Upper Extremity: Forearm Flashcards
Forearm
- Elbow to wrist
- Radius and ulna
- Connected by interosseous membrane
- Divided into compartments by deep fascia and interossesous membrane
- Muscles primarily are involved in wrist and finger movement (also elbow)
Interosseous Membrane of Forearm
- Syndesmosis: fibrous joint that permits some movement
- Separates compartments
- Muscle attachment
Syndesmosis
- Fibrous joint that permits some movement
Proximal Joints of Forearm (Elbow Joint)
- Humeroradial
- Humeroulnar
- Proximal radioulnar
Distal Joints of Forearm
- Distal radioulnar
- Radiocarpal
Anterior Forearm Functions
- Flexors and pronators
Anterior Forearm Innervation
- Median nerve
- 1 ½ by ulnar
Anterior Forearm Muscle Origination
- Medial epicondyle
- Anterior surface of radius, ulna, interosseous membrane
Posterior Forearm Functions
- Extensors and supinators
Posterior Forearm Innervation
- Radial nerve or one of its branches
Posterior Forearm Muscle Origination
- Lateral epicondyle
- Supracondylar ridge
- Posterior surface of radius, ulna, interosseous membrane
Anterior Compartment Muscles
- 8 muscles
- Some have multiple “heads”
- 3 layers
Superficial (1st) Layer Muscles of Anterior Compartment
- Pronator teres
- Flexor carpi radialis
- Palmaris longus
- Flexor carpi ulnaris
Intermediate (2nd) Layer Muscle of Anterior Compartment
- Flexor digitorum superficialis
Deep (3rd) Layer Muscles of Anterior Compartment
- Flexor digitorum profundus
- Flexor pollicis longus
- Pronator quadratus
Superficial Layer Muscles Proximal Attachment
- All have proximal attachment to medial epicondyle via common flexor tendon
Flexor Carpi Ulnaris and Pronator Teres
- Both have 2 heads
Superficial Layer Muscle Innervation
- All innervated by median nerve
- EXCEPT FCU (innervated by ulnar nerve)
Flexor Carpi Radialis Distal Attachment
- Base of 2nd metacarpal
Flexor Carpi Radialis Function
- Wrist (hand) flexion and abduction
Palmaris Longus Distal Attachment
- Flexor retinaculum and palmar aponeurosis
Palmaris Longus Function
- Tenses palmar aponeurosis (wrist flexion?)
Flexor Carpi Ulnaris Proximal Attachment
- Humeral head: medial epicondyle (via common flexor tendon)
- Ulnar head: olecranon and posterior ulnar border
Flexor Carpi Ulnaris Distal Attachment
- Pisiform
- Hook of hamate
- 5th metacarpal
Flexor Carpi Ulnaris Function
- Wrist flexion and adduction
Pronator Teres Proximal Attachment
- Ulnar head: coronoid process
- Humeral head: medial epicondyle (via common flexor tendon) and medial supracondylar ridge
Pronator Teres Distal Attachment
- Lateral radius
Pronator Teres Function
- Pronation
Median Nerve Passes
- Deep to bicipital aponeurosis (lacertus fibrosus)
- Between the 2 heads of pronator teres
- Both are potential sites of entrapment
Flexor Digitorum Superficialis Proximal Attachment
- Humero-ulnar head: medial epicondyle (common flexor tendon) and coronoid process
- Radial head: anterior surface of proximal radius
Flexor Digitorum Superficialis Distal Attachment
- Base of middle phalanges of digits 2-5
Flexor Digitorum Superficialis Innervation
- Median nerve
Flexor Digitorum Superficialis Function
- Flexes proximal interphalangeal joint and MCP joint
Median Nerve and Ulnar Artery Pass
- Deep to flexor digitorum superficialis (FDS)
Flexor Digitorum Profundus Proximal Attachment
- Proximal ulna/interosseous membrane
Flexor Digitorum Profundus Distal Attachment
- Bases of distal phalanges 2-5
Flexor Digitorum Profundus Innervation
- Ulnar nerve: medial half (digits 4,5)
- Anterior interosseous nerve (median), lateral half (digits 2,3)
Flexor Digitorum Profundus Function
- Flexes distal interphalangeal joints of 2-5
Flexor Pollicis Longus Proximal Attachment
- Anterior radius
- Interosseous membrane
Flexor Pollicis Longus Distal Attachment
- Base of distal phalanx of thumb
Flexor Pollicis Longus Innervation
- Anterior interosseous nerve
Flexor Pollicis Longus Function
- Flexes interphalangeal joint of thumb
Pronator Quadratus Proximal Attachment
- Distal anterior ulna
Pronator Quadratus Distal Attachment
- Distal anterior radius
Pronator Quadratus Innervation
- Anterior interosseous nerve
Pronator Quadratus Function
- Pronation
8 Tendons of FDS and FDP Pass Through Carpal Tunnerl
- Deep to flexor retinaculum (transverse carpal ligament)
- Surrounded by a synovial sheath as they pass through the wrist (ulnar bursa)
Tendon of FPL Passes Through Carpal Tunnel
- Has its own synovial sheath (radial bursa)
Posterior Compartment Muscles of the Forearm
- 11 muscles
- 2 layers
- Innervated by radial nerve or a branch of radial nerve
Superficial Posterior Compartment Muscles of Forearm
- Brachioradialis
- Extensor carpi radialis longus
- Extensor carpi radialis brevis
- Extensor digitorum
- Extensor digiti minimi
- Extensor carpi ulnaris
Deep Posterior Compartment Muscles of Forearm
- Supinator
- Extensor indicis
- Abductor pollicis longus
- Extensor pollicis brevis
- Extensor pollicis longus