Muscles of the Arm Flashcards
What is the anatomical arm?
The shoulder joint to the elbow joint
What muscles are in the anterior arm?
Biceps brachii
Brachialis
Coracobrachialis
What muscles are in the posterior arm?
Triceps
Anconeus
What are muscles in the anterior compartment of the arm innervated by?
The musclocutaneous nerve
What kind of muscle is the biceps brachii?
Two headed
Where is nearly all the muscle mass of the biceps located?
Anterior to the humerus
Does the biceps have an attachment to the humerus?
No
What is the proximal attachment of the long head of the biceps brachii?
Supraglenoid tubercle of the scapula
What is the proximal attachment of the short head of the biceps brachii?
Tip of coracoid process of scapula
How is the muscle belly of the biceps brachii formed?
By the combination of the two heads
Where do the two heads of the biceps brachii combine?
At the level of the humeral shaft
How do the two heads of the biceps brachii combine?
The tendon of the long head passes through the shoulder joint and intertubercular groove of the humerus to meet the short head
What is the distal attachment of the biceps brachii?
Tuberosity of the radius and fascia of the forearm, via bicipital aponeurosis
What is the biceps brachii innervated by?
Musculocutaneous nerve (C5-7)
What does a tap on the biceps tendon test?
Spinal cord segment C6
What is the arterial supply of the biceps brachii?
Brachial artery
What is the action of the biceps brachii?
Supinates forearm, and when it is supine, flexes forearm
Short head resists dislocation of the shoulder
What happens as the biceps tendon enters the forearm?
A connective tissue sheet is given off, called the bicipital aponeurosis
What does the bicipital aponeurosis form?
The roof of the cubital fossa
What does the bicipital aponeurosis blend with?
The deep fascia of the anterior forearm
How common is a complete rupture of a body tendon?
Rare
What is one of more common tendons to rupture?
The long head of the biceps tendon
What does the rupture of the biceps tendon produce?
A characteristic bulge where the muscle belly is on flexing at the elbow, called the ‘Popeye Sign ‘
Would a patient with a rupture of the biceps tendon notice much weakness in the upper limb?
No, due to the action of the brachialis and supinator muscles
Where does the coracobrachialis muscle lie?
Deep to the biceps brachii in the arm
Where is the proximal attachment of the coracobrachialis?
Tip of the coracoid process of scapula
Where does the coracobrachialis pass?
Through the axilla
Where is the distal attachment of the coracobrachialis?
Middle third of the medial surface of the humerus, at the level of the deltoid tubercle
What is the innervation of the coracobrachialis?
Musculocutaneous nerve (C5, C6, C7)
What is the arterial supply of the coracobrachialis?
Brachial artery
What is the function of the coracobrachialis?
Helps flex and adduct the arm
Resists dislocation of the shoulder
Where does the brachialis muscle lie?
Deep to the biceps brachii, more distally than the other muscles of the arm
What does the brachialis form?
The base of the cubital fossa
What is the proximal attachment of the brachialis?
Distal half of anterior surface of humerus
What is the distal attachment of the brachialis?
Coronoid process
Tuberosity of ulna
What is the innervation of the brachialis?
Musculocutaneous nerve (C5, C6) Small lateral portion by radial nerve (C5, C7)
What is the arterial supply of the brachialis?
Brachial artery
Radial recurrent artery
What is the action of the brachialis?
Flexes forearm in all positions
What does the triceps brachii have?
Three heads
Where does the medial head of the triceps lie?
Deeper than the other two
When is the medial head visible?
When the other two heads have been dissected away
What is the proximal attachment of the long head of the triceps?
Infraglenoid tubercle of the scapula
What is the proximal attachment of the lateral head of the triceps brachii?
Posterior surface of the humerus, superior to radial groove
What is the proximal attachment of the medial head of the triceps brachii?
Posterior surface of the humerus, inferior to the radius groove
What happens to the three heads of the triceps brachii?
They combine to make one muscle and converge to a tendon
What is the distal attachment of the triceps brachii?
Proximal end of the olcranon of ulna
Fascia of forearm
What is the innervation of the triceps brachii?
Radial nerve (C6-8)
What is the arterial supply of the triceps brachii?
Deep brachial artery
What is the action of the triceps brachii?
Chief extensor of forearm
Long head resists dislocation of humerus
Especially important during adduction
What does a tap on the triceps tendon test?
Spinal segment C7
What is the proximal attachment of the anconeus?
Lateral epicondyle of humerus
What is the distal attachment of the anconeus?
Lateral surface of olecranon and superior part of posterior surface of ulna
What is the innervation of the anconeus?
Radial nerve (C7, C8, T1)
What is the arterial supply of the anconeus?
Recurrent interosseous artery
What is the action of the anconeus?
Assists triceps in extending the forearm
Stabilises elbow joint
May abduct ulna during pronation
