3 Muscles of the upper arm Flashcards
What are the two compartments of the arm?
Anterior (flexor)
Posterior (extensor)
What are the three muscles of the anterior compartment of the arm?
Biceps brachii
Coracobrachialis
Brachialis
What nerve innervates the anterior compartment of the arm?
Musculocutaneous nerve
What is the vascular supply for the muscles of the anterior compartment of the arm?
Muscular branches of brachial artery
Which muscles of the anterior compartment of the arm is most anterior?
Biceps brachii
Where does each head of the biceps brachii muscle originate from?
Long, supraglenoid tubercle of scapula
Short, coracoid process of scapula
Where does tendon of biceps brachii attach distally?
Radial tuberosity
Fascia of the forearm (via bicipital aponeurosis, connective tissue off tendon)
What is the function of the biceps brachii?
Supination of the forearm
Flexion of the arm at the elbow
Flexion of the arm at the shoulder
What is the biceps brachii tendon reflex testing?
C6
Where is the corachobrachialis?
Deep anterior compartment of arm proximal to brachialis
From coracoid process of scapula through the axilla to medial amrgin of humeral shaft about midline
What is the function of the corachobrachialis?
Flexion of arm at shoulder
Weak adduction of the arm at the shoulder
Where is the brachialis?
Deep anterior compartment of arm distal to coracobrachialis
From anterior, medial and lateral surfaces of distal half of humeral shaft to coronoid process of ulnar and ulnar tuberosity
What is the innervation of brachialis?
Musculocutaneous nerve (with some help from radial nerve)
What is the function of the brachialis?
Flexion of the elbow
Where does the musculocutaneous nerve come from?
The lateral chord of the brachial plexus and enters into arm by perforating the coracobrachialis
Where does the musculocutaneous nerve travel?
Between the biceps brachii and brachialis muscle then continuing as lateral cutaneous nerve of forearm
What is the segmental value of musculocutaneous nerve?
C5, C6, C7
For which part of the forearm does the musculocutaneous nerve carry cutaneous sensations?
Lateral part
What are the two muscles in the posterior compartment of the arm?
Triceps brachii
Anconeous
What is the arterial supply to the triceps brachii?
Profunda brachii artery
What are the heads of the triceps brachii?
Medial (deepest) covered by lateral and long
Where do the heads of the triceps brachii originate?
Medial - humerus, inferior to radial groove
Lateral - humerus, superior to radial groove
Long - infraglenoid tubercle of scapula
Where does the tendon of the triceps brachii attach distally?
Olecranon of the ulna
What is the function of the triceps brachii?
Extension of the arm at the elbow
What is the innervation of the triceps brachii?
Radial nerve
What is the triceps brachii tendon reflex testing?
C7
Where is the anconeus located?
Medially and superiorly to extensor compartment of forearm
Blendon with fibres of the triceps brachii
Where does the anconeus attach?
From lateral epicondyle of the humerus to posterior and lateral part of the olecranon
What is the function of the anconeus?
Extends the elbow joint
Stabilises the elbow joint
Abducts the ulna during pronation of the forearm
What is the innervation of the anconeus?
Radial nerve
What does the radial nerve arise from?
Terminal branch, posterior cord of the brachial plexus
Enters arm anterior to long head of the triceps brachii
How does the radial nerve travel through the arm?
Alongside profunda brachiii artery and curves around midshaft od humerus in the radial groove
What is the profunda brachial artery a branch of?
Brachial artery
What is the segmental value of the radial nerve?
C5, C6, C7, T1
What is a clinical sign of radial nerve injury?
Wrist drop as berve supplies extensors of elbow and wrist
