GENERAL INFORMATION
The extensor digiti minimi is a slender muscle located in the posterior compartment of the forearm. It is essential to extend the little finger and assist in wrist extension. This muscle is vital for precise movements of the pinky finger, contributing to grip and hand dexterity.
ORIGIN
The extensor digiti minimi originates from:
- Lateral Epicondyle of the Humerus: A common origin point for many of the forearm’s extensor muscles. It allows them to extend their little finger and assist in wrist movements.
INSERTION POINT
The extensor digiti minimi inserts into:
- Extensor Expansion of the Fifth Finger: It inserts into the dorsal expansion of the pinky finger. It enables the full extension of the finger.
MAJOR ARTERIES
It receives its blood supply from:
- Posterior Interosseous Artery: Provides oxygenated blood to the extensor muscles of the forearm, including the extensor digiti minimi.
- Radial Artery: Supplies blood to the radial side of the forearm and the wrist extensors.
NEURAL INNERVATION
The extensor digiti minimi is innervated by:
- Posterior Interosseous Nerve: A branch of the radial nerve provides motor control over the extension of the little finger. It also assists in wrist extension.
TRIGGER POINT
Trigger points in the extensor digiti minimi can develop from repetitive use or strain, particularly from actions involving frequent pinky finger extension. This can result in pain along the back of the hand and forearm, limiting finger and wrist movement.
CONCENTRIC FUNCTION
The concentric function of the extensor digiti minimi involves movements such as:
- Extension of the Little Finger: This enables the full extension of the pinky finger. It assists in movements like spreading the fingers or releasing objects.
- Wrist Extension: Assists in extending the wrist, providing additional support during gripping, pushing, or lifting tasks.
ECCENTRIC FUNCTION
The extensor digiti minimi plays an essential role in controlling movements through eccentric contractions:
- Flexion Control of the Little Finger: Eccentrically controls the flexion of the pinky finger, helping to return the finger to a relaxed position after extension smoothly.
- Wrist Flexion Control: Slows down the flexion of the wrist, maintaining control during the relaxation phase of wrist movements.
ISOMETRIC FUNCTION
The extensor digiti minimi engages isometrically to stabilise the little finger and wrist during static activities:
- Finger Extension Stability: Maintains the pinky finger’s extension during tasks requiring the finger to stay extended, such as playing musical instruments or typing.
- Wrist Stabilisation: Helps stabilise the wrist during isometric tasks that require the hand to remain steady, such as holding or carrying objects.
RELATED MUSCLES SCIENTIFIC NAMES
- Extensor Digitorum: Works alongside the extensor digiti minimi to extend the other fingers and the wrist. It provides balance and coordination during finger extension.
- Extensor Carpi Ulnaris: Assists in wrist extension and ulnar deviation. It’s working with the extensor digiti minimi to control wrist and finger movements.
- Flexor Digitorum Profundus: Acts as an antagonist by flexing the fingers, opposing the extensor digiti minimi during finger flexion.
- Lumbricals: Help flex the metacarpophalangeal joints while extending the interphalangeal joints. It works with this muscle to control finger movement.
ANTAGONIST
- Flexor Digiti Minimi Brevis: Opposes the action of the extensor Digi Minimi by flexing the little finger. Also, balance finger extension with flexion during gripping tasks.
- Flexor Carpi Ulnaris: Acts as an antagonist by flexing and ulnar deviating the wrist, counteracting the extension provided by the muscle.
- Flexor Digitorum Superficialis: Flexes the fingers and opposes the extension of the pinky finger. It helps balance hand movements during gripping and releasing actions.
COMMON INJURIES
- Lateral Epicondylitis (Tennis Elbow): An overuse injury can affect the extensor digiti minimi due to repetitive wrist and finger extension. It leads to pain and inflammation near the lateral epicondyle.
- Extensor Tendonitis: Inflammation of the tendons, particularly those responsible for extending the little finger. It may caused by repetitive strain, resulting in pain along the back of the hand and forearm.
- Trigger Finger: This condition can affect the flexor tendons but also influence the function of the muscle, leading to difficulty in extending or flexing the pinky finger smoothly.
- Radial Nerve Palsy: A condition where injury or compression of the radial nerve results in weakness or paralysis of the extensor muscles. It affects the extensor digiti minimi and leads to difficulty extending the little finger.
EXERCISES
- Wrist Extensions: Strengthens the extensor muscles of the forearm, including this muscle, by lifting the wrist upward against resistance. It improves wrist and finger extension.
- Finger Extensions with Resistance Band: Targets the extensor digiti minimi by extending the little finger against resistance. Enhancing strength and coordination in the pinky.
- Reverse Wrist Curls: Engages the extensor muscles by curling the wrist upward with light resistance. It helps to build endurance and strength in the forearm.
- Grip Squeeze Release: Focuses on the eccentric control of the extensor digiti minimi by squeezing and extending the fingers. It improves finger flexibility and control.
- Thumb and Finger Extensions: Strengthens the extensor muscles by extending each finger, including the pinky, with or without resistance, improving finger dexterity.
STRETCHES
- Wrist Extensor Stretch: This is performed by extending the arm and pulling the fingers downward with the opposite hand, stretching the extensor muscles, including the extensor digiti minimi.
- Finger Stretch: Gently stretch the little finger by pulling it backwards, improving flexibility in the muscle and reducing tension.
- Forearm Stretch: It involves extending the wrist and pulling the hand downward, stretching the muscles in the forearm that control finger and wrist extension.
- Pinky Stretch: Targets explicitly the extensor digiti minimi by gently extending the pinky finger, relieving tightness and improving mobility.
- Wrist Flexion Stretch: Stretches the wrist and forearm by bending the wrist and pulling it inward with the opposite hand, reducing tightness in the extensor tendons.