Anatomy -- Upper Limb 3 Flashcards
Describe the possible movements of the arm at the elbow joint
- Flexion
- Extension
- Pronation
- Supination
Define compartment syndrome
Any swelling (following trauma) in a compartment leading to increased pressure, which presses on the muscles, blood vessels and nerves.
If pressure is high enough, blood flow to the compartment will be blocked, and if it’s long enough, the muscles may die
2 compartments of arm muscles and the nerves that innervate them
- Posterior/extensor compartment (radial nerve)
- Anterior/flexor compartment (musculocutaneous nerve)
Exception to the function of the arm muscle compartments
Barchioradialis muscle originates from posterior compartment and is innervated by radial nerve, but it is involved in flexion of the forearm
3 muscles of the anterior arm compartment
- Coracobrachialis muscle
- Biceps brachii muscle
- Brachialis muscle
Function of biceps brachii muscle
Supination, flexion of forearm
Flexion of arm
Function of coracobrachialis muscle
Flexion and adduction of arm
Function of brachialis muscle
Flexion of forearm
Only muscle of the posterior arm compartment
Triceps muscle
Functions of triceps muscle
Extension of forearm and arm
Adduction of arm
2 important branches of the axillary/brachial artery
Radial artery
Ulnar artery
Vein commonly used for venipuncture in arm
Median cubital vein
Vessels connected by arteriovenous fistula for hemodialysis
Cephalic vein and radial artery
What does the musculocutaneous nerve innervate
Muslces of the anterior compartment of the arm
Spinal levels of musculocutaneous nerve
C5, 6
What does the radial nerve innervate
Muscle of the posterior compartment of arm (triceps)
Spinal level of radial nerve
C5 - T1
Describe the cutaneous innervation of arm by musculocutaneous, axillary and radial nerves
- Axillary = upper arm towards shoulder
- Radial nerve = lateral upper arm and posterior arm
- Musculocutaneous nerve = Elbow
- Rest of arm = cutaneous branches of brachial plexus or intercostal nerves
Bices brachii origin and insertion
Origin = scapula
Insertion = radius
Main action(s) of biceps brachii
Flexion of arm/forearm
Supination of forearm
Innervation of biceps brachii
Musculocutaneous nerve
Origin and insertion of coracobrachialis muscle
Origin = scapula
Insertion = humerus
Main action of coracobrachialis muscle
Adduction/flexion of arm
Innervation of coracobrachialis muscle
Musculocutaneous nerve
Origin and insertion of brachialis muscle
Origin = humerus
Insertion = ulna
Main action of brachialis muscle
Flexion of forearm
Innervation of brachialis muscle
Musculocutaneous nerve
Origin and insertion of triceps brachii muscle
Origin = scapula/humerus
Insertion = ulna
Main actions of triceps brachii muscle
Extension of arm/forearm
Adduction of arm
Innervation of triceps brachii muscle
Radial nerve
Origin and insertion of the brachio-radialis muscle
Origin = humerus
Insertion = radius
Main action of brachio-radialis muscle
Flexion of forearm
Innervation of brachio-radlias muscle
Radial nerve
Define the cubital fossa
Pathway for neurovascular bundles to run from arm to forearm
Define the boundaries of the cubital fossa
Pronator teres muscle = medial
Brachioradialis muscle = lateral
Superior = imaginary line between medial and lateral epicondyles of humerus
Describe the spatial relationships of the vessles in the cubital fossa
- Brachial artery lateral to median nerve
- Median cubital vein most superficial
Describe the transfer of force through the forearm from the hand
- Hand to radius
- Radius to ulna via interosseus membrane
- Ulna to humerus
Functions of the interosseus membrane
- Transmit force from the radius to the ulna
- Prevent dislocation during pronation/supination movement
Describe the strengthening of the elbow joint
- Enclosed in a capsule
- Reinforced by:
- Radial collateral ligament
- Annular ligament
- Ulnar collateral ligament
What allows the radius to rotate on the surface of the humerus
Annular ligament
