W1: Upper limb vasculature and nerves Flashcards
Discuss pulse points
Radial pulse: lateral of the wrist.
Ulnar pulse: medial of the wrist.
Brachial pulse: in the antecubital fossa.
Axillary pulse: inferiorly of the lateral wall of the axilla.
Allen test: measures arterial competency, digital compression of both ulnar and radial arteries at the level of the wrist. - see if whole hand goes white and goes pink when one released
Which artery do we use to measure blood pressure?
Brachial
What order does the blood supply come in
Subclavian artery
Axillary artery
Brachial artery
Radial artery+ Ulnar artery
Digital arteries
What veins used for venopuncture most commonly?
Superficial veins of the arm: basilic vein
cephalic vein
median cubital vein
(in the antecubital fossa).
These veins are recommended as they are well supported by muscle and connective tissue, visible and easily palpable.
Theoretically, any sufficiently large and palpable vein across the body can be used for venepuncture.
What comes off aortic arch?
Brachiocephalic
Left common carotid
Left subclavian
What does the brachiocephailc split into?
Right subclavian and right common carotid
What does axillary split into?
Subscapular
Posterior circumflex humeral artery
Anterior circumflex humeral artery
Brachial artery
Where can subclavian originate from?
Right = brachiocephalic trunk
Left = arch of the aorta
Discuss axillary artery
The axillary artery lies deep to the pectoralis minor and is enclosed in the axillary sheath (a fibrous layer that covers the artery and the three cords of the brachial plexus).
Discuss brachial artery
The brachial artery is a continuation of the axillary artery past the lower border of the teres major. It is the main supply of blood for the arm.
Immediately distal to the teres major, the brachial artery gives rise to the profunda brachii (deep artery), which travels with the radial nerve in the radial groove of the humerus and supplies structures in the posterior aspect of the upper arm (e.g. triceps brachii). The profunda brachii terminates by contributing to an anastomotic network around the elbow joint.
The brachial artery proper descends down the arm. As it moves through the cubital fossa, underneath the bicipital aponeurosis, the brachial artery terminates by bifurcating into the radial and ulnar arteries.
What does the brachial split into? Discuss
Radial and ulnar
Radial artery – supplies the posterolateral aspect of the forearm. It contributes to anastomotic networks surrounding the elbow joint and carpal bones. The radial pulse can be palpated in the wrist
Ulnar artery – supplies the anteromedial aspect of the forearm. It contributes to an anastomotic network surrounding the elbow joint.
Also gives rise to the anterior and posterior interosseous arteries, which supply deeper structures in the forearm.
These two arteries anastomose in the hand by forming two arches – the superficial palmar arch, and the deep palmar arch.
Where does the radial artery enter the hand?
Floor of anatomical snuffbox
Discuss palmar arches
Superficial palmar arch – located anteriorly to the flexor tendons in the hand and deep to the palmar aponeurosis. It gives rise to the digital arteries, which supply the four fingers.
Deep palmar arch – located deep to the flexor tendons of the hand. It contributes to the blood supply to the digits and to the wrist joint.
Allen test: measures arterial competency, digital compression of both ulnar and radial arteries at the level of the wrist.
Discuss venous drainage
Digital veins -> dorsal venous arch of the hand - both basilic (ulnar aspect) and cephalic (radial aspect) veins of forearm -> median cubital vein at anterior elbow (join briefly) -> the basilic then joins deep veins (called venae comitantes) -> these form the axillary vein into which the cephalic eins drain inferior to the clavicle -> axillary then drains into subclavian
Discuss lymphatic drainage
Runs parallel to venous
Lateral nodes drain most of the lymph - then drain into central - then into apical
Axillary lymph nodes drain the lymph from lateral quadrants of the breast
What is the brachial plexus formed by?
Anterior rami of cervical spinal nerves - C5 C6 C7 C8 T1
What are the divisions of the brachial plexus?
Read that damn cadaver book
roots, trunks, divisions, cords and branches
What are the terminal branches of the brachial plexus?
Musculocutanous
Axillary
Median
Radial
Ulnar
Where do the roots pass to enter the neck? What are the roots?
What are the trunks?
Superior trunk – a combination of C5 and C6 roots.
Middle trunk – continuation of C7.
Inferior trunk – combination of C8 and T1 roots.
Draw the brachial plexus
Discuss the cords
What are the divisions?
Discuss the cords
Once the anterior and posterior divisions have entered the axilla, they combine together to form three cords, named by their position relative to the axillary artery.
The lateral cord is formed by:
- The anterior division of the superior trunk
- The anterior division of the middle trunk
The posterior cord is formed by:
- The posterior division of the superior trunk
- The posterior division of the middle trunk
- The posterior division of the inferior trunk
The medial cord is formed by:
- The anterior division of the inferior trunk.
The cords give rise to the major branches of the brachial plexus.
What are the major branches?
Musculocutaneous Nerve
anterior arm muscls - biceps, coracobrachialis, brachialis
sensory to lat forearm c345
Axillary Nerve
Roots: C5 and C6.
Motor Functions: Innervates the teres minor and deltoid muscles.
Sensory Functions: Gives off the superior lateral cutaneous nerve of arm, which innervates the inferior region of the deltoid (“regimental badge area”).
Median Nerve
Roots: C6 – T1. (Also contains fibres from C5 in some individuals).
Motor Functions: Innervates most of the flexor muscles in the forearm (except unlar FDP and FCU), the thenar muscles, and the two lateral lumbricals associated with the index and middle fingers.
Sensory Functions: Gives off the palmar cutaneous branch, which innervates the lateral part of the palm, and the digital cutaneous branch, which innervates the lateral three and a half fingers on the anterior (palmar) surface of the hand.
Radial Nerve
Roots: C5 – T1.
Motor Functions: Innervates the triceps brachii, and the muscles in the posterior compartment of the forearm (which are primarily, but not exclusively, extensors of the wrist and fingers).
Sensory Functions: Innervates the posterior aspect of the arm and forearm, and the posterolateral aspect of the hand.
Ulnar Nerve
Roots: C8 and T1.
Motor Functions: Innervates the muscles of the hand (apart from the thenar muscles and two lateral lumbricals), flexor carpi ulnaris and medial half of flexor digitorum profundus.
Sensory Functions: Innervates the anterior and posterior surfaces of the medial one and half fingers, and associated palm area
The dermatomes of the upper limb are as follows:
C4 = tip of shoulder
C5 = regimental badge patch area
C6 = lateral aspect of forearm and thumb
C7 = middle finger
C8 = little finger
T1 = medial aspect of proximal forearm
The movement most strongly associated with each myotome is as follows:
C5 = elbow flexion
C6 = wrist extension
C7 = elbow extension
C8 = finger flexion
T1 = finger abduction
Physical mneumonic for nerve roots
3 musketeers
2 were assassinated
5 men
5 rats
2 unicorns
Nerve root to small muscles of hand
C8 T1
Pick T1 if there is only one option
