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# Forearm and Hand

### Muscles, clinical correlation, etc.

Question | Answer |
---|---|

What is Colles fracture? | caused by doriflexion of wrist, "dinner fork deformity" |

What happens during colles fraction | -complete transverse fracture of distal radius -distal radial fragment is displaced dorsally -ulnar styloid process may be avulsed Associated injuries: medial and ulnar n. injury, carpal fracture, dislocation of radioulnar joint |

What is the cause, presentation, and associated injury of the smith fracture? | Cased by falling on flexed wrist, complete transverse fracture of distal radius, distal radial fragemnt is displaced ventrally, ulnar styloid process maybe avulsed acoociated injure: acute carpal tunnel syndrome, compressive neuropathy, ishemia |

What are the 8 carpal bones of the wrist? | Scapoid, lunate, triquetrium, pisimform, trapezium, trapezoid, capitate, and hamat |

What happens w/ scaphoid fracture? | pain and tenderness in the anatomial suffbox, could get avascular necrosis: damage to the palmar carpal branch of radial artery |

What happens w/ hamate fracture? | Hamat fracture can compress the ulnar nerve, leading to loss of sensation in the medial half of digit 4 and digit 5 |

What's so special bout the capometacarparl joint of digit 1? | saddle-type of synovial joint b/w trapezium and 1st base of metacarpal. Has a separate joint cavity--allows for movement in multiple planes |

Difference b/w MCP and PIP/DIP? | MCP: synovial joint, condyloid type, allows flexion/extension, and abduction/adduction PIP/DIP: synocial joints, hinge type, allow only flexion/extension |

What is mallet finger and how does it present? | "baseball finger", long extensor tendon avulsion presentation: hyperflexion at the DIP, inability to extend DIP |

Interosseous membrane separates forearm into anterior and posterior compartments, what are contents of each of compartment? | Anterior: flexors and pronators, largely median and some ulnar nerve innervation Posterior: extensors and supinators, radial nerve innervation |

What is antebrachial fascia? | thickens around wrist, anteriorly as the palmar carpal ligament and felxor retinaculum posteriorly as extensor retinculum prevents bowstringing of muscle tendons |

flexor retinacular (transverse carpal ligament) converts the concavity formed by carpal bones into the carpal tunnel, what are the contents of tunnel and fxn of tendon? | Contents: Median N. Flexor difitorum superficialis, flexor pollicis longus, flexor digitorum profundus Fxn: prevents bowstringing of tendon |

What is palmar aponeurosis? | strong covering of the soft tissues, overlies the long tendons, contributes to the flexor tendon sheaths distally |

What is dpuytren contracture? | Fascial thickening causes shortening on the medial side of hand You get Flexion at metacarpophalangeal and proximal interphalangeal joints |

What are the anterior muscles of the forearm? | Superfical: Pronator tere, flexor carpi radialis, palmaris longus, flexor carpi ulnaris intermediate: flexor digitorum superficialis deep: flexor pollicis longus, flexor digitorum profundus, pronator quadratus |

What do the superficial muscles of forearm orginate from? | common flexor tendon--attached to the emdial epicondyle of humerrus |

What is the origin, insertion, action, and innervation of the pronator teres? | Origin Humeal head: Medial epicondyle (via common flexor tendon) Ulnar head: coronoid process Insertion Middle portion of lateral radius Action Pronates and flexes forearm (at elbow) Innervation Median nerve |

What is the origin, insertion, action, and innervation of the flexor carpi radialis? | Origin Medial epicondyle (via common flexor tendon) Insertion Base of 2nd metacarpal Action Flexes and abducts hand at wrist Innervation Median nerve |

What is the origin, insertion, action, and innervation of the palmaris longus? | Origin Medial epicondyle (via common flexor tendon) Insertion Palmar aponeurosis (apex) and flexor retinaculum Action Flexes hand (at wrist); tenses palmar aponeurosis Innervation Median nerve |

What is the origin, insertion, action, and innervation of the flexor carpi ulnaris | Origin Humeral head: Medial epicondyle (via common flexor tendon), Ulnar head: Olecranon process Insertion Pisiform, hook of hamate, 5th metacarpal Action Flexes and adducts (ulnar deviation) hand (at wrist) Innervation Ulnar nerve |

What is the origin, insertion, action, and innervation of the Flexor digitorum superficialis? | Origin Humeroulnar head: Medial epicondyle, coronoid process Radial head: Superior portion of radius Insertion Intermediate phalanx, digits 2-5 Action Flexes middle phalanges at the PIP of digits 2-5; may assist flexion of proximal phalanges at |

What is the origin, insertion, action, and innervation of the Felxor digitorum profundus? | Origin Proximal ulna and interosseous membrane Insertion Bases of distal phalanx of digits 2-5 Action Flexes distal phalanges at the DIP of digits 2-5 Innervation Digits 2-3: Anterior interosseous nerve (branch of median nerve) Digits 4-5: U |

What is the origin, insertion, action, and innervation of the Flexor pollicis longus? | Origin Radius, interosseous membrane Insertion Base of distal phalanx of digit 1 (pollex) Action Flexes phalanges of digit 1 Innervation Anterior interosseous nerve (a branch of the median nerve) |

What is the origin, insertion, action, and innervation of the pronator quadratus? | Origin Distal ulna Insertion Distal radius Action Pronates forearm; bind radius and ulna together Innervation Anterior interosseous nerve (a branch of the median nerve) |

What are muscles of the Posterior comparment innervated by? | radial n. |

What is the origin, insertion, action, and innervation of the Brachioradialis | Origin Supracondylar ridge of humerus Insertion Distal lateral radius Action Flexes (weakly) forearm at elbow, but strong in mid-pronated position Innervation Radial nerve |

What is the origin, insertion, action, and innervation of the extensor carpi radialis longus | Origin Supracondylar ridge of humerus Insertion Base of 2nd metacarpal Action Extend and abduct (radial deviation) the hand at the wrist, also active during fist clenching Innervation Radial nerve |

What is the origin, insertion, action, and innervation of the brachioradialis? | Origin Lateral epicondyle Insertion Base of 3rd metacarpal Action Extend and abduct (radial deviation) the hand at the wrist Innervation Deep branch of radial nerve |

What is the origin, insertion, action, and innervation of the Extensor digitorum | Origin Lateral epicondyle Insertion Extensor expansion of digits 2-5 Action Primary extension at metacarpophalangeal joint digits 2-5 Secondary extension at interphalangeal joints (distal, middle and proximal phalanges) innerva: deep branch |

What is the origin, insertion, action, and innervation of the Extensor digiti minimi | Origin Lateral epicondyle Insertion Extensor expansion of digit 5 Action Primary extension at metacarpophalangeal joint digit 5 Secondary extension at interphalangeal joints for digit 5 inv: deep branch radial n. |

What is the origin, insertion, action, and innervation of the Extensor carpi ulnaris | Origin 2 heads: Lateral epicondyle, and posterior border of ulna Insertion Base of 5th metacarpal Action Extends and adducts (ulnar deviation) the hand at wrist Innervation Deep branch of radial nerve |

What is the origin, insertion, action, and innervation of the supinator? | Origin Lateral epicondyle, radial collateral and annular ligament, ulna Insertion Proximal 1/3 of the radius Action Supinates forearm Innervation Deep branch of radial nerve |

What is the origin, insertion, action, and innervation of the abductor pollicis longus | Origin Proximal ½ of posterior ulna, radius, and interosseous membrane Insertion Base of 1st metacarpal Action Abducts thumb and extends it at carpometacarpal joint Innervation Posterior interosseous nerve (continuation of deep branch of radi |

What is the orgin, insertion, action, and innervation of the extensor pollicis brevis? | Origin Distal 1/3 of posterior radius and interosseous membrane Insertion Base of proximal phalanx of Digit 1 Action Extends proximal phalanx of thumb at the MCP joint; also extends CMC joint Innervation Posterior interosseous nerve (radial |

What is the origin, insertion, action, and innervation of the extensor pollicis longus? | Origin Middle 1/3 of posterior ulna and interosseous membrane Insertion Base of distal phalanx of Digit 1 Action Extends distal phalanx of thumb at interphalangeal joint; extends CMC and MCP joints Innervation Posterior interosseous nerve |

What is the origin, insertion, action, and innervation of the extensor indicis? | Origin Distal 1/3 of posterior ulna and interosseous membrane Insertion Extensor expansion of digit 2 Action Extends proximal phalanx of digit 2, also extends hand at wrist Innervation Posterior interosseous nerve |

3 thenar muscles? | opponens pollicis, abductor pollicis brevis, flexor pollicis brevis |

Abductor pollicis brevis? | Origin Flexor retinaculum, tubercles of scaphoid and trapezium Insertion Lateral side of proximal phalanx of digit 1 Action Abduction of the thumb Innervation Recurrent branch of median nerve |

FLexor pollicis brevis? | Origin Flexor retinaculum, tubercles of scaphoid and trapezium Insertion Lateral side of base of 1st proximal phalanx Action Flexes thumb Innervation Recurrent branch of median nerve |

pponens pollicis? | Origin Flexor retinaculum, tubercles of scaphoid and trapezium Insertion Lateral side of 1st metacarpal Action Opposition towards digit 5 Innervation Recurrent branch of median nerve |

3 hypothenar muscles? | abductor digiti minimi, flexor digiti minimi brevis, opponens difiti minimi |

Abductor digiti minimi | Origin Pisiform Insertion Medial side of base of 5th proximal phalanx Action Abduction of digit 5 Innervation Deep branch of ulnar nerve |

Flexor digiti minimi brevis | Origin Hook of hamate and the flexor retinaculum Insertion Medial side of base of 5th proximal phalanx Action Flexes proximal phalanx of digit 5 Innervation Deep branch of ulnar nerve |

opponens digiti minimi | Origin Hook of hamate and the flexor retinaculum Insertion Medial border of 5th MC Action Opposition towards digit 1 Innervation Deep branch of ulnar nerve |

Adductor pollicis (adductor muscle) | Origin Oblique head: bases of 2nd and 3rd MCs, capitate and adjacent carpals Transverse head: Anterior surface of 3rd MC Insertion Medial side of base of digit 1’s proximal phalanx Action Adducts thumb towards ulnar n. innv. |

origin, insertion, action of 4 lumbricals | Origin Tendons of flexor digitorum profundus Insertion Lateral sides of extensor expansions of 2nd-5th digits Action Flex metacarpophalangeal joint, extend interphalangeal joints of digits 2-5 |

What is the innervationo fthe 4 lumbricals | Lumbricals 1 & 2: Median nerve (medial and lateral branches) Lumbricals 3 & 4: Deep branch of ulnar nerve |

3 palmar interossei? | Origin Palmar surfaces of 2nd, 4th, and 5th MCs (unipennate) Insertion 2nd, 4th, and 5th proximal phalanges and extensor expansions Action Adduction of 2nd, 4th, 5th digits and flexion of the MCP joint Innervation Deep branch of ulnar nerve |

4 dorsal interossei? | Origin Adjacent surfaces of MCs Insertion Digits 2-4, bases of proximal phalanges & extensor expansion Action Abduction of digits 2-4 and flexion at the metacarpophalangeal joint Innervation Deep branch of ulnar nerve |