Session 5.2: The Arm and Elbow

Anterior compartment

Flexor compartment

Muscles act on the shoulder/elbow to flex them

Posterior compartment

Extensor compartment

Muscles act to extend the elbow

All the muscles in the anterior compartment of the arm are innervated by...

The musculocutaneous nerve

All the muscles in the posterior compartment of the arm are innervated by...

The radial nerve

Surgical neck of the humerus is prone to...

Fracture

Risk of axillary nerve damage

Shaft of the humerus is prone to...

Mid-shaft fractures through the spiral groove (posteriorly) can damage the radial nerve & profunda brachii artery

What nerve passes posterior to the medial epicondyle (funny bone) of the humerus?

Ulnar nerve

Regional pain/tenderness over this region can indicate tendoinitis

Areas of transition in the upper limb

Axilla, cubital fossa, carpal tunnel

Compartments of the arm

Anterior: flexion of shoulder and elbow

Posterior: extension of shoulder and elbow

The compartments of the arm are enclosed in a ___ ___ with two ___ ___, attached to the humerus bone.

The compartments of the arm are enclosed in a deep fascia with two fascial septa, attached to the humerus bone.

What are the muscles in the anterior compartment of the arm

Biceps brachii

Corachobrachialis

Brachialis

What is the blood supply to the anterior compartment of the arm

Brachial artery

What is the nerve supply to the anterior compartment of the arm

Musculocutaneous nerve

Biceps brachii

Flexes forearm and supinates forearm

Innervated by musculocutaneous nerve (C5 - C7)

Corachobrachialis

Flexes and adducts arm

Innervated by musculocutaneous nerve (C5 - C7)

Brachialis

Flexes forearm in all positions

Innervated by musculocutaneous nerve (C5 - C6) and radial nerve (C5 - C7)

Testing for the C5, C6 reflex

Tap the biceps tendon

What structures pass through the anterior compartment of the arm?

- Musculocutaneous nerve

- Median nerve

- Ulnar nerve

- Brachial artery

- Basilic vein

- Radial nerve (lower end of the compartment)

Popeye deformity

Rupture of biceps long head tendon

Torn from attachment at supraglenoid tubercle of scapula

Detached muscle belly forms a ball

Occurs due to wear/tear

What are the muscles in the posterior compartment of the arm

Triceps brachii

Anconeus

What is the blood supply to the posterior compartment of the arm

Profunda brachii

Ulnar collateral arteries

What is the nerve supply to the posterior compartment of the arm

Radial nerve

Triceps brachii

Extends forearm at elbow

Innervated by the radial nerve (C6 - C8)

Anconeus

Extends forearm at elbow; stabilises elbow joint

Innervated by the radial nerve (C7 - T1)

What structures pass through the posterior compartment of the arm?

- Radial nerve

- Ulnar nerve

Posterior Compartment of the Arm

What structures pass through the quadrangular space?

Axillary nerve

Posterior circumflex arteries

Posterior Compartment of the Arm

What structures pass through the triangular interval & spiral groove?

Radial nerve

Profunda artery

Posterior Compartment of the Arm

What structures pass through the triangular space?

Circumflex scapular arteries

Testing the C7, 8 reflex

Tap the triceps tendon

Axillary nerve

Mixed sensory & motor nerve (C5, 6)

Innervates teres minor & deltoid muscles

Sensation to skin above deltoid (regimental badge area) and shoulder joint

Axillary nerve damage

The axillary nerve can become damaged when the shoulder dislocates

Damage to the axillary nerve leads to weak abduction (deltoid) and weak external rotation (teres minor).

Musculocutaneous nerve

Mixed sensory & motor nerve (C5-C7)

Innervates BBC (biceps brachii, brachialis, corachobrachialis)

Radial nerve

Mixed sensory & motor nerve (C5-T1)

Radial nerve lies under brachioradialis and divides into superficial radial nerve (dosrum of hand) and posterior interosseous nerves (extensors of forearm)

Radial nerve damage

Radial nerve can become damaged by humeral fractures involving the spiral groove (mid-shaft).

This leads to wrist drop & reduced grip strength

Anaesthesia of the 1st dorsal web space

Median nerve

Mixed sensory & motor nerve (C6-T1)

Travels with the brachial artery

Gives off the anterior interosseous nerve below cubital fossa which supplies deep muscles of the flexor compartment.

Median nerve continues down the forearm and gives off the palmar cutaneous branch just before the wrist - which innervates thenar eminance.

Ulnar nerve

Mixed sensory & motor nerve (C8, T1)

Descends medially under medial epicondyle of elbow to enter forearm. Innervates the flexor carpi ulnaris and half of the flexor digitorum profundus.

Ulnar nerve injury

Claw hand deformity

Small muscles of hand wasted (except thenar eminance and lateral lumbricals which are innervated by the median nerve).

Myotome

Group of muscles innervated by a single spinal nerve

Myotome testing is an essential part of the neurological examination when suspecting radiculopathy

Deep tendon reflexes

Biceps

C5 + C6

Deep tendon reflexes

Triceps

C7, C8

Deep tendon reflexes

Brachio-radialis

C5 + C6 + RADIAL NERVE

What type of joint is the elbow

Synovial hinge joint

What ligaments support the elbow?

Medial collateral ligament

Lateral collateral ligament

Bursae found around elbow joint

- Olecranon bursa (overlies olecranon posteriorly)

- Subtendinous bursa (between triceps and olecranon)

Olecranon bursa

Lies between olecranon process and skin

Subtendinous bursa

Bursa that prevents friction between bone and a muscle tendon

Movements at the elbow joint

Flexion and extension

CHIEF FLEXORS

- Brachialis

- Biceps brachii

MAIN EXTENSORS

- Triceps brachii

- Anconeus

Elbow injuries: avulsion fracture of medial epicondyle

This injury can occur after a fall caused by severe abduction of fully extended forearm

Elbow injuries: posterior elbow dislocation

This injury can occur after fall on outstretched hand (FOOSH)

___ nerve is vulnerable to damage with injury, fracture or dislocation of the elbow

Ulnar nerve is vulnerable to damage with injury, fracture or dislocation of the elbow

Cubital fossa

Elbow pit

Depression on the anterior aspect of the elbow

Borders of the cubital fossa

- Lateral = Brachioradialis (lateral)

- Medial = Pronator teres (medial)

- Superior = Imaginary line between two humeral epicondyles

Cubital fossa floor and roof

Floor = supinator muscle lateraly & brachialis muscle medially

Roof = skin & fascia, reinforced by bicipital aponeurosis

Contents of the cubital fossa

From medial to lateral:

- Median nerve

- Bifurcation of brachial artery into ulnar/radial

- Tendon of biceps muscle

- Radial nerve and its deep branch

The muscle labelled X in the image above is the ___ muscle.

The nerve that supplies this muscle is the ___ nerve.

The muscle labelled X in the image above is the deltoid muscle.

The nerve that supplies this muscle is the axillary nerve.

The muscle labelled X in the image above is the ___ muscle.

This muscle forms the ___ wall of the axilla.

The muscle labelled X in the image above is the latissimus dorsi muscle.

This muscle forms the posterior wall of the axilla.

The biceps are supplied by the ___ nerve

Musculocutaneous

The three muscles have their origin at the coracoid process are...

a) Corachobrachialis, pec major, short head of biceps

b) Short head of biceps, long head of biceps, coracobrachialis

c) Long head of biceps, coracobrachialis, pec minor

d) Short head of biceps, pec minor, corachobrachialis

d) Short head of biceps, pec minor, corachobrachialis

On examination, a patient experienced pain when abducting their shoulder between 60 and 120 degrees. The tendon for which one of the following muscles is most likely to be inflamed in this case?

a) Infraspinatus

b) Subscapularis

c) Supraspinatus

d) Teres major

e) Teres minor

c) Supraspinatus

Supraspinatus tendinitis is also known as impingement syndrome or painful arc syndrome. It results from the inflamed tendon pressing against the acromium.

A man suffers a penetrating wound through the posterior axillary fold, with resulting damage and weakness in shoulder adduction and medial rotation. Which one of the following muscles is most likely to have been damaged...

a) Latissimus dorsi

b) Teres minor

c) Infraspinatus

d) Trapezius

e) Serratus anterior

a) Latissimus dorsi

The structures highlighted in green in the following illustration form parts of which muscle?

Triceps

Which two of the rotator cuff muscles have opposing actions at the shoulder joint?

a) Subscapularis and supraspinatus

b) Teres minor and supraspinatus

c) Infraspinatus and subscapularis

d) Teres minor and infraspinatus

c) Infraspinatus and subscapularis

A) Which muscle is a major abductor of the arm, and can also be a flexor of the arm, or an extensor of the arm?

B) What nerve innervates this muscle?

A) Deltoid muscle

B) Axillary nerve

What medical term is given to the symptom of a tingling sensation?

Paraesthesia

What artery passes behind the middle of the clavicle and becomes named something different once crossing rib 1?

Subclavian artery