Limbs 2 Flashcards
What is a nerve plexus?
- multi-segmental peripheral nerves
- formed by the merging and splitting of peripheral spinal nerve roots
What are the 3 nerve plexuses?
- cerival plexus
- brachial plexus
- lumbo-sacral plexus (split into lumbar plexus and sacral plexus)
What is the upper limb innervated by?
Brachial plexus
What is the lower limb innervated by?
Lumbo-sacral plexus
What are the 5 roots of the brachial plexus?
C5, C6, C7, C8 and T1
What are the 3 trunks of the brachial plexus and which roots are they formed from?
- superior trunk (C5 and C6)
- middle trunk (C7)
- inferior trunk (C8, T1)
What do each of the trunks divide into?
Anterior and posterior divisions, making 6 divisions in total
What are the 3 cords of the brachial plexus and what do they form from?
- lateral cord (anterior division of superior and medial trunk)
- medial cord (anterior division of inferior trunk)
- posterior cord (all three posterior divisions)
How are the cords of the brachial plexus named?
According to their relationship to the axillary artery
What are the two main groups of nerves from the brachial plexus?
- supraclavicular branch (branch from the roots and the trunks)
- infraclavicular nerves (branches from distal part of BP to pectoral girdle muscles and the main peripheral nerves)
What are the two sub-groups of the infraclavicular nerves?
- side branches
- large terminal branches
Which nerves make up the brachial plexus? (14/16)
- dorsal scapular nerve
- nerve to subclavius
- suprascapular nerve
- lateral pectoral nerve
- thoracodorsal nerve
- musculocutaneous nerve
- axillary nerve
- radial nerve
- median nerve
- ulnar nerve
- medial cutaneous nerves of arm and forearm
- medial pectoral nerve
- upper and lower subscapular nerves
- long thoracic nerve
What is the musculocutaneous nerve?
- terminal branch of the lateral cord
- muscluar innervation to anterior muscles of the arm
- cutaneous innervation of the lateral forearm
What is the route of the musculocutaneous nerve?
- exits the axilla to enter anterior arm
- pierces coracobrachalis to reach biceps and brachalis
- crosses elbow joint to innervate lateral arm
What is the ulnar nerve?
- terminal branch of the medial cord
- cutaneous innervation of the medial hand
- passes behind medial epicondyle of the humerus where it can be easily damaged
What is the route of the ulnar nerve?
- travels posteriorly to medial epicondyle of the humerus
- branches to medial forearm muscles
- crosses wrist to enter hand
- branches to intrinsic hand muscles
What is the median nerve?
- from the lateral and medial cords
- innervates most of the anterior forearm muscles and some intrinsic hand muscles
- cutaneous innervation of the lateral palmar hand and 3.5 digits
- commonly damaged at wrist and in distal arm
What is the route of the median nerve?
- runs medially in arm
- crosses elbow joint and branches to anterior forearm muscles
- crosses the wrist and enters hand through carpal tunnel
- branches to intrinsic hand muscles
What is the axillary nerve?
- from posterior cord
- innervates deltoid muscles and upper lateral aspect of the arm
What is the radial nerve?
- innervates triceps brachii and posterior forearm muscles
- cutaneous branches in the arm and forearm
- cutaneous innervation of the lateral dorsum of hand and lateral posterior 3.5 digits
What are the two branches of the radial nerve?
- superficial branch (cutaneous innervation of the dorsolateral hand)
- deep branch (motor supply to the posterior forearm muscles)
Which three nerves provide sensory innervation to the hand?
- median, radial and ulnar nerves
- median nerve supplies lateral anterior 3.5 digits
- ulnar nerve supplies medial 1.5 digits
- radial nerve supplies medial posterior surfaceof hand
Where does most of the blood supply to the upper limb come from?
- left and right subclavian arteries
- branch of the aortic arch
- becomes axillary artery when it enters the arm
What are some branches of the axillary artery?
- circumflex humeral arteries
- brachial artery
What is the brachial artery?
- main blood supply to arm
- largest branch = profundus brachii artery
- crosses elbow joint into forearm where it divides into the radial and ulnar arteries
What does the ulnar artery branch into?
Anterior and posterior interosseous arteries
Which arteries supply the scapula?
- Scapular arteries
- anastamose to provide sufficient constant supply
What happens when the arteries of the forearm cross the wrist?
They form arterial arches
Which arches do the radial and ulnar arteries form in the hand?
Superficial and deep palmar arches
What does the posterior interosseous artery form in the hand?
Deep dorsal arch
Which blood vessels supply the digits?
Palmar and doral digital arteries
What are the two types of venous return in the upper limbs?
- deep venous return (accompanying arteries)
- superficial venous return (on the limb surface)
What are the deep veins of the upper limb?
- subclavian vein
- axillary vein
- brachial vein
- anterior and posterior circumflex humeral veins
- profundus brachii veins
- radial and ulnar veins
- posterior interosseous vein
How are the deep veins of the upper limb structures?
Venae comitantes (VC)
What are venae comitantes?
- accompanying veins
- multuple veins forming a network of smaller veins with accompanying arteries
- connect with each other
- allow heat exchange
- artery pulse promotes venous flow
What is the pattern of superficial venous return?
- small veins in digits drain into superficial venous network on dorsum of the hand
- form basilic and cephalic veins at wrist which run up the limb
How do the basilic and cephalic veins run?
- basilic vein runs medially
- cephalic vein runs laterally
- connected by the median cubital vein at elbow joint in most people
- drain into the axillary vei
How does the lymphatic drainage of the upper limb work?
- lymphatic vessels run with the veins
- cubital nodes drain distal limb
- axillary nodes drain limb and breast
