The Arm

Skin

Cross-section through midshaft of humerus

front of arm

front of arm

back of arm

front of arm

back of arm

MEDIAL

front of arm

back of arm

MEDIAL

LATERAL

front of arm

back of arm

MEDIAL

LATERAL

Subcutaneous Fat

front of arm

back of arm

MEDIAL

LATERAL

Humerus

front of arm

back of arm

MEDIAL

LATERAL

HumerusSeptumSeptum

front of arm

back of arm

MEDIAL

LATERAL

Humerus

front of arm

back of arm

MEDIAL

LATERAL

Humerus

Anterior or Flexor Compartment

front of arm

back of arm

MEDIAL

LATERAL

Humerus

Anterior or Flexor Compartment

front of arm

back of arm

MEDIAL

LATERAL

Humerus

Posterior or Extensor Compartment

Anterior or Flexor Compartment

Muscles

3 Muscles in Anterior Compartment

Biceps

3 Muscles in Anterior Compartment

Biceps

Brachialis

3 Muscles in Anterior Compartment

Brachialis

Biceps

Coracobrachialis

3 Muscles in Anterior Compartment

Brachialis

Biceps

Coracobrachialis

front of arm

back of arm

MEDIAL

LATERAL

Humerus

Posterior or Extensor Compartment

Anterior or Flexor Compartment

front of arm

back of arm

MEDIAL

LATERAL

Humerus

Posterior or Extensor Compartment

front of arm

back of arm

MEDIAL

LATERAL

Humerus

Posterior or Extensor Compartment

front of arm

back of arm

MEDIAL

LATERAL

Humerus

Brachialis

Posterior or Extensor Compartment

front of arm

back of arm

MEDIAL

LATERAL

Humerus

Brachialis

Posterior or Extensor Compartment

front of arm

back of arm

MEDIAL

LATERAL

Humerus

Brachialis

BicepsLong Head

Posterior or Extensor Compartment

front of arm

back of arm

MEDIAL

LATERAL

Humerus

Brachialis

BicepsLong Head

BicepsShort Head

Posterior or Extensor Compartment

Nerves

All Muscles of Anterior Arm are innervated by

the

Musculocutaneous Nerve

Lateral fibres of

Brachialisalso receives innervation

from the

Radial Nerve

front of arm

back of arm

MEDIAL

LATERAL

Humerus

Brachialis

BicepsLong Head

BicepsShort Head

Musculocutaneous Nerve

Posterior or Extensor Compartment

front of arm

back of arm

MEDIAL

LATERAL

Brachialis

BicepsLong Head

BicepsShort Head

Radial nerve

Humerus

Posterior or Extensor Compartment

Summary of Muscles

Anterior ArmBiceps Brachii

Origin Short head: tip of coracoid process of scapula; Long head: supraglenoid tubercle of scapula

Insertion Tuberosity of radius and fascia of forearm via bicipital aponeurosis

Action Supinates and flexes forearmNerve Supply Musculocutaneous nerve (C5

and C6) Blood Supply Muscular branches of brachial

artery

Anterior ArmBrachialis

Origin Distal half of anterior surface of humerus

Insertion Coronoid process and tuberosity of ulna

Action Flexes forearm and elbow joint in all positions

Nerve Supply Musculocutaneous nerve (C5, C6) Radial Nerve (C5, C6)

Blood Supply Muscular branches of brachial artery, recurrent radial artery

Anterior ArmCoracobrachialis

Origin Tip of coracoid process of scapula

Insertion Upper half of medial surface of humerus

Action Flexes and adducts armNerve Supply Musculocutaneous nerve (C5,

C6) Blood Supply Muscular branches of brachial

artery