Extends And Abducts The Hand

9.9B: Muscles of the Wrist and Mitt

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Muscles in the forearm move the wrists, and hand motility is caused past both forearm and hand muscles.

Learning Objectives

Outline the movements of the wrist and hand muscles

Central Points

Movements of the wrist include abduction, adduction, extension, and flexion.
Movements of the fingers and pollex include abduction, adduction, extension, and flexion.
Rotation of the thumb and pinkie allows for opposition.
Muscles of the forearm that act on the wrist and hand are referred to as extrinsic muscles, or external to the hand.
Muscles within the wrist and hand are referred to as intrinsic muscles.

Key Terms

Palmaris Longus: A long muscle originating near the elbow and passing through into the wrist, attaching to the base of the hand.
Flexor Digitorum Superficialis: A fundamental muscle decision-making wrist and finger flex.
Flexor Carpi Ulnaris: A long musculus originating near the elbow and passing through into the wrist, attaching to one of the carpal bones in the wrist.
Flexor Carpi Radialis: A long muscle originating most the elbow and passing through into the wrist, attaching to the base of the digits (fingers).
Flexor Digitorum Profundus: A long muscle originating most the elbow and passing through into the wrist, flexing the wrist and the well-nigh distant regions of the fingers.
Pronator Teres: A rectangular musculus that pronates the forearm.
Flexor Pollicis Longus: A long, deep muscle responsible for flexing the thumb.
Pronator quadratus: A square-shaped muscle located adjacent to the wrist.

Muscles associated with the wrist include those of the forearm and hand that move the wrist and digits. The wrist and hand showroom a remarkable range of motion, fundamental for grasping and interaction with objects. These muscles can generate highly variable force, from the strong grip required when lifting a heavy object to the frail movements required to write.

This diagram of the forearm depicts muscles including the flexor digitorum profundus, flexor pollicus longus, biceps, and supinator.

Muscles and tendons of the forearm and manus: The extrinsic muscles of the forearm are responsible for movement of the wrist and fingers. Often providing the more forceful movements required.

Muscles of the forearm that human activity on the wrist and manus are referred to as extrinsic muscles, or external to the hand. Those located within the hand are referred to as intrinsic.

Muscles of the Forearm

As with the upper arm, the forearm is split into inductive and posterior compartment. Each contains many more muscles than described below due to the requirement for more circuitous movements in the wrist and paw.

Inductive

The inductive compartment of the forearm is split into superficial, intermediate, and deep layers. These muscles are by and large responsible for flexing of the wrist and fingers and pronation of the forearm.

Superficial Layer

Three muscles are located in the superficial layer of the anterior compartment of the forearm.

Flexor Carpi Ulnaris: A long musculus originating well-nigh the elbow and passing through into the wrist.
- Attachments: Originates from the humerus and ulna and attaches to one of the carpal basic in the wrist.
- Actions: Flexion and adduction at the wrist.
Palmaris Longus: A long muscle originating near the elbow and passing through into the wrist.
- Attachments: Originates from the humerus and attaches to the base of the hand.
- Deportment: Flexion at the wrist.
Flexor Carpi Radialis: A long muscle originating near the elbow and passing through into the wrist.
- Attachments: Originates from the humerus and attaches to the base of the digits.
- Actions: Flexion and abduction at the wrist.
Pronator Teres: A rectangular muscle.
- Attachments: The pronator teres has two origins, one on the proximal cease of the humerus and 1 of the distal end of the ulna. Information technology attaches to the mid region of the radius.
- Deportment: Pronates the forearm.

Intermediate Layer

There is only one muscle in the intermediate layer of the anterior compartment of the forearm.

Flexor Digitorum Superficialis: Lying below the superficial region, the flexor digitorum superficialis is a key muscle controlling wrist and finger flex.
- Attachments: Originates from the humerus and the radius, splitting into four tendons at the wrist which travel through the carpal tunnel and attach to the fingers.
- Actions: Flexes fingers and wrist.

Deep Layer

There are iii muscles in the deep layer of the inductive compartment of the forearm.

Flexor Digitorum Profundus: A long musculus originating near the elbow and passing through into the wrist, lying adjacent to the flexor pollicis longus.
- Attachments: Originates from the ulna, splitting into four tendons at the wrist which travel through the carpal tunnel and attach distally to the fingers.
- Actions: Flexes the wrist and the near distal regions of the fingers.
Flexor Pollicis Longus: A long muscle originating nigh the elbow and passing through into the wrist, lying adjacent to the flexor digitorum profundus.
- Attachments: Originates from the radius and attaches to the base of the thumb.
- Actions: Flexes the pollex.
Pronator quadratus: A square-shaped muscle located adjacent to the wrist.
- Attachments: Originates from the ulna and attaches to the radius.
- Actions: Pronates the forearm.

Posterior

The posterior compartment of the forearm is split up into superficial and deep regions. The muscles are by and large responsible for extension of the wrist and fingers.

Superficial Layer

The superficial layer of the posterior forearm contains seven muscles.

Aconeus: The aconeus is located in the superficial region of the forearm posterior compartment and is composite with the triceps brachii.
- Attachments: Originates from the humerus and attaches to the ulna.
- Deportment: Moves the ulna during pronation and extends the forearm at the elbow.
Brachioradialis: The brachioradialis is located in the superficial region of the forearm posterior compartment.
- Attachments: Originates from the humerus and attaches to the distal cease of the radius.
- Deportment: Flexes the forearm at the elbow.
Extensor Carpi Radialis Longus and Brevis: A pair of muscles located on the side of the forearm, allowing them to command extension and abduction of the wrist.
- Attachments: Both originate from the humerus and attach to the base of the hand.
- Actions: Extend and abduct the wrist.
Extensor Digitorum: The extensor digitorum is the main extensor of the fingers.
- Attachments: Originates from the humerus, splitting into four tendons at the wrist which travel through the carpal tunnel and adhere to the digits.
- Actions: Extends fingers.
Extensor Digiti Minimi: Originates from the extensor digitorum. In some people, these muscles cannot be individually defined.
- Attachments: Originates from the humerus and attaches to the little finger.
- Deportment: Extends the little finger, and contributes to extension at the wrist.
Extensor Carpi Ulnaris: Located on the other side of the forearm to the extensor carpi radialis longus and brevis, it performs a similar role.
- Attachments: Originates from the humerus and attaches to the base of the hand.
- Actions: Extension and adduction of wrist.

Deep Layer

In that location are 4 muscles in the deep layer of the posterior compartment of the forearm.

Supinator: The supinator is located in the deep region of the forearm posterior compartment.
- Attachments: The supinator has ii heads: ane originates from the humerus, the other from the ulna. Together they attach to the radius.
- Deportment: Supinates the forearm.
Abductor Pollicis Longus: The abductor pollicis longus is situated immediately distal to the supinator muscle.
- Attachments: Originates from the radius and ulna attaching to the base of the pollex.
- Actions: Abducts the thumb.
Extensor Pollicis Brevis: The extensor pollicis brevis is located below the abductor pollicis longus.
- Attachments: Originates from radius and attaches to the base of the thumb.
- Actions: Extends the pollex.
Extensor Indicis Proprius: This muscle allows the index finger to be independent of the other fingers during extension.
- Attachments: Originates from the ulna and attaches to the alphabetize finger.
- Actions: Extends the index finger.

Muscles of the Mitt

The extrinsic muscles of the paw are responsible for the larger calibration, stronger movements of the wrist and paw. The intrinsic muscles produce finer, more controlled movements and play important roles in maintaining grip.

Thenar Muscles

This diagram depicts the muscles of the hand, including palmaris brevis, abductor digiti quinti, opponens pollicis, abductor pollicis brevis, flexor pollicis brevis, adductor pollicis trans, and flexor digitorum sublimis.

Muscles of the mitt

The thenar muscles are three short muscles located at the base of the thumb and responsible for its fine movement.

Opponens Pollicis: The opponens pollicis is the largest and deepest-lying of the thenar muscles.
- Attachments: Originates from the wrist and attaches to the thumb.
- Actions: Rotates the thumb towards the palm, producing opposition and improving grip.
Abductor Pollicis Brevis : Located anteriorly to the opponens pollicis and proximal to the flexor pollicis brevis.
- Attachments: Originates from the wrist and attaches to the thumb.
- Deportment: Abducts the thumb.
Flexor Pollicis Brevis: The smallest and most distal of the thenar muscles.
- Attachments: Originates from the wrist and attaches to the thumb.
- Actions: Flexes the pollex.

Hypothenar Muscles

The hypothenar muscles are located at the base of the pinkie. Their naming, office, and organization are like to those of the thenar muscles.

Opponens Digiti Minimi: The opponens digit minimi is the deepest-lying of the hypothenar muscles.
- Attachments: Originates from the wrist and attaches to the pinkie.
- Actions: Rotates little finger towards the palm, producing opposition and improving grip.
Abductor Digiti Minimi: The most superficial of the hypothenar muscles.
- Attachments: Originates from the wrist and attaches to the little finger.
- Actions: Abducts the little finger.
Flexor Digiti Minimi Brevis: Located laterally to the digiti minimi.
- Attachments: Originates from the wrist and attaches to the pinkie.
- Actions: Flexes little finger.

Lumbricals

These are iv lumbricals in the hand, each associated with an individual finger.

Attachments: Originates from a tendon of attached to the flexor digitorum profundus of the forearm, each attaching to an individual finger
Actions: Flexes and extends the fingers.

Interossei

The interossei muscles are located between the fingers; they can exist separate into two groups.

Dorsal Interossei: Located superficially on the dorsal side of the hand, there are iv dorsal interossei muscles.
- Attachments: Originates from the base of the finger, each attaching subsequently the showtime finger joint.
- Actions: Abducts the fingers.
Palmar Interossei: Located on the anterior side of the hand, in that location are iii palmar interossei, with the index finger controlled by the extensor indicis proprius.
- Attachments: Originates from the base of the finger, each attaching after the first finger joint.
- Actions: Adducts the fingers.

Other Muscles

One other musculus in the paw is not easily grouped with the above categories.

Palmaris Brevis: The palmaris brevis is a small superficial muscle institute in the palm.
- Attachments: Originates from the fascia of the palm and attaches to the dermis.
- Deportment: Wrinkles the skin and deepens the curvature of the palm improving grip.