Flexor digitorum superficialis O:Medial epicondyle of humerus ulnar head: medial coronoid process radial head: upper 2/3 of anterior border of radius just distal to radial tuberosity I:sides of middle phalanx of four digits (palmar surface) A:Flexion of fingers at MCP and PIP joints, flexion of wrist, weak flexion of elbow

Intermediate Layer (Anterior) Flexor digitorum superficialis

Movements of the Thumb Flexion and Extension Abduction and Adduction

Helpful Hints “pollicis” – thumb (1 st ) “indicis” – index finger (2 nd ) “pollicis” and “indicis” exclusive to wrist and fingers

Flexor digitorum profundus O:Proximal ¾ anterior and medial ulna I:Base of distal phalanx of four fingers A:Flexion of four fingers at MCP, PIP, and DIP joints, wrist flexion

Flexor pollicis longus O: Middle anterior surface of radius and anterior medial border of ulna distal to coronoid process I: Base of distal phalanx of thumb (palmar surface) A: flexion of thumb CMC, MCP, IP joints, flexion, abduction of wrist

Deep Layer (Anterior) Flexor digitorum profundus Flexor pollicis longus *Pronator Quadratus

Extensor indicis O: Middle to distal 1/3 of posterior ulna I: Base of middle and distal phalanxes of 2 nd phalange (dorsal surface) A: Extension of index finger at MCP joint, weak wrist extension, weak supination of forearm from pronated position

Extensor pollicis longus O: Posterior lateral surface of lower middle ulna I: Base of distal phalanx of thumb (dorsal surface) A: Extension of thumb at CMC, MCP, and IP joints, wrist extension and abduction, weak supination from a pronated position

Extensor pollicis brevis O: Posterior surface lower middle radius I: Base of proximal phalanx of thumb (dorsal surface) A: Extension of thumb at CMC and MCP joint, weak wrist extension and abduction

Abductor pollicis longus O: Posterior aspect of radius and midshaft of ulna I: Base of 1 st metacarpal (dorsal surface) A: Abduction and extension of thumb at CMC joint, abduction of wrist, weak supination of forearm from a pronated position

Deep Layer (Posterior) Extensor indicis Extensor pollicis longus Extensor pollicis brevis Abductor pollicis longus *Supinator

Static Equilibrium Whenever an object is completely motionless, it is in static equilibrium For an object to be in static equilibrium: 1)  F v = 0 2)  F h = 0 3)  T = 0

Example: How much force must be exerted by the biceps brachii, attaching at 90º to the radius at 3 cm from the elbow joint, to support a weight of 70 N held in the hand, a distance of 30 cm from the elbow joint?

Known: d m = 3 cm = 0.03 m d wt = 30 cm = 0.3 m wt = 70 N F m = ?

 T = 0  T = (F m )(d m ) - (wt)(d wt ) = 0

Example: How much force must be exerted by the biceps brachii, attaching at 100º to the radius at 3 cm from the elbow joint, to support a weight of 70 N held in the hand, a distance of 30 cm from the elbow joint?

Carpal Tunnel Syndrome Swelling of tissue within the compartment causes compression on the median nerve Symptoms include: –Pain and numbness along the median nerve –Clumsiness of finger function –Weakness and atrophy of muscles Most common in middle-aged women or older

Carpal Tunnel

Mechanism of Injury