nerve (10), which
plunges between the flexor and abductor
digiti minimi to reach the deeper layer of the
palm.

119. • The superficial palmar arch lies deep to the palmar
fascia and in front of the flexor tendons and digital
branches of the medial nerve.
• Three common palmar digital arteries are given
off from the convexity of the superficial palmar arch
and travel distally on the second, third, and fourth
lumbricals.
• Each merges with the palmar metacarpal artery
from the deep palmar arch and then divides into
two proper palmar digital arteries, 1 cm proximal to
the web.

120. A. Typical radioulnar communication of superficial
palmar arch (35% of cases)
B. Superficial palmar arch formed only by ulnar artery
(39% of cases)
C. Superficial palmar arch completed by ulnar and
median artery; the latter, replacing the radial artery,
accompanies the median nerve (4% of cases)
D. Three arteries (ulnar, median, and superficial branch
of radial artery) join together to form the arch (1% of
cases).
E. In this incomplete arch, the proper palmar arteries
are derived from the radial and ulnar arteries, without
communication across the middle line of the hand at the
superficial level (16% of cases).
F. Three arteries (ulnar, median, and superficial branch
of radial artery) separately contribute to the digital
vessels, without anastomosing with each other at
the superficial level (5% of cases)

121. Dorsal carpal arch
This is formed mainly by the radial artery, deep to the thumb extensors.
The skin over the extensor retinaculum is supplied by the rete carpi
dorsale, With contributions from the radial, anterior and posterior
interosseous, and the dorsal carpal branch of the ulnar artery.
Palmar carpal arch
The flexor aspect of the wrist is supplied by branches of the radial and
ulnar arteries, with contributions from the median artery if present.
Dorsal metacarpal arteries
With exception of the FDMA ,the dorsal matacarpal arteries usually arise
from the dorsal carpal arch.

122. • The dorsal metacarpal arteries run axially and distally
between the metacarpal bones in a fascial pocket of the
dorsal interosseoi.
• These dorsal arteries are joined by a varying number of
vessels perforating from the deep palmar metacarpal
arteries. In fact, the dominant supply to the dorsal
metacarpal arteries may come from these perforators
• The DMA bifurcates into two dosal digital arteries of the
adjacent digits at the MP joint and terminates at
approximately the middle portion of the proximal phalanx,
where it joins the proximal portion dorsal branch of the
proper PDA. These branches of DMA give off some twigs

123. Each artery gives off a skin
perforator approximately 1cm
proximal to the webspace, on
which small skin flaps can be
designed
Quaba flap

124. Each proper palmar digital artery travels along the
side of the flexor tendon, dorsal to the digital nerve and
deep to Cleland’s ligament, which is a thin fibrous
sheet attaching from the lateral side of the phalanx to
the dermis of the palmar skin in the finger.
palmar digital artery

128. Allen test VS Modified Allen
1. the examiner palpates both radial arteries with the
thumb while supporting the wrist with the fingers. The
PT is then asked to close the hand as tightly as
possible to squeeze the blood out of the hand.
2. The examiner then occludes the radial artery by
compressing the wrist between the thumb and the
fingers. The patient next opens the hand partially while
the examiner maintains compression of the radial
artery.
3. The examiner observes for return of color to the hand.
A delay in return of color to the hand suggests
obstruction of collateral flow through the ulnar artery or
the presence of an incomplete palmar arch. Although
no specific time has been mentioned, a delay of
greater than 5 seconds should be considered
significant.

129. occluding the patient’s
ulnar and radial arteries while the patient
makes a fist
After that hand is open, the examiner releases
the ulnar artery while continuing to maintain
pressure on the radial artery
Modified Allen
It is better
to report the result of the Allen test in terms
of the radial and/or ulnar arteries
being patent or occluded instead of positive
or negative to avert any
misunderstanding.

130. • Although two digital arteries (radial and ulnar) usually perfuse each finger, there
are differences in the diameter of the radial versus ulnar digital arteries.
• In the thumb, the ulnar digital artery is usually much larger.
• The index finger is similarly ulnar-dominant whereas the small finger is radial-
dominant.
• The arteries to the middle and ring fingers do not have appreciable size
differences between radial and ulnar sides.
• This anatomic variation may be important in finding adequate vessels for micro
anastomosis during replantation or revascularization.

131. • This is performed by compressing both digital
arteries at the base of the finger using the index
finger and thumb .
• The patient is asked to elevate the hand and
fully flex the finger several times. This will result
in a blanched finger.
• The hand is then lowered, and the compression
on one of the digital arteries is released. If the
finger continues to remain blanched when only
one digital artery is compressed, the opposite
digital artery must be divided or occluded.
• The test can be be repeated to
check the other digital artery
Digital Allen test

132. • Veins generally follow the arterial
pattern in the deep system as venae
comitantes.
• An abundant superfcial system of
venous drainage also exists.
Ultimately, these superfcial veins
contribute to the cephalic and basilic
veins of the upper extremities.
• Lymphatic drainage terminates in the
axillary, supraclavicular, and
subclavicular nodes
Veins and Lymphatics

133. Questions and Comments

135. Thank You !