DR2: Arm and brachial plexus Flashcards
What are the 3 flexor muscles of the arm?
Biceps brachii
Coracobrachialis
Brachialis
What is the origin, insertion and function of biceps brachii?
Origin: supraglenoid tubercle of scapula (long head), coracoid process (short head)
Insertion: radial tuberosity
Function: flexion at shoulder and elbow, supinator of forearm
What is bicipital aponeurosis?
Extension of biceps tendon
Crosses medially over superficial flexors of forearm to attach to posterior border of ulna via deep fascia
What is the origin, insertion and function of coracobrachialis?
Origin: coracoid process
Insertion: medial aspect of humerus, halfway down shaft
Function: flexion at shoulder
What is the origin, insertion and function of brachial?
Origin: distal half of anterior of humerus
Insertion: ulna tuberosity
Function: flexion at elbow
What muscles are in the posterior compartment of the arm?
Triceps brachii
What is the origin, insertion and function of triceps brachii?
Origin: infraglenoid tubercle (long head), posterior aspect of humerus above spiral groove (lateral head), posterior aspect of humerus below spiral groove (medial head)
Insertion: olecranon process of ulna
Function: extension
What are the roots of the brachial plexus?
C5 C6 C7 C8 T1
What branches come from the lateral cord?
Lateral pectoral nerve
Lateral head median nerve
Musculocutaneous nerve
What does the lateral pectoral nerve supply?
Pectoral muscles
Describe the path of the musculocutaneous nerve
Pierces coracobrachialis 5cm distal to conjoint tendon
Emerges on lateral aspect just above elbow
What is a terminal branch of the musculocutaneous nerve?
Lateral cutaneous nerve of forearm
What does the lateral cutaneous nerve of the forearm supply?
Skin of lateral forearm on dorsal and ventral aspects
What are the branches of the medial cord?
Medial pectoral nerve
Cutaneous nerves of arm and forearm
Ulnar nerve
Medial head median nerve
What does the medial pectoral nerve supply?
Pectoralis muscles
What does the ulnar nerve supply?
Flexor muscles of forearm and small muscles in the hand
What does the median nerve supply?
Muscles in the anterior compartment of the arm (flexors)
What are the branches of the posterior cord?
Upper subscapular Thoracodorsal Lower subscapular Radial nerve Axillary nerve
What does the radial nerve supply?
muscles and skin over posterior aspect of upper limb, triceps and extensor muscles of forearm
Describe the path of the radial nerve
Leaves axilla into posterior compartment. spirals laterally around shaft of humerus on medial side of triceps, through spiral groove then into anterior compartment under muscles on lateral side of foreaem
What does the axillary nerve supply?
Teres minor
Deltoid
Badge area of skkin
What forms the quadrangular space?
Borders of teres minor, teres major, humerus and long head of triceps
What is the stem artery to the upper limb?
Subclavian artery
What does the right subclavian branch from?
Brachiocephalic trunk
What does the left subclavian branch from?
Arch of aorta
What happens to the subclavian artery as it passes over the 1st rib?
It becomes the axillary artery
When does the axillary become the brachial artery?
When it crosses lower border of teres major
What is a major branch of the brachial artery?
Profunda brachii artery which supplies triceps and elbow joint
