L8 Flashcards
What is the nerve supply of the posterior forearm?
Posterior interosseus nerve, from deep branch of the radial nerve
Deep branch of radial nerve - posterior interosseous nerve
Winds around the neck of radius pierces the 2 heads of supinator to become the (P) interosseus nerve.
Where is the blood supply for the posterior compartment of forearm from?
Posterior interosseus artery
What is the posterior interosseus artery? (from)
A branch of the common interosseous from the ulnar artery
What is the posterior compartment blood supply reinforced by?
Perforating branches of anterior interroseus artery
What are the muscles on the radial/lateral side of the posterior forearm?
- Brachioradialis
- Ext. Carpi Radialis Longus
- Brevis
What are the muscles on the middle and ulna side of the posterior forearm?
- Ext. Digitorum,
- Ext. Digiti Minimi
- Ext. Carpi Ulnaris
What tendons of thumb muscles form the anatomical snuffbox?
- Abductor Policis Longus
- Extensor Policis Brevis
- Extensor Policis Longus
What is the insertion of brachioradialis?
Base of styloid process of radius
What is the origin of brachioradialis?
Upper 2/3 of (L) supracondylar ridge of humerus
What muscle forms the lateral border of the cubital fossa?
Brachioradialis
Give the clinical for brachioradialis
Can be transplanted into flexor pollicis longus to produce flexion of the thumb in median nerve palsy
Test for damage to brachioradialis?
Place forearm in midprone position and flex against resistance while palpating the muscle belly.
What is the nerve supply for brachioradialis?
Branch of Radial nerve (C5,C6) arising above elbow
What is the action of brachioradialis?
Pulls on radial styloid process flexing at forearm. Ulna follows passively falling into the midprone position weak pronating
What is the course of the brachioradialis?
- Forms (L) border of the cubital fossa - along preaxial border of the forearm - overlies radial nerve & artery as they lie on: Supinator / Pronator Teres tendon / FDS & FPL
What is the lower part of the tendon of brachioradialis overlaid by?
- Abductor policis longus
- Extensor policis brevis
What are the actions of the extensor carpi radialis longus?
Extensor & radial abductor of the wrist - important as a synergist enabling finger flexors to produce a grip.
Test of carpi radialis longus
Pronate forearm & extend the wrist then abduct against resistance palpate muscle belly (L) side of elbow & tendon proximal to anatomical snuffbox.
What is the origin of extensor carpi radialis longus?
Lower 2/3 lateral supracondylar ridge of humerus
What is the insertion of extensor carpi radialis longus?
base of 2nd metacarpophalangeal
What is the action of extensor carpi radialis longus?
Extensor & radial abductor of the wrist - important as a synergist enabling finger flexors to produce a grip.
What is the course of extensor carpi radialis longus?
Behind brachioradialis - beneath deep outcropping thumb muscles - across floor of anatomical snuffbox
What is the nerve supply of extensor carpi radialis longus?
Branch of radial nerve (C6,C7) arising above the elbow.
What is the common extensor origin?
Anterior aspect of lateral epicondyle
What muscles fuse with the common extensor tendon?
- Extensor carpi radialis brevis
- Extensor digitorum
- Extensor digiti minimi
- Extensor carpi ulnaris
Clinical of common extensor tendon
Chronic mechanical degradation of the tendon due to overuse injury results in common extensor tendonosis more commonly known as Tennis elbow
What is the origin of extensor carpi radialis brevis?
Common extensor origin
Insertion of extensor carpi radialis brevis
Base of the 3rd metacarpophalangeal
What is the innervation of extensor carpi radialis brevis?
Deep branch of radial nerve (C6,C7)
Actions of extensor carpi radialis brevis
Indispensable as a synergist in forming a strong grip.
What muscle has a symmetrical insertion to flexor carpi radialis?
Extensor carpi radialis brevis
Course of common extensor origin
Deep to extensor carpi radialis longus - tendon
crossed deep outcropping thumb muscles - floor of anatomical snuffbox
What is the origin of extensor digitorum?
Common extensor tendon
What is the insertion of extensor digitorum?
Extensor expansions of 2nd - 5th digits.
What is the nerve supply of the extensor digitorum?
Posterior interosseous branch of the radial nerve (C7,C8)
What are the actions of extensor digitorum?
Extends the digits and assists with wrist extension
What is the test of extensor digitorum?
Pronate forearm and extend fingers at MCP joints push proximal phalanges into flexion
What are the relations of extensor digitorum?
Rounded belly by mid-forearm - diverges from 3 muscles on radial side - separated from them by deep thumb muscles - 4 tendons pass under extensor retinaculum - tendons are crowded together and overlie EI tendon - over the dorsum of
the hand the tendons are joined together to a variable degree by tendinous bands - tendons insert into the extensor expansion
What is the origin of extensor digit minimi?
Common extensor tendon
What is the insertion of the extensor digiti minimi?
Extensor expansion on dorsum of 5th MCP joint.
Innervation of extensor digiti minimi
Interosseous nerve C7,C8
What is the test for extensor digiti minimi?
Pronate forearm and extend fingers at MCP joints push proximal phalanges into flexion
What are the actions of extensor digiti minimi?
Assists extensor digitorum with extension of the little finger and wrist joint
What are the relations of extensor digiti minimi?
Muscle belly separates from common origin - becomes tendinous - tendon passes beneath extensor retinaculum - lies on dorsum of distal radio-ulnar joint - tendon splits into 2 slips which lie together on 5th MCP - tendon of ED joins them as a band near the MCP joint.
What is the origin of extensor carpi ulnaris?
- Common extensor tendon
- Aponeurosis from subcutaneous border of ulna
What is the insertion of extensor carpi ulnaris?
Base of 5th MCP
What are the relations of extensor carpi ulnaris?
Aponeurotic origin is in common with FCU - tendon lies in groove beside the ulnar styloid process symmetrical to insertion of FCU on the palmar aspect of 5th MCP.
Nerve supply of extensor carpi ulnaris
Posterior interosseous nerve in the forearm (C6, C7).
Actions of extensor carpi ulnaris
Extension and ulna deviation
- Adduction of the wrist synergistic action in
fixation of the wrist allowing the long finger flexors to produce a strong grip.
Test of extensor carpi ulnaris
Pronate the forearm and extend the fingers then adduct and extend the wrist against resistance while palpating muscle belly in proximal forearm and tendon distally at the head of the ulna.
What are the relations of abductor policis longus?
- Forms (A) boundary of anatomical snuffbox
- Bursa lies between 2 tendons distally.
What is the origin of abductor policis longus?
Oblique area of radius distal to posterior oblique line, more proximally the ulna and adjacent interosseous membrane deep part
Insertion of abductor policis longus?
Trapezium superficial part and variable no. of tendons
attaching to base of 1st MCP.
What is the nerve supply of abductor policis longus?
Posterior interosseous nerve (C7,C8)
What are the actions of abductor policis longus?
Abduction of the thumb assists in abduction and flexion of the wrist deep tendon stabilises the trapezium so the 1st MCP can move.
Test abductor policis longus?
Abduction of the thumb against resistance while palpating the tendon on the radial side of the ASB.
What is the origin of anconeus?
Dorsal side of the lateral epicondyle
What is the insertion of anconeous?
Lateral side olecranon
What is the innervation of anconeus?
branch of radial nerve arising in radial groove pierces triceps with nerve to (M) head
What is the action of anconeus?
Extensor and abductor of elbow joint that occurs during pronation.
What are the relations of anconeus?
Fibres fan out from humerus to olecranon - upper fibres are horizontal - transversely across forearm - (L) fibres are vertical - in axis of forearm.
What is the insertion of the deep supinator muscle?
Between the anterior and posterior oblique lines.
What is the course of supinator?
Posterior interosseous nerve passes between the 2 parts of the muscle as it leaves the cubital fossa winding around the neck of radius on its way to the posterior compartment
What is the origin of deep part of supinator?
- Supinator fossa
- Crest of the ulna fibres
What is the origin of superficial part of supinator?
- Distal border of the lateral epicondyle
- Radial collateral ligament of elbow
- Behind the supinator crest of the ulna
What is the insertion of the superficial part of supinator?
Insert into the radius above the anterior oblique line.
Where do the supinator slope?
Slope downwards over the deep horizontal fibres
What is the innervation of supinator?
Posterior interosseous nerve (C5,C6)
What is the action of the supinator?
Fixator of the forearm in the supinated position - prime
mover for supination only when the elbow is extended
What is a more powerful supinator, supinator or biceps?
Biceps
Can supinator be tested?
No - too deep to be seen/palpated
What is the origin of extensor indicis?
From ulna distal to extensor pollicis longus
What is the insertion of extensor indicis?
Extensor expansion of Index finger
What is the nerve supply of extensor indicis?
Posterior interosseous nerve
What is the action of extensor indicis?
Extends index finger as in pointing assisting extensor digitorum
What is the course of extensor indicis?
Tendon remains deep - over distal radius under bunched up tendons of ED - shares a common synovial sheath - dorsal surface of MCP on Ulnar side of ED tendon
What is the anatomical snuffbox formed by?
- Extensor policis longus (ulnar side)
- Extensor policis brevis
- Abductor policis longus (radial side)
What crosses the tendons of anatomical snuffbox muscles?
Cutaneous branches of the radial nerve
What vein commences in the snuffbox?
Cephalic vein
What lies in the floor of anatomical snuffbox?
- Radial artery
- Tendons of extensor carpi radialis & brevis
What are the palpable bony points of anatomical snuffbox?
- Radial styloid
- Scaphoid,
- Trapezium
- Base of 1st MCP
What is the nerve supply of anatomical snuffbox?
Posterior interosseous nerve
What is the course of the posterior interosseous nerve in the anatomical snuffbox?
Enters (P) compartment between 2 heads of supinator - down over abductor pollicis longus - deeper to reach the interosseous membrane - between deep muscle & interosseous membrane to the wrist joint
What is the motor supply of anatomical snuffbox?
Muscles of the common extensor tendons deep muscles of (P) compartment
What is the sensory supply of the anatomical snuffbox?
Intersseous membrane Periosteum of radius & ulna wrist joint & intercarpal ligaments
What is the blood supply of the anatomical snuffbox?
Interosseous artery
What is the origin of the interosseous artery?
Arises from the common interosseus branch of the ulna artery
What is the course of the interosseous artery?
Between radius & ulna -
between oblique cord & interosseous membrane - accompanies posterior interosseus nerve
What does the interosseous artery supply?
Deep muscles of the
compartment at lower border of extensor indicis
What is the blood supply of interosseous artery reinforced by?
A branch of the anterior interosseus
What does the branch of the anterior interosseus that reinforces interosseous artery pierce?
The interosseous membrane above pronator
quadratus
Where does the branch of the anterior interosseus that reinforces interosseous artery end?
In the dorsal carpal anastomosis on the back of the wrist
What is the extensor retinaculum?
Thickening of the deep fascia of the forearm which forms a ribbon like band < 2.5cm wide stretching across the dorsum of the wrist
What are the attachments of the extensor retinaculum?
Anterolateral aspect of radius lateral to pronator quadratus - pisiform & triquetral bones
Does the extensor retinaculum attach to ulna?
NO
What is the function of the extensor retinaculum?
- Prevents bowstringing of extensor tendons when passing across wrist septa pass from it’s deep surface to radius and ulna
- Dividing the extensor tunnel into 6 compartments
What does the extensor expansion consist of?
- Hood
- Central
- Two co-lateral slips.
What does the hood of extensor expansion cover?
Covers dorsal aspect of metacarpophalangeal joint & passes to palmar ligaments/fascia
What does the central slip of extensor expansion insert?
Into the middle phalanx
What do the two co-lateral slips of extensor expansion pass?
Either side of the proximal interphalangeal joint and then merge over the middle phalanx to insert into the
distal phalanx.
Clinical of extensor expansion
Ruptures of parts of the expansion produce Boutonniere, Swan Neck, and Mallet finger deformities
What tendinous attachments does the extensor expansion receive?
Of the lumbrical and interossei muscles
What type of joint is the radiocarpal joint?
Synovial, ellipsoid (condylar) joint with two degrees of freedom.
What are the capsular ligaments of the radiocarpal joint?
Attached to the articular margins with thickened radial and ulnar collateral
ligaments.
Details of radial collateral ligament
Attached between the styloid process of the radius and the scaphoid, lunate
and triquetrum
Details of ulnar collateral ligament
Attached between the styloid process of the ulna and the triquetrum, lunate and scaphoid.
What are the ligaments of the radiocarpal joint other than radial, ulnar collateral?
: palmar radio / ulno - carpal ligaments are strong. The dorsal radiocarpal
ligament is weaker.
What is stronger palmar radio / ulno - carpal ligaments or dorsal radiocarpal?
Palmar radio / ulno - carpal ligaments
What does the synovial membrane of the radiocarpal joint line?
Non-articular surfaces / joint cavity separate from that of carpal joint.
What is the nerve supply of the radiocarpal joint?
- Anterior interosseous branch of the median nerve
- Posterior interosseous termination of the radial nerve.
Is the radiocarpal joint stable?
No, inherently unstable
What aids stability in the radiocarpal joint?
The flexor and extensor retinacula by binding the tendons closer to the wrist bones
What is the strength of the radiocarpal joint dependent on?
On the surrounding tendons and strong collateral
ligaments
What is the most commonly dislocated carpal bone?
Lunate
Is the radiocarpal joint prone to dislocation?
No - tight bands of tendons anteriorly and posteriorly
What are the flexion prime movers of the radiocarpal joint ?
- Flexors carpi radialis & ulnaris Assisted by - Palmaris longus - Flexor digitorum superficialis - Flexor digitorum profundus - Flexor pollicis longus. Ex
What are the extension prime movers of the radiocarpal joint ?
- Extensors carpi radialis longus, brevis and carpi ulnaris Assisted by - Extensors pollicis longus, brevis, - digitorum - indicis - digiti minimi
What are the abductor prime movers of the radiocarpal joint ?
e abductor pollicis longus, flexor
carpi radialis, and extensors carpi radialis longus and brevis
What are the adductor prime movers of the radiocarpal joint ?
- Flexor carpi ulnaris
- Extensor carpi ulnaris
ROM of the radiocarpal joint for flexion
80º
ROM of the radiocarpal joint for extension
60º
ROM of the radiocarpal joint for abduction
15º
ROM of the radiocarpal joint for adduction
45º
