Anatomy of the arm Flashcards
In a patient with difficulty retracting the scapula, which muscle is most likely affected?
Rhomboid minor
Which of the following can extend, adduct and medially rotate the arm?
Latissimus dorsi
Which muscle is responsible for retracting the scapula and is often strengthened during exercise like rowing?
Rhomboid major
What is the name of the bone of the skeleton?
Humerus
What are the different structures in the humerus?
1) Head of the humerus
2) Neck of the humerus
3) Surgical neck of the humerus
4) Shaft of the humerus
5) Lateral epicondyle
6) Medial epicondyle
7) Bicipital groove
8) Greater tubercle
9) Lesser tubercle
10) Deltoid tuberosity
Anteriorly:
1) Capitulum (where the head of the radius articulate)
2) Trochlea (articulates with the trochlear fossa of the ulna)
3) Coronoid fossa
4) Radial fossa
Posteriorly:
1) Olecranon fossa (for the olecranon process of the ulnar)
2)
The ulnar nerve is behind which structure of the humerus?
The medial epicondyle
Define the elbow joint
The combination of the trochlea with the trochlear fossa of the ulna & capitullem with head of the radius
What type of joinT is the elbow join?
Synovial hinge joint
- Only flexes and extends uniaxially
The rotation that happens in the arm/forearm are due to which structure?
Between the radius and the ulna
What are the compartments of the arm?
Anterior and posterior
- Divided by the humerus and 2 intermuscular septa
- Each compartment has its own muscle nerves and arteries
- Anterior compartment contains the flexor group which flexes the elbow and shoulder joint, while the posterior contains the extensors
What connects the deep fascia with the lateral border of the humerus?
Lateral intermuscular septa
What connects the deep fascia to the medial border of the humerus?
Medial intermuscular septa
In which compartment of the arm is the triceps found?
Posterior compartment
In which compartment of the arm are the biceps, brachialis & coracobrachialis found?
Anterior compartment
What is a brachium?
It is another name of the humerus
What is the landmark of the ulnar nerve?
It is behind the medial epicondyle
What is the landmark of the musculocutaneous nerve?
It pierces the coracobrachialis muscle
What is the change that occurs to the musculocutaneous nerve once it pierces the fascia?
It becomes the cutaneous nerve
Which muscles will be supplied by the axillary nerve?
It loops around the surgical neck and supplies the deltoid and teres minor
What is the origin of the bicep brachii?
1) Long head:
- Supraglenoid tubercle of the scapula within the shoulder joint
2) Short head:
- Tip of the coracoid process in common with the coracobrachialis
Where is the bicep brachii inserted?
1) Via a strong tendon it is inserted into the posterior rough part of the radial tuberosity
2) via bicipital aponeurosis (arises from the tendon of the biceps) which blends with the deep fascia of the forearm
What is the nerve supply of the bicep brachii?
Musculocutaneous nerve
What are the different actions of the bicep brachii?
Both heads:
- Supination of the flexed forearm
- Flexion of the elbow joint
Short head:
- Weak flexor of the shoulder joint
Long head:
- Prevents the upward dislocation of the shoulder joint
What is the origin of the coracobrachialis muscle?
Tip of the coracoid process, common with the short head of the biceps
What is the place of insertion of the coracobrachialis muscle?
Medial border of the humerus
What is the nerve supply of the humerus?
Musculocutaneous nerve
What is the action of the coracobrachialis muscle?
Flexion and adduction of the arm
What is the origin of the brachialis muscle?
1) Lower 1/2 of the front of the humerus
2) Lateral and medial intermuscular septa
What is the site of insertion of the brachialis muscle?
Ulnar tuberosity
What is the nerve supply of the brachialis muscle?
1) Musculocutaneous nerve
2) Radial nerve supplies a small part of its lateral side
What is the action of the brachialis muscle?
Flexion of the elbow
- Main flexor of the elbow joint
What is the origin of the long head of the triceps?
Infraglenoid tubercle of the scapula
What is the site of origin of the lateral head of the biceps?
Upper 1/2 of the posterior surface of the shaft of the humerus above the spiral groove of the scapula
What is the site of origin of the medial head of the triceps?
1) Posterior surface of the lower 1/2 of the shaft of the humerus below the spiral groove
2) Back of the lateral & medial intermuscular septa
What is the site of insertion of the triceps brachii?
The 3 heads fuses together in a common tendon attaching to the posterior part of the upper surface of the olecranon process of the ulna
What is the nerve supply of the triceps brachii?
- Each head receives a separate branch from the radial nerve
What is the action of the triceps brachii?
- Powerful extensors of the elbow joint
- Main function is to keep the elbow extended when someone is pushing an object
What are the nerves of the anterior compartment of the arm?
1) Musculocutaneous nerve (the nerve that pierces the coracobrachialis muscle)
2) Median nerve
3) Ulnar nerve
What are the muscles supplies by the musculocutaneous nerve?
all anterior compartment muscles (brachialis, coracobrachialis, and biceps)
Describe the root of the musculocutaneous nerve through the anterior compartment of the arm
It enters through the coracobrachialis muscle, moves across the biceps and pierces the deep fascia to become the lateral cutaneous nerve of the forearm
What is the origin of the brachial artery?
It is a continuation of the axillary at the lower border of the teres major
Describe the course of the brachial artery
Passes downwards and laterally from the medial side of the humerus to the front of the arm
Where is the brachial artery terminated?
Opposite to the neck of the radius by dividing into the radial and ulnar arteries
What are the branches of the brachial artery
1) Profunda brachii (biggest branch the supplies the posterior compartment)
- Leaves the anterior compartment through the lower triangular space and then runs in the posterior compartment in the spiral groove, and terminates as it branches into anterolateral-descending & posterolateral descending
- It will give muscular branch to the triceps, nutrient artery branch to the humerus & lateral descending which will share anastomosis around the humerus from the lateral epicondyle
2) Superior ulnar collateral (share anastomoses with the ulnar)
3) Inferior ulnar collateral (shares anastomoses around the elbow)
- superior and inferior will share anastomoses around the medial epicondyle
4) Muscular (from the profunda brachii branch)
5) Nutrient artery (from the profunda brachii branch to the humerus)
6) Terminal artery (radial and ulnar arteries)
