Flexor digitorum superficialisO: Medial epicondyle of humerus

ulnar head: medial coronoid processradial 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 (1st)

• “indicis” – index finger (2nd)

• “pollicis” and “indicis” exclusive to wrist and fingers

Flexor digitorum profundusO: Proximal ¾ anterior and medial ulnaI: Base of distal phalanx of four fingersA: Flexion of four fingers at MCP, PIP, and DIP joints, wrist flexion

Flexor pollicis longusO: Middle anterior surface of radius and anterior medial border of ulna distal to coronoid processI: 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 indicisO: Middle to distal 1/3 of posterior ulnaI: Base of middle and distal phalanxes of 2nd

phalange (dorsal surface)A: Extension of index finger at MCP joint,

weak wrist extension, weak supination of forearm from pronated position

Extensor pollicis longusO: Posterior lateral surface of lower middle ulnaI: 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 brevisO: Posterior surface lower middle radiusI: Base of proximal phalanx of thumb (dorsal surface)A: Extension of thumb at CMC and MCP joint, weak wrist extension and abduction

Abductor pollicis longusO: Posterior aspect of radius and midshaft of ulnaI: Base of 1st 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) Fv = 0

2) Fh = 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:

dm = 3 cm = 0.03 m

dwt = 30 cm = 0.3 m

wt = 70 N

Fm = ?

T = 0

T = (Fm)(dm) - (wt)(dwt) = 0

m

wtm d

)d)(wt(F

N 700m 03.0

)m 30.0)(N 70(Fm

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