Upper Extremity Muscles

Upper Extremity Muscles II

Compartments

• Divided by lateral and medial intermuscular septum

• Anterior and posterior

• Anterior compartment

• 3 nerves:

• Ulnar
• Medial
• Musculocutaneous

• Terminates anterior part of brachium

• Biceps brachii (brachium)

• Two heads:

• Long: biarticular (crosses 2 joints) muscle → cant be an agonist

• Always a synergist

• Assists brachialis in elbow flexion

• Supraglenoid tube

• Short

• Coracoid process

• Forearm supination, assists elbow flexion
• Musculocutaneous nerve

• Brachialis

• Primary elbow flexor

• Agonist for elbow flexion

• Musculocutaneous nerve

• Coracobrachialis

• Assists in shoulder flexion and adduction
• Fixator for elbow flexion

• Fixes shoulder joint so only elbow flexion occurs

• Musculocutaneous nerve

• Posterior compartment

• Supplied by radial nerve
• Triceps brachii

• Three heads:

• Long- infraglenoid tubercle

• Biarticular → crosses shoulder and elbow joint

• Lateral-posterior humerus superior to radial groove

• Uniarticular

• Medial- posterior humerus inferior to radial groove

• uniarticular

• Elbow Extensor→Agonist
• Antagonist for elbow flexion

• Radial nerve

• Anconeus

Compartments of the Forearm

• Anterior/posterior intermuscular septum
• Interosseous membrane
• Anterior compartment

• All flexors (flex wrist and fingers)
• Forearm flexors
• Pronators

• Posterior compartment

• All extensors (extend wrist and digits)
• Forearm extensors
• Supinators

Compartments

• Anterior (flexor/ pronator)

• Supplied by median nerve
•  1 ½ exceptions by ulnar

• 1 flexor (anterior)
• ½ flexor digitorum profundus  (½ ulnar, ½ median)

• Posterior (extensor/ supinator)

• Supplied by radial nerve

• Radial takes care of everything in posterior

Anterior

Flexor Carpi Radialis

• Wrist flexion, radial deviation
• Median nerve

Flexor Capri Ulnaris

• Wrist flexion, ulnar deviation
• Ulnar nerve

Posterior

Extensor carpi Radialis Longus

• Wrist extension, radial deviation
• Radial nerve

Extensor Carpi Ulnaris

• Wrist extension, ulnar deviation
• Radial nerve

Flexion and Extension occurs on the sagittal plane alone the Medial/ Lateral Axis

Flex/ext are both anterior to the medial lateral axis

Abduction→Radial Deviation

Adduction→Ulnar Deviation