Quadrangular Space

Definition

It is an intermuscular space, also known as quadrilateral space or foramen humerotricipitale

Location

It is located below the shoulder (glenohumeral) joint.

The Borders

Superiorly: Subscapularis m., Teres minor m. , Capsule of the shoulder joint

Inferiorly: Teres major m.

Medially: The long head of triceps m.

Laterally: The surgical neck of the humerus bone

Note\ For some sources, there is a diversity to the muscle that is considered as the superior border, in the anterior view, the subscapularis m. appears as the superior border, in the posterior view, the teres minor m. appears as the superior border.

Quadrangular space Posterior view ,right upper limb.

The contents

There are two structures that pass through the quadrangular space (1 nerve, 1 artery):
1. Axillary nerve
Its fibers arise from the posterior cord of the brachial plexuses.
divides after passing through the space into:

a) The anterior branch that innervates the deltoid m. & the skin over it.

b) The posterior branch that innervates the teres minor m. & continue as the superior lateral cutaneous nerve of the arm.

2. Posterior circumflex humeral vessels
It is a branch of the 3rd part of the axillary artery
winds around the surgical neck of the humerus bone after passing through the space to share with arterial anastomosis around the shoulder joint.

Posterior view, right upper limb.

Clinical importance

This space considers a passageway from the anterior region of the axilla to the posterior region of it.

This space is also vulnerable to “Quadrilateral space syndrome” .

Quadrilateral space syndrome (QSS)

A rare condition that the neural & vascular structures are entrapped in the quadrilateral space for some reason.

The possible causes of QSS

Any movement or structure that decreases the area of the quadrilateral space so causes compression on the structures that pass through it.

1. Fibrous bands

Note

( located between the teres major m. & long head of the triceps m.)

which causes compression to the contents during shoulder abduction & external rotation .

2. Scapular bone fracture.

3. Benign or malignant mass.

The Symptoms

1. A little pain in the shoulder.

2. Non-cutaneously tingling on the lateral side of the shoulder & arm.

These symptoms which are shown above, are increased during shoulder abduction & external rotation.

3. Insensitivity over the quadrilateral space on palpation.

4. Neurotrophic loss

Note

Neurotrophic loss means loss of neural conduction of the muscle

of teres minor m. & deltoid m.

The Diagnosis

1. The specialist uses plain radiographs to detect fractures or any mass that cause pressure on the structures.
2. The specialist uses the EMG to test the activity of the axillary nerve & exclusion of other nerve pain causes.
3. The specialist uses MRI images or CT to detect muscle atrophy

Note

diminution of the size of the muscle or stop the growth of the muscles.

& detect the condition of the structures that passes through the space.

Note\ The modern method that uses to diagnose the QSS is to inject a lidocaine fluid in a certain percentage at a selected point on the shoulder region, if the pain is decreased & the patient can perform the shoulder movements without pain, the test is considered positive.

The treatment

1. The treatment is non-surgical treatment including non-steroidal anti-inflammatory drugs ( NSAIDs

Note

a set of medicines that work as a painkiller

), alteration of the activity & physical therapy.
2. If this method won’t work to decrease the pain for 6 months, surgical treatment is needed in this case & the surgery method is dependent on the surgeon’s experience & the available equipment.

A simple way to memorize the borders of the anatomical spaces in the upper limb.

References

Snell’s Clinical Anatomy By Regions (10th Edition) 258,349,374_375-376

BD_Chaurasia’s_Human_Anatomy, Volume 1 - Upper Limb Thorax (6th Edition) 71

Gray’s Anatomy For Students (4th Edition) 719

Advanced Techniques in Musculoskeletal Medicine & Physiotherapy 113

Quadrilateral space syndrome- Journal of Shoulder and Elbow Surges http://bonefix.co.nz/portals/160/images/Flynn%20Quadrangular%20space%20syndrome.pdf

Nonsteroidal Anti-inflammatory Drugs (NSAIDs)- Books- https://www.ncbi.nlm.nih.gov/books/NBK547742/
Quadrilateral Space Syndrome- physipedia- https://www.physio-pedia.com/Quadrilateral_Space_Syndrome

Grant’s Atlas Of Anatomy (13th Edition )6.42, 6.28
Gray’s Atlas Of Anatomy (2nd Edition) 414
https://youtu.be/YetQwcWCuFQ

Fig 5-The way to memorize- Pinterest- https://pin.it/10zLzjN