L11: Functional anatomy of the hand and wrist Flashcards
What forms the wrist joint?
Distal radius, triangular fibrocartilage complex (TFCC), the scaphoid and lunate
Ulna not part of wrist
What type of joint is the wrist joint?
Ellipsoid type of synovial joint
Between convex surface or carpal bones and concave surface of radius and triangular fibrocartilage
What types of movement are there at the wrist?
Two axes
Flexion and extension
Abduction (radial deviation) and adduction (ulna deviation)
Circumduction–> all four movements together- move hand in a circle
What stabilises the wrist joint?
Stabilised by ligaments
Dorsal and palmar radiocarpal ligaments
Ulnar and radial collateral ligaments
What do the radiocarpal ligaments ensure?
The hand follows the hand follows the radius during pronation and supination of the forearm
What are the main muscles responsible for flexion of the wrist?
Flexor carpi ulnaris (inserts onto pisiform, hook of hamate and base of 5th metacarpal)
Flexor carpi radialis (inserts onto base of 2nd and 3rd metacarpal)
Palmaris longus (Inserts onto palmar aponeurosis)
What other muscles assist in flexion?
Flexor digitorum superficialis (Base of middle phalanx of 4 fingers)
Flexor digitorum profundus (base of distal phalanx of four fingers)
Flexor pollicis longus (base of distal phalanx of thumb)
What are the main extensors?
Extensor carpi radialis longus (dorsal surface of 2nd metacarpal bone)
Extensor carpi radialis brevis (dorsal surface of 3rd metacarpal bone)
Extensor carpi ulnaris (Base of 5th metacarpal)
What muscles assists extension?
Extensor digitorum (Extensor hood of the 4 fingers)
Extensor indicies (extensor hood of index finger, ulnar side of extensor digitorum)
Extensor digit minimi (extensor hood of little finger)
Extensor pollicis longus (distal phalanx of thumb)
Extensor pollicis brevis (proximal phalanx of thumb)
Abductor pollicis longus (radial side of base of first metacarpal)
What muscles produce ulnar deviation (adduction)?
Flexor carpi ulnaris
Extensor carpi ulnaris
What muscles produce radial deviation (abduction)?
Flexor carpi radialis
Extensor carpi radialis longus and brevis
What is the innervation to the wrist?
3 nerves that supply the hand from the radial, ulnar and median nerves
How many bones are there in the hand?
8 carpal
5 metacarpal
14 phalanges
What are the 8 carpal bones? How are they arranaged?
'Straight Line To Pinky, Here Comes The Thumb!' Proximal row -Scaphoid -Lunate -Triquetrum -Pisiform Distal row -Hamate -Capitate -Trapezoid -Trapezium
Which bones articulate with the radius?
Scaphoid and lunate
Which bones articulate with the metacarpal bones?
Distal row
Hamate, Capitate, Trapezoid and Trapezium
What is significant about the hamate bone?
Hamate has a hook on it
Forms ulna border of carpal tunnel
Radial border of Guyons canal
Attachment site for flexor retinaculum and tendon of flexor ulnaris carpi
What is unusal about the scaphoid?
Unusual blood supply- retrograde flow
Via dorsal carpal branch of the radial artery
Enters dorsal surface of scaphoid distally, supplies proximal 80% of scaphoid by retrograde flow (flow back towards the wrist)
Important to understanding why scaphoid fracture have a high rate of non-union
What do each of the metacarpal bones articulate with?
I- trapezium proximally, proximal phalanx of the thumb distally
II- trapexoid proximally, proximal phalanx of index finger distally
III- capitate proximally, proximal phalanx of middle finger distally
IV- Hamate proximally, proximal phalanx of ring finger distally
V- Hamate proximally, proximal phalanx of little finger distally
What is the structure of the metacarpal bones?
Base, shaft and head
Medial and lateral surfaces are concave (accomodate interossei muscles)
What movements are possible at the thumb?
Flexion* Extension* Radial abduction* Radial adduction Palmar abduction Palmar adduction Opposition Reposition Retropulsion Circumduction
*in coronal plane
What is flexion of the thumb?
Bending of the thumb
Bend at metacarpophalangeal joint and interphalangeal joint
What is extension of the thumb?
Returns flexed thumb to anatomical position
What is radial abduction?
Contunation of extension beyond the anatomical plane
In coronal plane
(if you were to spread your fingers out your thumb would be radially abducted)
What is opposition?
Rotatory movement of the thumb over the palm
Enables the thumb to touch the tips of the fingers
What is reposition?
Returning the thumb to the anatomical position from the position of opposition
What is palmar abduction?
Raising the thumb in the sagittal plane
Perpendicular to the palm
(perpendicular plane to radial abduction)
What is adduction?
Opposite of both palmar abduction and radial adduction
What is retropulsion?
Extending the thumb posteriorly beyond the coronal plane
What is circumduction?
Winding your thumb round in circles
What movement are possible with the fingers?
Flexion Extension Abduction Adduction Circumduction
What is the difference between the intrinsic and extrinsic muscles of the hand?
Intrinsic–> originate within the hand and insert within the hand
Extrinsic–> originate the forearm and insert within the hand
How can the intrinsic muscles of the hand be divided?
Four compartments Thenar compartment Adductor compartment (adductor pollicis) Hypothenar compartment Central compartment
What muscles are in the thenar compartment?
Form the thenar eminence
Abductor pollicis brevis
Flexor pollicis brevis
Opponens pollicis –> largest, lies deepest
What muscles are in the hypothnar compartment?
Abductor digit minimi
Flexor digiti minimi
Opponens digiti minimi–> deepest
What muscles are in the central compartment?
Lumbricals
Interossei
Palamaris Brevis
What is the origin, insertion, innervation and function of the opponens pollicis?
Largest lies deepest
O: Trapezium and flexor retinaculum
I: Lateral border of 1st metacarpal
F: Opposes thumb (by medially rotating and flexing 1st metacarpal)
Innervation: Median nerve
What is the origin, insertion, innervation and function of the abductor pollicis brevis?
O: Scaphoid, trapezium and flexor retinaculum
I: Lateral border of proximal phalanx of thumb
F: Palmar abducts the thumb
Innervation: Median nerve
What is the origin, insertion, innervation and function the flexor pollicis brevis?
O: Superficial head: trapezium and flexor retinaculum
Deep head: Trapezoid and capitate
I: Ulnar aspect of base of proximal phalanx of thumb (with adductor pollicis)
F: Flexes metacarpophalangeal joint of thumb
Innervation: SH: Median nerve
DH: Ulnar nerve
What is the origin, insertion, innervation and function of the adductor pollicis?
O: Transverse head: shaft of 3rd metacarpal
Oblique head: capitate and base of 2nd and 3rd metacarpal
I: Ulnar aspect of base of proximal phalanx
F: Adductor of the thumb both the palmar adduction and radial adduction
Innervation: Ulnar nerve
What is the origin, insertion, innervation and function of the opponens digiti minimi?
Deepest
O: Hook of hamate, flexor retinaculum
I: Ulnar margin of 5th metacarpal
F: Rotates the 5th metacarpal towards the palm, enabling opposition against the thumb
Innervation: ulnar nerve
What is the origin, insertion, innervation and function of the abductor digiti minimi?
O: Pisiform and tendon of flexor carpi ulnaris
I: Base of proximal phalanx of little finger
F: Abduct the little finger (only in coronal plane)
Innervation: Ulnar nerve
What is the origin, insertion, innervation and function of flexor digiti minimi brevis?
O: Hook of hamate and flexor retinaculum
I: Base of proximal phalanx of little finger
F: Flexion of metacarpophalangeal joint of little finger
Innervation: Ulnar nerve
What is the origin, insertion, innervation and function of palmaris brevis?
O: Palmar aponeurosis and flexor retinaculum
I: Dermis of skin on medial margin of hand
F: Wrinkles the skin of hypothenar eminence, deepens the curvature of the palm, improving grip
Innervation: Ulnar nerve
What is the function of the lumbrical muscles?
Link the flexor digitorum tendon to the extensor digitorum tendon
Contract–> flex fingers at the metacarpophalangeal joint and extend at the interphalangeal joints
What is the muscles structure of the lumbircals?
Unipennate–> muscle fibres originate on same side of tendon
–> index and middle finger
Bipennate–> muscle fibres originate on opposite sides of the tendon
–> ring finger and little finger
What is the origin, insertion, innervation and function of each of the lumbricals?
I–> FDP to index finger –> Extensor digitorum (ED) to index finger
II–> FDP to middle finger –> ED to middle finger
III–> FDP to middle and ring finger –> ED to ring finger
IV–> FDP to ring and little finger –> ED to little finger
F: Extend the interphalageal joints, flex the metacarpophalangeal joints
Innervation: I and II–> Median nerve, III and IV–> ulnar nerve
What are the interossei muscles?
Located between the metacarpal bones PADs and DABs Palmar interossei--> adduct Dorsal interossei--> abduct All innervated by the ulnar nerve
What are the dorsal interossei?
Abduct away from the midline
Bipennate muscles
Originate from own metacarpal and adjacent metacarpal bones
What is the origin, insertion, innervation and function of dorsal interossei muscles?
I–> between thumb and first finger
O: Shaft of first and second metacarpals
I: Radial aspect of base of proximal phalanx of index finger and extensor expansion
II–>
O: Shaft of 2nd and 3rd metacarpals
I: Radial surface of base of proximal phalanx of middle finger and extensor expanion
III–>
O: Shaft of 3rd and 4th metacarpals
I: Ulnar surface of base of proximal phalanx of middle finger and extensor expansion
IV–>
O: Shaft of 4th and 5th metacarpal
I: Ulnar surface of base of proximal phalanx of ring finger and extensor expansion
F: Abduction away from the midline assist in flexing the metacarpophalangeal joint and extending the interphalangeal joint
Innervation: Ulnar nerve
What are the palmar interossei? Why is there less?
Adduct towards the midline
Unipennate muscles
Only three muscles
Thumb adduction carried out adductor pollicis
Middle finger is moved side to side by DABs
What is the origin, insertion, innervation and function of the palmar interossei?
O and I: Shaft of second metacarpal–> Ulnar side of base of proximal phalanx of index finger and extensor expansion
Shaft of fourth metacarpal–> Radial side of base of proximal phalanx of ring finger and extensor expanson
Shaft of fifth metacarpal–> Radial side of base of proximal phalanx of little finger and extensor expansion
F: Adduction
Innervation: Ulnar nerve