MSK - Brachial Plexus And Axillary Flashcards
Describe the features of the Musculocutaneous nerve?
HINT : Which roots, what it innervates
Descends between the biceps brachii and brachialis
From roots C5 C6 C7
Innervates the muscles of the anterior compartment of arm
(Biceps, brachialis)
What are the 5 regions of the brachial plexus?
Roots Trunks Divisions Cords Terminal nerves
What are the features of the Axillary nerve?
Winds around the surgical neck deep into deltoid.
Innervates the Teres minor, deltoid muscle
What are the features of the median nerve?
Lateral and medial cords merge to form this.
Innervates muscles of the anterior forearm compartment
C5 C6 C8 T1
What are the features of the radial nerve?
Larger terminal branch of the posterior cord
Innervates all muscles of the posterior compartment of arm/forearm
Skin of posterior arm
What are the features of the ulnar nerve?
Large terminal branch of the medial cord
Supplies forearm muscles, intrinsic hand muscles
C8 T1
What is the Axilla?
The pyramidal shaped area providing a passageway for the neurovascular structures that serve the upper limb
What are the 6 boundaries of the Axilla called?
Apex, base, anterior wall, posterior wall, medial wall, lateral wall.
How is the apex formed?
Bounded by 1st rib
Clavicle and superior scapula edge.
What is the base boundary?
Formed by the concave skin, subcutaneous tissue, and Axillary fascia
What is the anterior wall bounded by?
The pectoralis minor and major
What is the posterior wall bounded by?
Scapula, and subscapularis and Teres major and latissmus dorsi
What is the medial wall formed by?
The thoracic wall (1st-4th ribs) and serratus anterior.
What this the lateral wall formed by?
Intertubercular sulcus in humerus
What are the Axillary lymph nodes?
Fibrofatty connective tissue containing many lymph nodes
They drain the lymph from the arm, breast, chest wall
What would a tearing injury to the superior brachial plexus result in?
Injures superior roots (C5, C6)
Waiters tip position limb hangs by side in medial position.
Deltoid, biceps and brachialis are affected
What happens after a long period of holding arm above head?
The cords are compressed between the coraciod process of spacula and pectoralis minor tendon.
This leads to pain down the arm, tingling
What is the venous supply of the Axilla region?
The cephalic vein runs up under the deltoid
The basilic vein carries blood up from the arm to the Axilla
They both join the Axillary vein
What is the arterial supply of the Axilla?
The subclavian artery travels down the arm and becomes the Axillary artery.
The artery is posterior to the vein.
What is an example of a fist class lever?
The seesaw like movement of the neck with the force in the opposite side to the load.
What is an example of a second class lever?
Wheelbarrow like mechanism with the force and the load to the left of the fulcrum. E.g ball of foot
What is the third class lever?
Fishing rod mechanism. The force and the load on right of fulcrum.
E.g the forearm
What are agonists?
Prime movers (main muscle responsible for movement)
What are antagonists?
Muscles that oppose prime movers
What are synergists?
Assist in prime movers
What are fixators?
These stabilise action of prime mover
What is isotonic muscle contraction?
Muscle changes length with constant tension
Concentric - muscle shortens e.g arm
Eccentric - muscle extends e.g walking downhill
What is isometric contraction?
Constant muscle length e.g hand grip
What is muscle tone?
Muscles resistance to passive stretch during rest.
What are the 4 things that cause hypotonia?
Cerebral spinal neural shock
Lesion of lower motor neurone
Lesion of sensory afferents from muscle
Myopathy of primary muscle.
