Muscles of the forearm Flashcards
How did we classify the muscles of the forearm?
We classified them based on their relationship with various joints, their attachments and mode of action
What is the first group of forearm mucles composed of?
Those are the muscles that are attached to the radius, and are only involved in the movements of bones of the forearm
What is the second group of forearm mucles composed of?
This gorup of muscles extends to the metacarpus and produces the wrist movements
What is the third group of forearm mucles composed of?
Those are the mucles which extend to the phalanges and are responsible for finger movements
What is the main border that separates the muscles of the forearm in 2 big groups?
Those are the ulna, the radius and the interosseous membrane. They divide the muscles into 2 groups:
VENTRAL: flexors
DORSAL: extensors.
It’s the other way around in the leg.
How did we classify the extensors and the flexors?
Into 2 groups: the superficial and the deep muscles
How did we divide the msucles based on their inervations?
The ones from inervated by the:
DORSAL or the VENTRAL side of the plexus
Name all the muscles of the ventral superficial layer
(PFPFF) Pronator teres, Flexor carpi radialis, Palmaris longus, Flexor digitorum superficialis, Flexor carpi ulnaris.
Name all the muscles of the ventral deep layer
(PFF)
Pronator quadratus (rly close to the wrist)
Flexor digitorum profundus
Flexor pollicis longus
What is the origin of m. pronator teres, and what’s the starting muscle structure called?
It has 2 heads. The HUMERAL one, originates from the medial epicondyle and from the MEDIAL INTERMUSCULAR SEPTUM.
The ULNAR ONE that origins from the coronoid process of the ulna.
What is the insertion point of m. pronator teres?
Pronator duberosity of the radius.
What’s m. pronator teres used for?
Pronates the arm w the m. pronator quadratus. It also contibutes to the flexion of the forearm.
What’s the inervation of the m. pronator teres?
Median nerve. C6-C7
What are the origin sites of m. flexor carpi radialis?
- Medial epicondyle
2. Superficial fascia of the forearm
The insertion point of m. flexor carpi radialis?
Palmar surface of the 2nd metacarpal bone. Sometimes it can attach to the third metacarpal as well.
How does the m. flexor carpi radialis get to the insertion point?
Runs through the carpal tunnel, in a groove of the TRAPEZIUM.
Which movements is the m. flexor carpi radialis responsible for?
Weak flexor and pronator of the elbow joint. Participates in palmar flexion and can also produce radial abduction.
What’s the inervation of the m. flexor carpi radialis?
Median nerve. C6-C7.
Explain the position of the m. palmaris longus.
Arises from the medial epicondyle, radiates into the palmar surface of the hand w a palmar aponeurosis (flatlike muscle tendon)
What is the purporse of m. palmaris longus?
Palmar flexion
What’s the inervation of m. palmaris longus.?
Median nerve C7!-T1
What is the origin point of m. flexor digitorum superficialis?
It has 3 heads. The HUMERAL one arises from the medial epicondyle. The ULNAR one arises from the coronoid process (just like pronator teres!!!). The RADIAL one arises from the radius. Close to the r. tuberosity.
What is the structure that stretches between the heads of m. flexor digitorum superficialis?
A tendinous arch.
What structures cross the tendinous arch of the m. flexor digitorum superficialis?
Median nerve, ulnar artery and vein.
How many distal tendons does the m. flexor digitorum superficialis have?
- All of them inserts onto the bony crests of the lateral side of metacarpal bones goint from 2nd to 5th. Here the tendons divide into 2 slips.
THE TENDONS OF M. FLEXOR DIGITORUM PROFUNDUS GLIDE BETWEEN AND THROUGH THEM.
What is the function of m. flexor digitorum superficialis?
It’s a really weak elbow flexor, but a really strong carpal flexor + finger joint flexor.
What is the inervation of the m. flexor digitorum superficialis?
It’s the median nerve.
C7-T1.
The origin points of m. flexor carpi ulnaris?
The medial epicondyle, the olecranon, the 2/3 of the prosterior margin of the ulna.
What is the insertions of the m. flexor carpi ulnaris?
It inserts onto the pisiform, and extends by the pisohamate ligament as far as the hamate. It goes by the pisometacarpal ligament all the way to the 5th metacarpal.
What is the position of the tendon of m. flexor carpi ulnaris in relation to the carpal tunnel?
It runs outside the carpal tunnel.
What are the functions of the m. flexor carpi ulnaris?
It does the palmar flexion, (it’s more effective than the flexor carpi radialis), helps with ulnar adduction (deviation)
What is the nerve supply for the m. flexor carpi ulnaris?
It is the ulnar nerve.
C7-C8.
What is the place of origin of the m. pronator quadratus?
Distal quarter of the palmar surface of the ulna.
What is the insertion point of m. pronator quadratus?
It’s the distal quarter of the palmar surface of the raduis.
What is the function of m. pronator quadratus?
Pronation of the forearm, assisted by the m pronator teres
What’s the inervating structure of m. pronator quadratus?
It’s the anterior interosseous branch of the median nerve (C8-T1)
What’s the origin of the m. flexor digitorum profundus?
It arises from the proximal two thirds of the palmar surface of the ulna and the interosseous membrane.
How and where is the m. flexor digitorum profundus attached?
It’s attached by 4 tendons to the base of the terminal phalanges of the second to fifth fingers.
What is the other name for m. flexor digitorum profundus? Why?
It’s also called the PERFORATING muscle, cuy its tendonts pierce through the terminal tendons of m. flexor digitorum superficialis.
Which muscles arise from the m. flexor digitorum profundus?
The lumbrical muscles arise from the radial side of it’s tendons.
What is the function of m. flexor digitorum profundus?
it’s a flexor of the wrist, midcarpal, metacarpophalengeal and phalengeal joints
What is the nerve supply for m. flexor digitorum profundus?
It’s the anterior interosseous branch of the median nerve and the ulnar nerve (C7-T1)
What’s the origin of m. flexor pollicis longus?
Anterior surface of the radius, distal to the radial tuberosity and from the interosseous membrane.
What is the exact position of m. flexor pollicis longus?
It’s surrounded by it’s own tendon sheath, extends through the carpal tunnel and lies between the heads of the flexor pollicis brevis and continues to the base of the terminal phalanx of the thumb.
What’s the function of m. flexor pollicis longus?
Flexing the terminal phalanx of the thumb and is able to abduct it in the radial direction.
What’s the nerve supply for m. flexor pollicis longus
Interosseous branch of the median nerve (C7-C8)
What is the origin of the m. extensor carpi radialis brevis?
It is the common head on the lateral epicondyle, the radial colateral ligament and the annular ligament of the radius.
What is the insertion point of m. extensor carpi radialis brevis?
It is the base of the 3rd metacarpal (dorsal side)
What are the movements which m. extensor carpi radialis brevis enables?
It brings the wrist back to midposition after ulnar deviation (adduction), it also flexes the wrist dorsally
What is the inevration of m. extensor carpi radialis brevis?
It’s the deep branch of the radial nerve (C7)
The origin of m. extensor carpi radialis longus?
Lateral supraepicondylar ridge, lateral inermuscular septum, lateral epicondyle.
What’s the path of the tendon of m. extensor carpi radialis longus?
It goes through the second tendon compartment, together with the m. extensor carpi radialis brevis.
What is the attachment site of m. extensor carpi radialis longus?
It’s the dorsal surface of the 2nd metacapal’s base
Movement of m. extensor carpi radialis longus?
Weak pronator when the elbow is flexed, weak supinator when the arm is extended. Main movements: radial deviation (with the m. flexor carpi radialis) + dorsoflexion (with the m. extensor carpi ulnaris)
Inervation of m. extensor carpi radialis longus?
The deep branch of the radial nevre (C6-C7)
How do we call the m. extensor carpi radialis longus + m. extensor carpi radialis brevis?
We call them FIST CLENCHERS.
Where does m. brachioradialis originate from?
It originates from the lateral supraconylar ridge and the lateral intermuscular septum.
What is the insertion point of m. brachioradialis?
It is the radial surface of the radial styloid process.
What is the main movement of the m. brachioradialis, how many joints does it have an effect on?
It has an effect on only one joint (elbow) (radioulnar). It brings the forearm into midposition between pronation and supination. From that position it can act like a flexor.
What is the inervation of m. brachioradialis?
It is inervated by the radial nerve. (C5-C6)
What is the origin of m. externsor digitorum? Which group of muscles does it belong to?
The origin of this superficial dorsal muscle is a flat like extension, going from the lateral epicondyle, the annular r. ligament, the radial colateral ligament and antebrachial fascia.
Through which tendon compartent does the tendon of m. externsor digitorum go?
It goes through the fourth tendinous compartment
What does the m. externsor digitorum create, and what is its insertion point?
It’s distal end creates the dorsal aponeurosis, from the 2nd to the 5th finger, and it then attaches to the dorsal side of the proximal phalanges of the 2-5th fingers.
How do we call the structures that connect the individual tendons of m. externsor digitorum?
We call them the intertendinous connections.
What is the function of m. externsor digitorum?
The function is dorso-flexion, ulnar deviation and it also spreads the fingers.
What is the inervation of m. externsor digitorum?
It’s a deep branch of the radial nerve (C6-C8)
What is the origin point of m. extensor digiti minimi?
It’s the common head with the extensor digitorum
Which tendon compartment does the m. extensor digiti minimi go through?
It goes through the 5th tendon compartment.
Where does the m. extensor digiti minimi go to, and what is it’s usual deviation?
It goes to the dorsal aponeurosis of the fifth finger, and usually the tendon itself is missing, so it is replaced by and extra tendon of m. extensor digitorum.
Where does the m. extensor capri ulnaris originate from?
It originates from the common head + the ulna
Which compartment does the m. extensor capri ulnaris run through?
It runs through the 6th compartment.
What is the function of m. extensor capri ulnaris ?
Strong ulnar abductor. Causes dosriflextion or the radiocarpal joint and palmarflexion of the midcarpal joint. These 2 funct. balance each other out.
Which muscle is the antagonist of m. extensor capri ulnaris ?
It is the abductor pollicis longus.
Inervation of m. extensor capri ulnaris ?
Deep branch of the radial nerve C7-C8
What is the origination point of the m. supinator?
Those are: SUPINATOR CREST OF THE ULNA, lateral epicondyle, radial colateral ligament and the annular radial ligament.
What is the insertion point of the supinator muscle?
The insertion point of this muscle is the radius. It inserts inbetween the radial tuberosity and the inserion point of the m. pronator teres.
What is the function of the supinator muscle?
It is supination. It encircels the radius, supinating the forearm in both the fkexion and extension of the elbow joint.
Inervation of the supinator muscle?
It is a deep branch of the radial nerve.
What is the origin of the m. abductor pollicis longus?
It is the dorsal suface of the ulna (distal to the supinator crest), dorsal surface of the radius and also the interossious membrane.
What is the insertion point of m. abductor pollicis longus?
It inserts onto the dorsal face of the first metacapal. A part of the tendon reaches the trapezium, and another one is fused with the tendon of m. extensor pollicis brevis.
What is the fucntion of m. abductor pollicis longus?
It is: abduction of the thumb, radial abduction and flexion of the hand towards the palm.
What is the origin of m. extensor pollicis brevis?
It originates from the dorsal side of the radius, dorsal side of the ulna (distal to the abductor pollicis longus) and the interosseous membrane.
The inserion point of m. extensor pollicis brevis?
It is the proximal phalanx of the thumb.
The function of m. extensor pollicis brevis?
It is extension of the thumb, and also it’s abduction, because of ti’s close relation to the m. abducton pollicis longus. It runs through the first tendon compartment.
What is the origin of m. extensor pollicis longus?
The origin of this muscle is the dorsal side of the ulna (distal to the origination point of the m. abductor pollicis longus), and the interosseous membrane
What is the insertion of m. extensor pollicis longus?
It goes dorsally to the wrist joint, and uses the dorsal radial tubercle as a fulcrum, and attaches itself to the distal phalanx of the thumb, doing the act of extension. Besides the extension it also does the dorso-flexion and radial abduction.
