Anatomy - Muscles of the Back Labelled
I have set out the muscles of the back labelled within a diagram in order to help improve your knowledge
of the major muscle groups. There might be some cross over from the other anatomy diagrams such as shoulders.
This is important to realize as the back is a large area with the muscles supporting different functions such
as arm movement, stabalizing the spine and also works in conjunction with the pectoral girdle (chest and rib cage).
The back muscles also move the hips, head and pelvis. We could group the muscles of the back into three groups, upper, lower and deep spinal.
The lower skeletal muscle of the back work with the hip muscles to tilt the pelvis backwards and forwards. They also extend and flex the lower spine.
The upper skeletal muscle of the back depress, elevate and rotate the scapula (shoulder blade), and aid in moving the
humerus (long bone of upper arm) in all of its movements.
These muscles are mainly responsible for all 'pulling'
movements in conjunction with the biceps.
The deep spinal muscles both move and stabalise the vertebrae. There are no exercises or even daily movements
that do not require some contribution from your back.
Now lets move on and look at the anatomy of the Back:
Muscles of the Back Labelled (Fig 1a and 1b)
- Trapezius - Stabalizes, raises and rotates the Scapula (Bone also known as the shoulder blade).
- Latissimus Dorsi - Works with other muscles to move the Humerous bone (long bone of upper arm); also pulls the shoulder backwards.
- Deltoid Group - Covers the shoulder joint; raises the arm from the body and rotates the shoulder.
- Teres Major - Acts with latissimus Dorsi to extend the arm.
- Teres Minor - Holds Humerous in shoulder socket (known as gleniod cavity); part of the "rotator cuff" group of muscles.
- Levator Scapulae - works with the trapezius to move the shoulder blade up and inwards.
- Serratus Posterior Superior - Acts to pull the upper ribs 'up' during breathing in.
- Serratus Posterior Inferior - Moves ribcage down during breathing out.
- Eractor Spinae -Controls bending forward (flexion)and maintains upright postre; part of the "core muscle" group.
- Infraspinatus - Holds humerus in gleniod cavity, rotates humerus laterally as in backhand stroke in tennis; part of the "rotator cuff" group of muscles.
- Subscapularis - Part of the "rotator cuff" group of muscles that help stablize the shoulder joint.
- Supraspinatus - Part of the "rotator cuff" group of muscles that help stablize the shoulder joint.
- Rhomboid Major - Acts with Rhomboid Minor to pull the scapula back
- Rhomboid Minor - Pulls scapula backwards
Deep Muscles (Fig 2)
- Semispinalis Capitis Muscle - Attaches to the base of the skull and helps support the head.
- Rotatores Cervicis Muscles - Acts upon the cervical vertebrae to extend and rotate this segment of the vertebral column.
- Semispinalis Thoracis Muscles - Extends the vertebral column and head.
- Rotatores Thoracis Muscles - Work together to extend and rotate the vertebral column.
- External Intercostal Muscles - draws togethor ribs during respiration.
- Levatores Costarum Muscles - Helps to elevate the ribs during respiration.
- Quadratus Lumborum - Helps maintain erect posture, flexes the spine laterally; part of the "core muscle" group.
- Transverse Abdominis - Wraps from abdomen to the back; part of the "core muscle" group.
- Multifidus Muscle - Helps to extend and rotate the vertebrae and stabalize movement; part of the "core muscle" group.
Muscles Supporting the Head and Neck (Fig 3)
The muscles in the neck attached from the top of the spine and skull help to extend, rotate and keep the head upright.
Note that the Trapezius
starts at the base of the skull at the Occiput (the Occiput articulates with the first vertebra or atlas vertebra of the backbone).It also aids in
extension of the neck and also connects the the thoracic vertebrae and scapula.
- Sternocleidomastoid, aids as a stabalizing muscle (in exercises such as lateral raise).
- Trapezius - large muscle that extends down to back.
- Scalene Muscles - Acts to flex and rotate the neck
- Splenius Capitis Muscle - Rotates and extends the head laterally and backwards.