Rhomboids

Rhomboid minor. It arises from the lower part of the ligamentum nuchae and the spinous processes of C7 and T1, with their supraspinous ligaments. It inserts as a narrow band, roughly 1 to 2 cm wide, onto the medial border of the scapula at the root (base) of the scapular spine, the smooth triangular area where the spine meets the medial border.

Rhomboid major. It arises from the spinous processes of T2 to T5 and the intervening supraspinous ligaments, and inserts along the medial border from the root of the scapular spine down to the inferior angle. Much of the insertion is through a tendinous arch that attaches firmly at its upper and lower ends with a thinner membranous middle, a detail that matters when you are looking for suture purchase.

Fused more often than not. A thin fascial cleft may separate the two, but rhomboid minor is frequently fused with rhomboid major. In a minority of people the two are entirely separate with a clear interval, and in others rhomboid minor is doubled.

Fibre direction. Both run inferolaterally from spine to scapula at roughly 45 degrees. That oblique orientation means their pull retracts and elevates the medial border, producing downward rotation of the glenoid.

Landmarks for the incision. With the arm at the side, the root of the scapular spine lies at the level of the T3 spinous process and the inferior angle at T7, which lets you site an incision without imaging. The medial border is subcutaneous in a thin patient and is the direct route to both muscles.

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The only motor supply. The dorsal scapular nerve arises very proximally from the C5 ventral ramus, before the roots unite to form the upper trunk. That is the anatomical fact that gives it its diagnostic power. The root value is C5 in approximately 70 per cent of dissected nerves, and a C4 contribution is described in a proportion of individuals.

Course. From neck to scapula it runs in four steps:

1. It passes posterolaterally and pierces the middle scalene muscle in most specimens (74 per cent in the largest cadaveric series), roughly at the level of the C5-C6 intervertebral space, together with or just above the long thoracic nerve.
2. It emerges on the deep surface of levator scapulae, which it supplies in addition to the direct C3 and C4 branches. In a cadaveric series of 23 nerves it reached levator in every specimen, and in about half (48 per cent) it supplied levator alone, never continuing to the rhomboids.
3. It descends deep to levator scapulae and then deep to the rhomboids, parallel to and 1 to 2 cm medial to the medial border of the scapula, accompanied by the dorsal scapular artery.
4. It supplies rhomboid minor first, then rhomboid major, through a series of short branches entering the deep surface at intervals along the descent. The motor entry points are therefore spread along the whole medial border rather than concentrated at a single hilum.

Purely motor. The nerve has no cutaneous sensory territory. Interscapular pain arising from dorsal scapular nerve pathology is deep, aching and non-dermatomal, so a normal sensory examination does not exclude it.

Level-marker of the plexus. Because the nerve leaves the C5 root proximal to the upper trunk, rhomboid EMG separates two plexus lesions that look identical clinically. How to read it is set out under Clinical Relevance.

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Dorsal scapular artery. This is the dominant supply. It arises either as the deep branch of the transverse cervical artery from the thyrocervical trunk, the more common pattern, or directly from the third part of the subclavian artery as a true dorsal scapular artery in a substantial minority of shoulders.

The direct origin. A dorsal scapular artery arising from the subclavian passes between the trunks of the brachial plexus, typically between the upper and middle trunks. That is why one can be encountered unexpectedly during supraclavicular plexus exploration.

Course and drainage. The artery runs deep to levator scapulae and descends with the nerve on the deep surface of the rhomboids, anastomosing inferiorly with the circumflex scapular and subscapular systems around the scapular circle. Venae comitantes accompany it and drain into the transverse cervical and subclavian veins.

Why the pedicle position is a surgical fact. Three consequences follow from where this vessel runs:

• If it is divided off the medial border during a Judet approach, a scapulothoracic fusion or a rhomboid harvest, it bleeds briskly and retracts into the paraspinal muscle.
• It is the pedicle of the lower trapezius island flap and part of the supply of the scapular and parascapular fasciocutaneous flaps, so it must be preserved when those reconstructions are planned.
• It contributes to the scapular anastomosis, the collateral pathway that keeps the arm perfused when the axillary artery is occluded between the thyrocervical trunk and the subscapular artery.

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Superficial. Trapezius covers the rhomboids throughout. In the lower part its lateral border and the superior border of latissimus dorsi frame the triangle of auscultation, with rhomboid major in its floor; the triangle is described with the approaches under Surgical Relevance.

Deep, moving away from the surgeon. The layers follow in order:

• The dorsal scapular nerve and artery, immediately on the deep surface
• Serratus posterior superior, then the erector spinae medially
• The ribs and intercostal muscles, and immediately deep to them the parietal pleura. In a thin patient the pleura is only millimetres beyond the rhomboid layer at the third to fifth intercostal spaces.

The scapulothoracic planes. Serratus anterior lies on the costal side of the scapula, forming the gliding surface with the chest wall. The rhomboids and serratus anterior therefore sandwich the medial border between them, and the two scapulothoracic bursae, infraserratus and supraserratus, sit in these planes.

Structures at risk. Any interscapular dissection meets the dorsal scapular nerve and artery 1 to 2 cm medial to the border, the pleura deep to the ribs, and the spinal accessory nerve on the deep surface of the trapezius, encountered on the way in. The pedicle is the subject of the alert below; the pleura is covered under Complications.

Causes. The nerve or its root can be injured in five settings:

• Dorsal scapular nerve injury at the middle scalene, from traction, direct trauma or a penetrating injury to the posterior triangle
• Surgery: a posterior approach to the cervicothoracic spine, first rib resection or scalenectomy for thoracic outlet syndrome, or the medial dissection of a scapulothoracic procedure
• An interscalene brachial plexus block, because the dorsal scapular and long thoracic nerves both pierce the middle scalene and can be injured by needle trauma or by local anaesthetic neurotoxicity
• Neuralgic amyotrophy (Parsonage-Turner syndrome), typically as part of a patchy multi-nerve pattern with severe prodromal pain
• C5 root pathology: foraminal stenosis, disc herniation, or root avulsion in a traction plexus injury

Presentation. The patient rarely presents complaining of weakness; they present with pain and a shoulder that feels wrong. The complaint is a vague, dull, deep interscapular ache, worse with sustained postural loading, with fatigue and a sense of instability on pulling and overhead activity and the sense that "the shoulder blade feels loose".

What you see. On careful observation the scapula sits slightly lateral and slightly inferior, and the medial border lifts subtly, most visibly during slow lowering from forward flexion and on resisted retraction with the hand on the hip.

Differential of interscapular pain with a wing. The alternatives each have a discriminating feature:

• Trapezius (spinal accessory) palsy - drooped shoulder, weak shrug
• Serratus (long thoracic) palsy - gross medial winging on the wall push
• C5 cervical radiculopathy - dermatomal sensory change, weak deltoid
• Scapulothoracic bursitis or snapping scapula - audible or palpable crepitus
• Osteochondroma of the ventral scapular surface - a fixed, non-dynamic pseudo-wing

Dorsal scapular nerve entrapment syndrome is a well-described but under-recognised compression neuropathy at the point where the nerve pierces the middle scalene.

Causes. Hypertrophy or fibrosis of the middle scalene, a fibrous band within it, a cervical rib or an anomalous scalene slip can compress the nerve. So can repetitive overhead and rotational loading in throwing and racquet athletes, rowers and musicians with a forward head posture.

Symptoms. A deep, dull ache along the medial border of the scapula, sometimes radiating around the chest wall or down the lateral aspect of the arm and forearm in a non-dermatomal distribution. It is aggravated by sustained protraction, such as driving or desk work, and by overhead activity. There is no sensory loss, because the nerve is purely motor, and this preserved sensation is what distinguishes it from a C5 radiculopathy.

Signs. Look for tenderness over the middle scalene at the C5-C6 level and along the medial scapular border. The pain is reproduced with the head rotated to the opposite side while the shoulder is depressed, and there may be subtle rhomboid weakness or asymmetry.

Investigation. EMG of the rhomboids and levator scapulae, and cervical MRI to exclude a root cause. A diagnostic middle scalene local anaesthetic block is both confirmatory and predictive of surgical benefit.

Treatment. Escalate in order:

1. Posture and scapular control rehabilitation
2. A scalene block, with or without botulinum toxin
3. In the refractory case, surgical decompression by division of the middle scalene fibres around the nerve through a supraclavicular approach

Warn the patient about the phrenic nerve on the anterior scalene and the long thoracic nerve in the same middle scalene muscle.

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Strain. Acute rhomboid strain is common in rowers, weightlifters, particularly during heavy rows and cleans, and racquet sports. It presents with sharp interscapular pain and localised tenderness and settles with load management.

Avulsion. Frank avulsion from the medial border is rare and is usually described after a violent eccentric pull. Ultrasound or MRI shows retraction and a fluid-filled gap. Repair is described for a symptomatic, retracted avulsion in an athlete; the technique is under Surgical Relevance.

Scapular dyskinesis. Rhomboid weakness contributes to scapular dyskinesis and secondary shoulder impingement. In the overhead athlete with scapular dyskinesis, though, the more usual finding is rhomboid over-activity rather than weakness. The rhomboids and levator dominate over an inhibited serratus anterior and lower trapezius, holding the scapula in downward rotation and anterior tilt and narrowing the subacromial space. Rehabilitation therefore targets serratus and lower trapezius activation with rhomboid and levator down-training, not rhomboid strengthening.

Snapping scapula. Inflammation of the infraserratus bursa, between serratus anterior and the chest wall, produces crepitus and pain that can be mistaken for rhomboid pathology. Assess for a superomedial angle prominence and consider CT to look for a bony cause.

Muscular dystrophy. In facioscapulohumeral dystrophy the periscapular muscles, including the rhomboids, are affected together with the trapezius and serratus. The result is gross multidirectional winging, which points toward scapulothoracic fusion rather than any single tendon transfer.

Indication. Open reduction and internal fixation of displaced scapular body, neck and glenoid fossa fractures, and access to the posterior glenoid.

Position and incision. Position the patient lateral decubitus or prone, with the arm draped free so it can be placed in flexion and internal rotation to relax the deltoid. The boomerang (Judet) incision runs along the scapular spine laterally to the acromion and turns distally along the medial border to the inferior angle.

The classical Judet exposure. It is developed in two layers:

1. Superficially, the deltoid is elevated off the scapular spine and reflected laterally, protecting the axillary nerve as it emerges from the quadrangular space, and the trapezius is elevated medially.
2. In the medial parascapular interval, the rhomboids and levator scapulae are detached flush with the medial border of the scapula, subperiosteally, leaving a repairable tendinous cuff. This releases the medial tether and allows infraspinatus and teres minor to be raised as a laterally based flap on their pedicle, exposing the whole dorsal scapula.

The modified (minimally invasive) Judet. The muscle flap is not raised. The work is done through two windows: the interval between infraspinatus and teres minor for the lateral border and glenoid neck, and the plane along the medial border deep to the rhomboids for the medial border. This spares the rhomboid detachment entirely and has largely replaced the full Judet in most units.

The rule for the rhomboid detachment. Detach with a knife on bone, hugging the medial border: the dorsal scapular nerve and artery lie 1 to 2 cm medial to your blade. Retract the released muscle medially with a broad retractor placed against the muscle, never with a self-retainer biting into the paraspinal mass.

Triangle of auscultation. It is bounded by the medial scapular border laterally, the lateral border of trapezius medially and the superior border of latissimus dorsi inferiorly, with rhomboid major in the floor. Bringing the arm forward across the chest retracts the scapula laterally and widens the triangle, giving direct access to the posterior chest wall at the level of the sixth rib without dividing any muscle. It is the classical muscle-sparing route for a posterior thoracotomy or a rib biopsy.

Posterior cervicothoracic spinal approaches. Subperiosteal elevation from the spinous processes takes the rhomboid origins along with the trapezius. Stay strictly subperiosteal and avoid lateral excursion beyond about 4 cm from the midline at C7-T1 to protect the dorsal scapular nerve and vessels.

Scapulothoracic fusion. The rhomboids and trapezius are elevated from the medial border, the ventral scapular surface and the underlying ribs are decorticated, and cerclage wires or cables are passed around ribs 3 to 7, usually reinforced with a plate along the medial border. Pleural injury is the characteristic complication, and a routine post-operative chest radiograph is mandatory.

Scapulothoracic bursectomy and superomedial angle resection. These are performed open through a medial border incision or arthroscopically from medial portals, with the rhomboid and levator insertions released and repaired. Over-resection of the superomedial angle risks detaching the levator insertion entirely and destabilising the scapula.

The role of the rhomboids. In the Eden-Lange transfer for irreparable trapezius palsy the rhomboids provide two of the three limbs:

• Rhomboid minor is detached from the medial border and transferred laterally onto the infraspinatus fossa, substituting for the middle trapezius.
• Rhomboid major is detached and transferred laterally onto the infraspinatus fossa below the minor, substituting for the lower trapezius.
• Levator scapulae, the third limb, goes laterally onto the scapular spine to substitute for the upper trapezius. In the modified transfer it is carried further laterally, toward the lateral spine or acromion, to lengthen its upward-rotation moment arm.

Technical requirements. The technique has four requirements:

• Confirm the dorsal scapular nerve is intact on EMG. All three donors depend on it, and transferring denervated muscle is a wasted operation.
• Detach each muscle with a wafer of bone or a tendinous cuff for suture purchase; the membranous middle of rhomboid major is poor suture tissue.
• Protect the dorsal scapular pedicle, which enters the deep surface medially and must not be tethered or divided as the muscle is swung laterally. The pedicle, too, limits excursion to a few centimetres.
• Fix through bone tunnels or troughs in the infraspinatus fossa with transosseous sutures, tensioned with the arm at about 30 degrees of abduction.

Outcome. Expect reliable pain relief with improvement in scapular position and cosmesis; abduction improves but is rarely normalised. Long-term follow-up shows the correction is durable where the trapezius palsy is truly isolated, and the reported failures had a coexisting long thoracic and dorsal scapular nerve lesion.

Repairing the medial border after a Judet approach. Restoring the rhomboid and levator insertions is not optional. Leave a tendinous cuff on the muscle, drill transosseous tunnels through the medial border every 1.5 to 2 cm, and repair with heavy non-absorbable suture while the scapula is held retracted. Protect in a sling for 4 to 6 weeks with no active retraction, then begin progressive scapular control work.

Failure of repair. Non-healing of the medial detachment produces a painful, laterally translated scapula with subtle winging, an iatrogenic rhomboid palsy without any nerve injury at all. This is one of the reasons the modified, muscle-sparing Judet has displaced the classical flap.

Rhomboid avulsion repair. For a genuine traumatic avulsion in an athlete, approach through a longitudinal incision over the medial border and identify the retracted muscle. Mobilise it gently without dissecting medially into the pedicle, and reattach it along the medial border footprint with suture anchors or transosseous sutures.