Arm and Elbow SDL Flashcards
Boundaries of the axilla?
The axilla is a pyramidal space with four walls and an inferiorly facing base made up by the skin and fascia of the armpit.
Walls of the axilla?
Lateral: intertubercular sulcus
Medial: the serratus anterior and the thoracic wall
Posterior: subscapularis, teres major and latissimus dorsi.
Anterior: contains the pectoralis major and the underlying pectoralis minor and the subclavius muscles.
The neurovascular bundle of the upper limb enters through the apex of the axilla after passing between the clavicle and the first rib.
What is contained within the neurovascular bundle of the axilla?
- Axillary artery
- Axillary vein
- Brachial plexus (and branches)
What is the axillary artery a continuation of?
The subclavian artery that travels under the clavicle
Where does the axillary artery become the brachial artery?
At the point that it crosses teres major
In the axilla, what are the 2 important branches of the axillary artery?
The posterior and anterior circumflex humeral arteries
What do the anterior and posterior circumflex humeral arteries form?
An anastomosis around the surgical neck of the humerus
As the brachial artery travels down the anterior compartment of the arm, what branch does it give off?
The profunda brachii / deep artery of the arm
What does the profunda brachii supply?
It is the main supplier of blood to the upper arm
Where does the profunda brachii travel?
Travels around the back of the humerus and runs down the posterior aspect of the humerus in the radial / spiral groove
What does the profunda brachii run alongside in the radial groove?
The radial nerve
The brachial artery runs down the anterior arm. Where does it birfurcate?
At the level of the elbow joint (cubital fossa)
What does the brachial artery divide into?
The radial and ulnar arteries
Where does the axillary vein lie in relation to the axillary artery?
Medial
Where does the axillary vein commence? Where does it become the subclavian vein?
It commences at the lower border of teres major (same place where axillary artery becomes brachial artery) and ascends through the axilla.
It becomes the subclavian at the lateral border of the first rib
What are the 2 types of veins in the upper limb?
Deep and superficial veins
Where do both the deep and superficial venous networks drain into?
Alll the way up to the axillary vein
What are the 2 major superficial veins in the arm?
Basilic and cephalic veins
What is the axillary vein a continuation of?
The basilic vein
Where does the cephalic vein empty into?
The cephalic vein is a tributary of the axillary vein
What is the median cubital vein? Is it superficial or deep?
This vein connects the cephalic and basilic veins in the regino of the antecubital fossa (i.e. anterior to the elbow joint)
This is a superficial vein
What does the brachial plexus give rise to?
The plexus gives rise to nerves which provide the motor and sensory innervation to the whole of the upper limb.
What cord does the:
Musculocutaneous
Axillary
Median
Radial
Ulnar
come from?
Roots of the 5 terminal branches of the brachial plexus?
Musculo - C5-C7
Axillary - C5-C6
Radial - C5-T1
Median - C5-T1
Ulnar - C8-T1
What is the only nerve that passes through the carpal tunnel?
Median nerve
What muscles are innervated by the musculocutaneous nerve? (i.e. motor functions of this nerve)?
Innervates the muscles in the anterior compartment of the arm:
- Biceps
- Brachialis
- Coracobrachialis
What skin is innervated by the musculocutaneous nerve (i.e. sensory function)?
- In the forearm, the musculocutaneous nerve gives rise to the lateral cutaneous nerve.
- This nerve initially enters the deep forearm, but then pierces the deep fascia to become subcutaneous.
- In this region, it can be found in close proximity to the cephalic vein
- The lateral cutaneous nerve of forearm innervates the skin of the anterolateral aspect of the forearm.
In simple: skin of the anterolateral aspect of the forearm
What is motor function of the axillary nerve (i.e. what muscles does it innervate)?
- Deltoid
- Teres minor
What is the sensory function of the axillary nerve (i.e. what skin does it innervate)?
- The sensory component of the axillary nerve is delivered via its posterior terminal branch.
- After the posterior terminal branch of the axillary nerve has innervated the teres minor, it continues as the upper lateral cutaneous nerve of the arm.
- It innervates the skin over the inferior portion of the deltoid
I.e. upper lateral aspect of arm
What muscles does the median nerve innervate (i.e. what is motor function)?
In the forearm, the median nerve directly innervates muscles in the superficial and intermediate layers:
- Superficial layer: Pronator teres, flexor carpi radialis and palmaris longus.
- Intermediate layer: Flexor digitorum superficialis.
The median nerve also gives rise to the anterior interosseous nerve, which supplies the deep flexors:
- Deep layer: Flexor pollicis longus, pronator quadratus, and the lateral half of the flexor digitorum profundus
In the hand, the median nerve innervates some of the muscles via two branches:
- The recurrent branch: innervates the thenar muscles
- The palmar digital branch: innervates the lateral two lumbricals
What are the thenar muscles?
muscles associated with movements of the thumb
What are the actions of the lateral two lumbricals?
these muscles perform flexion at the metacarpophalangeal joints and extension at the interphalangeal joints of the index and middle fingers
What is the sensory function of the median nerve (i.e. what skin does it innervate)?
Responsible for the cutaneous innervation of part of the hand via two branches:
- Palmar cutaneous branch
- Arises in the forearm and travels into the hand
- It innervates the lateral aspect of the palm
- Palmar digital cutaneous branch
- Arises in the hand
- Innervates the palmar surface and fingertips of the lateral three and half digits
Does the palmar cutaneous branch of the median nerve pass through the carpal tunnel?
No - is spared in carpal tunnel syndrome.
What muscles are innervated by the radial nerve?
In the posterior upper arm: triceps
In the posterior forearm: gives rise to branches that supply the brachioradialis and extensor carpi radialis longus (muscles of the posterior forearm).
A terminal branch of the radial nerve, the deep branch, innervates the remaining muscles of the posterior forearm.
What skin is innervated by the radial nerve?
Upper posterior arm:
- Lateral aspect of the arm
- The posterior surface of the arm
Posterior forearm:
- Innervates a strip of skin down the middle of the posterior forearm
Posterior hand:
- The superfical branch (a terminal division of the radial nerve) innervates the dorsal surface of the lateral three and half digits and the associated area on the dorsum of the hand.
What muscles does the ulnar nerve innervate?
Innervates muscles in the anterior compartment of the forearm, and in the hand.
Anterior forearm:
- Flexor carpi ulnaris
- Flexor digitorum profundus (medial half)
Hand:
- The majority of the intrinsic hand muscles (apart from the thenar muscles and two lateral lumbricals)
- Hypothenar muscles
- Medial two lumbricals
- Adductor pollicis
- Palmar and dorsal interossei of the hand
- Palmaris brevis
What skin does the ulnar nerve innervate (sensory)?
There are three branches of the ulnar nerve that are responsible for its sensory innervation.
Two of these branches arise in the forearm, and travel into the hand:
- Palmar cutaneous branch – innervates the medial half of the palm.
- Dorsal cutaneous branch – innervates the dorsal surface of the medial one and a half fingers, and the associated dorsal hand area.
The last branch arises in the hand itself:
- Superficial branch – innervates the palmar surface of the medial one and a half fingers.
The brachial plexus can be anaesthetised. What does this mea for surgery? What is this called?
Surgery on the upper limb can be performed without giving a patient a general anaesthetic –> brachial plexus block.
How may groups of lymph nodes does the axilla contain? What do they drain?
The axilla contains 4 groups of nodes. These drain 75% of the lymph from the breast.
What is the clinical significance of the axillary lymph nodes?
Axillary lymphadenopathy refers to enlargement of the axillary lymph nodes. Common causes include:
- Infection of the upper limb
- Infection of the pectoral region and breast
- Metastasis of breast cancers
Removal and analysis of the axillary lymph nodes is often a vital tool for the staging of breast cancers.
What may interruption of the lymph drainage of the upper limb result in?
- Lymphoedema (accumulated lymph in the subcutaneous tissue leads to painful swelling of the upper limb)
- Risk of damage to either of the long thoracic nerve (potentially causing a winged scapula deformity) or the thoracodorsal nerve.
The arm is divided into two morphological and functional compartments by the deep (brachial) fascia of the arm. What are these?
- Flexor compartment –> lies anterior to the humerus
- Extensor compartment –> lies posterior to the humerus
What are the 3 muscles of the anterior compartment of the arm?
- Biceps
- Brachialis
- Coracobrachialis
Proximal attachment of the bicep?
Short head: coracoid process
Long head: supraglenoid tubercle on the scapula
Distal attachment of the biceps?
Both long and short heads form one common tendon that attches to the radial tuberosity on the radius
Action of the biceps?
- Flexes the arm at the shoulder and the elbow
- Supination of the forearm
Proximal attachment of the brachialis?
Humeral shaft
Distal attachment of the brachialis?
Ulna tuberosity on the ulna
Action of the brachialis?
Flexes the arm at the elbow joint
Proximal attachment of the coracobrachialis?
Coracoid process of the scapula
Distal attachment of the coracobrachialis?
Humeral shaft
Action of the coracobrachialis?
Flexion of the arm at the shoulder, and weak adduction.
Common innervation of the biceps, brachialis and coracobrachialis?
Musculocutaneous nerve
What is the biceps reflex?
An upper limb reflex tested as part of the peripheral neurological examination:
- The tendon of the muscle is tapped with a tendon hammer
- The muscle fibres stretch, and this is detected by stretch receptors within the muscle spindles
- This information is carried to the spinal cord by afferent fibres which synapse with efferent (motor) fibres, which then stimulate contraction of the muscle, producing movement
How is the biceps reflex performed?
The patient’s arm should rest on their lap with the elbow slightly flexed. The examiner palpates the biceps tendon in the cubital fossa and places the thumb or forefinger over the tendon, and then allows the head of the hammer to swing down onto their thumb / finger.
What would you expect to see with a normal biceps reflex?
A normal response will cause the biceps to contract, drawing the lower arm upwards.
Which peripheral nerve and which spinal nerves / cord segments are being tested in the biceps reflex?
Musculocutaneous nerve; C5-C6
Elbow flexion tests spinal nerve C6
What is the only muscle in the posterior compartment of the upper arm?
Triceps brachii
How many muscle bellies does triceps have? What is their common distal insertion?
3
All converge distally onto one common tendon which attaches to the olecranon (on the ulna)
Origin of the long head of the triceps?
Infraglenoid tubercle of the scapula
Origin of the lateral head of triceps?
Originates from the humerus, superior to the radial groove (posterior)
Origin of the medial head of triceps?
This lies the deepest (is covered by the other 2 heads)
Originates from the humerus, inferior to the radial groove (posterior)
Action of the triceps?
Extension of the arm at the elbow
Innervation of triceps?
Radial nerve
Which structures run in the radial groove?
Radial nerve, profunda brachii (deep branch of the brachial artery)
Which artery supplies the posterior compartment of the arm?
Profunda brachii
What is the triceps reflex?
Another tendon reflex tested as part of the peripheral neurological examination.
How is the triceps reflex performed?
To test the triceps reflex, the patient’s arm is held across their body and the weight of the limb supported. The examiner palpates the triceps tendon superior to its insertion onto the olecranon process and taps it with the tendon hammer.
What would you expect to see with a normal triceps reflex?
A sudden contraction of the triceps muscle causes extension and indicates a normal reflex
Which peripheral nerve and which spinal nerves / cord segments are being tested during the triceps reflex?
Elbow extension –> C7 spinal nerve
Peripheral nerve –> radial nerve
The tendon of the long head of triceps brachii crosses teres major and teres minor at right angles. What important anatomical landmark does this point mark?
the quadrilateral (quadrangular) space.
What is the superior border of the quadrilateral space?
Teres minor
Inferior border of quadrilateral space?
Teres major
Medial border of quadrilateral space?
Long head of triceps
Lateral border of quadrilateral space?
Surgical neck of humerus
Which artery and nerve travel though the quadrilateral space?
Axillary nerve and posterior circumflex humeral artery (branch of axillary artery in the axilla)
The elbow joint is formed by the articulation between which three bones?
Humerus, radius, ulna
What does the head of the radius articulates with the radial notch of the ulna to form? What movement does this allow?
proximal radioulnar joint. This joint allows pronation and supination of the forearm and hand.
What happens to the radius when the forearm is pronated?
It crosses the ulna
What movements are possible at the elbow joint?
Flexion and extension
What bony structure prevents hyperextension of the elbow joint?
?
The joint capsule of the elbow is relatively thin anteriorly and posteriorly. What strengthens the lateral and medial aspects of the joint?
Collateral ligaments (radial and ulnar)
What ligament holds the head of the radius in place?
The annular ligament (orbicular ligament) –> a strong band of fibers that encircles the head of the radius, and retains it in contact with the radial notch of the ulna.
What is ‘pulled elbow’?
The head of the radius may sublux or dislocate from the anular ligament – this is commonly seen in children rather than adults
What is muscle D?
Biceps
What does A indicate? What is C?
A - Long head of the triceps (attaches to the infraglenoid tubercle)
C - lateral head
What is A? B? C?
A - posterior cord –> identifiable because it divides into two branches
B - axillary nerve –> branch of posterior cord that leaves the axilla near the surgical neck of the humerus
C - Radial nerve –> disappears into the posterior compartment of the arm
The short head of biceps orginates from which bony landmark of the scapula?
Coracoid process
Letter C indicates the:
Medial cord
What is B?
The segment of the brachial plexus indicated by the letter A is formed by??
B - axillary nerve
A is the posterior cord - formed from the posterior divisions of the superior, middle and inferior trunks
Which tendon of the bicep lies in the bicipital groove?
Long head
What is A?
Long head of the tricep:
- Lies medially in the posterior arm
- Forms the medial border of the quadrilateral space
- Is innervated by the radial nerve and so an injury to the posterior cord - from which the radial nerve arises - would impair the functioning of triceps.
- The long head of triceps inserts on the infraglenoid tubercle and hence extends the shoulder when it contracts.
Identify the structure indicated by the letter B.
Trochlea
The muscle indicated by the letter A is:
Brachialis - This is brachilais, because it attaches to the shaft of the humerus and travels distally across the elbow joint.
It is distinguished from biceps (which lies superficial and has been removed) because biceps has two tendons proximally. Coracobrachialis is a muscle located proximally in the medial arm, attached to the coracoid process and proximal part of the humeral shaft.
The nerve indicated by letter D is comprised of nerve fibres from which spinal cord segments?
D is the D is the musculocutaneous nerve. It is a branch of the lateral cord and contains spinal nerve fibres C5-7.
What is C?
Is the medial cord
What is D?
Olecranon fossa
What is A? What is D?
A –> anterior fibres of deltoid
D –> biceps
What is A? What segments of the spinal cord does it contain fibres from?
A is the posterior cord.
C5-T1
Brachialis inserts onto which bony landmark?
H - ulnar tuberosity
Identify the artery labelled B.
Brachial
Which one of the following structures is most at risk from this injury?
Radial shaft –> radial nerve
The nerve labelled C contains fibres from which segments of the spinal cord?
C is the radial nerve
A 23 year old man has swelling over his right elbow which has gradually increased in size. There is no history of trauma. The swelling is soft and slightly tender, but movement is normal. Which differential diagnosis best explains the appearance of his elbow?
Inflammation of the olecranon bursa (bursitis)
Name them
A - superior trunk, formed by ventral rami of C5 and C6 spinal nerves
B - inferior trunk, formed by ventral rami of C8 and T1
C - medial cord, formed by anterior division of inferior trunk
D - musculocutaneous nerve, a branch from the lateral cord comprising C5,6 and 7 spinal nerve fibres
E - median nerve, formed by contributions from both the medial and lateral cord
F - radial nerve, a large branch from the posterior cord
G - ulnar nerve, terminal branch from the brachial plexus containing C8-T1 spinal nerve fibres
What are they?
A - superior trunk
B - inferior trunk
C - medial cord –> divides to form the ulnar nerve and a contribution to the median nerve
D - musculocutaneous nerve
E - median nerve –> tavels through the anterior arm to the antecubital fossa
F - radial nerve –> the only terminal branch of the brachial plexus to innervate muscles in both the arm and forearm
What is the only terminal branch of the brachial plexus to innervate muscles in both the arm and forearm?
Radial nerve
Identify the vessel labelled A.
Cephalic vein
What specific bony landmark is labelled D?
Radial neck
Which neurovascular structures run in the region circled?
This is BACK of the arm:
- Profunda brachii artery
- Radial nerve
Identify nerve A
Median nerve
Which nerve innervates muscle A?
Musculocutaneous
Identify muscle C.
Brachialis - attaches to ulnar tuberosity
Identify the head of triceps labelled A.
Medial
What is C?
Short head of bicep
This injury risks which nerve?
This is a radial shaft fracture –> radial nerve
Paralysis of the muscle indicated by the letter A would result from injury to which nerve?
Accessory nerve (cranial nerve XI)
Image of ulnar nerve around medial epicondyle
The muscle indicated by the letter A inserts onto which bony feature on the humerus?
Intertubercular sulcus
This injury has the potential to damage a nerve composed of which spinal nerve fibres?
C5, C6
Name them
A - superior trunk
B - inferior trunk
C - medial cord
D - musculocutaneous nerve
E - median nerve
F - radial nerve
G - ulnar nerve
Letter A indicates?
Posterior cord
Which head of biceps lies in the intertubercular sulcus?
Long head of biceps
Movements of biceps?
- Flexion of arm
- Flexion of shoulder
- Supination of arm
When is the only time that biceps can contribute to supination?
Only when elbow is flexed
What movement is tightening a screw clockwise?
Supination (with flexed elbow)
How does tightening a screw clockwise for a left/right handed person differ?
Right - supination
Left - pronation
Is pronation or supination a stronger movement?
Supination
What is the only head of the triceps that can extend the shoulder?
The long head
Boundaries of cubital fossa?
Superior (base): imaginary line between medial and lateral epicondyles
Medial: lateral boundary of pronator teres
Lateral: medial border of brachioradialis
What artery is at risk during venepuncture?
The brachial artery or one of its branches (brachial artery bifurcates in the antecubital fossa)
What vein is being pointed to? What is its route? What does it drain?
Cephalic vein
- Drains hand and forearm
- Comes up lateral aspect of upper arm
- Drains into axillary vein
What vein is being pointed to?
The basilic vein
- Courses up medial side of forearm and arm, turning into axillary vein
- Drains hand and forearm
Where does basilic and cephalic vein sit in relation to each other in the cubital fossa?
Lateral - cephalic
Medial - basilic
What does ‘acf’ stand for?
Antecubital fossa
