forearm Flashcards
Anconeus
origin: Lateral epicondyle of humerus
insertion: Lateral surface of olecranon process of ulna
nerve: Radial nerve
action: Extends the elbow joint
Brachioradialis
origin: Upper 2/3rd of lateral supracondylar ridge of humerus
insertion: Base of styloid process of radius
nerve: Radial nerve
action: Flexes the forearm at elbow joint in mid prone position
Extensor Carpi Radialis longus
origin: Lower 1/3rd of lateral supracondylar ridge of humerus
insertion: Posterior surface of base of 2nd metacarpal
nerve: Radial nerve
action: Extends and abducts hand at wrist joint
Extensor Carpi Radialis Brevis
origin: Lateral epicondyle of humerus
insertion: Posterior surface of base of 3rd metacarpal
nerve: PIN
action: Extends and abducts hand at wrist joint
Extensor Digitorum
origin: Lateral Epicondyle of humerus
insertion: Bases of middle phalanx of 2nd -5th digits
nerve: PIN
action: Extends the digits of hand
Extensor digiti minimi
origin: Lateral epicondyle of humerus
insertion: Dorsal digital expansion of little finger
nerve: PIN
action: Extensor of meta-carpophalangeal joint of little finger
Extensor carpi ulnaris
origin: Lateral epicondyle of humerus
insertion: Bases of 5th metacarpal
nerve: PIN
action: Extends and adducts the hand at wrist joint
Supinator
origin: Lateral epicondyle of humerus,
radial collateral and anular ligaments,
supinator fossa,
crest of ulna
insertion: Lateral, posterior, and anterior surfaces of proximal third of radius
nerve: PIN
action: Supinations forearm
Abductor pollicis longus
origin: Posterior surface of shaft of radius and ulna
insertion: Base of first metacarpal on the dorsal surface
nerve: PIN
action: Abducts and extends thumb
Extensor pollicis brevis
origin: Posterior surface of shaft of radius
interosseous membrane
insertion: dorsal Base of proximal phalanx of thumb
nerve: PIN
action: Extends metacarpophalangeal joint of thumb
Extensor pollicis longus
origin: Posterior surface of ulna, interosseous membrane
insertion: dorsal Base of distal phalanx of thumb
nerve: PIN
action: Extends distal phalanx of thumb
Extensor indicis
origin: Posterior surface of shaft of ulna
interosseous membrane
insertion: Dorsal digital expansion of index finger
nerve: PIN
action: Extends the metacarpophalangeal joint of index finger
Pronator teres
origin: Medial epicondyle of humerus
insertion: Middle of lateral aspect of shaft of radius
nerve: Median nerve
action: Pronation of forearm
Flexor carpi radialis
origin: Medial epicondyle of humerus
insertion: Bases of second and third metacarpals
nerve: Median nerve
action: Flexes and abducts the hand at the wrist
Palmaris longus
origin: Medial epicondyle of humerus
insertion: Flexor retinaculum and palmar aponeurosis
nerve: Median nerve
action: Flexes wrist joint
c: absent in some people. leaves median nerve more vulnerable because it is deep to pl tendon.
Flexor digitorum superficialis
* Humero ulnar head
* Radial head
origin: Medial epicondyle of humerus; medial border of
coronoid process of ulna
Anterior oblique line of shaft of radius
insertion: Divided into 4 tendons. Each tendon splits into two, gets inserted to the sides of middle phalanx of 2nd to 5th digits
nerve: Median nerve
action: Flexes the middle phalanx and assists in flexing of proximal phalanx and the wrist joint
Flexor carpi ulnaris
* Humeral head
* Ulnar head
origin: Medial epicondyle of humerus
Medial aspect of olecranon process and posterior
border of ulna
insertion: Pisiform bone; further tendon extends and gets inserted to the hook of the hamate and base of fifth metacarpal bone
nerve: Ulnar nerve
action: Flexes and adducts hand at the wrist joint
Flexor digitorum profundus
origin: Medial and anterior surface of proximal 3/4 of ulna and interosseous membrane
insertion: Palmar base of distal phalangeal bones of medial four digits
nerve: Medial half by ulnar nerve. Lateral half by anterior
interosseous nerve
action: Flexes distal phalangeal bones of medial four digits, assists with flexion of hand at wrist
C: Test by flexing DIP joint while holding PIP joint in extension
Flexor pollicis longus
origin: Upper 3/4 of anterior surface of shaft of radius; adjoining anterior surface of interosseous membrane
insertion:Palmar base of distal phalanx of thumb
nerve: Anterior interosseous nerve
action: Flexes phalangeal bones of thumb
Pronator Quadratus
origin: Distal fourth of anterior ulna
insertion: Distal fourth of anterior radius
nerve: Anterior interosseous nerve
action: Superficial fibres pronates the forearm
Deep fibres-fixes the lower ends of radius and ulna
What are the cutaneous nervres and their areas of distribution in the forearm
Medial Side
1. Medial cutaneous nerve of forearm (C8 and T1) which arises from the medial cord of the brachial plexus
Lateral Side
1. Lateral cutaneous nerve of the forearm (C5 and C6) from the musculocutaneous nerve from the lateral cord of the brachial plexus
- Continuion of musculocutaneous nerve which emerges at the lateral border of the biceps and divides into anterior and posterior branches.
Posterior side
1. Posterior cutaneous nerve of the forearm (C6,7,8) from radial nerve, a branch from the posterior cord of the brachial plexus..
- Runs down the posterior aspect of forearm up to wrist.
Describe the Flexor Retinaculum, and describe its attachments.
Flexor Retinaculum is a strong fibrous band which bridges the anterior cavity of carpus and converts it into an osseofibrous tunnel (carpal tunnel) for the passage of flexor tendons of the digits.
It is rectangular and formed due to thickening of deep fascia in front of carpal bones
Attachments:
1. Medially it is atttached to the pisiform and the hook of hamate
2. Laterally, it is attached to the tubercle of scaphoid and crest of trapezium.
Structures passing above the flexor retinaculum:
1. Superficial palmar branch of radial artery
2. Palmar cutaneous branch of median nerve
3. Tendon of palmaris longus
4. Palmar cutaneous branch of ulnar nerve
Describe the Extensor Retinaculum, and describe its attachments.
Extensor retinaculum is the deep fasciaon the back of the wrist which is thickened to form an oblique fibous band.
It is directed downwards and laterally, about 2cm broad vertically
Attachments:
1. Medial end is attached to the styloid process of ulna, triquetral, and pisiform bones
2. Laterally attached to the lower part of the anterior border of radius.
Has 6 compartments, 4 of which are conencted to radius, and 2 to ulna. Substructures embedded within this
Describe the Origin, Course of the Ulnar Artery
Origin:
- Larger terminal branch of the brachial artery and begins in the cubital fossa.
Course:
- Runs obliquely downwards and medially in the upper 1/3 of the forearm.
- In the lower 2/3 of forearm, its course is vertical
- Enters the palm by passing superficia lto the flexor retinaculum.
Describe the Relations and Branches of the Ulnar Artery
Relations:
- Anteriorly → Upper half (artery is deep and covered by muscles from the common flexor origin), Lower half (artery is superficia and covered only by skin/fascia
- Posteriorly → Lies on brachialis and on the flexor digitorum profundus
- Medially → Related to the ulnar nerve and to the flexor carpi ulnaris
- Laterally → related to the flexor digitorum superficialis and median nerve
- Venae comitantes (anastomoses)
Branches:
1. Muscular branches
2. Anterior and posterior ulnar collateral
3. Common interosseous artery
4. Anterior an posterior ulnar carpal branches
5. Larger Superficial branch continues to become superficial palmar arch while the smaller deep branch joins the deep palmar arch.
Describe the Origin and Course of the Radial Artery
Originates from the smaller terminal branch of the brachial artery in the cubital fossa.
Course:
- It runs downwards to the wrist with a lateral convexity
- Leaves the forearm by turning posteriorly and entering the anatomical snuff box
- Quite superficial throughout its whole course,
Describe the Relations and Branches and Applied Anatomy of the Radial Artery
Relations:
- Anteriorly → Overlpped by the brachioradialis in upper part, but in lower half it is only coverd by skin/fascia
- Posteriorly → related to the muscles attached to the anterior surface of radius, biceps brachii, flexor policis longus, flexor digitorum superficialis, and pronator quadratus
- Medially → Related to the pronator teres in the upper 1/3 and tendon of the flexor carpi radialis
- Laterally → Brachioradialis in the whole extent and the radial nerve in the middle 1/3
The artery is accompanied by venae comitantes.
Branches:
- Muscular branches to the lateral muscles of forearm
- Radial recurrent artery arises in the cubital fossa and takes part in the formation of arterial anastomose aorund the elbow joint
- Palmar carpal branch, arises near the wrist and anastomosis with the palmar carpal branch of the ulnar artery
- Superfiicial palmar branch arises just above the wrist and etners the palm of the hand by passing in front of the flexor retinaculum. It joins the terminal part of the ulnar artery to complete the superficial palmar arch.
- Anastomosis around the elbow joint
Applied anatomy:
1. Abberant ulnar artery
2. Examination of radial pulse
3. Volkmann’s ischemic contracture (ischemic compartment syndrome)
4. Suicidal cuts of wrist
