The Axilla and Brachial Plexus Flashcards
What is the Axilla?
It is the space between the upper arm and the side of the upper chest. The apex is formed by the outer border of the first rib medially, the clavicle anteriorly and the superior border of the scapula posteriorly.
From the anterior sagittal view of the Axilla, name the parts in order from superior to inferior
Trapezius –> Clavicle –> Pectoralis major (in front) –> Subclavian muscle –Costocoracoid ligament–> Pectoralis Minor –> Suspensary ligament of the Axilla –> Axillary fascia
From the posterior sagittal view of the Axilla, name the parts in order from superior to inferior
Trapezius –> Supraspinatus muscle –> Subscapularis (in front) –> Infraspinatus muscle (under spine of scapula) –> Teres minor –> Teres major –> Latissimus dorsi
What is the brachial plexus divided into?
Roots –> Trunks –> Divisions –> Cords –> Terminal/Peripheral nerves
What are the roots of the brachial plexus and what are they connected to?
C5, C6, C7, C8, T1
C5 and C6 connected to the superior trunk, C7 connected to the middle trunk, C8 and T1 connected to the inferior trunk.
What divisions (6) do the trunks connect to?
Superior trunk divides into 1 Sup (ant) and 1 Mid (pos).
Middle trunk divides into 1 Sup (going over the sup –> mid [ant]), 1 Mid (pos).
Inferior trunk divides into 1 Mid (pos), 1 Inf (ant)
What are the division connected to?
Superior –> Lateral cord
Middle –> Posterior cord
Inferior –> Medial cord
What does the lateral cord connect to?
It connects to the musculocutaneous nerve and to the median nerve (goes over other nerves)
What does the posterior cord connect to?
It connects to the radial nerve and the axillary nerve.
What does the median cord connect to?
It connects to the Medial cutaneous nerve of the arm and forearm.
It also connects to the Ulnar nerve and the Median nerve.
What does the musculocutaneous nerve do?
It originates from the lateral cord and it innervates the biceps brachii, coracobrachialis and brachialis muscles in the arm. It connects to the lateral cutaneous nerve of the forearm and innervates the lateral cutaneous aspect of the forearm.
What does the median nerve do?
It originates from the lateral and medial cords. It does not innervate anything in the arm. It innervates 3/4 of the lateral and medial aspect of the anterior of the forearm and 5/20 (1/4) muscles in the hand. It innervates the lateral 3.5 digits of the hand (skin and muscles).
What does the ulnar nerve do?
It originates from the medial cord. It does not innervate anything in the arm. It innervates 1/4 of the medial and lateral aspect of the anterior of the forearm and 15/20 (3/4) of the muscles in the hand. It innervates the medial 1.5 digits of the hand (skin and muscles)
What does the Axillary nerve do?
It originates from the posterior cord. It innervates the Teres minor and the deltoid muscle. The cutaneous distribution is of the upper region of the arm.
What does the Radial nerve do?
The radial nerve originates from the posterior cord. It innervates the muscles in the posterior part of the arm and the posterior part of the forearm.
It also innervates all the other cutaneous areas that are not innervated by the other nerves. (It excludes the medial cutaneous nerve of arm+forearm, lateral cutaneous nerve of forearm, ulnar nerve and median nerve).
The median nerve innervates the fingertips of the lateral 3.5. The ulnar nerve innervates all parts of the medial 1.5. digits
