ANAT337-L Forearm & Hand

Radius

forearm bone that is more lateral

Ulna

forearm bone that is more medial; monkey wrench shaped

2

How many radioulnar joints are there?

Proximal radioulnar joint

pivot joint where main mechanism of pronation occurs

Pronation

movement resulting from the crossing of the radius over the ulna

Elbow joint

comprised of humeroradial joint, humeroulnar joint, and proximal radioulnar joint (ligaments include radial collateral ligament, ulnar collateral ligament, and annular ligament)

Posterior elbow dislocation

this dislocation often occurs from the FOOSH mechanism

requires professional help because neurovasculature in cubital fossa

Nursemaid’s elbow

radial head dislocation that occurs often in children, because bones are smaller and not yet fully ossified (i.e. swinging child around by hands)

Capitulum

 part of the humerus that articulates with the head of the radius

Trochlea

part of the humerus that articulates with the ulna

Radiocarpal joint

contains radius, scaphoid, and lunate bones; true wrist joint

Scaphoid fracture

most commonly fractured wrist bone, also by FOOSH mechanism

has poor blood supply, so bone can die off when broken

Pronator teres

anterior superficial muscle of forearm

• action: pronates forearm

• origin: medial epicondyle of humerus

• innervation: median nerve

Flexor carpi radialis

anterior superficial muscle of forearm

• action: flexes wrist and abducts hand

• origin: medial epicondyle of humerus

• innervation: median nerve

Palmaris longus

anterior superficial muscle of forearm *superficial to retinaculum

• action: weak wrist flexor

• origin: medial epicondyle of humerus

• innervation: median nerve

Flexor retinaculum

band of tissue holding down flexor tendons

adds a mechanical advantage for grip strength by holding them tight to joint

Flexor carpi ulnaris

anterior superficial muscle of forearm

• action: flexes wrist and adducts hand

• origin: medial epicondyle of humerus

• innervation: ulnar nerve

Flexor digitorum superficialis

anterior intermediate muscle of forearm

• action: flexes wrist, 2nd-5th MP joints, and PIP joints

• origin: medial epicondyle of humerus

• insertion: middle phalanges of fingers 2-5

• innervation: median nerve

Pronator quadratus

anterior deep muscle of forearm

• action: pronates forearm

• innervation: median nerve

Flexor pollicis longus

anterior deep muscle of forearm

• action: flexes MP joint of thumb, IP joint of thumb

• insertion: distal phalanx of thumb

• innervation: median nerve

Flexor digitorum profundus

anterior deep muscle of forearm

• action: flexes wrist, 2nd-5th MP joints, PIP joints, and DIP joints

• insertion: distal phalanges of fingers 2-5

• innervation: lateral = median nerve, medial = ulnar nerve

Extensor carpi radialis longus

posterior superficial muscle of forearm

• action: extends wrist, abducts hand

• innervation: radial nerve

Extensor carpi radialis brevis

posterior superficial muscle of forearm

• action: extends wrist, abducts hand

• origin: lateral epicondyle of humerus

• innervation: radial nerve

Extensor digitorum

posterior superficial muscle of forearm

• action: extends wrist, 2nd-5th MP joints, PIP joints, and DIP joints

• origin: lateral epicondyle of humerus

• innervation: radial nerve

Extensor digiti minimi

posterior superficial muscle of forearm

• action: extends wrist, MP, and PIP joints of finger 5

• origin: lateral epicondyle of humerus

• innervation: radial nerve

Extensor carpi ulnaris

posterior superficial muscle of forearm

• action: extends wrist, adducts hand

• origin: lateral epicondyle of humerus

• innervation: radial nerve

Abductor pollicis longus

posterior deep muscle of forearm

• action: abducts thumb

• innervation: radial nerve

Extensor pollicis brevis

posterior deep muscle of forearm

• action: extends MP joints of thumb

• innervation: radial nerve

Extensor pollicis longus

posterior deep muscle of forearm

• action: extends MP and IP joints of thumb

• innervation: radial nerve

Extensor indicis

posterior deep muscle of forearm

• action: extends MP, PIP, and DIP joints of finger 2

• innervation: radial nerve

Supinator

posterior deep muscle of forearm

• action: supinates forearm

• origin: lateral epicondyle of humerus

• innervation: radial nerve

medial epicondyle; lateral epicondyle

Elbow flexors are often attached to the ___. Elbow extensors are often attached to the ___.

Coronal

What plane does thumb flexion/extension occur in?

sagittal

What plane does thumb abduction/adduction occur in?

Flexor pollicis brevis

member of thenar group

• action: flexes thumb

• innervation: median nerve

Abductor pollicis brevis

member of thenar group

• action: abducts thumb

• innervation: median nerve

Opponens pollicis

member of thenar group

• action: opposes thumb

• innervation: median nerve

Flexor digiti minimi brevis

member of hypothenar group

• action: flexes finger 5

• innervation: ulnar nerve

Abductor digiti minimi

member of hypothenar group

• action: abducts finger 5

• innervation: ulnar nerve

Opponens digiti minimi

member of hypothenar group

• action: opposition of finger 5

• innervation: ulnar nerve

Lumbricals

member of midpalmar group

• action: flexes 2-5 MP joints and extends 2-5 PIP/DIP joints

• innervation: lateral 2 = median nerve, medial 2 = ulnar nerve

Dorsal interossei

member of midpalmar group

• action: abducts fingers 2-5

• innervation: ulnar nerve

Palmar interossei

member of midpalmar group

• action: adducts fingers 2-5

• innervation: ulnar nerve

Adductor pollicis

member of midpalmar group

• action: adducts thumb

• innervation: ulnar nerve

Carpal tunnel syndrome

reduced space in this area (often resulting from inflammation of flexor tendons) can cause compression of median nerve