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The hand
Anatomy Lecture
Faculty of Medicine – Ain Shams University

The Hand
Bony skeleton of the hand
1)

Carpal bones: 8 bones arranged in
two rows:
• Proximal row from lateral to medial:
 Scaphoid, lunate, triquetrum, and
pisiform
...

2) Metacarpals: 5 bones
...


Carpals:
They can summarized in the following words from lateral to medial:
‫سميحة الزم تلعب بولنج – تكسب تخسر كله هلس‬
Proximal row:
Scaphoid,
Lunate,
Triquetrum,
Pisiform
Distal row:
Trapezium,
Trapezoid,
Capitate
Hamate

Muscles of the hand:
Muscles of the hand are arranged into 3 groups:
• Intrinsic muscles of the thumb(laterally)
...

• Intrinsic muscles of the fingers(in the middle)
...

Flexor pollicis brevis
...


They form the thenar eminence
...


2) Intrinsic muscles of the little finger:
•
•
•

Abductor digiti minimi
...

Opponens digiti minimi (deep)
...


 Actions: according to names
...


•

Palmaris brevis: subcutaneous
muscle superficial to the
hupothenar eminence
...


3) Intrinsic muscles of the fingers:
a) The 4 lumbricals:
• They originate from the tendons of flexor
digitorum profundus muscle
...

• 1st and 2nd: unipennate
...

 Actions: they act with interossei muscles to
put the hand in the writing position
(flexion of the metacarpophalangeal joints
+ extension of the interphalangeal joint
...

• One muscle for each finger EXCEPT middle
finger, which has no palmar interossei
...

 Don’t forget writing position
...
B: the axis of the hand is the middle
finger, so adduction or abduction of fingers
is according to the movement toward or
away from the middle finger
...

• Middle finger has 2 dorsal interossei
...

 Don’t forget writing position
...

N
...

• Each expansion receives a tendon of
extensor digitorum, a lumbrical muscle &
tendons of 1 or 2 interosseii muscles
...

• Muscles attached to extensor expansion of
each finger (see the dorsum of the hand)

Nerve supply of intrinsic muscles of the hand:
All muscles of the hand are supplied by ULNAR nerve EXCEPT:
• Thenar muscles: (abductor pollicis brevis, flexor pollicis brevis, and
opponens pollicis)
...

• They are supplied by median nerve
...


Deep fascia of the palm of the hand:
1) Flexor retinaculum:
• Definition:
 It is a thickened fibrous band of deep fascia which crosses in front of the
carpus and converts its anterior concavity into the carpal tunnel
...

 Laterally: It splits into 2 laminae; a superficial one & a deep one, for the
tendon of flexor carpi radialis
...

 Superiorly: It is continuous with the deep fascia of the forearm
 Inferiorly: It is continuous with palmar aponeurosis
...


• Structures related to flexor retinaculum:
Structures deep to the retinaculum
- Median nerve
...

- Ulnar and radial bursae
...

- Ulnar nerve and vessels
...

- Tendon of palmaris longus muscle
...
B: Tendon of flexor carpi radialis passes through the retinaculum
...

• Attachments:
 Apex: is continuous with the tendon of
palmaris longus muscle
...
Each slip is attached to the base
of the proximal phalanx and and the
fibrous flexor sheath of the
corresponding finger
...

• Function:
 It protects the underlying nerves, vessels,
and tendons
...


Clinical anatomy (Dupuytren’s contracture):
It is shortening of the palmar aponeurosis as
a result of its fibrosis, which is more severe
at the medial side leading to progressive
flexion of the 4th and 5th fingers
...

Attachments:
On either side: attached to sides of the phalanges
...

 Inferiorly: attached to the base of the distal phalanx
...


Synovial sheaths of the palm of the hand:
•
•
•
•

Common flexor synovial sheath (ulnar bursa)
...

Digital synovial sheaths (synovial sheaths of flexor tendons of fingers)
...


Comparison between ulnar bursa and radial bursa:
Ulnar bursa
Radial bursa
- It is a common synovial
- It is he synovial sheath that
sheath which is invaginated
surrounds the tendon of flexor
from its radial side by the
pollicis longus muscle
...

Proximal They start 1 - 1 ½ inches above the flexor retinaculum
...

the little finger as far as their
Distal
insertion (into the base of the
distal phalanx)
...


Fascial compartments and spaces of the hand:
The thenar compartment
Lateral to the lateral
Site
palmar septum
...

Three hypothenar muscles (abductor
digiti minimi, flexor digiti minimi, and
opponence digiti minimi)
...

- The fascia covering the
Posterior
interossei muscles
...

- The adductor pollicis muscle
...

- The intermediate palmar
septum
...

• Attachments:
 Medially: it is attached to triquetrum and pisiform bones
...

• Function:
 It keeps the extensor tendons in place, preventing their displacement
during muscles contraction
...

- 2nd: tendons of extensor carpi radialis
longus and brevis
...

- 4th: four tendons of extensor digitorum,
tendon of extensor indicis, posterior
interosseous nerve, and anterior
interosseous artery
...

- 6th: tendon of extensor carpi ulnaris
(between head of ulna and its styloid
process)
...

- Dorsal cutaneous branch of ulnar nerve
(most medial)
...


2) The anatomical snuff box:
• Definition:
 It is the depression on the radial side
of the wrist which appears on full
extension of thumb
...

 Medially: 3rd compartment of the
extensor retinaculum (tendon of
extensor pollicis longus muscle)
...

• Contents:
 Deep close to the floor: radial artery
...


Wrist joint
Type:
• Ellipsoid synovial joint
...

The fibrous capsule:
• Above, it is attached to the distal ends of
radius and ulna + the articular disc of
inferior radio-ulnar joint
...

Synovial membrane:
It lines the fibrous capsule
...

• Radial collateral ligament (styloid process
of radius + scaphoid)
...


N
...

- See before the structures
related to each
retinaculum
...

- Palmaris longus
...

Extension
- Extensor carpi radialis longus
...

- Extensor carpi ulnaris
...

- Extensor carpi radialis longus
...

Adduction - Flexor carpi ulnaris
...


Other joints of the hand:
Intercarpal:
• Plane synovial joints
...

Intermetacarpal joints:
• Plane synovial joints
...

Interphalangeal joints:
• Hinge synovial joints

Movements of the metacarpophalangeal (knuckle) joints:
Movement
Main muscles performing it
Flexion
- Flexor digitorum superficialis
...

- Lumbricals with interossei
...

- Extensor digiti inimi
...

Abduction - Dorsal interossei (DAP)
...




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