ANATOMY OF THE HAND
Jeshika Luckrajh | jeshika.luckrajh@uct.ac.za
Rm 3.02, Anatomy Building, Medical Campus
Learning objectives
• Describe the bones, ligaments and joints of the hand
• Describe the origin, insertion, innervation and action of the intrinsic muscles of the hand
• Describe the neurovascular supply of the hand
Introduction
• Region of the upper limb distal to the wrist joint
• 3 parts: wrist (carpus), the metacarpus, and the digits (5 fingers
including the thumb)
• Resting position: little finger is the most flexed and index finger is least
flexed
• Anatomical position: all fingers are extended
• Has 2 surfaces: anterior (palm) and dorsal surface (dorsum)
• Movements are defined with respect to the long axis of the middle
finger
• Movements of thumb are defined at right angles to the movements of
the other digits
Osteology
3 groups of bones in the hand: 8 carpals, 5 metacarpals,
phalanges
• 8 carpals arranged in 2 rows:
• Distal row (L→M): trapezium (4 sided), trapezoid, capitate,
hamate (has a hook)
• Proximal row (L→M): scaphoid (boat-shaped) lunate (crescent
shape), triquetrum (3 sides), pisiform (pea shaped)
• Carpal bones don’t lie in a flat plane- they form an arch
• Flexor retinaculum attaches to the sides of the arch ( pisiform &
hook of hamate
Osteology
3 groups of bones in the hand: 8 carpals, 5 metacarpals,
phalanges
• Metacarpals
• Each is related to 1 digit
• Consists of a base, shaft (body), head
• Bases articulate with carpal bones and with the bases of the
adjacent metacarpal bases
• Heads for knuckles, articulate with proximal phalanges
• Phalanges
• Thumb has 2: proximal and distal
• Other digits have 3: proximal, middle and distal
• Each phalanx has a base, shaft, head
• Base articulates with the head of each metacarpal
• Head of distal phalanx is flattened into a tuberosity
Joints of the hand
1. Wrist Joint
• Synovial joint between the distal radius, articular disc of ulna, scaphoid, lunate, triquetrum
• Allows abduction, adduction, flexion and extension of the hand
• Capsule of the wrist joint is reinforced by the palmar radiocarpal, palmar ulnocarpal, dorsal radiocarpal ligaments
as well as radial and ulnar collateral ligaments
Joints of the hand
2. Carpal Joints
• Synovial joint between carpal bones reinforced by many
ligaments
• Limited movement at intercarpal joints
3. Carpometacarpal Joints
• 5 joints between metacarpals and distal row of carpal bones
• Saddle joint between metacarpal 1 and trapezium= wide range
of movement of thumb (flexion, extension, abduction,
adduction, rotation, and circumduction)
• The rest of carpometacarpal joints (metacarpals 2-5) only allow
gliding movements
Joints of the hand
4. Metacarpophalangeal Joints
• Between heads of metacarpals and proximal phalanges
• Condylar joints: allow flexion, extensions, abduction, adduction,
circumduction, limited rotation
• Reinforced by palmar and medial and lateral collateral ligaments
• Deep transverse metacarpal ligaments (3) connect the palmar
ligaments of the metacarpophalangeal joints of the fingers to
each other
5. Interphalangeal Joints
• Hinge joints: allows flexion and extension
• Reinforced by collateral ligaments and palmar ligaments
Carpal Tunnel
• Formed anteriorly at the wrist by a deep arch formed by the carpal bones and flexor retinaculum
• Flexor retinaculum: thick connective tissue ligament that bridges the space between the medial and lateral sides of the
base of the arch and converts the carpal arch into the carpal tunnel
• Base of the carpal arch is formed medially by the pisiform and the hook of hamate and laterally by the tubercles of
scaphoid and trapezium
• Median nerve and tendons of the flexor digitorum profundus, flexor digitorum superficialis, and flexor pollicis longus
pass through the carpal tunnel
Palmar Aponeurosis
• Triangular sheet of deep fascia which covers the palm
• Continuous with the palmaris longus tendon (if absent, it anchors to the
flexor retinaculum)
• From the apex, fibres radiate to extensions at the base of each digit
• Nerves, vessels and long flexor tendons lie deep to palmar aponeurosis
Fibrous digital sheaths
• After exiting the carpal tunnel, tendons of the flexor digitorum
superficialis and profundus muscles cross the palm and enter fibrous
sheaths on the palmar aspect of the digits
• Begin anterior to the metacarpophalangeal joints, extend to distal
phalanges
• Formed by fibrous ligaments attached posteriorly to the margins of
the phalanges and to the palmar ligaments associated with the
metacarpophalangeal and interphalangeal joints
• Holds tendons to the bony plane and prevent the tendons from
bowing when the digits are flexed.
Extensor hoods
• The tendons of the extensor digitorum and extensor pollicis longus muscles pass onto the dorsal aspect of the digits and
expand over the proximal phalanges to form complex “ extensor hoods ” or “ dorsal digital expansions ”
• The tendons of the extensor digiti minimi, extensor indicis, and extensor pollicis brevis muscles join these hoods.
• Each extensor hood is triangular
• Many of the intrinsic muscles of the hand insert into the free margin of the hood on each side, therefore are responsible
for complex delicate movements of the digits that could not be accomplished with the long flexor and extensor tendons
alone.
Muscles
• Extrinsic: forearm muscle tendons which extend into the hand
• Intrinsic: within the palm of the hand, adjusting the hand during
grip, carry out fine skill movements
• 20 muscles divided into 4 groups
• Thenar (3) + Thumb adductor (1)
• Hypothenar (4)
• Interossei: dorsal (4) and palmar(4)
• Lumbricals (4)
Thenar Group
Muscle Origin Insertion Innervation Action
Abductor pollicis brevis Scaphoid, trapezium, flexor retinaculum Proximal phalanx & extensor hood of thumb Median nerve Abduct thumb at metacarpophalangeal joint
Flexor pollicis brevis Trapezium, flexor retinaculum Proximal phalanx of thumb Median nerve Flex thumb at metacarpophalangeal joint
Opponens pollicis Trapezium, flexor retinaculum Metacarpal 1 Median nerve Medial rotation of the thumb
Adductor pollicis Transverse head: metacarpal 3 Proximal phalanx, extensor hood of the Ulnar nerve Adducts thumb
Oblique head: capitate, metacarpals 2 & 3 thumb
Hypothenar Group
Muscle Origin Insertion Innervation Action
Palmaris brevis Palmar aponeurosis, flexor retinaculum Skin (medial margin of hand) Ulnar nerve Improves grip
Opponens digiti minimi Hamate, flexor retinaculum Metacarpal 5 Ulnar nerve Lateral rotation of the 5th digit
Abductor digiti minimi Pisiform, tendon of flexor carpi ulnaris Proximal phalanx, extensor hood of 5th digit Ulnar nerve Abducts 5th digit
Flexor digiti minimi brevis Hamate, flexor retinaculum Proximal phalanx of 5th digit Ulnar nerve Flexes 5th digit
Interossei
Muscle Origin Insertion Innervation Action
Dorsal interossei (four Adjacent sides of metacarpals Extensor hood and base of proximal phalanges Deep branch of Abduction of index, middle, and
muscles) of index, middle, and ring fingers ulnar nerve ring fingers at the
metacarpophalangeal joints
Palmar interossei (three Sides of metacarpals Extensor hoods of the thumb, index, ring, and Deep branch of Adduction of the thumb, index,
or four muscles) little fingers and the proximal phalanx of ulnar nerve ring, and little fingers at the
thumb metacarpophalangeal joints
Lumbricals
Origin Insertion Innervation Action
Tendons of flexor digitorum profundus Extensor hoods of index, ring, middle, and little fingers Medial two by the deep branch of the Flex metacarpophalangeal joints while
ulnar nerve; lateral two by digital extending interphalangeal joints
branches of the median nerve
Arterial supply
• By radial and ulnar arteries, which form two interconnected
vascular arches (superficial and deep) in the palm
• Radial artery contributes to the supply of the thumb and the
lateral side of the index finger
• Remaining digits and the medial side of the index finger are
supplied mainly by the ulnar artery
Ulnar artery & superficial palmar arch
• Lies between palmaris brevis and flexor retinaculum
• Crosses laterally across palm to form the superficial palmar arch
• This arch is superficial to flexor tendons, deep to palmar aponeurosis
• Laterally communicates with palmar branch of radial artery
• Ulnar artery gives off deep palmar branch which supplies hypothenar
muscles
• Superficial palmar arch gives rise to common palmar digital arteries
which eventually lead to proper palmar digital arteries which supply
the digits
Radial artery & deep palmar arch
• Enters hand between 2 heads of 1st dorsal interossei,
adductor pollicis to enter the deep plane of the palm
• Crosses medially forming the deep palmar arch
• Lies between metacarpals and flexor tendons
• Medially communicates with deep palmar branch of
ulnar artery
• Branches:
• Dorsum: dorsal carpal a., first dorsal metacarpal a.
• Princeps pollicis a., radialis indicis a.
• From arch: 3 palmar metacarpal a., 3 perforating a.
Veins
• Superficial veins drain into dorsal venous network which
drain into the cephalic or basilic veins
• Cephalic vein originates from the lateral side of the dorsal
venous network and passes over the anatomical snuffbox
into the forearm.
• Basilic vein originates from the medial side of the dorsal
venous network and passes into the dorsomedial aspect of
the forearm.
Nerves
• The hand is supplied by the ulnar, median, and radial nerves
• All three nerves contribute to cutaneous or general sensory
innervation
• The ulnar nerve innervates all intrinsic muscles of the hand
except for the three thenar muscles and the two lateral
lumbricals, which are innervated by the median nerve.
• The radial nerve only innervates skin on the dorsolateral side
of the hand
Nerves
• The median nerve is the most important sensory
nerve in the hand because it innervates skin on the
thumb, index and middle fingers, and lateral side
of the ring finger
• Motor supply to thenar muscles and lateral 2
lumbricals
