Ulnar claw
Encyclopedia
A hand imitating an ulnar claw created by distal ulnar lesion or papal hand of a proximal median nerve lesion. The metacarpophalangeal joint
s of the 4th and 5th fingers are extended and the Interphalangeal joints of the same fingers are flexed.
An ulnar claw, also known as claw hand, is an abnormal hand position that develops due to a problem with the ulnar nerve
. A hand in ulnar claw position will have the 4th and 5th fingers drawn towards the back of the hand at the first knuckle
and curled towards the palm at the second and third knuckles.
Some sources refer to the ulnar claw as a "hand of benediction
". However, the term "hand of benediction" more commonly refers to a similar hand position which is caused by damage to the median nerve
and is only present when the patient is asked to make a fist.
s (MCP) and flexion
at the distal and proximal Interphalangeal (IP) joints of the 4th and 5th digits (ring and little finger) .
The clawing will become most obvious when the person is asked to straighten their fingers.
Patients exhibiting an ulnar claw are also very frequently unable to spread (abduct) or pull together (adduct) the fingers against resistance. This occurs because the ulnar nerve also innervates the palmar
and dorsal interossei
of the hand. Patients with this deficit will become increasingly easy to identify over time as the paralyzed first dorsal interosseous muscle atrophies, leaving a prominent hollowing between the thumb and forefinger.
which results in the partial or complete denervation of the medial two lumbricals of the hand
. Since the lumbricals normally flex the MCP joints
(aka the proximal knuckles), their denervation causes these joints to become extended by the newly unopposed action of the extensor muscles of the forearm (namely the extensor digitorum and the extensor digiti minimi). However, if the lesion of the ulnar nerve occurs at the level of the wrist, the innervation of the medial half of the flexor digitorum profundus muscle
(FDP), which is responsible for flexing the IP joints (the two distal joints of the fingers), is unaffected. It is the extension of the MCP joints coupled with the slight flexion of the IP joints that gives the hand the claw-like appearance.
(FDP). If the ulnar nerve lesion occurs more proximally (closer to the elbow), the flexor digitorum profundus muscle may also be denervated. As a result, flexion of the IP joints is weakened, which reduces the claw-like appearance of the hand. (Instead, the fourth and fifth fingers are simply paralyzed in their fully extended position.) This is called the "ulnar paradox" because one would normally expect a more debilitating injury to result in a more deformed appearance.
s (MCP) and flexion
at the Interphalangeal (IP) joints of the 2nd and 3rd digits (index and middle). The pathogenesis is similar to that of ulnar clawing (loss of the relevant lumbricals and unopposed action of forearm flexors and extensors), and a median claw hand will appear almost identical to an ulnar claw when the patient with a median claw is asked to make a fist.
The following signs may be used to distinguish median nerve clawing from ulnar nerve clawing clinically.
is a deformity of the hand due to thickening and fibrosis of the palmar aponeurosis and eventual contracture of the 4th and 5th digits. Presenting as a small hard nodule in the base of the ring finger, it tends to affect the ring and little finger as puckering and adherence of the palmar aponeurosis to the skin. Eventually the MCP and IP joints of the 4th and 5th digits become permanently flexed. This claw appearance can be distinguished from an ulnar claw in that the MCP is flexed in Dupuytren’s but hyperextended in ulnar nerve injuries.
(C8 - T1). The condition may arises from the limb being suddenly pulled upward. For example, Klumpke paralysis
can occur from excessive pulling of the infant's forelimb during parturition.
Metacarpophalangeal joint
The metacarpophalangeal joints are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow cavities on the proximal ends of the first phalanges, with the exception of that of the thumb, which presents more of the characters of a ginglymoid joint...
s of the 4th and 5th fingers are extended and the Interphalangeal joints of the same fingers are flexed.
An ulnar claw, also known as claw hand, is an abnormal hand position that develops due to a problem with the ulnar nerve
Ulnar nerve
In human anatomy, the ulnar nerve is a nerve which runs near the ulna bone. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest unprotected nerve in the human body , so injury is common...
. A hand in ulnar claw position will have the 4th and 5th fingers drawn towards the back of the hand at the first knuckle
Knuckle
The knuckles are the joints of the fingers and toes, which are brought into prominence when the hand is clenched and a fist is made. The word is cognate to similar words in other Germanic languages, such as the Dutch "Knokkel" or German "Knöchel" , i.e., Knöchlein, the diminutive of the German...
and curled towards the palm at the second and third knuckles.
Some sources refer to the ulnar claw as a "hand of benediction
Hand of benediction
The hand of benediction results from a severed Median nerve at the level of the elbow or upper arm. The ability to flex the digits 2–3 at the metacarpophalangeal joints, proximal interphalangeal joints and distal interphalangeal joints is lost. This is due to the loss of innervation of the lateral...
". However, the term "hand of benediction" more commonly refers to a similar hand position which is caused by damage to the median nerve
Median nerve
The median nerve is a nerve in humans and other animals. It is in the upper limb. It is one of the five main nerves originating from the brachial plexus....
and is only present when the patient is asked to make a fist.
Presentation
The hand will show hyper-extension of the metacarpophalangeal jointMetacarpophalangeal joint
The metacarpophalangeal joints are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow cavities on the proximal ends of the first phalanges, with the exception of that of the thumb, which presents more of the characters of a ginglymoid joint...
s (MCP) and flexion
Flexion
In anatomy, flexion is a position that is made possible by the joint angle decreasing. The skeletal and muscular systems work together to move the joint into a "flexed" position. For example the elbow is flexed when the hand is brought closer to the shoulder...
at the distal and proximal Interphalangeal (IP) joints of the 4th and 5th digits (ring and little finger) .
The clawing will become most obvious when the person is asked to straighten their fingers.
Patients exhibiting an ulnar claw are also very frequently unable to spread (abduct) or pull together (adduct) the fingers against resistance. This occurs because the ulnar nerve also innervates the palmar
Palmar interossei muscles
The palmar interossei are small muscles in the hand that lie on the anterior aspect of the metacarpals. They are smaller than the dorsal interossei of the hand, which lie between the metacarpals.-Structure:...
and dorsal interossei
Dorsal interossei of the hand
The dorsal interossei of the hand are muscles that occupy the space between the metacarpals.-Structure:There are four dorsal interossei in each hand...
of the hand. Patients with this deficit will become increasingly easy to identify over time as the paralyzed first dorsal interosseous muscle atrophies, leaving a prominent hollowing between the thumb and forefinger.
Pathogenesis
An ulnar claw may follow an ulnar nerve lesionLesion
A lesion is any abnormality in the tissue of an organism , usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.- Types :...
which results in the partial or complete denervation of the medial two lumbricals of the hand
Lumbricals of the hand
The lumbricals are intrinsic muscles of the hand that flex the metacarpophalangeal joints and extend the interphalangeal joints.-Structure:There are four of these small, worm-like muscles on each hand. These muscles are unusual in that they do not attach to bone...
. Since the lumbricals normally flex the MCP joints
Metacarpophalangeal joint
The metacarpophalangeal joints are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow cavities on the proximal ends of the first phalanges, with the exception of that of the thumb, which presents more of the characters of a ginglymoid joint...
(aka the proximal knuckles), their denervation causes these joints to become extended by the newly unopposed action of the extensor muscles of the forearm (namely the extensor digitorum and the extensor digiti minimi). However, if the lesion of the ulnar nerve occurs at the level of the wrist, the innervation of the medial half of the flexor digitorum profundus muscle
Flexor digitorum profundus muscle
- References :...
(FDP), which is responsible for flexing the IP joints (the two distal joints of the fingers), is unaffected. It is the extension of the MCP joints coupled with the slight flexion of the IP joints that gives the hand the claw-like appearance.
Ulnar paradox
The ulnar nerve also innervates the medial half of the flexor digitorum profundus muscleFlexor digitorum profundus muscle
- References :...
(FDP). If the ulnar nerve lesion occurs more proximally (closer to the elbow), the flexor digitorum profundus muscle may also be denervated. As a result, flexion of the IP joints is weakened, which reduces the claw-like appearance of the hand. (Instead, the fourth and fifth fingers are simply paralyzed in their fully extended position.) This is called the "ulnar paradox" because one would normally expect a more debilitating injury to result in a more deformed appearance.
Median claw
Caused by median nerve lesions. The hand will show hyper-extension of the metacarpophalangeal jointMetacarpophalangeal joint
The metacarpophalangeal joints are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow cavities on the proximal ends of the first phalanges, with the exception of that of the thumb, which presents more of the characters of a ginglymoid joint...
s (MCP) and flexion
Flexion
In anatomy, flexion is a position that is made possible by the joint angle decreasing. The skeletal and muscular systems work together to move the joint into a "flexed" position. For example the elbow is flexed when the hand is brought closer to the shoulder...
at the Interphalangeal (IP) joints of the 2nd and 3rd digits (index and middle). The pathogenesis is similar to that of ulnar clawing (loss of the relevant lumbricals and unopposed action of forearm flexors and extensors), and a median claw hand will appear almost identical to an ulnar claw when the patient with a median claw is asked to make a fist.
The following signs may be used to distinguish median nerve clawing from ulnar nerve clawing clinically.
| Ulnar nerve | Median nerve |
|---|---|
| Deficit is primarily in 4th and 5th fingers | Deficit is primarily in 2nd and 3rd fingers. |
| Deficit is most prominent at rest and when the patient is asked to extend his fingers. | Deficit is most prominent when the patient is asked to make a fist. |
| Often accompanied by inability to abduct or adduct the 2nd, 3rd, 4th, and 5th finger. | Often accompanied by difficulty opposing the thumb. |
| Often accompanied by apparent atrophy of the first dorsal interosseous muscle Dorsal interossei of the hand The dorsal interossei of the hand are muscles that occupy the space between the metacarpals.-Structure:There are four dorsal interossei in each hand... of the hand |
Often accompanied by wasting of muscles of the thenar eminence Thenar eminence The thenar eminence refers to the group of muscles on the palm of the human hand at the base of the thumb... |
Dupuytren's contracture
Dupuytren's contractureDupuytren's contracture
Dupuytren's contracture , is a fixed flexion contracture of the hand where the fingers bend towards the palm and cannot be fully extended...
is a deformity of the hand due to thickening and fibrosis of the palmar aponeurosis and eventual contracture of the 4th and 5th digits. Presenting as a small hard nodule in the base of the ring finger, it tends to affect the ring and little finger as puckering and adherence of the palmar aponeurosis to the skin. Eventually the MCP and IP joints of the 4th and 5th digits become permanently flexed. This claw appearance can be distinguished from an ulnar claw in that the MCP is flexed in Dupuytren’s but hyperextended in ulnar nerve injuries.
Klumpke paralysis
A claw hand can result of injuries to the inferior brachial plexusBrachial plexus
The brachial plexus is a network of nerve fibers, running from the spine, formed by the ventral rami of the lower four cervical and first thoracic nerve roots...
(C8 - T1). The condition may arises from the limb being suddenly pulled upward. For example, Klumpke paralysis
Klumpke paralysis
Named after Augusta Déjerine-Klumpke, Klumpke's paralysis is a variety of partial palsy of the lower roots of the brachial plexus. The brachial plexus is a network of spinal nerves that originates in the back of the neck, extends through the axilla , and gives rise to nerves to the upper limb...
can occur from excessive pulling of the infant's forelimb during parturition.
External links
- http://www.wheelessonline.com/ortho/intrinsic_weakness_and_claw_hand