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o

Head – form the knuckles, articulate with the proximal
phalanges, increase in diameter dorsal to palmar; pearshaped
o Neck
*collateral ligaments – dorsal to the axis of flexion
- eccentrically placed
- taut when in flexion, lax in extension

THE HAND
ANATOMY
Lecture Notes By: John Lorenz Beleno, RM, RN, MD

The Hand
- “The hand is the human being’s most exquisite organ of direct
interaction with the surrounding universe”
Terminology:
- Surfaces:
o Palmar
o Dorsal
- Borders:
o Ulnar
o Radial
- The digits are designated as:
o Thumb
o Index
o Middle/ Long
o Ring
o Small/ Little
-

distal to the carpal arch
Arrangement of the carpus is U-shaped, gutter like
Arches of the hand pass through the metacarpals
Keystone: METACARPOPHALANGEAL JOINT

•

1st metacarpal – shortest and most mobile
- Does not lie on the same plane as the others, more anterior
- Abducted and rotated
- Rotated medially through the a right angle, extensor surface is
directed laterally and not backward
- Carpometacarpal of 1st digit is shorter and stouter, for pronation
and abduction, thumb apposition
- Metatarsal head is bicondylar (radial condyle is larger than ulnar
condyle)

•
•

2nd and 3rd, relatively fixed
1st 4th and 5th relatively mobile

BONES
2 main bones:
- Metacarpals (5)
- Phalanges (3 for each finger but only 2 for the thumb)
Metacarpal Bones
- Each metacarpal is divided into 4 parts:
o Base – articulate with the distal row of carpal bones, twice
as wide as the shaft; likened to a footing or base foundation
o Shaft – convex as approach distally on the dorsal surface;
palmar surface is concave (thicker than the convex surface);
slightly concave forward, triangular in transverse section

Joints
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•
•
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Phalanges
- 4 parts
o Base
o Shaft - concave palmar surface, straight dorsal surface
o Neck
o Head/condyle – bicondylar, wider on one side than the
other
- Distal phalanx has 4 parts:
o Base
o Shaft
o Tuft
*no condyle

Metacarpophalangeal joint*
Carpometacarpal joint
Proximal interphalangeal*
Distal interphalangeal*
* joints are stabilized by collateral ligaments (on both sides) and
volar plate (palmar/ anteriorly)

Skin
•
•

Dorsal – skin is thin, loose and mobile
Palmar – skin is thicker, coarser and more vascular than the dorsal
- thin over the thenar eminence and esp
...
THENAR MUSCLES
- Located on radial side
- all three muscles arise from the flexor retinaculum and inserts on the
thumb
o ABDUCTOR POLLICIS BREVIS
o FLEXOR POLLICIS BREVIS
o OPPONENS POLLICIS
* all are innervated by median nerve
*flexor pollicis brevis – dual innervation: ulnar and median nerves
II
...
LUMBRICALES
- 4 fleshy muscles
- Origin: superficial tendons of the flexor digitorum profundus
- Insertion: radial side of the tendinous expansions of the extensor
digitorum communis (lateral extensor expansion) of the medial 4 fingers
- Action: flex metacarpophalangeal joints and extends interphalangeal joints
- Innervations:
• 1st and 2nd – median nerve
• 3rd and 4th – ulnar nerve

IV
...
DORSAL (4)
-origin: shafts between the adjacent of metacarpal
bones(1,2,3,4)
- insertion: both sides of dorsal extensor expansion
B
...
ADDUCTOR POLLICIS
- origin: palmar border of the 3rd metacarpal and capitates
- divided into two heads by radial artery
• Tranverse head (distal)
• Oblique head (proximal)
- insertion: base of the 1st phalanx of the thumb
- action: draws thumb across palm, keeps palm and thumb
approximated to each other
- should not be confused with action of opponens, which
approximates the tip of the thumb to tip of 5th finger
- innervation: ulnar nerve
VI
...
E
...

o Game keeper’s/skier’s thumb- ulnar collateral injury

NAIL BED
- 3 parts:
o Nail fold
o Germinal matrix - longitudinal growth
o Sterile matrix - thickening of nail
- Nail growth - 0
...

o Dorsal instability- volar plate injury
o Lateral instability- collateral injury
o Volar instability- central slip

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DIP jt
o
o

•

•
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Mallet finger- disruption of the terminal extensor tendon to the
distal phalanx, leads to flexion of DIP, inability to extend DIP
Jersey finger- avulsion of FDP from its insertion, could not flex
DIP, ring finger commonly affected

Ulnar neuritis
o Entrapment at Guyon’s canal
- Handle bar palsy
- Hypothenar hammer syndrome - ulnar artery
thrombosis; hook of hammate fracture
Carpal tunnel syndrome – entrapment of median nerve as it passes
through the carpal tunnel
Bowler’s thumb
o Digital nerve to the thumb esp
...
e

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