Back Muscles

Original Editor - Lucinda hampton

Top Contributors - Lucinda hampton and Kim Jackson  

Introduction

Drawing Back Muscles

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 breathing.

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.

Physiotherapy Relevance

• A good understanding of the back muscle anatomy is critical for correct diagnosis and treatment. Generalized back pain is a common presenting symptom in clients , with the etiology of the pain commonly traced 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

Muscles in this group are fairly large and superficial and they are easily identified by palpation.

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. They are also thought to have a role as accessory muscles for respiration.

Deep/Intrinsic Muscles

A well muscled back

The deep muscles of the back are well-developed, and collectively extend from the sacrum to the base of the skull. They are associated with the movements of the vertebral column, and the control of posture.

The muscles themselves are covered by deep fascia, which plays a key role in their organisation.

The deep muscles of the back are subdivided into their own

1. Superficial,
2. Intermediate and
3. Deep layers.

The Superficial Muscles

Splenius capitis and cervicis

There are two muscles in this group

1. Splenius Capitis
2. Splenius Cervicis

They are both associated with movements of the head and neck. They are located on the posterolateral aspect of the neck, covering the deeper neck muscles.

Erector Spinae.

Erector spinae group

The Erector Spinae (ES) group (medially to laterally) consist of:

1. Iliocostalis
2. Longissimus
3. 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. Unilaterally they assist with lateral bending and rotation of the spine.

The Deep Intrinsic Muscles - Transversospinales

Back: Deep Muscles

Transversospinales muscle group is a deep group of back muscles that lies deep to the Erector Spinae. It consists of 3 major subgroups:

1. Semispinalis,
2. Multifidus
3. Rotatores.

The transversospinalis muscles group runs obliquely and medially from the transverse process of the vertebra below to the spinous process, filling the groove on either side of the spinous process.

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.

Nerves

Ventral and Dorsal Rami Formation

Nervous supply to the intrinsic/deep back primarily arises from dorsal rami of the spinal nerves, providing sensation the skin of the back, and the deep muscles of the back.

This innervation is in contrast to the extrinsic muscles of the back, which are innervated by ventral rami.

Core Muscles and Back Pain

Core stability exercises

The core muscles consist of the major muscles that stabilizes and controls the pressure inside the trunk; these are the pelvic floor, abdominal wall, back muscles, and diaphragm muscles.

Through core strength training, patients with chronic low back pain can strengthen their deep trunk muscles. Core strength training, including deep back muscles, is more effective than typical resistance training for alleviating chronic low back pain.