Muscles in The Finger
By Lily Condy, CHT, OT
Are There Muscles in your Fingers?
The quick answer is no. Each of your fingers don’t contain any muscle. All the muscles that control finger motion are located in the hand and forearm.
5 Basic Movements of the Fingers
- Flexion
- Extension
- Abduction
- Adduction
- Circumduction
Each finger can move independently of one another but coordinate to work well as a team.
Finger Phalanges
Each finger comprises three bones known as the proximal, middle, and distal phalanges (starting at the hand and moving outward). The thumb has just two bones, the proximal and distal phalanx. The closest set of knuckles are known as the metacarpal phalangeal joints (MCP), and then moving distally are the proximal interphalangeal joint (PIP) and the distal interphalangeal joint (DIP).
What is Finger Flexion?
Finger flexion is what happens when you make a fist. Flexion is the strongest movement that the fingers perform and is used during grasp and pinch. Each finger has two muscles involved in flexion; flexor digitorum profundus, which attaches to the distal phalanx, and flexor digitorum superficialis, which attaches to the middle phalanx. These long flexors originate near the elbow and run through the forearm. The lumbricals control the proximal phalanx’s flexion and are the only muscles in the body that do not attach to the bone. They originate from the flexor digitorum profundus and attach to the extensor hood.
There are no muscles in your fingers. Here are the muscles of your hand and wrist.
What is Finger Extension?
Finger extension occurs when you straighten out your hand. Extension happens when releasing an item from your grasp, pointing a finger, or pushing up from a flat surface. The muscles that control finger extension are called the extensor digitorum communialis. These muscles originate near the elbow, run through the forearm’s back, and insert onto the proximal phalanx. The central tendon continues distally and inserts at the middle phalanx, and the lateral bands insert onto the distal phalanx. This complex system acts to extend the digit fully. The extensor hood surrounds the metacarpal phalangeal joints and receives tendinous fibers from the interossei and lumbrical muscles. The lumbricals also help to extend the PIP joints.
Each finger is capable of abduction and adduction. These terms mean to move away and bring together, such as spreading your fingers apart and squeezing them back together again. These motions are controlled by palmar and dorsal interossei, which connect to the extensor hood to control movement.
Function of the Thumb
Lastly, the thumb has its own set of muscles to perform functions that make the human hand unique. There are two flexors, flexor pollicis longus and flexor pollicis brevis, two extensors, extensor pollicis longus and extensor pollicis brevis, and two abductors, abductor pollicis longus and abductor pollicis brevis. These muscles flex, extend, and abduct the thumb, respectively.
There is also a set of opponens muscles, which move the thumb out toward the small finger, allowing for a cylindrical grip around a soda can, for example. Lastly, the thumb has an adductor pollicis, which contributes to the pinching grip. Some of these muscles originate in the forearm, and some originate from within the hand. Working together, these muscles can circumduct the thumb.
With so many different muscles and systems controlling the fingers, it’s no wonder that a small injury can significantly impact function. Selecting health care professionals who specialize in hand and finger injuries is important to maximize your success!
To schedule an appointment at JOI Rehab with one of our outstanding hand therapist, please call 904-858-7045.
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Written by: Lily Condy, CHT, OT