Muscles of the arm, forearm and hand Flashcards
coracobrachialis
- is normally pierced by the musculocutaneous nerve in the middle portion of the muscle belly
Action: Adducts and flexes GH joint
Origin: Coracoid process
insertion: Middle medial shaft of humerus
Innervation: Musculocutaneous nerve
blood supply: brachial artery
brachialis
Action: Elbow flexion
origin: distal humerus
insertion: proximal ulna
Innervation: Musculocutaneous nerve
blood Supply: radial artery
brachioradialis
lateral to the flexor carpi radialis
superficial to pronator teres
looks like the muscles of the forearm, but it doesn’t actually cross the wrist
Action:Flexes elbow
Origin:Lateral distal humerus
Insertion:Styloid process of radius
innervation:Radial nerve
Blood Supply: radial artery
biceps Brachii
This muscle has two heads.
- this is just medial to the Brachialis
Action: Flexes GH joint, elbow flexion, supination of forearm
Origin:
long head: Supraglenoid tubercle
short head: coracoid process of the scapula
insertion: Radial tuberosity and bicipital aponeurosis
Innervation: Musculocutaneous nerve
Blood Supply: brachial artery
extensor carpi radialis longus
- On the radial side of the forearm
- deep to the brachioradialis
- has a longer tendon and is just superficial and lateral to the extensor carpi radialis brevis
Action:Extends wrist, abducts hand
origin: Lateral distal humerus
insertion: Base of 2nd metacarpal
innervation: Radial nerve
blood supply: radial artery
extensor carpi radialis brevis
- On the radial side of the forearm
- deep to the brachioradialis
- has a shorter tendon and is just deep to the extensor carpi radialis longus
action: Extends wrist, abducts hand
origin: Lateral epicondyle of humerus
insertion: Base of metacarpal III
Innervation: Radial nerve
blood supply: radial artery
extensor carpi ulnaris
most medial muscle of the posterior superficial forearm muslces
action: Extends wrist, adducts hand
origin: Lateral epicondyle of humerus
insertion: Base of 5th metacarpal
Innervation: Radial nerve
blood supply: ulnar artery
extensor digitorum
Note that there is only one extensor digitorum muscle, so there is no other descriptor in the name
action: Extends wrist, 2nd–5th MP joints, PIP joints, & DIP joints
origin: Lateral epicondyle of humerus
insertion: Distal & middle phalanges of digits 2–5
Innervation: Radial nerve
extensor digiti minimi
just medial to the extensor digitorum and is lateral to the extensor carpi ulnaris
allows you to you can extend your 5th digit much farther while the others are flexed
action: Extends wrist, MP, and PIP joints of finger 5
origin: Lateral epicondyle of humerus
insertion: Proximal phalanx of finger 5
Innervation: Radial nerve
extensor indicis
- deep to the extensor digitorum
- medial to the extensor pollicis longus
action: Extends MP, PIP, and DIP joints of finger 2
insertion: second digit
innervation: radial nerve
supinator
- this is a deep muscle in the posterior arm
- is deep and more difficult to find, but it can be observed running from the lateral epicondyle to the shaft of the radius.
- this is just distal to the elbow
action: Supinates forearm
origin: Lateral epicondyle of humerus & proximal ulna
insertion: Anterolateral radius
Innervation: Radial nerve
blood supply: radial artery
abductor pollicis longus
- a deep muscle in the forearm
- this is on the lateral side and wraps around the tendons of the extensor carpi radialis longus and brevis
- this is lateral to the extensor pollicis brevis
action: Abducts thumb
origin: Proximal radius and ulna
insertion: Lateral 1st metacarpal
Innervation:Radial nerve
extensor pollicis brevis
- a deep muscle of the forearm
- it’s tendon sits between the abductor pollicis longus and extensor pollicis longus tendons
- this is on the lateral side and wraps around the tendons of the extensor carpi radialis longus and brevis
- this is just medial to the abductor pollicis longus
action: Extends MP joints of thumb
origin: Posterior radius
insertion: thumb
Innervation:Radial nerve
extensor pollicis longus
- a deep muscle of the forearm
- just lateral to the extensor indicis muscle
action: Extends MP and IP joints of thumb
origin: Posterior ulna
insertion: thumb
Innervation:Radial nerve
superficial layer of the anterior forearm
pronator teres
Flexor carpi radialis
flexor carpi ulnaris
palmaris longus
pronator teres
deep to brachioradialis and flexor carpi radialis
this is more superior in the forearm
the shortest muscle originating from the medial epicondyle
Action:Pronates forearm
Origin:Medial epicondyle of humerus
Insertion:Lateral radius
innervation:Median nerve
blood supply: ulnar and radial arteries
Flexor carpi radialis
- this muscle is going to be medial to the brachioradialis
- this is lateral to the palmaris longus
- cross only the wrist joints
- inserts on the ulnar side of the wrist and assists with radial deviation (wrist abduction)
Action:Flexes wrist and abducts hand
Origin:Medial epicondyle of humerus
Insertion:Base of 2nd & 3rd metacarpals
innervation:Median nerve
blood supply: ulnar artery
palmaris longus
- this is going to be medial to the flexor carpi radialis
- this is lateral to the flexor carpi ulnaris
- a very small muscle
- not present in 10-20% of the population.
Action:Weak wrist flexor
Origin:Medial epicondyle of humerus
Insertion:Palmar aponeurosis
innervation:Median nerve
blood supply: ulnar artery
flexor carpi ulnaris
- cross only the wrist joints
- inserts on the radial side of the wrist and also assists with radial deviation (wrist abduction)
Action: Flexes wrist and adducts hand
Origin:Medial epicondyle of humerus
Insertion:Medial carpal and metacarpal bones
innervation:Ulnar nerve
Blood supply: ulnar artery
flexor digitorum superficialis (FDS)
- this is the only muscle in the intermediate layer of the anterior arm
- crosses the wrist, MCP, and PIP joints of digits 2-5 in the hand.
- Notice how this muscle splits and inserts on the middle phalanx of these digits.
- the tendons of this muscle are pierced by the tendons of flexor digitorum profundus
Action:Flexes wrist, 2nd–5th MP joints, and PIP joints
Origin:Medial epicondyle of humerus
Insertion:Middle phalanges of fingers 2–5
innervation:Median nerve
blood supply: ulnar artery
deep layer of the anterior forearm
flexor digitorum profundus (FDP)
flexor pollicis longus
pronator quadratus
flexor digitorum profundus (FDP)
- is deep to the flexor digitorum superficialis
- runs deep to the tendon of FDS through its split at the middle phalanx and continues distally
Action:Flexes wrist, 2nd–5th MP joints, PIP joints, & DIP joints
Origin:Anteromedial ulna
Insertion:Distal phalanges of fingers 2–5
innervation:
- Lateral 1⁄2 = median nerve - Medial 1⁄2 = ulnar nerve
flexor pollicis longus
- lateral to the flexor digitorum profundus
- sends its tendon across the IP joint of the first digit to insert on the distal phalanx of digit 1, the thumb
Action:Flexes MP joint of thumb, IP joint of thumb
Origin: Anterior shaft of radius
Insertion:Distal phalanx of thumb
innervation:Median nerve
pronator quadratus
- very deep on the anterior aspect of the distal forearm
- sits just anterior to the interosseous membrane
Action:Pronates forearm
Origin:Distal ulna
Insertion:Distal radius
innervation:Median Nerve
opponens pollicis muscle
- deep to flexor pollicis brevis and abductor pollicis brevis
- within the thenar eminence
action: opposition of thumb
innervation: median nerve
Blood supply: superficial palmar arch
flexor pollicis brevis
- within the thenar eminence
- medial to the abductor pollicis brevis
Action:Flexes thumb
innervation:Median nerve
blood supply: superficial palmar arch
abductor pollicis brevis
- within the thenar eminence
- lateral to the flexor pollicis brevis
Action: Abducts thumb
innervation: Median nerve
blood supply: superficial palmar arch
1/2 LOAF
this stands for what the median nerve is innervating in the hand
- the lateral 2 lumbricals
- opponens pollicis abductor pollicis brevis
- flexor pollicis brevis
Opponens digiti minimi
- this is in the hypothenar eminence
- is deep to the flexor digiti minimi and abductor digiti minimi.
Action: Opposition of finger 5
innervation: ulnar nerve
blood supply: ulnar artery
flexor digiti minimi
- this is in the hypothenar eminence
- this is medial and deep to the abductor digiti minimi
Action:Flexes finger 5
innervation: Ulnar nerve
blood supply: ulnar artery
abductor digiti minimi
- this is in the hypothenar eminence
- this is lateral and superficial to the flexor digiti minimi brevis
Action: Abducts finger 5
innervation: Ulnar nerve
blood supply: ulnar artery
adductor pollicis
- is part of the deep muscles of the hand.
- It has two heads: one runs from the thumb horizontally across the hand, while the other runs from the same origin obliquely across the palm.
- These two heads create a “7” shape. This muscle acts to adduct the thumb.
Action: adduct the thumb
innervation: ulnar nerve
blood supply: deep palmar arch
lumbricals
- attach to the flexor tendons within the hand.
- These thin muscles help you form an “L” with your 2nd-4th digits
Action: Flexes 2nd–5th MP joints and extends 2nd–5th PIP and DIP joints
innervation:
- Lateral 2 lumbricals: median nerve
- Medial 2 lumbricals: ulnar nerve
blood supply: superficial palmar arch
dorsal interossei
- can see from the dorsal aspect of the hand
- Dorsal interossei ABduct the digits DAB
- The interosseous muscle on the lateral aspect of the digit with its fibers running distally towards the midline are dorsal interossei
- middle (3rd) digit can only abduct, so it has only dorsal interossei on either side of it
Action: Abducts fingers 2–5; flexes MP joints 2–5, and extends PIP and DIP joints
innervation: Ulnar nerve
blood supply: superficial palmar arch
palmar interossei
- can see from the dorsal aspect of the hand
- Palmer interossei ADduct the digits PAD
- the interosseus muscle on the medial aspect of the digit with its fibers running proximally towards the midline are palmar interossei
Action: Adducts fingers 2–5; flexes MP joints 2–5, and extends PIP and DIP joints
innervation: Ulnar nerve
blood supply: superficial palmar arch
