Opponens Digiti Minimi Muscle
Table of Contents
Opponens Digiti Minimi Muscle Anatomy
Opponens Digiti Minimi is a muscle in the hand. It is of a triangular form and placed immediately beneath the palmaris brevis, abductor digiti minimi, and flexor digiti minimi brevis. It is one of the three hypothenar muscles that control the little finger.
Together, they make up the hypothenar eminence, which is situated between the base of the fifth digit (distally) and the wrist (proximally) on the ulnar side of the palm.
The majority of the opponens digiti minimi is between the fifth metacarpal bone and the hamate bone, a carpal bone. This muscle aids in the flexion, lateral rotation, and opposition of the little finger by working on the carpometacarpal joint. These movements, particularly the last one, are crucial for a firm hand grip.
Origin
It originates from the hook of the hamate and flexor retinaculum.
Insertion
It inserts on the medial border of the 5th metacarpal (in hand, the 3rd digit is orientation of mid-line).
Nerve supply
The deep branch of the ulnar nerve supplies the muscle.
Blood supply
The deep palmar arch of the ulnar artery supplies the muscle.
Action
It draws the 5th metacarpal anteriorly and rotates it, bringing the little finger (5th digit) into opposition with the thumb.
Function
Opponens digiti minimi act on the fifth carpometacarpal joint to cause finger flexion and lateral rotation, which help to deepen the hollow of the palm. In addition, when these actions are combined with flexion and lateral rotation at the metacarpophalangeal and interphalangeal joints, the result is the opposition of the little finger with the thumb. This happens when trying to touch your thumb and fifth digit on the palmar side of the hand.
Relations
The muscles known as the Opponens digiti minimi are situated deep to the abductor digiti minimi and flexor digiti minimi brevis. Opponens digiti mini merges with the surrounding hypothenar muscles on several occasions throughout its path, giving it a somewhat blended appearance.
Two neurovascular structures have a close connection to the Opponens digiti minimi. The ulnar artery’s deep palmar branch passes through the opponens digiti minimi directly or deeply before joining the radial artery. As it approaches the flexor tendons, the opponens digiti minimi is also punctured by the deep branch of the ulnar nerve.
Clinical relevance
The oponones digiti minimi which form part of the intrinsic muscles provide fine motor movement of the hand. This is usually seen when trying to grip round or irregular objects such as a ball.
The ulnar nerve which supplies the hypothenar muscles including opponens digiti minimi passes through the hook of hamate and pisiform bone (Guyon’s canal), compromise to the nerve at this point leads to atrophy of the ODM with a resulting weakness in moving the 5th finger. There’s also numbness, tingling, and pain in the 4th and 5th finger that comes with ulnar nerve entrapment.
Assessment
The base of the thenar eminence is palpated for atypical tenderness in order to make the assessment. Ask the patient to exert more resistance while opposing their fifth finger to their thumb to check for muscular weakness.
Exercise of Opponens digiti minimi
Opponens digiti minimi Strengthening exercises
Thumb Opposition
This is the exact action you should use to isolate and strengthen the opponens digiti minimi muscle, which opposes the little finger. The easiest method to accomplish this is to just alternate between completely extending all four fingers and then bringing your little finger and thumb together while maintaining full extension of the other three fingers. This is an activity that you can do practically anywhere: at home, at work, or even on the tube.
You can counter the movement with the fingers of your other hand to increase resistance. Another option for adding resistance is to hold something slightly malleable, like a stress ball, in your hands. Every day, try performing this exercise five times in a row.
Opponens digiti minimi Stretching Exercise
Little Finger Stretch
Exercises that stretch the opponens digiti minimi and adjacent muscles can help reduce stiffness and increase flexibility. Here is a basic opponens digiti minimi stretching exercise:
To begin a finger stretch, extend your arm in front of you with your palm facing away. Feeling a stretch in the little finger’s base and palm, use your other hand to carefully bring it back towards your body. Stretch for 15 to 30 seconds, keeping your breathing slow and steady. On each hand, perform the stretch a few times.
FAQs
Deep
Within the hand lies a hypothenar muscle called the opponens digiti minimi. In relation to the other hypothenar muscles, it is located deep.
The fleshy pad of the hand on the little finger side (hypothenar eminence) may become painful if the abductor, flexor, and opponens digiti minimi muscles of the little finger are overused.
The most medial of the hypothenar muscles is the abductor digiti minimi, which is located superficial to the opponens digiti minimi muscle and along the ulnar border of the flexor digiti minimi brevis. The hypothenar eminence is made up of these three muscles together.
Thumb Opposition Exercise
The easiest method to do this is to just alternate between completely extending all four fingers and then bringing your little finger and thumb together while maintaining full extension of the other three fingers. This is an activity that you can do practically anywhere: at home, at work, or even on the tube.
References
- BSc, A. R. (2023, November 3). Opponens digiti minimi muscle of hand. Kenhub. https://www.kenhub.com/en/library/anatomy/opponens-digiti-minimi-muscle
- Thakkar, D. (2023, April 28). Opponens Digiti Minimi Muscle Origin, Insertion, Function, Exercise. Samarpan Physiotherapy Clinic. https://samarpanphysioclinic.com/opponens-digiti-minimi-muscle/
- Opponens digiti minimi muscle of hand. (2022, November 12). In Wikipedia. https://en.wikipedia.org/wiki/Opponens_digiti_minimi_muscle_of_hand
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