7: Contents Of Forearm Flashcards
Anterior compartment
(Muscle actions & innervation)
Flexors and pronators are present in the anterior compartment, mainly supplied by the median nerve
Posterior compartment
(Muscle actions & innervation)
Extensors and supinatorsare present in the posterior compartment, supplied by the radial nerve
As the deep fascia is attached to bones and joints, usually infections are confined to the compartments, except ……..?
except that from the flexor compartment which is continuous with that of the palm through the carpal tunnel (canal), the infection can spread to the palm and vice versa
Neurovascular bundle is found in more than one place in the ….. compartment. It’s important when you operate in this area.
Anterior
Muscles of Anterior Compartment (superficial layer)
1- Pronator teres
2- Felxor carpi radialis
3- Palmaris longus
4- Flexor carpi ulnaris
Muscles of Anterior Compartment (intermediate layer)
Flexor digitorum superficialis
Muscles of Anterior Compartment (deep layer)
1- Flexor digitorum profundus
2- Flexor pollicis longus
3- Pronator quadratus
Muscles of Posterior Compartment (superficial)
1- brachioradialis
2- extensor carpi radialis longus
3- extensor carpi radialis brevis
4- extensor digitorum
5- Extensor digiti minimi
6- extensor carpi ulnaris
7- anconeus
Muscles of Posterior Compartment (deep)
1- supinator
2- Abductor pollicis longus
3- extensor pollicis longus
4- Extensor pollicis brevis
5- Extensor indicis
Pronator teres
A. Origin
B. Insertion
C. Action
A. humerus & ulna
B. middle of radius
C. pronates and flexes the forearm
Felxor carpi radialis
A. Origin
B. Insertion
C. Action
A. CFO (medial epicondyle)
B. second metacarpal
C. flexes and abducts the wrist joint
Palmaris longus
A. Origin
B. Insertion
C. Action
A. CFO (Medial epicondyle)
B. palmar aponeurosis
C. Not mentioned (absence in 10% of people)
Flexor carpi ulnaris
A. Origin
B. Insertion
C. Action
A. CFO & ulna
B. pisiform, hamate and 5th
metacarpal
C. flexes and adducts the wrist joint
Flexor digitorum superficialis
A. Origin
B. Insertion
C. Action
A. From humerus, ulna and radius
B. middle phalanges of medial four fingers
C. flexion of middle phalanges at PIP joints and at MCP joints
Flexor digitorum profundus
A. Origin
B. Insertion
C. Action
A. Ulna & interosseous membrane
B. bases of distal phalanges of 2 to 5 fingers
C. Flexes distal phalanges
Flexor pollicis longus
A. Origin
B. Insertion
C. Action
A. Anterior surfaces of radius & interosseous membrane
B. Base of distal phalanx of thumb
C. Flexes distal phalanx of thumb
Pronator quadratus
A. Origin
B. Insertion
C. Action
A. distal part of ulna
B. Distal part of radius
C. Binds radius and ulna and pronates the forearm
Brachioradialis
A. Origin
B. Insertion
C. Action
A. Lateral supracondylar ridge
B. Distal end of radius
C. Flexor of forearm especially when the forearm is in mid-prone position
Extensor carpi radialis longus
A. Origin
B. Insertion
C. Action
A. lateral supracondylar ridge
B. base of second metacarpal
C. extends and abducts wrist joint
Extensor carpi radialis brevis
A. Origin
B. Insertion
C. Action
A. CEO (lateral epicondyle)
B. base of 3rd metacarpal
C. extends and abducts wrist joint
Extensor digitorum
A. Origin
B. Insertion
C. Action
A. CEO (lateral epicondyle)
B. middle phalanges of medial for fingers
C. extends medial four fingers at MCP & IP’s joints
Extensor digiti minimi
A. Origin
B. Insertion
C. Action
A. CEO (lateral epicondyle)
B. 5th digit
C. similar to ED (extends at MCP and IP)
Extensor carpi ulnaris
A. Origin
B. Insertion
C. Action
A. CEO & posterior border of ulna
B. base of 5th MCP joint
C. extends and adducts the wrist joint
Anconeus
A. Origin
B. Insertion
C. Action
A. CEO
B. posterior surface of ulna
C. weak extensor of elbow
Supinator
A. Origin
B. Insertion
C. Action
A. CEO & ulna
B. proximal third of radius
C. supinates the forearm
Abductor pollicis longus
A. Origin
B. Insertion
C. Action
A. proximal parts of radius, ulna and interosseous membrane
B. base of first metacarpal
C. Abducts and extends the thumb
Extensor pollicis longus
A. Origin
B. Insertion
C. Action
A. middle third of ulna and interosseous membrane
B. Base of distal phalanx of thumb
C. extends distal phalanx of thumb
Extensor pollicis brevis
A. Origin
B. Insertion
C. Action
A. distal third of radius and interosseous membrane
B. Base of proximal phalanx of thumb
C. Extends proximal phalanx of thumb
Extensor indicis
A. Origin
B. Insertion
C. Action
A. distal third of ulna and interosseous membrane
B. dorsal digital expansion of index finger
C. extends the second finger
Chief gripping muscle
FDP (Flexor digitorum profundus )
Anterior interosseous nerve is a branch of ..?
Median nerve
What does the median nerve innervate in the forearm
flexor muscles innervated by the median nerve (except one and a half: FCU & FDP medial part)
Posterior interosseous nerve is deep branch of …?
Radial nerve
Muscles supplied by radial nerve?
Extensor carpi radialis longus & Brachioradialis (posterior compartment)
Muscles supplied by posterior interosseous nerve (deep branch of radial)?
posterior compartment muscles except: Extensor carpi radialis longus & Brachioradialis
Ulnar nerve supply?
1.5 muscles supplied by ulnar
1 = Flexor carpi ulnaris
0.5 = medial part of flexor digitorum profundus
Deep fascial band on the back of the wrist which holds the extensor tendons is called
Extensor retinaculum
Extensor retinaculum lateral & medial attachments
Laterally to inferior end of radius
Medially to styloid process of ulna, triquetral and pisiform
Function of extensor retinaculum?
prevents bowstringing of tendons during extension of wrist
six osseofascial compartment: mention tendons in each in order
1: abductor pollicis longus & extensor pollicis brevis
2: extensor carpi radialis (longus & brevis)
3: extensor pollicis longus
4: Extensor digitorum & extensor indicis
5: extensor digiti minimi
6: extensor carpi ulnaris
Cubital fossa boundaries
A. Lateral
B. Medial
C. Base
D. Apex
A. Lateral = brachioradialis
B. Medial = pronator teres
C. Base = imaginary line passing through epicondyles
D. Meeting points of A & B
Cubital fossa (roof & floor)
Roof = roof is formed by the skin, superficial & deep fascia + bicipital aponeurosis
Floor = brachialis and supinator
contents of cubital fossa (medial to lateral side)
median nerve, termination of brachial artery, tendon of biceps, radial nerve
Biceps reflex (tests what? How performed?)
- Biceps reflex: a deep tendon reflex-elicited to test musculocutaneous nerve (C5, C6) or the same spinal cord segments
- The examiner’s thumb is firmly placed on the biceps tendon and the reflex hammer is tapped at the base of the nail bed
(Normal reflex is jerk-like flexion of elbow)
Neurovascular Bundle (name 2 arteries, 2 veins & 3 nerves) of forearm
Artery = radial & ulnar
Vein = cephalic and basilic (superficial) & radial, ulnar, and interosseous veins (deep)
Nerve = median, ulnar, radial
What interconnects the cephalic and basilic veins?
Median cubital veins
What are perforating veins
communicate the superficial veins with the deep veins
Deep veins proximally join the ….(a)…, which in turn join the …(b)… in the axilla
a = brachial vein
b = axillary vein
Ulnar artery (branches? Supplies what?)
Radial artery (branches? Supplies what?)
Which artery gives a branch that enters the hand into the anatomical snuff box
Radial artery
Which muscle is responsible for:
- flexion at PIP joint
- flexion at DIP joint
PIP = FDS (superficialis)
DIP = FDP (profundus)
This muscle causes flexion at MCP joint
Flexor digitorum superficialis
This muscle is absent in 10% of people
Palmaris longus
1- main nerve of forearm ?
2- main nerve of hand ?
1- median nerve
2- ulnar nerve
What happens in case of injury to: (name the deformity)
1- radial nerve?
2- ulnar nerve?
3- median nerve?
1- wrist drop
2- claw hand
3- ape hand
Patient presented with pain over the lateral epicondyle which radiates over the posterior surface of forearm when open a door or lift a glass. what’s your diagnosis?
Tennis elbow/elbow tendinitis/tendinosis/lateral epicondylitis
Causes of Tennis elbow
In fractures of radius above insertion of pronator teres muscle, what’s the orientation of the proximal and distal fragments?
In fractures of middle or distal radius that are distal to insertion of
pronator teres muscle what happens to proximal and distal fragments?
What’s a common type of ulna fracture. What is seen on xray?
Fractures of distal part of radius (mention two types)
- distal part displaced dorsally = colles fracture (posterior)
- distal part displaced ventrally = smiths fracture (anterior)
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