GENERAL INFORMATION
The abductor pollicis brevis is a short muscle located in the palm. It plays a key role in the abduction and opposition movements of the thumb, allowing for grasping as well as pinching actions.
ORIGIN
This muscle originates from the flexor retinaculum, which is a band of connective tissue in the wrist, as well as the tubercle of the scaphoid bone and the trapezium bone.
INSERTION POINT
The abductor pollicis brevis inserts onto the radial side of the base of the proximal phalanx of the thumb.
MAJOR ARTERIES
This muscle receives its blood supply from branches of the radial artery, such as the princeps pollicis artery. These arteries provide oxygenated blood to the muscle for its proper function.
NEURAL INNERVATION
The recurrent branch of the median nerve innervates the abductor pollicis brevis. The median nerve arises from the brachial plexus and provides motor innervation to the muscle.
TRIGGER POINT
Trigger points in this muscle may develop due to muscle tension or overuse. These trigger points can cause localised pain, tenderness, or referred pain patterns in the hand as well as the thumb.
CONCENTRIC FUNCTION
The concentric function of this muscle involves the contraction of the muscle fibres, resulting in the abduction and opposition of the thumb. This contraction allows for movements that involve spreading the thumb away from the hand and bringing it towards the fingers.
ECCENTRIC FUNCTION
The eccentric function of this muscle occurs when the muscle fibres lengthen under tension. This function assists in controlled retraction and return of the thumb to its resting position.
ISOMETRIC FUNCTION
The isometric function of the abductor pollicis brevis involves contracting and generating tension without changing the length of the muscle. This function aids in stabilising the thumb during activities that require a static hold or resistance.
RELATED MUSCLE SCIENTIFIC NAMES
Its scientific name is also known as the abductor pollicis brevis:
- Musculus abductor pollicis brevis: This muscle is primarily responsible for the abduction of the thumb, moving it away from the hand’s midline and enabling opposition movements.
ANTAGONIST MUSCLES
The antagonist muscles to the abductor pollicis brevis include the adductor muscles located on the medial side of the hand. These muscles work in opposition to this muscle, allowing for coordinated movements of the thumb and hand.
COMMON INJURIES
Common injuries associated with this muscle may include:
- Tendinitis: Inflammation or irritation of the tendon of the abductor aollicis brevis due to repetitive use or strain.
- Muscle Strain: Overexertion or sudden traumatic events can lead to strain or tears in the Abductor Pollicis Brevis muscle.
EXERCISES
Exercises that target and strengthen the abductor pollicis brevis include:
- Thumb abduction exercises: Use resistance bands to spread the thumb away from the hand.
- Opposition exercises: Touch the thumb to each fingertip to enhance skill and strength.
- Pinch grip exercises: Squeeze small objects between the thumb and fingers to improve grip strength.
STRETCHES
Stretching the abductor pollicis brevis can help improve flexibility and prevent stiffness. Some stretches that target this muscle include:
- Thumb adduction stretch: Gently pull the thumb towards the palm with the opposite hand.
- Thumb extension stretch: Extend the thumb away from the hand and hold.
- Wrist flexion stretches: Flex the wrist while keeping the fingers straight to stretch the muscles in the thumb and hand.