Nerve and blood supply to the upper limbs Flashcards
Broadly speaking what is the “stem” artery of the upper limb? Where does it originate?
Subclavian artery
- Right from the brachiocephalic trunk
- Left from arch of the aorta
Describe the trajectory of the “stem” artery of the upper limb. State the way in which it divides and the anatomical structure relevant to this
Passes through scalene triangle (over the first rib)
Divided into 3 parts by scalenus anterior
- 1st: Medial to muscle
- 2nd: Behind muscle
- 3rd: Lateral to muscle
State the branches of the subclavian artery
1st
- vertebral artery
- thyrocervical trunk (to thyroid, cervical, scapular) it contributes to scapular anastomosis
2nd
3rd
- dorsal scapular artery (from 2nd/3rd part) it contributes to scapular anastomosis
Where does the subclavian artery end?
Wheres does the axillary artery end?
Ends as it crosses the outer border of first rib to become the axillary artery
Ends at lower border of teres major to become the brachial artery
Describe the divisions of the axillary artery
Divided into three parts by pectoralis minor
1st- medial to muscle
2nd- behind muscle
3rd- lateral to muscle
1st/2nd parts closely associated with the brachial plexus
What is the clinical relevance of the surgical neck of the humerus?
- Risk of fracture, trauma to ant/post circumflex humeral arteries (to neck/shaft of humerus)
Which division of the axillary artery gives rise to the subcapsular artery and the ant/post circumflex humeral arteries? Where do these vessels supply?
Subcapsular from the 3rd division supplies scapular anastomosis
Ant/post circumflex humeral arteries supply neck/shaft of humerus
Describe the brachial artery
consider its location, function and divisions
- Superficial throughout arm
- Supplies flexors
- Large branch = profunda brachii artery (supplies extensors)
- Contributes to anastomosis around elbow
- Divides in cubital fossa into radial and ulnar arteries
Describe the profunda brachii artery
How is it clinically relevant?
- It accompanies radial nerve in spiral groove
- Fracture to humerus can result in trauma to profunda brachii artery
Describe the radial artery
How does it end in the hand?
- Lateral side of forearm (in anatomical position)
- Smaller of the two terminal branches
- Covered by brachioradialis muscle
- Forms deep palmer arch (below flexor tendons)
- At wrist it winds around to dorsum of hand
- Through anatomical snuff box and pierces first dorsal interosseous muscle
Describe the ulnar artery
How does it end in the hand?
- medial side of forearm
- Covered by flexor carpi ulnaris muscle
- Deep branch: common interosseous artery
- Forms superficial palmar arch
- Branch to deep palmer arch to superficial palmer arch (above flexor tendons)
- Gives rise to palmer digital arteries
Describe the venous return of the upper limb
- Variable
- Drains into axillary vein into subclavian vein in the deltopectoral groove
DEEP VEINS: paired veins, venae comitantes
SUPERFICIAL VEINS: (from dorsal venous arch, posteriorly)
- cephalic: lateral forearm
- basilic: medial forearm
Which vein connects the basilic and cephalic vein
Medial cubital vein
Describe the lymphatic drainage of the upper limb
Lymph drains to axillary nodes from
- deltopectoral node (cephalic vein)
- cubital nodes (basilic vein)
What is the brachial plexus?
How is it divided?
- Nerve supply to the upper limb
- It carries motor, sensory and sympathetic axons
- Produces mixed nerves (contains axons from multiple spinal nerves which is important in supply of large muscle groups)
- Divided into roots, trunks, division, cords and terminal branches (=mixed nerves)
State the roots of the brachial plexus AND the movements facilitated by different by the motor axons within each root
Roots are ventral primary rami of C5-T1
C5- Shoulder abduction and adduction
C6/C7- Elbow flexion and extension
C7/C8- Wrist flexion and extension
C8/T1- Movement of the digits
Roots of the brachial plexus form trunks. Where doe these trunks pass through?
Scalene triangle
Trunk- superior + middle + inferior
The trunks of the brachial plexus divide into anterior and posterior division. Describe these
ANTERIOR
- Axons to flexor compartments (forms lateral and medial cords)
POSTERIOR
- Axons to extensor compartments (forms posterior cord)
The cords of the brachial plexus are found…..
They are named in relation to which artery?
Under pectoralis minor
Cords named in relation to axillary artery (i.e. posterior cord lies behind the axillary artery)
How does the lateral cord terminate?
Terminates as musculocutaneous nerve and lateral part of median nerve
- The musculocutaneous nerve provides motor supply to the anterior arm (innervates biceps brachii muscle) and sensory to the lateral forearm (gives rise to lateral cutaneous nerve).
How does the medial cord terminate?
Terminates as medial part of median nerve and ulnar nerve
State the function of the median nerve
- Motor to anterior forearm and lateral hand
- Sensory to lateral palm hand, d1,2,3 + half d4
State the function of the ulnar nerve
- Motor to medial side anterior forearm (flexor carpi ulnaris muscle) and hand
- Sensory to medial hand + half d4, d5
How does the posterior cord terminate?
Terminates as radial and axillary nerve
State the function of the radial nerve
MOTOR
- Posterior arm (triceps) and posterior forearm (supinator muscle + brachioradialis muscle)
SENSORY
- Posterior arm and posterior forearm + lateral dorsum hand
State the function of the axillary nerve
MOTOR
- Deltoid and teres minor
SENSORY
- Badge area of arm
What is a dermatome
What is the clinical relevance?
An individual area of skin innervated by a single spinal nerve
- established during development
- lots of overlap/variation
Altered sensation in the region of a dermatome indicates damage to specific spinal nerve of spinal cord segment (i.e. proximal nerve injury)
How does the dermatome map differ to cutaneous innervation by terminal branches?
What is the clinical relevance?
Terminal branches contain axons from multiple spinal nerve
Altered sensation in one of the above areas indicates damage to a more distal nerve segment (i.e. distal nerve injury)
