Nerve and blood supply to the upper limb Flashcards
Main arterial supply to the upper limb
- Subclavian artery supplies the upper limb
- Right –> from brachiocephalic trunk
- Left –> from arch of the aorta
What does the subclavian artery pass through
- Passes through scalene triangle (over first rib)
- Divided into 3 parts by scalenus anterior:
1. Medial to muscle
2. Behind muscle
3. Lateral to muscle
Anatomical course - Aortic arch –> digital arteries
Aortic arch –> brachiocephalic trunk –> right common carotid + right subclavian –> right subclavian –> right axillary –> right brachial –> right radial + ulnar –> digital arteries
Aortic arch –> left subclavian –> left axillary –> left brachial –> left radial + left ulnar –> digital arteries
What does the dorsal scapular artery supply (from 2nd or 3rd part)
- Contributes to scapular anastomosis
- Supplies the levator scapulae, rhomboids and trapezius
- Dorsal scapular artery arises from the subclavian
What does thyrocervical trunk supply
- Thyrocervical trunk(to thyroid, cervical, scapular)
- Contributes to scapular anastomosis
Where does the subclavian artery end
- Ends as it crosses outer border of first rib
- Becomes axillary artery
What does the axillary artery divide into
Divided into three parts by pec minor:
1st Medial to muscle
2nd Behind muscle
3rd Lateral to muscle
What are the first and second parts of the axillary artery associated with
- Brachial plexus
Where does the axillary artery end
- Ends at lower border of teres major
What does the axillary artery become
- Becomes brachial artery
What can fractures to the surgical neck of humans cause trauma to
- Ant/post circumflex humeral
Features of the brachial artery
- Superficial throughout arm
- Large branch - profunda brachii artery
- Contributes to anastomosis around elbow
What does the brachial artery supply
- Supplies flexors
What does the brachial artery divide into
- Divides in cubital fossa to form the radial artery + ulnar artery
What does the profunda brachii artery accompany
- Accompanies radial nerve in spiral groove
What is the quadrangular space
It is an intermuscular space through which the axillary nerve and posterior circumflex humeral vessels pass through backwards to encircle the surgical neck of the humerus.
It is bounded above by subscapularis and teres minor and below by teres major.
What is a fracture to the humerus likely to damage
- Trauma to profounda brachii artery
Features of the radial artery
- Lateral side of forearm
- Smaller of the two terminal branches
- Covered by brachioradialis muscle
- Forms deep palmer arch
Path of the radial artery in the hand
- At wrist, winds around to dorsum of hand through anatomical snuff box
- Pierces first dorsal interosseous muscle
Features of ulnar artery
- Medial side of forearm
- Covered by flexor carpi ulnaris muscle
- Deep branch - common interosseous artery
- Forms superficial palmar arch
Features of venous return from the hands
- Considerably variable
- Drains into axillary into subclavian vein
Deep veins - paired veins + venae comitantes
Superficial veins - cephalic(lateral forearm), basilic(medial forearm)
From dorsal venous arch
What do the cephalic and basilic veins drain into
- Axillary vein
Features of lymphatic drainage in the upper limb
- Relatively few lymph nodes in upper limb
- Lymph drains to axillary nodes
Lymph nodes in the upper limbs
- Deltopectoral node (cephalic vein)
- Axillary nodes (axillary vein)
- Cubital nodes (basilic vein)
Features of the brachial plexus
- Nerve supply to the upper limb
- Carries motor, sensory and sympathetic axons
- Produces mixed nerves (i.e. contains axons from multiple spinal nerves) - important to supply large muscle groups
What is the brachial plexus divided into
- Roots, trunks, division and cords
= mixed nerves
Brachial plexus roots
- Roots are ventral parimary rami of C5-T1
- Motor axons within each root innervate a different functional group of muscles (myotomes)
C5 root innervation
- Shoulder abduction and adduction
C6/7 root innervation
- Elbow flexion and extension
C7/8 root innervation
- Wrist flexion and extension
C8/T1 root innervation
- Movement of the digits
What do brachial plexus roots form
- Roots form trunks
- C5 + C6 –> Superior
- C7 –> Middle
- C8 + T1 –> Inferior
What do brachial plexus trunks pass through
- Scalene triangle
What does each brachial plexus trunk divide into
- Each trunk divides into anterior and posterior divisions
- Anterior: Axons to flexor compartments (forms lateral and medial cords)
- Posterior: Axons to extensor compartments (forms posterior cord)
Location of cords of brachial plexus
- Under pectoralis minor
What are the cords of the brachial plexus named in relation to
- Cords named in relation to axillary artery
- Lateral, posterior, medial
What does the lateral cord terminate as
Terminates as: Musculocutaneous nerve
- Lateral part of median nerve
Divisions of the musculocutaneous nerve
Motor - anterior arm
Sensory - Lateral forearm
What does the medial cord terminate as
- Medial part of median nerve
- Ulnar nerve
Divisions of the median nerve
Motor - anterior forearm and lateral hand
Sensory - Lateral palm hand, d1, 2, 3 + half d4
Divisions of the ulnar nerve
Motor - medial side anterior forearm and hand
Sensory - medial hand + half d4 + d5
What does the posterior cord terminate as
- Radial nerve
- Axillary nerve
Divisions of the radial nerve
- Deep branch (motor)
- Superficial branch (sensory)
Motor - posterior arm and posterior forearm
Sensory - posterior arm and posterior forearm + lateral dorsum hand
Branches of the axillary nerve
Motor - deltoid and teres minor
Sensory - badge area of arm
What are upper limb dermatomes
‘An individual area of skin innervated by a single spinal nerve.’
- Established during development
- Lots of overlap/variation
What does altered sensation in the region of a dermatome indicate
- Indicates damage to specific spinal nerve of spinal cord segment (i.e. proximal nerve injury)
Why does the cutaneous innervation map look different to the dermatome map
- Terminal branches contain axons from multiple spinal nerve
- Altered sensation in one of these areas indicates damage to a more distal nerve segment (i.e distal nerve injury)
What is the expansion of the tendon of biceps
- An expansion of the tendon of biceps, the bicipital aponeurosis, crosses medially over the superficial flexors of the forearm and attaches to the posterior border of the ulna via the deep fascia
- As biceps crosses both the shoulder joint and the elbow joint, it exerts its flexor action on both joints
