Posterior compartment

muscles

Triceps

Origin

· long head (medial)

· infraglenoid tubercle at upper end of axillary border of scapula

· lateral head

· back of humerus

· from surgical neck to deltoid insertion

· medial head (deep)

· medial side of radial groove of humerus

· whole posterior surface of humerus below groove

· medial and lateral intermuscular septa

Path

· long and lateral head

· converge into flattened tendon

· tendon lies superficial to medial head

Insertion

· long and lateral head

· posterior part of upper surface of olecranon

· medial head

· into superficial tendon

· into olecranon directly

Nerve supply

· radial nerve (C7,8)

· by 4 branches that arise well above muscle

· 2 in axilla (long and medial)

· 2 in radial groove (lateral and medial)

nerves and vessels

Radial nerve

· leaves axilla through lower triangular space

· with profunda brachii vessels

· spirals behind humerus

· from medial to lateral

· lies in radial groove

· separated from bone by fibres of medial head

· pierces lateral IM septum

· enters anterior compartment

· crosses cubital fossa

· under brachioradialis

Profunda brachii artery

· accompanies radial nerve

· divides into anterior and posterior branches at lateral IM septum

· join cubital anasomosis

Ulnar nerve

· lies in contact with bone in groove behind medial epicondyle

· then against medial ligament of elbow joint

· then passes between 2 heads of FCU to enter forearm