Back Muscles

Original Editor - Lucinda hampton

Top Contributors - Lucinda hampton and Kim Jackson  

Introduction

A well muscled back

There are three major groups of back muscles:

1. Superficial: attached to the shoulder girdle
2. Intermediate: attached to the posterior thorax
3. Deep: attached to the vertebral column, also known as the intrinsic muscle group

These groups serve to allow: flexion/extension, rotation, and side bending of the back; movement of the limbs; locomotor function; and assistance in the respiratory effort.

Additional terminology

1. The superficial and intermediate muscle groups (or extrinsic muscles) are also called immigrant muscles, since they actually represent muscles of the upper limb that have migrated to the back during fetal development.
2. The deep/intrinsic back muscles, are also called true back muscles. They are located deep to the extrinsic muscles, being separated from them by the thoracolumbar fascia.

Generalized back pain is a common presenting symptom for patients, the etiology of the pain commonly traces to a strain of the skeletal muscle.

Superficial Group

A Trapezius D Latissimus Dorsi E Levator Scapulae F Rhomboid Major

The first category is the superficial back muscles. These muscles are located posteriorly on the back, whose function is to move the scapula.. The superficial muscles include:

• Trapezius
• Latissimus dorsi
• Levator scapulae
• Rhomboids

Each of the muscles in this group are fairly large and superficial and correctly locating any one of them by palpation is easily accomplished.

Intermediate Muscles

Serratus posterior inferior

The intermediate group contains two muscles:

• Serratus posterior superior
• Serratus posterior inferior

These muscles run from the vertebral column to the ribcage, and assist with elevating and depressing the ribs.

Both serratus posterior superior and inferior are thought to have a role as accessory muscles for respiration.

Deep/Intrinsic Muscles

Erector spinae group

Transversospinales group and segmental muscles

These muscles are responsible for the motion of the axial skeleton. The main movements are flexion/extension, side bending, and rotation. These muscles collectively work to help movements of the vertebral column (flexion/extension, side bending, and rotation) and to also control posture.

This group further subdivides into several categories in the back and neck. The main muscle groups in the intrinsic muscle group are the

The erector spinae group (medially to laterally) consisting of:

Iliocostalis

Longissimus

Spinalis

The muscle group is bilateral on either side of the vertebral column and when both sides are engaged function as the primary extensor of the back.[3] Unilaterally they assist with lateral bending and rotation of the spine.[3]

Transversospinalis group (deep to the erector spinae group) consisting of, from superficial to deep:

Semispinalis

Multifidus

Rotatores

Like the erector spinae group, the transversospinalis group is located bilaterally on the vertebral column between the transverse processes and the spinous processes. These muscles assist in bending the back posteriorly when contracted bilaterally. When unilateral contraction occurs, they are responsible for assisting with lateral bending and rotation.

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