Dominic Stone
Ulnar deviation is the tilting of the hand and wrist toward the little finger and ulna. This movement is made possible by the flexor carpi ulnaris and extensor carpi ulnaris muscles, which work together to cancel out flexion and extension, resulting in a balanced adduction (ulnar deviation) of the hand at the wrist. The flexor carpi ulnaris is the most medial flexor muscle in the forearm's superficial compartment, while the extensor carpi ulnaris is a fusiform muscle in the posterior forearm. These muscles are essential for various activities, such as hammering, throwing, and making a power grip.
| Characteristics | Values |
|---|---|
| Definition | Ulnar deviation is the tilting of the hand and wrist toward the pinky and ulna |
| Muscles Involved | Flexor Carpi Ulnaris, Extensor Carpi Ulnaris |
| Function | The muscles work together to cancel the flexion and extension, pulling toward the ulna |
| Blood Supply | Branches of the radial recurrent and posterior interosseous arteries |
| Innervation | Ulnar nerve |
| Joint Involvement | Radiocarpal joint, Midcarpal joint |
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What You'll Learn
Flexor carpi ulnaris
The flexor carpi ulnaris (FCU) is a muscle of the forearm that flexes and adducts at the wrist joint. It is the most medial flexor muscle in the superficial compartment of the forearm. The FCU is the only muscle in the anterior compartment that is fully innervated by the ulnar nerve. The ulnar nerve enters the forearm between the two heads of the FCU.
The FCU has two heads: a humeral head and an ulnar head. The humeral head originates from the medial epicondyle of the humerus via the common flexor tendon. The ulnar head originates from the medial margin of the olecranon of the ulna and the upper two-thirds of the dorsal border of the ulna by an aponeurosis. The FCU inserts onto the pisiform, hook of the hamate, and base of the fifth metacarpal. The FCU flexes and adducts at the wrist joint, allowing the hand to move sideways as well as flexing it.
The FCU is involved in ulnar deviation, which is the tilting of the hand and wrist toward the little finger and ulna. It works together with the extensor carpi ulnaris to cancel the flexion and extension and instead pull toward the ulna. The FCU can be palpated by locating the bony landmarks associated with the muscle, including the medial epicondyle, the olecranon process, and the pisiform bone.
The FCU is a vital muscle in wrist procedures such as wrist and hand tendon transfers and cubital tunnel release. It is also used as a surgical landmark for exposing the ulnar shaft in certain procedures. The FCU can be strengthened by exercises that resist its flexion, such as wrist rollers and wrist curls with dumbbells.
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Extensor carpi ulnaris
The extensor carpi ulnaris (ECU) is a skeletal muscle located on the ulnar side of the forearm. It is a fusiform muscle in the posterior forearm, spanning between the elbow and the base of the little finger. It is the most medial muscle of the posterior forearm.
The extensor carpi ulnaris is a key contributor to the extension and adduction of the wrist, playing a crucial role in various activities involving these movements. It extends the wrist, but when acting alone, inclines the hand toward the ulnar side. The muscle is innervated by the posterior interosseous nerve (C7 and C8), a branch of the deep division of the radial nerve.
The extensor carpi ulnaris is susceptible to injuries, particularly in athletes who engage in activities requiring forceful and repetitive wrist movements, such as gripping, throwing, or racket sports. Tennis elbow is a common injury associated with the extensor carpi ulnaris, occurring due to repetitive stress on the tendon. Symptoms of an injury include pain when shaking hands or squeezing/gripping an object, with the pain intensifying during wrist movements.
The extensor carpi ulnaris works in synergy with the flexor carpi ulnaris to produce ulnar deviation, which is the tilting of the hand and wrist toward the pinky finger and ulna. This muscle also works together with the extensor carpi radialis brevis and extensor carpi radialis longus to contribute to a balanced extension of the wrist without deviating the hand in the transverse plane.
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Ulnar deviation tilts the hand and wrist toward the little finger
Ulnar deviation is the tilting of the hand and wrist toward the little finger (also known as the "pinky" finger). This movement is made possible by the wrist, which is a series of small joints that connect the radius and ulna—the two bones in the forearm—to the carpals in the hand. The intersection of the distal end of the radius and the proximal row of carpals is called the radiocarpal joint, which allows the hand and wrist to move up and down, as well as side to side.
The muscles responsible for ulnar deviation are the flexor carpi ulnaris and the extensor carpi ulnaris. These muscles work together to cancel the flexion and extension of the wrist, instead pulling the hand and wrist towards the ulna (the bone in the forearm on the pinky finger side). The flexor carpi ulnaris is the most medial flexor muscle in the superficial compartment of the forearm. It can adduct and flex the wrist simultaneously, and it is the only muscle in the anterior compartment that is fully innervated by the ulnar nerve. The extensor carpi ulnaris, on the other hand, is a fusiform muscle in the posterior forearm, spanning between the elbow and base of the little finger. It belongs to the same muscle group as the flexor carpi ulnaris and contributes to the stability of the distal radioulnar joint.
The ulnar deviation movement is important for various activities such as hammering, throwing, golfing, and swinging a baseball bat. It is also necessary for making a strong grip, such as when clenching a fist or performing a tennis backhand. In addition to these functional movements, ulnar deviation can be used in physical therapy and assessment. For example, palpation of the flexor carpi ulnaris muscle can be achieved by asking a patient to perform ulnar deviation and wrist flexion simultaneously.
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Ulnar deviation is a balanced adduction of the hand at the wrist
Ulnar deviation is the tilting of the hand and wrist toward the little finger and ulna. This movement is made possible by the flexor carpi ulnaris and extensor carpi ulnaris muscles, which work together to cancel out flexion and extension, resulting in a balanced adduction of the hand at the wrist. This means that the hand tilts without added flexion or extension.
The flexor carpi ulnaris is the most medial flexor muscle in the superficial compartment of the forearm. It can adduct and flex the wrist simultaneously, acting in tandem with the flexor carpi radialis to flex the wrist and with the extensor carpi ulnaris to adduct the wrist. The flexor carpi ulnaris is the only muscle in the anterior compartment that is fully innervated by the ulnar nerve. It has a long linear origin from the olecranon and the posterior border of the ulna, with an additional humeral head origin from the medial epicondyle of the humerus.
The extensor carpi ulnaris, on the other hand, is a fusiform muscle in the posterior forearm, spanning between the elbow and the base of the little finger. It belongs to the group of superficial forearm extensors and participates in wrist extension. The blood supply to this muscle is provided by branches of the radial recurrent and posterior interosseous arteries, which stem from the radial and ulnar arteries, respectively. The contraction of the extensor carpi ulnaris muscle results in a combined extension and adduction of the hand, contributing to a balanced extension of the wrist.
Together, the flexor carpi ulnaris and extensor carpi ulnaris muscles enable ulnar deviation, which is essential for various activities such as hammering, throwing, golfing, and swinging a baseball bat. This movement also allows for strong clenching of the fist or making a power grip, as seen in a tennis backhand. The ulnar deviation is a complex motion that involves the coordination of multiple muscles and joints to achieve a balanced adduction of the hand at the wrist.
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Ulnar nerve innervation
The ulnar nerve is responsible for supplying motor and sensory innervation to the upper extremity. It originates from the C8-T1 nerve roots, which form the medial cord of the brachial plexus. This nerve runs down the hand, passing behind the medial epicondyle of the humerus at the elbow.
The ulnar nerve has three main branches in the forearm: the muscular branch, the palmar cutaneous branch, and the dorsal cutaneous branch. The muscular branch innervates two muscles in the anterior compartment of the forearm: the flexor carpi ulnaris and the flexor digitorum profundus (medial half). The flexor carpi ulnaris is the only muscle in the anterior compartment that is fully innervated by the ulnar nerve. It flexes and adducts the hand at the wrist joint. The flexor digitorum profundus flexes the ring and little fingers at the distal interphalangeal joint.
The palmar cutaneous branch innervates the medial half of the palm, while the dorsal cutaneous branch innervates the dorsal surface of the medial one and a half fingers, along with the associated dorsal hand area. At the wrist, the ulnar nerve travels superficially to the flexor retinaculum and enters the hand through the ulnar canal (Guyon's canal).
In the hand, the ulnar nerve provides motor innervation to several muscles, including the hypothenar muscles (opponens digiti minimi, abductor digiti minimi, and flexor digiti minimi brevis), the lumbricals, the adductor pollicis, and the flexor pollicis brevis. The superficial branch of the ulnar nerve innervates the palmaris brevis muscle, while the deep branch innervates the hypothenar muscles and other intrinsic hand muscles.
The ulnar nerve is susceptible to injury at the elbow and wrist, which can result in varying degrees of motor and sensory loss. Ulnar nerve entrapment commonly occurs at the elbow in the cubital tunnel, leading to conditions like cubital tunnel syndrome and Guyon canal syndrome.
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Frequently asked questions
Ulnar deviation is the tilting of the hand and wrist toward the little finger and ulna.
Ulnar deviation involves the flexor carpi ulnaris and extensor carpi ulnaris muscles working together.
The flexor carpi ulnaris muscle is involved in the flexion and adduction of the wrist and hand. It is the most medial flexor muscle in the superficial compartment of the forearm.
