Osteopathy Journals and Research by Darren Chandler

 

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  1. Introduction

    Traction or inflammation of the brachial plexus can account for a variety of cervical spine, periscapular and upper extremity symptoms.

    Myofascial causes of this has been largely attributed to thoracic outlet syndrome. A review of the fascia anatomy and physiology of thoracic outlet syndrome can throw new light on this condition in osteopathic practice. Specific considerations in this field are:

    1. Anatomy and mechanical strains of the prevertebral fascia that forms a sheath for the brachial plexus (axillary sheath).
    2. Hypertrophy of the scalene (prevertebral) fascia in thoracic outlet syndrome.
    3. Role of the omohyoid muscle in tensing the prevertebral fascia.
    4. The continuity of the prevertebral fascia with the costocoracoid membrane and intern the continuity of the costocoracoid membrane with the sheath of the brachial plexus (axillary sheath).
    5. Vascular changes in response to traction and the resultant fibrosis in the fascia of the brachial plexus this produces.

    The article is split into:

    • Anatomy of the brachial plexus.
    • Anatomy of the prevertebral fascia.
    • Anatomy of the clavipectoral fascia.
    • Anatomy of the thoracic outlet.
    • Pathological findings in the thoracic outlet.
    • Anatomical variations in the infraclavicular space.
    • Anatomy of the brachial plexus sheath.
    • Biomechanics of the brachial plexus and resultant inflammatory changes.
    • Traction forces causing inflammatory changes and fibrosis of the brachial plexus fascia.

    Anatomy of the brachial plexus (Revankar et al, 2013)

    1. Nerve roots of the brachial plexus (ventral rami):
    • The brachial plexus is formed by the union of the ventral rami from C5 to T1.
    • After exiting the intervertebral foramen these ventral rami run in the interval between the scalene anterior and scalene medius (scalene hiatus). This lies between the anterior tubercles (scalene anterior attachment) and posterior tubercles (scalene medius attachment) of the corresponding transverse processes of the cervical vertebrae.
    • As well as the prevertebral fascia splitting between the scalene anterior and medius to create the scalene hiatus it also ensheaths the intervening C5 to T1 nerve roots.
    • After leaving the scalene hiatus these nerve roots of the brachial plexus descend in front of the scalene medius.

        2. Ventral rami to the nerve trunks of the brachial plexus:

    • Upper trunk: formed where the C5 & C6 ventral rami unite at the lateral border of scalenus medius.
    • Middle trunk: continuation of the C7 ventral rami.
    • Lower trunk: formed where the C8 & T1 ventral rami unite behind the scalene anterior.

        3. Nerve trunks to nerve cords of the brachial plexus:

        As the brachial plexus descends through the costocoracoid space three cords are formed:

    • Posterior cord: formed from the posterior divisions of all three trunks (C5-C8, T1).
    • Lateral cord: formed from the anterior divisions of the upper and middle trunks (C5-C7).
    • Medial cord: continuation of the anterior division of the lower trunk (C8 & T1).

        4. Nerve cords to terminal branches:

        Just lateral to the Pectoralis Minor the nerve cords turn into the terminal nerve trunks:

    • Musculocutaneous nerve: formed from the lateral cord of the brachial plexus (C5-C7).
    • Axillary nerve: formed from the posterior cord of the brachial plexus (C5 & C6).
    • Radial nerve: formed from the posterior lateral and medial cords of the brachial plexus (C5-T1).
    • Median nerve: formed from the lateral (C5 & C6) and medial cords (C8 & T1) of the brachial plexus.
    • Ulna nerve: formed from the medial cord of the brachial plexus (C8 & T1).

    Anatomy of the Prevertebral fascia (Feigl, 2015 and Natale et al, 2015)

     Anteriorly:

    • Can attach to the cervical vertebral bodies.
    • Attaches to the Alar fascia.

    Posteriorly:

    • Covers the deep dorsal muscles of the neck.

    Superiorly:

    • Attaches to the basilar part of the occiput.
    • Envelopes the rectus capitis anterior and the vagus nerve.

    Descends:

    • Passes anteriorly to the prevertebral muscles and envelopes the scalene anterior.
    • At C6 the fascia splits. Laterally along the scalene anterior and medially along the longus colli. This creates a gap that forms the triangle of the vertebral artery.

    Laterally:

    • Attaches to the transverse processes of the cervical vertebrae.
    • Blends with the superficial cervical fascia at the Trapezius.

    Inferiorly:

    • Attaches to the upper border of the scapula.
    • Continues inferolaterally as the axillary sheath.
    • With the scalene anterior and medius to rib 1 and scalene posterior to rib 2 (Syed et al 1953)
    • Inserts into the fascia of the subclavis and from there to the costocoracoid membrane that runs to the axillary sheath.
    • Runs continuous with the endothoracic fascia.
    • Descends to the thoracic cavity within the adipose tissue of posterior mediastinum giving off fibrous bundles to the pericardium and the lung hilum proceeding up to the tendinous centre of the diaphragm.

    Envelopes:

    • Vagus nerve.
    • Phrenic nerve.
    • Sympathetic trunk.
    • Rectus capitis anterior.
    • Central tendon of the omohyoid.

    Anatomy of the clavicopectoral fascia

    The clavipectoral fascia is a deep layer of fascia in the pectoral regions. It acts to suspend the floor of the axilla and protect the axillary nerve, artery and vein. Its boundaries are:

    Laterally:

    • Coracoid process of scapula.
    • Coracoclavicular ligament.
    • Short head of bicep.
    • Suspensory ligament of the axilla.

    Medially:

    • First costal cartilage.
    • External intercostal membrane of the first two intercostal spaces.

    The portion extending between the first rib and coracoid process is often thicker and called the costocoracoid membrane.

    Superiorly:

    • The fascia splits anteriorly and posteriorly to enclose the subclavis and attach to the clavicle. The posterior part of the fascia that encloses the subclavis fuses with the prevertebral fascia and the axillary sheath.

    Inferiorly:

    • Invests the pectoralis minor.

    Deep:

    • Extends in continuity with the axillary sheath.

    Superficial:

    • Blends with the deep fascia of the pectoralis major.

    Anatomy of the thoracic outlet (Demondion et al 2006)

     The thoracic outlet is comprised of three confined anatomical spaces:

    1. Interscalene triangle.
    2. Costoclavicular space.
    3. Retropectoralis minor space.
    1. Interscalene triangle

    Boundaries:

    • Anterior: scalene anterior.
    • Posterior: scalene medius and posterior.
    • Inferior: rib 1.

    Contents:

    Inferior: sublclavian artery.

    Middle: Upper (C5 & C6 ventral rami) and middle (C7 ventral rami) trunks of the brachial plexus.

    Superior: Omohyoid muscle.

    Inferior and posterior: Lower (C8 & T1 ventral rami) trunk of the brachial plexus.

    Leonhard et al (2017) found anatomical variations in 62.1% of cadavers where the scalene anterior was pierced by the C5 ventral ramus, superior trunk or superior and middle trunks of the brachial plexus.

    Chen et al (1998) found in 88.3% of cadavers the T1 nerve root or the lower trunk of the brachial plexus crossed rib 1 over the proximal scalene minimus tendon.

        2. Costoclavicular space

    Boundaries:

    • Superior: clavicle.
    • Anterior: subclavis.
    • Posterior: rib 1 and scalene medius.

    Contents:

    • Anterior: subclavian vein
    • Posterior: subclavian artery.
    • Superior (above subclavian vessels): brachial plexus (lateral, medial and posterior cords).

        3. Retropectoralis minor space

    Boundaries

    • Anterior: posterior part of the pectoralis minor.
    • Postero-superior: subscapularis.
    • Postero-inferior: anterior chest wall.

    Contents: as costoclavicular space.

    Just lateral to the Pectoralis Minor the cords of the brachial plexus divide into the terminal branches (median, ulna, musculocutaneous, axillary and radial nerves).

    Pathological findings in the thoracic outlet

     Demiondion et al (2006) found:

    • Nerve compression: costoclavicular space = interscalene triangle.
    • Arterial compression: costoclavicular space > interscalene triangle.

    The retropectoralis minor space was rarely implicated in thoracic outlet syndrome.

    Fiske (1952) found that hypertrophy of the omohyoid can irritate the brachial plexus. Anatomical variations of the omohyoid can find it attaching to the C6 transverse process anterior to the scalene medius (Tubbs et al 2004). This can directly contribute to thoracic outlet syndrome.

    There is a possibility that the Omohyoid could mechanically predispose to thoracic outlet syndrome:

    • Williams & Warwick (1980) describes the Omohyoid as tensing the lower part of the prevertebral fascia. The prevertebral fascia forms the sheath of the brachial plexus. Could contraction of the Omohyoid predispose to tension in the brachial plexus sheath and the vascular and hypertrophic changes that ensue? (Refer below, 'biomechanics of the brachial plexus and resultant inflammatory changes').
    • The intermediate tendon of the omohyoid is attached to the clavice and rib 1 via a fascial sling from the prevertebral fascia. Could contraction of the omohyoid affect the mechanics of rib 1 and the clavicle creating a dynamic compression of the brachial plexus?  

    Pathological findings in thoracic outlet syndrome have largely been attributed to the scalene anterior and medius and its fascia (prevertebral fascia). It should be remembered that this fascia forms the sheath of the brachial plexus.

    Anatomical variations in the scalenes include:

    1. Scalene Minimus hypertrophy: compression of the T1 nerve root or the lower trunk of the brachial plexus (Chen et al 1998). Chuang et al (2016) found the scalenus minimus associated with 30-50% of patients with neurological thoracic outlet syndrome.
    2. Scalene anterior and scalene medius: crossed tendinous origins from the anterior and posterior tubercle of C4 and C5 transverse process can compress the C5 and C6 nerve root or the upper trunk of the brachial plexus (Chen et al 1998).
    3. Roos’ bands: compression from these fibrous bands can compress the brachial plexus rami. These bands extend from the cervical rib, rib 1, elongated C7 transverse process, scalene anterior and medius to rib 1 or the cupola of the lung (Demondion et al 2006 and Spears et al 2011).

    Chuang et al (2016) found in patients having thoracic outlet surgery:

    1. Tight or hypertrophic scalene anterior.
    2. Bifid insertion of the scalene anterior into rib 1.
    3. Thickened posterior fascia of the scalene medius with palpable intramuscular fibrosis.
    4. The scalenus minimus muscle was found to be associated with 30-50% of patients with neurological thoracic outlet syndrome.

    Tanna (1947) even found the thickened lateral edge of the cervical fascia posterior and lateral to the scalene anterior can become an organised fibrous cord. The author claimed this had pressed on the third portion of the subclavian artery resulting in a thrombosis.

    In addition to the scalene and its (prevertebral) fascia causing thoracic outlet syndrome by hypertrophic changes could it also cause a pathology of the triangle of the vertebral artery. The triange of the verterbral artery is formed where the prevertenral fascia splits between the longus colli and scalene anterior.

    Triangle of the vertebral artery (Tubbs et al 2005)

    Boundaries

    Inferior: subclavian artery.

    Posterior: scalene medius.

    Medial: Longus Colli.

    Lateral: scalene anterior.

    Contents

    • Vertebral artery.
    • Ganglionated sympathetic chain.
    • C7 and C8 spinal nerve.
    • Phrenic nerve.

    Stecco et al (2014) found at least some of these pathological findings in the scalene fascia can be reversed with osteopathic treatment. The authors found significant increased thickness of the scalene fascia in patients with neck pain. With manipualtion a significant decrease in pain and thickness of the fascia was found.

    Anatomical variations in the infraclavicular space

    Even though the subclavis, in standard anatomical form, is intimately related to the prevertebral and clavipectoral fascia it has not been directly related to thoracic outlet syndrome.

    Variations in the subclavis have been associated with compression of the subclavian artery and the brachial plexus in the costoclavicular space. Variations in this muscle is termed the subclavius posticus muscle or chondroscapularis. These anatomical variations include (Grigorita et al 2018):

    1. Originates from the postero-superior side of the costocoracoid membrane and costoclavicular ligament to insert onto the superior border of the scapula and on the superior transverse scapular ligament. This shares a common insertion with the inferior belly of the omohyoid muscle.

    This muscle runs under the subclavian artery, subclavian vein, and trunks of the brachial plexus. The suprascapular nerve as it runs above the superior transverse scapular ligament perforates and innervates this muscle. This muscle can cause an entrapment neuropathy of the brachial plexus and suprascapular nerve.

    2. Originates on the first costal cartilage or on the superior surface of the sternal end of the first rib. Variable insertion include:

    a. Superior boarder of the scapula mediocaudal to the inferior belly of the omohyoid.

    b. Superior boarder of the scapula and superior transverse scapular ligament.

    c. Transverse scapular ligament and coracoid process.

    d. Superior angle of the scapula.

    e. Medial margin of the suprascapular notch.

    f. Capsule of the acromioclavicular joint.

    g. Axillary sheath.

    h. Fascia covering the subscapularis muscle.

    Anatomy of the brachial plexus sheath

    Thompson & Rorie (1983) described the connective tissue forming the sheath of the brachial plexus as terminating via the axillary sheath at the anterior and posterior laminae of the medial intermuscular septum.

    Being organised more densely as it leaves the prevertebral fascia the sheath becomes more loosely organised distally as it ended by joining the medial intermuscular septum.

    The connective tissue of the sheath extends internally forming septa. These septa are similar in thickness and density as the surrounding fascia and compartmentalise the brachial plexus sheath. Brenner et al (2018) found fascial layers in the neurovascular sheath in the infraclavicular space.

    These sheaths run continuous proximally and distally. At the level of the axilla the compartment of the terminal nerve runs continuous with the cords that form it. Thus the compartment of the median nerve runs continuous with that of the medial and lateral cords and the compartment of the ulna nerve runs continuous with that of the medial cord.

    However Cornish and Leaper (2006) argued against a sheath for the brachial plexus. They found the brachial plexus runs between different tissues that closely surround the clavicle, scapula, chest wall, and humerus. So whilst the brachial plexus maybe surrounded by connective tissue, this tissue is not homogenous, but is derived from the surrounding structures. 

    Biomechanics of the brachial plexus and resultant inflammatory changes

    Mihara et al (2018) analysed strain on the brachial plexus during different movements they found:

    • C5 nerve root: strained during cervical spine extension and contralateral sidebending.
    • Lower trunk of the brachial plexus < C7 and C8 nerve roots: strained with upper limb abduction. However Pan et al (2008) found the lateral cord (C5 to C7) is still strained during abduction as it moves closer to the coracoid process at 60 degrees than at 30 degrees of abduction.
    • Kitamura et al (1995) found a reduction of traction of the brachial plexus by shoulder elevation therefore presumably an increase in traction by shoulder depression.

    Traction forces causing inflammatory changes and fibriosis of the brachial plexus

    Kitamura et al (1995) noted vascular and inflammatory changes to the brachial plexus accompany fibrotic changes to its surrounding connective tissue.

    They found the peripheral nerves had an extrinsic and intrinsic vascular supply:

    • Extrinsic vascular system: includes segmental regional vessels approaching the nerve trunk at various levels. These regional vessels run in the loose "adventitia" or along the paraneural tissue surrounding the nerve. The looseness of this “adventitia” allows the nerve trunk considerable mobility in its bed.
    • Intrinsic vascular system: includes numerous vascular plexa in the epineurium, perineurium, and endoneurium.

    When the peripheral nerves are stretched, the surrounding blood vessels are extended, resulting in decreased blood flow within the nerve bundle. How this effects the extrinsic and intrinsic blood flow varies:

    • Extrinsic system: blood flow decreases sharply in the presence of relatively small amount of traction and then decreases in a slow linear fashion with further increases in traction.
    • Intrinsic system: on the other hand, the blood flow through the intrinsic system showes a slower linear decrease in response to traction.

    The difference in blood flow between the two systems can be explained by the biomechanics of the nerve in response to stretch. If stretching the nerve stretches the blood vessels. Stretching the blood vessels results in less circulation. Then the area stretched the least and has the better circulation should redirect blood to the area that is stretched the most and has the worst circulation.

    When a nerve is stretched blood is supplied from the less elongated portion i.e. the extrinsic system as it flows through the loose “adventitia” to the more elongated portion i.e. the intrinsic system that gets pulled tighter.

    The sharp decrease in the blood flow through the extrinsic system can lead to local elevation of vascular permeability and oedema. With repeated stretching over a two week span this has been shown to lead to hypertrophic connective tissue and vascularization of the epineurium and the surrounding tissue. Could this cause a cascade that results in a further decrease movement and vascular changes? Could this also be the cause of fibrosis seen around the brachial plexus during operations on patients with traumatic thoracic outlet syndrome? (Chuang et al 2016).

    References

    Thoracic Outlet Syndrome: Past and Present—88 Surgeries in 30 Years at Chang Gung (2016). Chwei-Chin Chuang, David MD; Fang, Frank MD; Nai-Jen Chang, Tommy MD; Chuieng-Yi Lu, Johnny MD.

    Fascia and spaces on the neck: myths and reality (2015). Georg Feigl

    Is the cervical fascia an anatomical proteus? (2015). Natale G, Condino S, Stecco A, Soldani P, Belmonte MM, Gesi M.

    The Sheath of the Brachial Plexus: Fact or Fiction? (2006). Philip B. Cornish, Christopher Leaper.

    Imaging Assessment of Thoracic Outlet Syndrome (2006). Xavier Demondion, Pascal Herbinet, Serge Van Sint Jan, Nathalie Boutry, Christophe Chantelot, Anne Cotten

    Ultrasonographic Diagnosis of Thoracic Outlet Syndrome Secondary to Brachial Plexus Piercing Variation (2017). Vanessa Leonhard, Gregory Caldwell, Mei Goh, Sean Reeder, and Heather F. Smith.

    Anatomical relationship of Roos' type 3 band and the T1 nerve root (2011). Spears J, Kim DC, Saba SC, Mitra A, Schneck C, Mitra A.

    Ultrasonography in myofascial neck pain: randomized clinical trial for diagnosis and follow-up (2014). Stecco A, Meneghini A, Stern R, Stecco C, Imamura M.

    The triangle of the vertebral artery (2005). Tubbs RS, Salter EG, Wellons JC 3rd, Blount JP, Oakes WJ.

    Relation of roots and trunks of brachial plexus to scalenus anterior muscle and its clinical significance (2013). Yogesh , Viveka S , Sudha M J , Santosh Kumar S.C, Sanjay Revankar 

    The relationship of the lateral cord of the brachial plexus to the coracoid process during arthroscopic coracoid surgery: a dynamic cadaveric study (2008). Pan WJ, Teo YS, Chang HC, Chong KC, Karim SA.

    Fascial layers influence the spread of injectate during ultrasound-guided infraclavicular brachial plexus block: a cadaver study (2018). Brenner D, Mahon P, Iohom G, Cronin M, O'Flynn C, Shorten G.

    An Aberrant Subclavius Posticus Muscle - A Case Report (2018). Grigoriță L, Vaida MA, Jianu A.

    Brachial Plexus irritation due to hypertrophied omohyoid muscle; a case report (1952). Fiske LG.

    Unusual origin of the omohyoid (2004). Tubbs RS, Salter EG, Oakes WJ.

    Gray's anatomy (36th edition) (1980). Williams P Warwick R

    Cervical fascia anatomic and clinical: a joint anatomical and clinical investigation of the fascial spaces in the floor of the mouth and neck with special reference to the spread of  suppuration and infection (1953). Syed, Durwaish, Mohiuddin

  2. Introduction

    Entrapment neuropathy of the saphenous nerve in the subsartorial (adductor) canal can account for:

    • Anteromedial thigh and shin symptoms.
    • Knee medial joint line pain.
    • Restless leg syndrome (Lewis 1991).

    Outlined is a review of the anatomy of the subsartorial canal including its associated anatomical structures including:

    • Fascia Lata.
    • Medial Intermuscular septum.
    • Sartorious fascia.
    • Vastofemoral and Vastoadductor membrane.
    • Fascia overlying the Obturator Externus and Adductor Magnus.

    Subsartorial (adductor) canal

    Standring (2015) identified the subsartorial (adductor) canal as a intermuscular tunnel occupying the distal two thirds of the medial aspect of the thigh. 

    Boundaries

    The boundaries of the subsartorial canal include:

    • Proximal: apex of the femoral triangle.
    • Distal: distal attachment of the tendon of the adductor magnus.
    • Roofed: Sartorious muscle and its fascia and the vastoadductor membrane (Oliveira et al 2009).
    • Posterior: (proximal) Adductor Longus and (distal) Adductor Magnus (and its fascia that continues over the Obturator Externus. Kumka, 2010).
    • Anterolateral: Vastus Medialis.

    Contents

    The contents of the subsartorial canal include:

    • Superficial femoral artery.
    • Femoral vein.
    • Femoral nerve (Saphenous nerve and nerve to the Vastus Medialis)

    Oliveira et al (2009) found the connective tissue of the adductor canal continuous with the outer layer of the vessels. They identified this as a cause of inhibiting the vessels from sliding freely during movement and causing a dynamic compression mechanism.

    Soft tissues associated with the subsartorial canal

    The soft tissues associated with the Subsartorial canal are: 

    Fascia Lata

    The deep investing fascia which envelopes the muscles of the thigh is known as the Fascia Lata. It splits into two distinct layers at several locations in the thigh, either to enclose muscles such as Gluteus Maximus and Tensor Fascia Lata, or to create openings such as the saphenous opening for the great saphenous vein.

    Proximally the fascia lata has a complete attachment to the pelvic bone: anteriorly to the pelvic rami and inguinal ligament, laterally to the iliac crest (with a thickening at the iliac tubercle) and posteriorly to the ischial tuberosity, sacrotuberous ligament, sacrum and coccyx (Huang et al 2013)

    Stecco et al (2013) found the fascia lata continuous with the gluteus fascia and the crural fascia. It is thicker laterally and posterolaterally. They found it's not adhered to the muscles of the thigh due to a loose connective tissue between the fascia lata and the muscles. There are three exceptions:

    (1) In the distal thigh the fascia lata gives origin to some fibers of the vastus lateralis and vastus medialis.

    (2) Where the fascia lata gives a myofascial origin to the bicep femoris.

    (3) There is a complete adhesion of the vastus medialis to the fascia lata along its entire course.

    The fascia lata forms intermuscular septum these are:

    (1) Medial intermuscular septum: described below. It seperates the Vastus Medialis from the Adductor Longus and Magnus. It attaches to the linea aspera and medial supracondylar ridge (Burnet et al 2004).

    (2) Lateral intermuscular septum: it seperates the anterior and posterior compartments of the thigh. It lies between the Vastus Lateralis and Bicep Femoris and attaches to the linea aspera of the femur (Fairclough et al 2006). Fibers from the lateral intermuscular septum run from the femur to the iliotibial band. These form the horizontal fibers of the iliotibial band (Evans 1979)

    As well as the vastus lateralis, vastus medialis and the bicep femoris the fascia lata also receives muscular insertions from the gluteus maximus. These muscle fibers attach onto the iliotibial band and the lateral intermuscular septum.

    The iliotibial band is merely a lateral expansion of the fascia lata and made up of three layers: superficial, middle and deep.

    The superficial and middle layer encloses the tensor fascia lata anchoring it to the iliac crest. These layers unite at the distal end of the tensor fascia lata to form a tendon for the muscle. These united two layers receives fibers from the gluteus maximus and run down the lateral thigh. Fairclough et al (2006) found the iliotibial band attached to the region of, or directly to, the lateral epicondyle of the femur by strong fibrous strands before terminally attaching to gerdy's tubercle on the tibia. Evans (1979) found additional attachments to the patella retinaculum and lateral meniscus.

    The deep layer of the iliotibial band merges just distal to where the superficial and middle layers fuse distal to the tensor fascia lata (Putzer et al 2017). From here it runs deep attaching to the vastus lateralis and rectus femoris fascia. Coursing deeper still it follows the iliofemoral ligament to attach to the supraacetabular fossa between the tendon of the reflected head of the rectus femoris and the hip joint capsule. It resists hip extension.

    With reference to the subsartorial canal the fascia lata's importance lies in its attachments to the Adductor Longus, Adductor Magnus, it's strong attachments to the Vastus Medialis and Medial Intermuscular Septum. The importance of these are discussed below.

    Sartotious fascia

    Burnet et al (2004) describes a fascial envelope around the Sartorius in the upper thigh which in a majority of cases continues distally in the lower part of the muscle.

    Posteriorly this is reinforced by the thick aponeurotic roof of the subsartorial canal: the vastofemoral and vastoadductor membrane.

    Vastofemoral and Vastoadductor membrane

    The Vastofemoral and Vastoadductor membrane are two membranes in the subsartorial canal. They can be continuous with each other or discontinuous. Oliveira et al (2009) describes the Vastoadductor membrane as being the roof of the subsartorial canal.

    (a) Vastofemoral membrane

    Vastofemoral membrane lies proximal in the subsartorial canal. It runs between the Vastus Medialis and femoral artery (Elazab & Elazab 2017).

    (b) Vastoadductor membrane

    Tubbs et al (2007) found the vastoadductor membrane to originate from the medial intermuscular septum. Elazab & Elazab (2017) found the fibers of the vastoadductor membrane to originate from the adductor magnus tendon and the fascia overlying the adductor magnus. This fascia runs continuous proximally over the Obturator Externus (Kumka 2010).

    The vastoadductor membrane lies distally to the Vastofemoral membrane in the subsartorial canal. It bridges from the adductor longus proximally and adductor magnus distally to the vastus medialis (Elazab & Elazab 2017)

    Tubbs et al (2007) measured the vastoadductor membrane 7.6cm long. They measured 28cm from the ASIS to the proximal boarder of the vastoadductor membrane and 10cm from the adductor tubercle to the distal boarder.

    Subsartorial (adductor) canal

    All ready described above this intermuscular canal is bound on all sides by muscular and fascial tissue capable of causing an entrapment neuropathy and vascular claudication.

    Medial Intermuscular Septum

    From superficial to deep the medial intermuscular septum joins the fascia lata superficially before travelling deep through the thigh seperating the Vastus Medialis in the anterior compartment and the Adductor Longus and Magnus in the posterior compartment. Travelling deeper still it attaches to the medial lip of the linea aspera of the femur and its medial supracondylar ridge (Burnet et al 2004).

    Tubbs et al (2007) found the medial intermuscular septum to give origin to the vastoadductor membrane. This membrane bridges across the medial intermuscular septum from the vastus medialis to the adductor longus (proximally) and adductor magnus (distally). In contrast Elazab & Elazab (2017) found the vastoadductor membrane to originate from the adductor magnus tendon and fascia.

    Considerations in the myofascial treatment of the Subsartorial canal

    Obturator Externus & Adductor Magnus

    Elazab & Elazab (2017) found the fascia of the Obturator Externus and the Adductor Magnus gives origin to the Vastoaddutor membrane. The Adductor Magnus also forms a boundary for the Subsartorial canal.

    Obturator Externus

    Origin: the external bony margin of the obturator foramen and a few fibres from the obturator membrane.

    Insertion: Trochanteric fossa with some fibres extending towards the piriformis fossa.

    Action: primary function of external rotation with the hip in flexion.

    With the hip in extension the Obturator Externus does not function as an external rotator. In fact the Obturator Externus stretches slightly when extended and externally rotated (Gudena et al 2015). 

    Stretching the obturator externus

    The mean efficiency of stretching the muscle in internal rotation is (Gudena et al 2015):

    (1)    Most effective in hip extension.

    (2)    Secondly most effective in 90 degrees hip flexion.

    (3)    Thirdly most effective in a neutral hip position.

    Vaarbakken et al (2015) found the most effective way to stretch the Obturator Externus was in extension/abduction/internal rotation.

    Adductor Magnus

    Origin: pubis to the ischium

    Insertion: a point between the greater trochanter and the linea aspera, down the linea aspera to the medial condyle (adductor tubercle) of the femur.

    Action:

    The superior fibers that run horizontally to the more proximal part of the linea aspera flex the the thigh

    The fibers that attach to the linea aspera laterally rotates the thigh.

    The fibers that attach distally on the femur at the adductor tubercle medially rotates the thigh (Reimann et al 1996).

    The more vertical fibers that run more distally on the linea aspera and adductor tubercle extend the thigh.

    Vastus Medialis

    As well as forming a boundary for the Subsartorial canal the Vastus Medialis is an attachment for the vastoadductor membrane.

    Origin: femur

    Insertion: patella tendon

    Action: Pulls the patella medially and has a minimal roll in knee extension. Mixed results if the Vastus Medialis activates with joint hip adduction and knee extension.

    The Vastus Medialis muscle fibers run at an almost horizontal angle (50 to 55 degs to the shaft of the femur) giving it a minimal function in knee extension (Miao et al 2015). Studies are mixed supporting the activation of the Vastus Medialis with simultaneous knee extension and hip adduction with Miao et al (2015) finding only in patellofemoral pain did this actively recruit the Vastus Medialis. 

    Adductor Longus

    The Adductor Longus forms a boundary for the Subsartorial canal.

    Origin: ramus superior of the pubic bone and deep portion of the anterior pubic ligament.

    Insertion: linea aspera

    van de Kimmenade et al (2015) found the muscle a relatively thin muscle.

    The adductor longus forms a continuous 'complex' with the abdominal muscles (Schilders et al 2017):

    • Pyramidalis: the Adductor Longus has attachments to the pyramidalis and deep anterior pubic ligament.
    • External oblique and anterior rectus sheath: via the superficial anterior pubic ligament the aponeurosis of the external oblique and anterior rectus sheath connects with the fascia lata over the adductor area. 

    Action: flexion, adduction and internal rotation and external rotation of the femur.

    Flexion and abduction intensifies the lateral rotating function of the Adductor Longus. Extension and adduction intensifies the internal rotating function of the Adductor Longus (Reimann et al 1996).

    Sartorius

    The Sartorius fascia attaches to the Vastoadductor membrane.

    Origin: ASIS

    Insertion: (1) joins to the pes anserine tendon below the tibial tuberosity. (2) Below and medial to the medial tuberosity. (3) Deep fascia of the crus. (Dziedzic et al 2013).

    Action (Dziedzic et al 2013): 

    • Initialises hip and knee flexion from the phase of full extension. 
    • Weak external rotator and abductor of the hip joint.
    • Rotates the tibia and fibula internally with the knee joint flexed.

    References

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    Elazab EEB. Morphological study and relations of the fascia vasto-adductoria (2017).

    Flavia de Oliveira, Ricardo Bragança de Vasconcellos Fontes, Josemberg da Silva Baptista, William Paganini Mayer, Silvia de Campos Boldrini, and Edson Aparecido LibertiThe connective tissue of the adductor canal – a morphological study in fetal and adult specimens (2009). 

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    NEIL G. BURNET, TOM BENNETT-BRITTON , ANDREW C.F. HOOLE, SARAH J. JEFFERIES & IAN G. PARKINThe anatomy of sartorius muscle and its implications for sarcoma radiotherapy (2004). 

    Eman Elazab Beheiry Elazab. Subsartorial Compartments and Membranes in the Adductor Canal: Morphological, Histological and Immunohistochemical Study (2017) 

    Myroslava Kumka. Critical sites of entrapment of the posterior division of the obturator nerve: anatomical considerations (2010). 

    Lewis F. The role of the saphenous nerve in insomnia: a proposed etiology of restless legs syndrome. (1991). 

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    Gudena R, Alzahrani A, Railton P, Powell J, Ganz R.The anatomy and function of the obturator externus (2015). 

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    D. Dziedzic, U. Bogacka, B. Ciszek. Anatomy of sartorius muscle (2013) 

    Ernest Schilders, Srino Bharam, Elan Golan, Alexandra Dimitrakopoulou, Adam Mitchell, Mattias Spaepen, Clive Beggs, Carlton Cooke, and Per Holmich. The pyramidalis–anterior pubic ligament–adductor longus complex (PLAC) and its role with adductor injuries: a new anatomical concept (2017). 

    R. J. L. L. van de Kimmenade, C. J. A. van Bergen, P. J. E. van Deurzen and R. A. W. Verhagen. A Rare Case of Adductor Longus Muscle Rupture (2015)

    Miao P, Xu Y, Pan C, Liu H, Wang C. Vastus medialis oblique and vastus lateralis activity during a double-leg semisquat with or without hip adduction in patients with patellofemoral pain syndrome (2015). 

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    David Putzer, Matthias Haselbacher, Romed Hörmann, Günter Klima, and Michael Nogler. The deep layer of the tractus iliotibialis and its relevance when using the direct anterior approach in total hip arthroplasty: a cadaver study (2017)

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