Arm & Cubital Fossa *some anterior forearm Flashcards
Nerves of Arm, supply structures within arm?
Median-no
Ulnar-no
Musculocutaneous-yes
Radial-yes
Musculocutaneous N.
- where does it begin?
- course throughout arm? Any considerations?
- what does it supply in arm?
- where does it end?
-begins opposite the inferior border of the pectoralis minor
-pierces coracobrachialis
-continues distally between the biceps and the brachialis
-supplies all 3 muscles of the anterior compartment of the arm
-emerges lateral (pierces deep fascia proximal to cubital fossa initially moving with cephalic v. subQ tissue) to the biceps as the “lateral cutaneous n. of forearm”
-thus, supplies lateral skin of forearm
-
Radial N.
-course throughout arm? Any considerations?
- enters the arm posterior to the brachial a. (medial to the humerus, anterior to long head of the triceps, branching to the long and medial heads of triceps)
- descends inferolaterally with profunda brachii a.
- passes around humeral shaft in the radial groove
- branch of the radial n. to the lateral head of the triceps arises within the radial groove
- when it reaches the lateral border of the humerus, the radial n. pierces the lateral intermuscular septum, and continues inferiorly in the anterior compartment of the arm between the brachialis and the brachioradialis to the level of the lateral epicondyle of the humerus.
- anterior to the lateral epicondyle, divides into deep and superficial branches.
Deep Branch of Radial Nerve
-entirely muscular and articular in distribution
Superficial Branch of the Radial Nerve
-entirely cutaneous in its distribution, supplying sensation to the dorsum of the hand and fingers.
Radial Nerve
-supply?
- all muscles of posterior compartment of the arm and forearm
- sensation: dorsum of hand and fingers
Median Nerve
- course? considerations?
- supply?
- runs distally in the arm on the lateral side of the brachial a. until it reaches the middle of the arm, where it crosses to the medial side and contacts the brachialis.
- descends into the cubital fossa, where it lies deep to the bicipital aponeurosis and median cubital vein.
- no branches in axilla or arm
- supplies articular branches to the elbow joint
Ulnar Nerve
-course? considerations?
- passes distally from the axilla anterior to insertion of teres major and to the long head of triceps, on the medial side of the brachial a.
- around middle of arm, it pierces the medial intermuscular septum with the superior ulnar collateral a. and descends between the septum and the medial head of the triceps
- passes posterior to medial epicondyle and medial to the olecranon to enter the forearm
- posterior to medial epicondyle “funny bone”-vulnerable,superficial
- no branches in arm, but it supplies articular branches to the elbow joint
Cubital Fossa
-3 boundaries? Shape?
- triangular cubital fossa, superficially seen as depression on anterior aspect of elbow, deeply as a space filled with a variable amount of fat anterior to the most distal part of the humerus and elbow joint
- superior border: imaginary line connecting medial and lateral epicondyles
- medial border: pronator teres, or mass of flexor muscles of the forearm arising from common flexor origin (CF-ME)
- lateral border: brachioradialis, or mass of extensor muscles of forearm arising from lateral epicondyle and supra-condylar ridge
Cubital Fossa
- floor?
- roof?
- floor: brachialis and supinator muscles of the arm and forearm
- roof: continuity of brachial and antebrachial (deep) fascia reinforced by the bicipital aponeurosis, subQ tissue, and skin.
Cubital Fossa
-contents? (Textbook)
- terminal part of brachial a. and the commencement of its terminal branches, the radial and ulnar arteries. (Brachial a. lies between the biceps tendon and the median nerve)
- (Deep) accompanying veins of the arteries
- biceps brachii tendon
- median nerve
- radial nerve (deep between the muscles forming lateral boundary of the fossa “brachioradialis and brachialis”, dividing into its superficial and deep branches.
- muscles must be retracted to expose the radial nerve.
- superficially, in the subQ tissue overlaying the cubital fossa, are the median cubital vein, lying anterior to the brachial artery, and the medial and lateral cutaneous nerves of the forearm, related to the basilic and cephalic veins.
Anterior compartment muscles of arm
- 3 flexor muscles supplied by musculocutaneous nerve
- coracobrachialis
- acts (weakly) at the shoulder
- biceps (primary supinator of forearm, when elbow is flexed)
- brachialis (primary flexor of forearm)
- both acting at elbow
Posterior compartment of arm
- 3-headed extensor muscle, triceps (radial n.)
- long head: acts at shoulder, but mostly the heads work together to extend the elbow
Common supply to anterior and posterior compartments of arm
- brachial a. =>
- profunda brachii a. (Primarily posterior compartment)
Flexors and pronators of forearm
- which compartment?
- innervation? exceptions?
- anterior compartment
- median nerve
- 1.5 exceptions by ulnar nerve