Muscles of the arm and hand- origins, insertions, actions and antagonists.

In my last post I hinted that there were probably going to be more coming, and low and behold, the very next chapter we study a lot more. . .not surprisingly. I for one am swamped with homework, so I'm not going to stress about mastering them, as much as just trying to get a general idea of their location and names for now. (This will be a great resource for myself and others to check back on when needed though.)

Unfortunately, even if you know the general location, you need to know the jargon too. So later I will get into some terminology which will make all of this click.

Thankfully most muscles at least hint at their use with their name. For instance, if it starts with "extensor", it is a muscle that extends a joint, not flexes one. Which means in other words, that it brings it away from the fetal position. . . into the anatomical position.

Whereas, if the muscle is a flexor it is bringing the body into the fetal position. Closing the joints. On the arm, the flexors are all found on one side of the arm, and the extensors on the other. How you remember which is which is to think of the side of your arm that is free of hair, those are flexors. (Free of hair=flexors)

Also, if there are two synergistic muscles (that work together) and are close but one is longer, one is shorter, they include in their name longus, for long, or brevis, for short, or abbreviated.

Another clue as to where a muscle is has to do with the word carpi (which is pertaining to the wrist area), or the word Digit (which means pertaining to the fingers) or the word Pollicis (which means pertaining to the thumb) or palm which simply refers to the palm of your hand.

So given those hints, you can pretty much take an educated guess at what these muscles do, and where they are. So don't get overwhelmed, this is more for reference, or to help others copy and paste easier.

Extensor Carpi Radialis Longus

Action: extends and abducts hand
Origin: lateral supracondylar ridge of humerus
Insertion: 2nd metacarpal
Antagonist: extends and abducts hand

 Extensor Carpi Radialis Brevis
Action: Extends and abducts hand at wrist
Origin: lateral supracondylar ridge
Insertion: third metacarpal 
Antagonist: Flexor carpi ulnaris

Extensor Carpi ulnaris
Action: extends and adducts hand
Origin: lateral epicondyle of humerus
Insertion: 5th metacarpal
Antagonist: Extensor carpi radialis brevis muscle, Extensor carpi radialis longus muscle


Flexor Carpi Ulnaris
Action: flexes and adducts hand at wrist
Origin: Medial epicondyle of humerus
Insertion: pisiform, hook of hamate and base of 5th metacarpal
Antagonist: Extensor carpi radialis brevis muscle, Extensor carpi radialis longus muscle

Flexor Carpi Radialis
Action: Flexes and abducts wrist
Origin: Common flexor origin of medial epicondyle of humerus
Insertion: Bases of 2nd and 3rd metacarpals via groove in trapezium and slip to scaphoid
Antagonist: Abductor pollicis longus, Flexor digitorum superficialis and profundus, Flexor pollicis longus.

Extensor Digitorum
Action: Extends all joints of fingers.
Origin: Lateral epicondyle of humerus
Insertion: Extensor expansions of medial four digits

Antagonist: Extends medial four digits at metacarpophalangeal joints; Extends hand at wrist joint

Getting into the upper arm first, which is adding to my post dealing with the shoulders and trunk here, we have the many arm muscles like:

coracobrachialis
origin= tip of coracoid process of scapula
 insertion= middle third of medial surface of humerus

action= helps flex and adduct arm and resists dislocation of shoulder
Antagonist=Posterior Deltoid, Latissimus dorsi, Teres major, and the long head of the Triceps brachii.

Brachialis
Action: flexion of elbow joint
Origin: distal anterior humerus
Insertion: ulnar tuberosity & coronoid process of ulna
Antagonist: Triceps brachii


Anconeus
Action: Weak extensor of elbow. Moves (abducts) ulna in pronation
Origin: Smooth surface at lower extremity of posterior aspect of lateral epicondyle of humerus
Insertion: Lateral side of olecranon
Antagonist: Biceps brachii, brachialis, brachioradialis

Extensor Indicis
Action: Extends all joints of index finger
Origin: Lower posterior shaft of ulna (below extensor pollicis longus) and adjacent interosseous membrane
Insertion: Extensor expansion of index finger (tendon lies on ulnar side of extensor digitorum tendon)
Antagonist: It's complicated. (See http://thewellnessdigest.com/extensor-indicis-anatomy-origin-insertion-action/)



Palmaris Longus
Action: Flexes wrist and tenses palmar aponeurosis
Origin: Common flexor origin of medial epicondyle of humerus
Insertion: Flexor retinaculum and palmar aponeurosis
Antagonist:  extensor carpi radialis brevis, the extensor carpi radialis longus and the extensor carpi ulnaris.

Flexor Digitorum Superficialis
Action: Flexes proximal interphalangeal joints and secondarily metacarpophalangeal joints and wrist
Origin: Humeral head: common flexor origin of medial epicondyle humerus, medial ligament of elbow. Ulnar head: medial border of coronoid process and fibrous arch. Radial head: whole length of anterior oblique line
Insertion: Tendons split to insert onto sides of middle phalanges of medial four fingers
Antagonist: Flexor carpi radialis and ulnaris, Palmaris longus

Flexor Digitorum Profundus

Action: Flexes the second trough the fifth fingers at the distal interphalangeal joints, then secondarily flexes proximal interphalangeal and metacarpophalangeal joints and wrist
Origin: Medial olecranon, upper three quarters of anterior and medial surface of ulna as far round as subcutaneous border and narrow strip of interosseous membrane
Insertion: Distal phalanges of medial four fingers. Tendon to index finger separates early
Antagonist: Extensor digitorum muscle

Pronator Teres
Action: Pronates forearm and flexes elbow
Origin: Humeral head: medial epicondyle, medial supracondylar ridge and medial intermuscular septum. Ulnar head: medial border of coronoid process
Insertion: Just posterior to most prominent part of lateral convexity of radius
Antagonist: Supinator, biceps brachii, brachioradialis


Pronator Quadratus
Action: Pronates forearm and maintains ulna and radius opposed
Origin: Lower quarter of anteromedial shaft of ulna
Insertion: Lower quarter of anterolateral shaft of radius and some interosseous membrane
Antagonist: Supinator muscle

Abductor Pollicis Longus
Action: Abducts and extends thumb at carpometacarpal joint
Origin: Upper posterior surface of ulna and middle third of posterior surface of radius and interosseous membrane between
Insertion: Over tendons of radial extensors and brachioradialis to base of 1st metacarpal and trapezium
Antagonist: Adductor pollicis muscle








Adductor Pollicis Brevis
Action: Abducts thumb at metacarpophalangeal & carpometacarpal joints
Origin: Tubercle of scaphoid & flexor retinaculum
Insertion: Radial sesamoid of proximal phalanx of thumb & tendon of extensor pollicis longus
Antagonist: Adductor pollicis muscle

Flexor Pollicis Brevis
Action (all heads): flexes thumb
Origin:  trapezium, flexor retinaculum
Insertion: Insertion: proximal phalanx of pollex
Antagonist: Extensor pollicis longus and brevis

Opponens Pollicis
 Action: abducts thumbOrigin: trapezium, flexor retinaculum
Insertion: Insertion: proximal phalanx of thumb 

Antagonist: Opponens Digiti Minimi, Palmaris Brevis, Flexor Digiti Minimi, Abductor Digiti Minimi.

Flexor Pollicis Longus
Action: Flexes distal phalanx of thumb
Origin: Anterior surface of radius below anterior oblique line and adjacent interosseous membrane
Insertion: Base of distal phalanx of thumb
Antagonist: Extensor pollicis longus muscle, Extensor pollicis brevis muscle

Extensor Pollicis Longus 
Action: Extends interphalangeal and metacarpophalangeal joints of thumb
Origin: Middle third of posterior ulna (below abductor pollicis longus) and adjacent interosseous membrane
Insertion: Base of distal phalanx of thumb via Lister's tubercle (dorsal tubercle of radius).
Antagonist: Flexor pollicis longus muscle, Flexor pollicis brevis muscle

Extensor Pollicis Brevis
Action: Extends metacarpophalangeal joint of thumb
Origin: Lower third of posterior shaft of radius and adjacent interosseous membrane
Insertion: Over tendons of radial extensors and brachioradialis to base of proximal phalanx of thumb
Antagonist: Flexor pollicis longus muscle, Flexor pollicis brevis muscle

Lumbricals of the Hand
Action: Extends PIP and DIP joint.
Origin: FDP tendon
Insertion: Radial lateral band of the extensor expansion (tendon)
Antagonist: Flexor Digitorum Profundus

Palmar Interossei
Action: Adduct to axis of middle finger. Flex metacarpophalangeal joint while extending interphalangeal joints
Origin: Anteriorshafts of 2, 4, 5 metacarpals (unipennate)
Insertion: Proximal phalanges and dorsal extensor expansion on ulnar side of index and radial side of ring and little fingers and to ulnar sesamoid of thumb
Antagonist: Dorsal interossei

Dorsal Interossei
Action: Abduct from axis of middle finger. Flex metacarpophalangeal joint while extending interphalangeal joints
Origin: Bipennate from inner aspects of shafts of all metacarpals
Insertion: Proximal phalanges and dorsal extensor expansion on radial side of index and middle fingers and ulnar side of middle and ring fingers
Antagonist: Palmar interossei

A group of three muscles of the palm that control the motion of the little finger (a digit) are called the Hyposthenia Eminence. The three muscles of the Hypothenar Eminence are:

Abductor digiti minimi
Flexor digiti minimi brevis
Opponens digiti minimi

 Flexor Digiti Minimi Brevis

Action: Flexes metacarpophalangeal joint of little finger
Origin: Flexor retinaculum and hook of hamate
Insertion: Ulnar side of base of proximal phalanx of little finger

Antagonist: Extensor digiti minimi muscle

Abductor Digit Minimi
Action: Abducts little finger at metacarpophalangeal joint
Origin: Pisiform bone, pisohamate ligament and flexor retinaculum
Insertion: Ulnar side of base of proximal phalanx of little finger and extensor expansion
Antagonist: Flexor digiti minimi brevis muscle

Opponens Digiti Minimi
Action: Opposes (flexes and laterally rotates) carpometacarpal and metacarpophalangeal joints of little finger
Origin: Flexor retinaculum and hook of hamate
Insertion: Ulnar border of shaft of 5th metacarpal
Antagonist: Abductor Pollicis Brevis, Flexor Pollicis Brevis, Adductor Pollicis, Opponens Pollicis

And that's all folks. . .for the hand and arm anyways.