Extensor Forearm and Dorsum of Hand Flashcards
Interosseus Membrane
- Dense CT
- Partially divides forearm into flexor and extensor compartments
Antebrachial Fascia
- Deep fascia of the forearm
Posterior Compartment
- Most originate via a common extensor tendon on lateral epicondyle
- Action: extensors of wrist
-
Except:
- Brachioradialis: flexes elbow
- Suppinator (wraps around head of radius)
-
Except:
- Innervation: Radial n.
- Superficial branch (sensory)
- Deep Branch/Posterior Interosseus (motor)
- Blood Supply:
- Posterior Interosseus a.
- Anterior interosseous a. (distal part)
Brachioradialis
Innervation:
- Radial n.
Attachments:
- Humerus to distal radius
Action:
- Flexes elbow during pronation
Extensor Carpi Radialis Longus
Innervation:
- Radial n.
Insertion:
- Base of 2nd metacarpal
Action:
- Extend and ABduct the wrist
Extensor Carpi Radialis Brevis
Innervation:
- Radial n.
Insertion:
- Base of the 3rd metacarpal
Action:
- Extends and ABduct wrist
Extensor Digitorum
Innervation:
- Radial n.
Action
- Extends all wrist and MP joints (digits 2-5)
Extensor Digiti Minimi
Innervation:
- Radial n.
Insertion:
- Extensor expansion 5th digit
Action:
- Extends 5th digit
Extensor Carpi Ulnaris
Innervation:
- Radial n.
Insertion:
- Base of 5th metacarpal
Action:
- Extend and ADduct wrist
Supinator
Innervation:
- Radial n.
Action:
- Suppinates forearm
Abductor Pollicis Longus
Innervation:
- Radial n.
Insertion:
- Base of 1st metacarpal
Action:
- Abducts thumb
Extensor Pollicis Longus
Innervation:
- Radial n.
Insertion:
- Distal phalanx of thumb
Action:
- Extends thumb and wrist
Extensor Pollicis Brevis
Innervation:
- Radial n.
Insertion:
- Proximal phalanx of thumb
Action:
- Extends thumb and wrist
Extensor Indicis
Innervation:
- Radial n.
Insertion:
- Extensor expansion of 2nd digit
Action:
- Independently extends digit 2
Anatomic Snuff Box
- Lateral side of wrist
- Bounded by tendons of:
- Abductor pollicis longus
- Extensor pollicis brevis
- Extensor pollicis longus
- Radial a. travels through here
- Scaphoid bone forms floor
Scaphoid Fracture
- Distal, Waist or Proximal fracture
- Clinical Relevance: lose blood supply due to proximal fracture requires screw back together
Lateral Forearm Cutaneous Innervation
- Lateral cutaneous nerve of forearm (continuation of musculocutaneous)
Medial Cutaneous Innervation of Forearm
- Medial cutaneous nerve of forearm (from medial cord)
Posterior Cutaneous Nerve of Forearm
- Superficial branch of radial n.
Branches of Radial Nerve
Deep Branch of Radial:
- MOTOR
- After it pierces supinator is renamed posterior interosseous n.
Superficial Branch of Radial:
- Sensory only
- Deep to brachioradialis
- Lateral/dorsal hand
Where is the radial n. prone to injury?
- Axilla
- Fracture shaft of humerus
Where is deep branch of radial n. prone to injury?
- Fracture neck of radius
- Subluxation of head of radius (pierces supinator which wraps around head of radius)
Where is superficial branch of radial n. prone to inury?
- Wound to forearm (through brachioradialis)
Injury to deep branch of radial n.
- Problems:
- Extending wrist
- Abducting thumb
- Extending thumb
- Suppination
Injury to superficial branch of radial n.
- Sensory loss to posterior/lateral hand
What symptoms will you experience if you injure the radial n. in the cubital fossa or along the humeral shaft?
What symptons will you experience if you injure the radial nerve in the axilla?
