Anatomy, Shoulder and Upper Limb, Arm Quadrangular Space


Article Author:
Irfan Khan


Article Editor:
Matthew Varacallo


Editors In Chief:
Jasleen Jhajj
Cliff Caudill
Evan Kaufman


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Trevor Nezwek
Radia Jamil
Patrick Le
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Hassam Zulfiqar
Hussain Sajjad
Steve Bhimji
Muhammad Hashmi
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Sarosh Vaqar
Mark Pellegrini
James Hughes
Beata Beatty
Beenish Sohail
Nazia Sadiq
Hajira Basit
Phillip Hynes


Updated:
12/21/2018 9:41:14 PM

Introduction

The quadrangular (or quadrilateral) space (QS) is named based on the shape of its anatomic boundaries.  Located along the posterolateral shoulder, the QS serves as a passageway for the axillary nerve and posterior humeral circumflex artery (PHCA).  Quadrangular (or quadrilateral) space syndrome (QSS) can occur secondary to various compressive pathologies.  Although the incidence of such pathologies is rare, QSS has a known predilection for subgroups of athletic populations and can often suffer misdiagnosis or are clinically under-appreciated.  Thus, clinicians should maintain a heightened clinical suspicion for QSS in patients aged 20-40 years of age presenting with a history of current contact or overhead athletic performance (e.g., baseball pitchers, swimmers, etc.),[1][2] or overhead laborers secondary to repetitive stress mechanics on the shoulder.[3]

Structure and Function

The QS has four anatomic borders; the teres minor superiorly, the inferior border is the teres major muscle, the medial boundary is the long head of the triceps brachii muscle, and the humeral surgical neck forms the lateral bound. The QS functions as a passageway for the axillary nerve, and the posterior humeral circumflex artery (PHCA).[3] The latter provides the primary (two-thirds) of the blood supply to the humeral head.[4]

Blood Supply and Lymphatics

The posterior humeral circumflex artery (PHCA) within the quadrangular space originates from the axillary artery, and within the QS, the PHCA divides into anterior and posterior branches. The branches provide blood supply to primarily the superior, inferior, and lateral portions of the humeral head, the deltoid muscle, the teres minor muscle, and the teres major muscle. The branches of the PHCA wrap around the surgical neck of the humerus to provide the predominant blood supply to the proximal humerus.  The classic study by Hettrich et al. redefined the current concepts regarding the quantitative assessment of the anterior humeral circumflex artery and PHCA's relative contribution of the blood supply to the proximal humerus.  Hettrich's group confirmed that approximately two-thirds (64%) of the blood supply to the humeral head derived from the PHCA, and the remaining 36% came from the AHCA.[5]  The latter is clinically relevant as it helped provide insight regarding the relatively low rates of osteonecrosis seen in association with three- and four-part proximal humerus fractures.[3][5][6]

Nerves

The axillary nerve, which passes through the quadrangular space, originates on the posterior cord of the brachial plexus, crosses the anteroinferior aspect of the subscapularis muscle and tendon, and traverses posteriorly through the QS. Within the QS, the axillary nerve runs superiorly to the posterior humeral circumflex artery and splits into an anterior and posterior branch. The anterior branch supplies the anterior deltoid muscle, while the posterior branch supplies the posterior deltoid muscle, teres minor muscle, and gives off the superolateral brachial cutaneous nerve, which innervates the distal two-thirds of the posterior deltoid. Together, the anterior and posterior branches supply the middle third of the deltoid muscle and the shoulder joint capsule.[3][7]

Muscles

Three muscles directly comprise the quadrangular space; the teres minor, teres major, and long head of the triceps brachii. The teres minor originates on the lateral border of the scapula, inserts on the greater tubercle of the humerus, and functions with glenohumeral joint external rotation. The teres major originates on the inferior angle of the scapula, inserting on the medial lip of the humerus intertubercular groove, and functions to extend, adduct, and internally rotate the GH joint. The long head of the triceps brachii muscle originates on the infraglenoid tubercle of the scapula, inserts on the olecranon process of the ulna, and functions to extend and adduct the GH joint, and extend the elbow joint.

The deltoid muscle gets innervated and perfused by the branches of the axillary nerve and PHCA, which are the primary structures of the QS. The deltoid muscle originates on the lateral third of the clavicle, acromion process, and spine of the scapula and has its insertion on the deltoid tuberosity of the humerus. The entire deltoid functions to abduct the GH joint while the anterior deltoid performs GH flexion and internal rotation and the posterior deltoid is in charge of GH extension and external rotation.[8]

Surgical Considerations

Nonoperative treatment modalities

In the vast majority of patients, exclusive treatment with nonoperative treatment modalities is sufficient for the management of acute or chronic symptoms.  Most patients report improvement with at least 3- to 6-months of nonoperative therapies. These modalities include, but are not limited to:

  • Nonsteroidal anti-inflammatory drugs (NSAIDs)
  • Activity modification
  • Physical therapy
    • therapeutic regimens and rehabilitation protocols emphasize glenohumeral joint mobilization, periscapular and rotator cuff strengthening programs, and posterior capsular stretching
  • Diagnostic lidocaine block
    • to confirm the diagnosis of QSS, an injection of 1% lidocaine (3cc or 5cc typically) to the QS will cause pain relief and symptomatic resolution

Surgical management

Open surgical decompression is reserved for patients with refractory QSS and failure of all nonoperative treatment modalities.  In cases of an apparent space-occupying lesion, or the setting of significant weakness and/or functional disability, earlier surgical decompression is a consideration.[3]

Open decompression is beneficial in patients with evidence of fibrous adhesions or scarring that may be impingement and/or compressing the axillary nerve.  In the setting of paralabral cysts (often seen in association with labral pathologies in the shoulder) decompression of the cyst, in addition to concomitant shoulder labral repair can be performed.[3]

In patients with vascular quadrangular space syndrome, their surgical management depends on the extent of damage to the posterior humeral circumflex artery. Patients who have an aneurysm of the PHCA undergo aneurysm resection. In patients with a thrombus, surgeons typically perform PHCA ligation, with or without thrombolysis. Patients who have a thrombus in their PHCA and digital emboli usually have a thromboembolectomy completed.[9]

While performing surgery, the physician should identify, palpate, and track the axillary nerve and posterior humeral circumflex artery, and all care must be taken to mitigate any iatrogenic risk or injury to these neurovascular structures. Following decompression of the QS, palpation of the axillary nerve and PHCA should be performed as an assistant moves the patient’s glenohumeral joint throughout abduction and external rotation, to ensure the neurovascular structures can move without restriction and that the PHCA maintains a pulse throughout the motion.[10]

Clinical Significance

The neurovascular structures which pass through the quadrangular space are essential for upper extremity function and damage to them can cause debilitating neurovascular symptoms. Misdiagnosis can occur due to the sophisticated presentation of injuries to the quadrangular space, and great care is requisite while evaluating the shoulder to identify these injuries.

Neurovascular Compression

Quadrangular Space Syndrome (QSS) occurs when the neurovascular structures within the quadrangular space get compressed due to mechanical forces. There are three types of QSS:

  1. Neurogenic quadrangular space syndrome (nQSS) is when there is compression of the axillary nerve within the quadrangular space. Patients with nQSS may present with quadrangular space tenderness, radicular pain, and paresthesia that follows a non-dermatomal pattern (more common on the posterior and lateral arm), fasciculations of the deltoid muscle in abduction, and where the denervation of muscles has occurred, muscle atrophy and weakness.
  2. Vascular quadrangular space syndrome (vQSS) occurs when the posterior humeral circumflex artery gets compressed within the quadrangular space. In patients with vQSS, ischemia of the PHCA can occur, which causes pain, pallor, and diminished or absent distal pulses. When compression of the PHCA leads to the formation of an aneurysm, thrombi, or a distal digital embolus, symptoms such as cyanosis and coolness of the digits and hand may occur.
  3. Patients may present with both neurogenic and vascular quadrangular space syndrome due to the proximity of the posterior humeral circumflex artery to the axillary nerve in the quadrangular space.[9]

The most common cause of quadrangular space syndrome is fibrous bands within the quadrangular space, which extend from the fascia of the long head of the triceps brachii muscle to the teres major muscle. Fibrous bands tighten when the glenohumeral joint is abducted and externally rotated, leading to impingement of the underlying neurovascular structures. Muscular hypertrophy can lead to similar compressive mechanisms as well.

Glenohumeral abduction and external rotation are common in overhead sports such as baseball, volleyball, swimming, and when doing activities such as cleaning windows. Hypertrophy of the teres major muscle and space-occupying lesions such as paralabral cysts (most commonly inferior labral tears), lipomas, axillary schwannomas, humeral osteochondromas, and fracture fragments can all also cause compression of the neurovascular structures in the QS and lead to QSS.[3][11]

QSS is unquestionably a diagnostic challenge in the majority of clinical presentations.  Thus, employing advanced imaging (radiographs and magnetic resonance imaging)[12] for further investigation of particularly nonspecific cases of shoulder pain that have remained refractory to an initial period of nonoperative treatments is a prudent diagnostic course.  

Trauma

Patients who sustain proximal humeral fractures, especially of the proximal humeral shaft, may sustain traumatic injuries to the neurovascular structures in the QS or proximity to the QS, leading to advanced conditions like humeral head avascular necrosis. Therefore, it is imperative to assess neurovascular function in patients with proximal humeral fractures.[6]


  • Image 7295 Not availableImage 7295 Not available
    Image courtesy S Bhimji MD
Attributed To: Image courtesy S Bhimji MD

Interested in Participating?

We are looking for contributors to author, edit, and peer review our vast library of review articles and multiple choice questions. In as little as 2-3 hours you can make a significant contribution to your specialty. In return for a small amount of your time, you will receive free access to all content and you will be published as an author or editor in eBooks, apps, online CME/CE activities, and an online Learning Management System for students, teachers, and program directors that allows access to review materials in over 500 specialties.

Improve Content - Become an Author or Editor

This is an academic project designed to provide inexpensive peer-reviewed Apps, eBooks, and very soon an online CME/CE system to help students identify weaknesses and improve knowledge. We would like you to consider being an author or editor. Please click here to learn more. Thank you for you for your interest, the StatPearls Publishing Editorial Team.

Anatomy, Shoulder and Upper Limb, Arm Quadrangular Space - Questions

Take a quiz of the questions on this article.

Take Quiz
A tumor in the quadrangular space is most likely to cause which of the following?

(Move Mouse on Image to Enlarge)
  • Image 7157 Not availableImage 7157 Not available
    Contributed by Häggström, Mikael (2014). "Medical gallery of Mikael Häggström 2014"
Attributed To: Contributed by Häggström, Mikael (2014). "Medical gallery of Mikael Häggström 2014"



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Structures found in the quadrangular space include which of the following?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
During surgery on the left shoulder, the orthopedic surgeon notes a large mass in the space shown in the image below. The mass appears to be compressing the neurovascular structures running through this space. Prior to surgery, what deficit would have been noticeable in this patient?

(Move Mouse on Image to Enlarge)
  • Image 5972 Not availableImage 5972 Not available
    Image Courtesy S Bhimji MD
Attributed To: Image Courtesy S Bhimji MD



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A swimmer is complaining of posterior shoulder pain, accompanied with deltoid and teres minor muscle atrophy and weakness, and paresthesia over the deltoid muscle. What repetitive glenohumeral motions led to this patient's condition?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A baseball pitcher comes into your office complaining of pain, pallor, and paresthesia of his right upper extremity during practice as he pitches. Upon evaluation, you notice his distal upper extremity pulses are diminished, and he has posterior shoulder pain. What is the most likely diagnosis?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up

Anatomy, Shoulder and Upper Limb, Arm Quadrangular Space - References

References

Flynn LS,Wright TW,King JJ, Quadrilateral space syndrome: a review. Journal of shoulder and elbow surgery. 2018 May     [PubMed]
Hettrich CM,Boraiah S,Dyke JP,Neviaser A,Helfet DL,Lorich DG, Quantitative assessment of the vascularity of the proximal part of the humerus. The Journal of bone and joint surgery. American volume. 2010 Apr     [PubMed]
Khmelnitskaya E,Lamont LE,Taylor SA,Lorich DG,Dines DM,Dines JS, Evaluation and management of proximal humerus fractures. Advances in orthopedics. 2012     [PubMed]
Gurushantappa PK,Kuppasad S, Anatomy of axillary nerve and its clinical importance: a cadaveric study. Journal of clinical and diagnostic research : JCDR. 2015 Mar     [PubMed]
Terry GC,Chopp TM, Functional anatomy of the shoulder. Journal of athletic training. 2000 Jul     [PubMed]
Hangge PT,Breen I,Albadawi H,Knuttinen MG,Naidu SG,Oklu R, Quadrilateral Space Syndrome: Diagnosis and Clinical Management. Journal of clinical medicine. 2018 Apr 21     [PubMed]
Brown SA,Doolittle DA,Bohanon CJ,Jayaraj A,Naidu SG,Huettl EA,Renfree KJ,Oderich GS,Bjarnason H,Gloviczki P,Wysokinski WE,McPhail IR, Quadrilateral space syndrome: the Mayo Clinic experience with a new classification system and case series. Mayo Clinic proceedings. 2015 Mar     [PubMed]
Rollo J,Rigberg D,Gelabert H, Vascular Quadrilateral Space Syndrome in 3 Overhead Throwing Athletes: An Underdiagnosed Cause of Digital Ischemia. Annals of vascular surgery. 2017 Jul     [PubMed]
Nickerson M,Varacallo M, Swimmers Shoulder . 2018 Jan     [PubMed]
McClelland D,Hoy G, A case of quadrilateral space syndrome with involvement of the long head of the triceps. The American journal of sports medicine. 2008 Aug     [PubMed]
Mostafa E,Varacallo M, Anatomy, Shoulder and Upper Limb, Humerus . 2018 Jan     [PubMed]
    [PubMed]

Disclaimer

The intent of StatPearls is to provide practice questions and explanations to assist you in identifying and resolving knowledge deficits. These questions and explanations are not intended to be a source of the knowledge base of all of medicine, nor is it intended to be a board or certification review of Optometry-Basic Science. The authors or editors do not warrant the information is complete or accurate. The reader is encouraged to verify each answer and explanation in several references. All drug indications and dosages should be verified before administration.

StatPearls offers the most comprehensive database of free multiple-choice questions with explanations and short review chapters ever developed. This system helps physicians, medical students, dentists, nurses, pharmacists, and allied health professionals identify education deficits and learn new concepts. StatPearls is not a board or certification review system for Optometry-Basic Science, it is a learning system that you can use to help improve your knowledge base of medicine for life-long learning. StatPearls will help you identify your weaknesses so that when you are ready to study for a board or certification exam in Optometry-Basic Science, you will already be prepared.

Our content is updated continuously through a multi-step peer review process that will help you be prepared and review for a thorough knowledge of Optometry-Basic Science. When it is time for the Optometry-Basic Science board and certification exam, you will already be ready. Besides online study quizzes, we also publish our peer-reviewed content in eBooks and mobile Apps. We also offer inexpensive CME/CE, so our content can be used to attain education credits while you study Optometry-Basic Science.