Brachial Plexus And Axilla Flashcards
What do we call the different parts of the nerves from the neck downwards?
Roots, Trunks, Divisions, Cords and Branches
What are the roots of the brachial plexus?
C5-T1
How many trunks are there and what are they called?
3: superior, middle and inferior
What are the roots of each trunk?
Superior trunk = joining of C5 and C6
Middle trunk = continuation of C7
Inferior trunk = joining of C8 and T1
At which stage do the nerve fibres pass into the axilla?
When they are divisions
What do we call the divisions?
Anterior and posterior divisions
How many cords are there and what are they called?
3: lateral, posterior and medial
What are each of the cords made up of?
Lateral = joining of the anterior divisions of the superior and middle trunks Posterior = formed by the posterior divisions of all 3 trunks Medial = anterior division of the inferior trunk
How many branches are there and what are they called?
5 branches: musculocutaneous, axillary, median, radial and ulnar
What are the roots of each of the branches?
Musculocutaneous: C5, C6 and C7 Axillary: C5 and C6 Median: C5-T1 Radial: C5-T1 Ulnar: C8 and T1
What is Erb’s Palsy?
Damage to roots C5 and C6 due to excessive increase in angle between the neck and shoulder. It affects all the nerves derived from C5 and C6 and produces the “waiter’s tip” deformity.
What is Klumpke’s Palsy?
A nerve injury caused by excessive abduction of the arm. This affects the nerves derived mainly from T1 (ulnar and median) and paralyses the small muscles of the hands. Sensory loss along the medial side of the arm is common.
What is the axilla?
A pyramid shaped area under the shoulder and between the thorax and upper limb that contains nerves, vascular and lymphatic structures.
How many borders does the axilla have and what are their general names?
5 borders: apex, lateral, medial, anterior and posterior.
What makes up the apex of the axilla?
1st rib, clavicle and superior edge of subscapularis
What makes up the lateral border of the axilla?
Intertubercular groove of the humerus
What makes up the medial border of the axilla?
Serratus anterior and thoracic wall
What makes of the anterior border of the axilla?
Pectoralis major, pectoralis minor and subclavius
What makes up the posterior border of the axilla?
Subscapularis, teres major and latissimus dorsi
What is the brachial plexus?
A network of nerves supplying the skin and muscles in the upper limb that passes through the axilla.
When can long thoracic nerve injury occur and what does it cause?
Can be damaged in axillary node clearance and leads to paralysis on serratus anterior and the scapula protrudes (particularly when the patient pushes on a wall) - winged scapula
What does the musculocutaneous nerve innervate?
Brachialis, biceps brachii and coracobrachialis muscles.
A cutaneous branch of it innervates the anterio-lateral forearm.
What does the axillary nerve innervate?
Deltoid, teres minor and long head of biceps brachii.
Some divisions of the axillary nerve wrap around which structure and why can this be dangerous?
Wrap around the upper humerus, dangerous because fractures around this site can lead to damage to this nerve and cause paralysis of the deltoid.
What does the median nerve innervate?
Most of the flexor muscles in the forearm. Supplies to the palm and the anterior side of the lateral 3 and a half fingers.
Which sites of fracture can damage the median nerve?
Elbow and wrist
What does the radial nerve innervate?
The triceps and extensor muscles in the posterior forearm. It supplies to the posterior arm and forearm as well as the posterior lateral aspect of the hand.
Injuries in the axilla most commonly occur from what?
Shoulder dislocation
What does the ulnar nerve innervate?
Muscles of the hand and the anterior and posterior surfaces of the medial one and a half fingers.
How might we injure the axillary nerve?
Dislocation of shoulder or fracture at surgical neck of humerus
How do we test for axillary nerve damage?
Loss of sensation over regimental badge area of skin
Do NOT test motor function as could cause more damage
At which point does the subclavian artery become the axillary artery?
After passing the 1st rib
At which point does the axillary artery become the brachial artery?
After passing teres major
Where are the ulnar and radial arteries formed?
within the cubital fossa
