SCALENES

GENERAL INFORMATION

The Scalene muscles are a group of three muscles located on each side of the neck, known individually as the anterior, middle, and posterior scalenes. These muscles are deeply embedded in the lateral aspects of the neck, underlying the sternocleidomastoid. They are essential for their role in the respiratory process, particularly during forced breathing, as well as in facilitating various movements of the neck. Due to their location and function, they are also implicated in several neuromuscular and vascular conditions, such as thoracic outlet syndrome, which affects nerves that pass through the neck to the arm.

ORIGIN

• Anterior Scalene: Originates from the transverse processes of the third to sixth cervical vertebrae (C3-C6).

• Middle Scalene: Begins at the transverse processes of the first to seventh cervical vertebrae (C1-C7).

• Posterior Scalene: Starts from the transverse processes of the fifth to seventh cervical vertebrae (C5-C7).

• INSERTION POINT

• Anterior Scalene: Inserts onto the scalene tubercle of the first rib.

• Middle Scalene: Attaches to the first rib’s upper surface, just posterior to the subclavian artery.

• Posterior Scalene: Inserts into the outer surface of the second rib, providing additional elevation during deep inhalation.

MAJOR ARTERIES

The Scalene muscles receive arterial blood supply primarily from the branches of the thyrocervical trunk, part of the subclavian artery. This robust blood supply is crucial for their active involvement in respiratory and neck movements.

NEURAL INNERVATION

Innervation is provided by the cervical spinal nerves (C3-C8). These nerves ensure precise coordination and control over the muscle’s actions, allowing for effective neck movements and rib elevation during respiration.

TRIGGER POINT

Trigger points in this muscle can lead to referred pain, which may manifest as chest, shoulder, arm, and upper back pain. These symptoms are often intense due to the muscle’s proximity to several major nerves and blood vessels.

CONCENTRIC FUNCTION

Concentric contraction of the Scalenes results in elevation of the ribs during forced inhalation and assists in flexing and slightly rotating the neck. These actions are essential for increasing lung capacity and supporting the neck during various movements.

ECCENTRIC FUNCTION

Eccentrically, the Scalenes help to control the movement of the ribs during forced exhalation and moderate the neck’s return to a neutral position from a flexed or rotated posture, ensuring smooth transitions and stability.

ISOMETRIC FUNCTION

Isometrically, the Scalenes stabilize the neck and ribs, particularly in static postures that require sustained upper limb and head positions, such as when carrying heavy objects, driving, or working at a computer.

RELATED MUSCLE-SCIENTIFIC NAMES

• Sternocleidomastoid: Often works in conjunction with the Scalenes for neck rotation and flexion.

• Trapezius: Coordinates with the Scalenes for upper back and neck stability.

• Levator Scapulae: Assists in elevating the scapula, working together with the Scalenes during certain movements.

• Pectoralis Minor: Serves as an antagonist during respiratory movements, especially in the stabilization of the ribs.

ANTAGONIST

• Abdominal Muscles: Oppose the Scalenes during respiration by managing thoracic pressure.

• Upper Trapezius and Neck Extensors: Counteract the Scalenes’ actions in neck flexion and rotation.

COMMON INJURIES

• Neck Strains and Sprains: Common due to overextension or rapid movement.

• Thoracic Outlet Syndrome: Results from compression at the thoracic outlet, affecting nerves/blood vessels.

• Myofascial Pain Syndrome: Chronic pain involving trigger points in the muscle fibres.

• Stress-Related Tension: This can lead to tightness and chronic contraction, resulting in pain and reduced mobility.

EXERCISES

• Neck Side Tilts: Gently tilt the head from side to side, isolating the Scalenes and improving their strength and flexibility.

• Resistance Band Neck Rotations: Secure a band at forehead height and pull gently while rotating the head to each side, enhancing neck muscle strength.

• Shoulder Shrugs: Elevate and lower the shoulders to indirectly engage the Scalenes, aiding in rib lifting and scapular stabilization.

• Prone Y Lifts: Lie face down and lift your arms into a ‘Y’ shape to engage the upper back and neck muscles, including the Scalenes.

STRETCHES

• Lateral Neck Stretch: Gently pull the head toward each shoulder to stretch the Scalenes, relieving tension and improving range of motion.

• Upper Trapezius Stretch: Tilt the head diagonally toward the armpit, targeting the Scalenes for a deeper stretch.

• Doorway Stretch: Place arms on the door frame and gently lean forward to stretch the neck and upper back.

• Corner Stretch: Stand facing a corner with arms raised and lean into the corner to stretch the upper back and Scalenes.