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Anterior Hand
I.
Landmarks
A. thenar eminence – swelling at the base of the thumb
B. hypothenar eminence – swelling at the base of the little finger
C. landmarks in the wrist
1. in front of the wrist are two subcutaneous eminences produced by the
a. tubercle of the scaphoid and ridge of the trapezoid bones – radial side
b. pisiform - ulnar side
2. in back of the wrist the only clear carpal bone is the
a. triquetrum or triangular bone – just distal to the ulna: pisiform sits on it
II.
Osteology
A. carpal bones – radial to ulnar side
1. scaphoid. lunate, triangular, pisiform – proximal row
2. trapezium, trapezoid, cuneiform, hamate – distal row
B. metacarpal bones – number sequence from lateral (radial) to medial (ulnar) side
is 1st to 5th metacarpal bone: each has a head, shaft, and base
C. phalanges
1. thumb – two: a proximal (1st) and distal (2nd) phalanx
2. fingers - three: a proximal (1st), middle (2nd), and distal (3rd) phalanx
III.
Fascia, compartments, synovial sheaths, and clefts
A. deep fascia of the palm of the hand is continuous with the antebrachial fascia at the
wrist via the palmar carpal ligament
B. deep fascia and the septa radiating from it form compartments
1. deep fascia
a. thenar fascia – covers the short muscles of the thumb and forms a thenar
compartment
b. hypothenar fascia – covers the short muscles of the little finger to form the
hypothenar compartment
c. palmar aponeurosis – directly covers the central (midpalmar)
compartment
(1) bounded medially and laterally by hypothenar and thenar fascial septa
(2) superficially covered by the palmar aponeurosis and deeply by palmar
interosseous fascia
(3) contains – flexor digitorum superficialis and profundus tendons,
lumbricale muscles, superficial palmar arch, palmar branch of the
median nerve, and superficial branch of the ulnar nerve
d. palmar interosseous fascia – separates the compartments above from the
dorsal portion of the hand, which contains the interosseous and adductor
pollicis muscles, hence forming the interosseous-adductor compartment
C. contents of the osteofascial compartments
1. thenar compartment – three muscles have their origin from the lateral part of
the flexor retinaculum and crest (ridge) of the trapezium bone
a. abductor pollicis brevis muscle
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(1) inserts into the radial side of the base of the 1st phalanx of the thumb
(2) abducts the thumb – draws it away in a plane at right angles to palm
(3) innervation – recurrent branch of the median nerve (C6 & 7)
b. opponens pollicis muscle
(1) inserts into the whole length of the metacarpal bone of the thumb
(2) abducts, flexes, and rotates thumb – brings thumb out in front of the
palm to face the fingers
(3) innervation – recurrent branch of the median nerve (C6 & 7)
c. flexor pollicis brevis – has medial and lateral portions
(1) inserted into the radial side of the base of the 1st phalanx of thumb
(2) flexes and adducts the thumb
(3) innervation – very small medial (deep) portion by a deep branch of the
ulnar nerve (C8 & T1); the larger (superficial) lateral portion by the
recurrent branch of the median nerve (C6 & 7)
d. blood supply to thenar muscles is superficial branch of the radial artery
2. hypothenar compartment – all arise from medial side of flexor retinaculum
a.. palmaris brevis muscle
(1) inserts into skin on the ulnar side of the palm
(2) draws skin at the ulnar side of the palm to the middle of palm
(3) innervation – branch of ulnar nerve (C8)
b. abductor digiti minimi (quinti) muscle – also has an origin off pisiform
(1) inserts into ulnar side of the base of 1st phalanx of the little finger
(2) abducts the little finger and flexes the its proximal phalanx
(3) innervation – branch of ulnar nerve (C8 & T1)
c. flexor digiti minimi (quinti) brevis muscle – arises off hamate, also
(1) inserts into the ulnar side of the base of 1st phalanx of the little finger
(2) flexes the little finger
(3) innervation – branch of the ulnar nerve (C8 & T1)
(4) sometimes it is absent so the abductor is then usually made larger
d. opponens digiti minimi - also has an origin off the hamate
(1) inserts into the whole length of the ulnar side of the 5th metacarpal
(2) abducts, flexes, and rotates the 5th metacarpal, bringing the little finger
out to meet the thumb
(3) innervation – branch of the ulnar nerve (C8 & T1)
3. central compartment
a. contents – see section III, B, c, (3) of these notes
b. four lumbricale muscles – all arise from tendons of the flexor digitorum
profundus muscle
(1) the 1st and 2nd arise from the radial side of the tendons of the index and
middle fingers, respectively
(2) the 3rd arises from the contiguous sides of the tendons of the middle
and ring finger
(3) the 4th arises from the contiguous sides of the tendons of the ring and
little finger
(4) each passes to the radial side of the corresponding finger and inserted
into the tendinous expansion of the extensor digitorum muscle
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(5) flexes the metacarpophalangeal joints & extends the distal two phalanges
(6) innervation
(a) the 1st and 2nd by third and fourth digital branches of the median
nerve (C6 & 7)
(b) the 3rd and 4th by deep palmar branch of the ulnar nerve (C8)
4. adductor-interosseous compartment
a. adductor pollicis muscle – has two heads: oblique and transverse
(1) oblique head – arises from the capitate, bases of 2nd and 3rd metacarpals
(2) transverse head – arises from distal palmar surface of 3rd metacarpal
(3) insertion – both into the base of the proximal phalanx of the thumb
(4) both adduct, bringing the thumb toward the palm
(5) innervation – deep palmar branch of the ulnar nerve (C8 & T1)
b. three palmar interossei muscles – all are adductors towards middle finger
(1) origin - the 1st from the ulnar side of the second metacarpal and the
2nd and 3rd from the radial side of the fourth and fifth metacarpals,
respectively
(2) insertion – on the same side of the 1st phalanx of each respective digit
c. four dorsal interosseous muscles – all abductors away from middle finger
(1) origin – 1st from the adjacent sides of first and second metacarpals
2nd from adjacent sides of second and third metacarpals
3rd from adjacent sides of third and fourth metacarpals
4th from the adjacent sides of fourth and fifth metacarpals
(2) insertion – 1st into radial side of first phalanx of index finder
2nd and 3rd into radial and ulnar sides of first phalanx of
middle finger
4th into the ulnar side of the first phalanx of ring finger
(3) innervation – all interossei by the deep palmar branch of ulnar nerve
D. synovial sheaths – as the flexors pass under the flexor retinaculum they are
enclosed in synovial sheaths to reduce friction
1. ulnar bursa – larger
a. complex and contains tendons of the flexor digitorum superficialis and
profundus muscles
b.. continues into the little finger and not the other fingers
2. radial bursa
a. synovial sheath for the tendon of the flexor pollicis longus muscle
b. continues into the thumb
3. synovial sheaths for the tendons of the index, middle, and ring fingers are
separate bursas
E. clefts / spaces – these are planes of cleavage between fascial membranes
1. major fascial cleft is at the palmar interosseous fascia described in section III
of these notes – separates adductor-interosseous compartment from the thenar,
hypothenar, and central compartments
a. middle palmar cleft
b. thenar cleft – overlies palmar surface of the adductor pollicis muscle
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IV.
Arteries
A. radial artery branches in the hand
1. princeps pollicis artery – runs to the thumb and divides into two branches
2. radialis indicis artery – runs along the radial side of the index finger
3. deep palmar arch – terminal part of radial artery which anastomoses with the
deep palmar branch of the ulnar artery
4. palmar metacarpal arteries – three or four arising from the deep palmar arch
5. perforating branches – three or four arise from the deep palmar arch, pass
through the interosseous spaces to reach the back of the hand
6. recurrent braches – arise from the concavity of deep palmar arch supplying
the carpal bones and their articulations
B. ulnar artery branches in the hand
1. deep palmar branch –passes between the abductor digiti minimi and flexor
digiti minimi brevis muscles and anastomoses with the radial artery to complete
the deep palmar arch
2. superficial palmar arch – formed by the ulnar artery and usually completed by
the superficial palmar branch of the radial artery
3. common palmar digital arteries – arise from the superficial palmar arch
a. each receives the corresponding palmar metacarpal artery then divides into
a pair of proper palmar digital arteries
V.
Nerves given off in the hand
A. median nerve – C6, 7 and 8
1. palmar cutaneous branch - pierces the antebrachial fascia distal to the wrist
and divides into medial and lateral branches (C6, 7, & 8)
2. recurrent muscular branch - supplies the following muscles of thenar
eminence except the deep head of the short flexor
a. abductor pollicis brevis
b. opponens pollicis
c. flexor pollicis brevis
3. common palmar digital nerves – sensory to lateral 3 ½ digits and palm
a. 1st common palmar digital nerve –divides into three proper palmar
digital nerves: two to the thumb, one to index finger, one to 1st lumbricale
b. 2nd common palmar digital nerve – sends a twig to the 2nd lumbricale and
at the web between the index and middle fingers, splits into proper palmar
digital nerves
c. 3rd common palmar digital nerve – forms proper palmar digital nerves
for the adjacent sides of the middle and ring fingers
B. ulnar nerve – C8 and T1
1. palmar branch – terminal portion of the ulnar nerve under cover of the
palmaris brevis muscle and has the following branches
a. superficial branch – supplies the palmaris brevis and skin over the
hypothenar eminence
(1) divides into digital branches – supplying sensory to the adjacent sides
of the ring and little fingers plus the ulnar side of the latter
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b. deep branch
(1) passes between the abductor digiti minimi and flexor digiti minimi
muscles accompanied by the deep branch of the ulnar artery
(2) supplies motor fibers to the following
(a) 3rd and 4th lumbricales
(b) all of the interosseous muscles
(c) adductor pollicis
(d) deep head of the flexor pollicis brevis