Flexor Pulley System of the Fingers
By : Malak AlsammanDefinition
The flexor pulley system of the hand is a complex structure that co-ordinates flexion of the digits.
It consists of:
• Long flexor tendon (Flexor digitorum profundus [FDP],Flexor digitorum superficialis [FDS], Flexor pollicis longus [FPL]) and their associated synovial sheathes .
• Annular pulleys : 5 associated with each finger …except the thumb which has 2 associated with it .
• Cruciate pulleys : 3 associated with each finger …except the thumb which has instead:
Oblique pulley : 1 associated with the thumb .
It consists of:
• Long flexor tendon (Flexor digitorum profundus [FDP],Flexor digitorum superficialis [FDS], Flexor pollicis longus [FPL]) and their associated synovial sheathes .
• Annular pulleys : 5 associated with each finger …except the thumb which has 2 associated with it .
• Cruciate pulleys : 3 associated with each finger …except the thumb which has instead:
Oblique pulley : 1 associated with the thumb .
Functions of Flexors Pulley System
• The main function of the flexor pulley system is to hold the flexor tendons against the phalanges.
• preventing them from pulling away and bowstringing.
• This allows efficient flexion of the individual digits by the long flexor muscle.
• preventing them from pulling away and bowstringing.
• This allows efficient flexion of the individual digits by the long flexor muscle.
Annular Pulleys
They are band of tissue or thickened parts of fibrous sheath (over the (synovial)tendon sheath of finger)
Briefly they are ligaments that hold the tendon sheaths in place.
In the medial four fingers they are 5 pulleys (A1 , A2 , A3, A4, A5).
• A1 : it is over the level of the metacarpophalangeal joint.
• A2 : it is over the proximal two_third of the proximal phalanx.
• A3 :it is over the proximal interphalangeal joint .
• A4 :it is over the middle of the middle phalanx .
• A5 :it is over the distal interphalangeal joint .
Notes :
• The A1 pulley is the most frequently involved ligament in trigger finger.
• A2 and A4 are most important in preventing bowstringing of the flexor tendons and they are also the strongest.
• The A2 and A4 are the major pulleys of the system (they are the only pulleys that attach directly to the bone) and are most prone to injury CUZ they take the most load.
• The A1, A3, and A5 pulleys are more flexible and attach to the volar plate ( it is a ligament that connects two phalanges together).
Briefly they are ligaments that hold the tendon sheaths in place.
In the medial four fingers they are 5 pulleys (A1 , A2 , A3, A4, A5).
• A1 : it is over the level of the metacarpophalangeal joint.
• A2 : it is over the proximal two_third of the proximal phalanx.
• A3 :it is over the proximal interphalangeal joint .
• A4 :it is over the middle of the middle phalanx .
• A5 :it is over the distal interphalangeal joint .
Notes :
• The A1 pulley is the most frequently involved ligament in trigger finger.
• A2 and A4 are most important in preventing bowstringing of the flexor tendons and they are also the strongest.
• The A2 and A4 are the major pulleys of the system (they are the only pulleys that attach directly to the bone) and are most prone to injury CUZ they take the most load.
• The A1, A3, and A5 pulleys are more flexible and attach to the volar plate ( it is a ligament that connects two phalanges together).
Cruciate pulleys
They are additional crossing fibres between the components of the Annular Pulley System.
The functions of cruciate pulleys are to provide the ability to approximation annular pulleys during flexion ….also to keep flexor sheaths safe …and to prevent these sheaths expansion during the movement of the fingers .
• First cruciate pulley (C1): It is located between A2 and A3.
• Second Cruciate Pulley (C2): It is located between A3 and A4.
• Third Cruciate Pulley (C3): It is located between A4 and A5.
The functions of cruciate pulleys are to provide the ability to approximation annular pulleys during flexion ….also to keep flexor sheaths safe …and to prevent these sheaths expansion during the movement of the fingers .
• First cruciate pulley (C1): It is located between A2 and A3.
• Second Cruciate Pulley (C2): It is located between A3 and A4.
• Third Cruciate Pulley (C3): It is located between A4 and A5.
The Thumb
The pulleys of the thumb are 3
2 annular … 1 oblique
• A1 – It is over metacarpophalangeal joint.
• Oblique – It is over the proximal half of proximal phalanx.
• A2 – It is over the distal half of proximal phalanx.
2 annular … 1 oblique
• A1 – It is over metacarpophalangeal joint.
• Oblique – It is over the proximal half of proximal phalanx.
• A2 – It is over the distal half of proximal phalanx.
Clinical points - Trigger Finger
Also known as trigger thumb or "stenosing tenosynovitis"
is a condition in which the finger or thumb lock when in flexion, preventing a return to extension.
• Sometimes the flexor tendon may swell and form a bump near the the pulley at the base of your finger A1
• When you bend your finger the swollen area on the tendon may cause catching or triggering sensation as it initially gets hung on the pulley then slips underneath it….
• If not treated the tendon may swell enough until it can not pass through the pulley
• That will cause your finger to stuck in bent (flexion) position.
The Symptoms of Trigger Finger
• A tender lump on your palm at the base of your finger
• A catching or locking sensation when you move your finger
• Pain when you bend or straighten your finger
• A catching or locking sensation when you move your finger
• Pain when you bend or straighten your finger
The Causes of Trigger Finger
The causes of trigger finger are not known but there are few conditions that can increase the risks for it like :
• Diabetes
• Rheumatoid arthritis (it is a chronic inflammatory disorder where your immune system attacks the healthy cells that lining your joints )
• Gout (it is a common form of inflammatory arthritis that can cause a lot of pain )
• Repeated injuries
• Repetitive hand gripping
• Diabetes
• Rheumatoid arthritis (it is a chronic inflammatory disorder where your immune system attacks the healthy cells that lining your joints )
• Gout (it is a common form of inflammatory arthritis that can cause a lot of pain )
• Repeated injuries
• Repetitive hand gripping
Trigger Finger treatment
• Rest your hand and avoid activities that could make it worst
• Anti-inflammatory medications could help or a corticosteroid injection to reduce the swelling
• You may also need to wear a finger splint to keep your finger straight
• If non-surgical treatment hasn't worked I am sorry to tell you that you may need a surgical procedure (we will cut the pulley to free the tendon )
• Anti-inflammatory medications could help or a corticosteroid injection to reduce the swelling
• You may also need to wear a finger splint to keep your finger straight
• If non-surgical treatment hasn't worked I am sorry to tell you that you may need a surgical procedure (we will cut the pulley to free the tendon )
Bowstring phenomenon
• Bowstringing is a rare hand injury that involves finger trigger movements (it’s a multiple pulley injury).
• It is occur when the pulleys that located in the middle of the fingers ruptured like A2 or A4
• Bowstringing can result from excessive external stress on the fingertip that causes one or more of the essential flexor tendon pulley to rupture. This external stress result from putting an excess weight on a pulley,
It can also occur when deep cut to hand or finger sever apulley
• This results is inefficient flexion of the finger, reducing its range of motion
Notes
• Bowstring can be obvious only after a rupture in A2 , A3 , A4 pulleys
• It is often occur with climbers CUZ climbing increases the load on A2 pulley almost 30 plus times ,it also increases the load on A4 pulley about 4 times .
• The treatment of pulley injury depends on the type of pulley injury and the grade of pulley injury that you have
So if you had a partial ligament tear (sprain)
You would have to rest your finger or motion exercises or sometimes in the worst states you may need to use a splint …then you can transition to use a thermoplastic pulley ring
But if you had a complete tear (rupture) like bowstring ….I think it is necessary to get a surgery …
• It is occur when the pulleys that located in the middle of the fingers ruptured like A2 or A4
• Bowstringing can result from excessive external stress on the fingertip that causes one or more of the essential flexor tendon pulley to rupture. This external stress result from putting an excess weight on a pulley,
It can also occur when deep cut to hand or finger sever apulley
• This results is inefficient flexion of the finger, reducing its range of motion
Notes
• Bowstring can be obvious only after a rupture in A2 , A3 , A4 pulleys
• It is often occur with climbers CUZ climbing increases the load on A2 pulley almost 30 plus times ,it also increases the load on A4 pulley about 4 times .
• The treatment of pulley injury depends on the type of pulley injury and the grade of pulley injury that you have
So if you had a partial ligament tear (sprain)
You would have to rest your finger or motion exercises or sometimes in the worst states you may need to use a splint …then you can transition to use a thermoplastic pulley ring
But if you had a complete tear (rupture) like bowstring ….I think it is necessary to get a surgery …
References
Hand Pulleys , physiopedia ,https://www.physio-pedia.com/Hand_Pulleys
The Flexor Pulley System of the Hand - Annular - Cruciate , TeachMeAnatomy https://teachmeanatomy.info/upper-limb/misc/flexor-system-hand/
Location of A1 – A5 pulleys From Neumann, D. A. (2002). Kinesiology of the Musculoskeletal System. St. Louis: Mosby.
Injury to the flexor pulleys From Neumann, D. A. (2002). Kinesiology of the Musculoskeletal System. St. Louis: Mosby.
The long flexor tendons of the fingers , TeachMeAnatomy http://teachmeseries.com/
The annular and cruciate ligaments of the fingers , TeachMeAnatomy https://teachmeanatomy.info/wp-content/uploads/Flexor-Pulley-System-of-Fingers-1024x1024.jpg
The flexor pulley system of the thumb is formed by the A1, oblique and A2 pulleys , TeachMeAnatomy https://teachmeanatomy.info/wp-content/uploads/Flexor-Pulley-System-of-Thumb-1024x1024.jpg
Flexor Pulley System - Hand - Orthobullets
https://www.orthobullets.com/hand/6004/flexor-
pulley-system
Flexor pulley injury - Back to activity sport and spinal https://backtoactive.com.au/flexion-pulley-injury/
Climbing Finger Pulley Injury: Splinting and Rehabilitation https://www.unionpt.com/climbing-finger-pulley-injury/
Schematic image of the finger pulley system ,ultrasonography https://www.e-ultrasonography.org/journal/Figure.php?xn=usg-15051.xml&id=f13-usg-15051&number=113&p_name=0216_113
Injuries to flexor tendon pulley system of the hand / SonoSkills https://www.sonoskills.com/en/article/injuries-to-the-flexor-tendon-pulley-system-of-the-hand/
Trigger finger release | healthdirect https://www.healthdirect.gov.au/surgery/trigger-finger-release
Trigger finger - Symptoms and causes , Mayo Clinic https://www.mayoclinic.org/diseases-conditions/trigger-finger/symptoms-causes/syc-20365100
The Flexor Pulley System of the Hand - Annular - Cruciate , TeachMeAnatomy https://teachmeanatomy.info/upper-limb/misc/flexor-system-hand/
Location of A1 – A5 pulleys From Neumann, D. A. (2002). Kinesiology of the Musculoskeletal System. St. Louis: Mosby.
Injury to the flexor pulleys From Neumann, D. A. (2002). Kinesiology of the Musculoskeletal System. St. Louis: Mosby.
The long flexor tendons of the fingers , TeachMeAnatomy http://teachmeseries.com/
The annular and cruciate ligaments of the fingers , TeachMeAnatomy https://teachmeanatomy.info/wp-content/uploads/Flexor-Pulley-System-of-Fingers-1024x1024.jpg
The flexor pulley system of the thumb is formed by the A1, oblique and A2 pulleys , TeachMeAnatomy https://teachmeanatomy.info/wp-content/uploads/Flexor-Pulley-System-of-Thumb-1024x1024.jpg
Flexor Pulley System - Hand - Orthobullets
https://www.orthobullets.com/hand/6004/flexor-
pulley-system
Flexor pulley injury - Back to activity sport and spinal https://backtoactive.com.au/flexion-pulley-injury/
Climbing Finger Pulley Injury: Splinting and Rehabilitation https://www.unionpt.com/climbing-finger-pulley-injury/
Schematic image of the finger pulley system ,ultrasonography https://www.e-ultrasonography.org/journal/Figure.php?xn=usg-15051.xml&id=f13-usg-15051&number=113&p_name=0216_113
Injuries to flexor tendon pulley system of the hand / SonoSkills https://www.sonoskills.com/en/article/injuries-to-the-flexor-tendon-pulley-system-of-the-hand/
Trigger finger release | healthdirect https://www.healthdirect.gov.au/surgery/trigger-finger-release
Trigger finger - Symptoms and causes , Mayo Clinic https://www.mayoclinic.org/diseases-conditions/trigger-finger/symptoms-causes/syc-20365100
