Advanced Anatomy & Physiology
Unit 2 – Muscles
Lesson 2.2 – Posterior muscles of the body
Advanced Anatomy and Physiology
Lesson 2.2 Posterior muscles of the body
Step 1 – Aims
This lesson will enable you to describe the location and function of the gluteals,
erector spinae, trapezius, latissimus dorsi and rhomboids.
Step 2 – The posterior muscles of the body
We’ll begin this lesson by looking at the trapezius, latissimus dorsi and erector
spinae.
The individual muscles in this diagram are discussed on the next few steps.
Step 3 – Gluteals
Gluteus means rump and
gluteus maximus is one of
the three large muscles
which form the buttock (the
others are gluteus medius
and gluteus minimus).
The gluteus maximus serves
to extend and abduct the hip
and laterally rotate the thigh.
It is part of the abductor
group along with the gluteus
medius, gluteus minimus and
the tensor fasciae latae
(TFL), which together abduct
the hip joint.
May 2015
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Advanced Anatomy and Physiology
Lesson 2.2 Posterior muscles of the body
The gluteus minimus and medius both originate on the ilium and insert on the
greater trochanter of femur. The gluteus maximus originates on the iliac crest,
sacrum, coccyx and aponeurosis of sacrospinalis. The point of insertion is the
iliotibial tract of fascia lata and gluteal tuberosity of femur.
Step 4 – Erector spinae
The erector spinae is a generic term for a
group of muscles consisting of the iliocostalis,
the longissimus, the spinalis dorsi and
divisions of these muscles in the lumbar,
thoracic and cervical regions of the vertebral
column.
This group of muscles are the major extensors
of the spine. When all three muscle columns
on both sides act together, extension of the
lumbar, thoracic and cervical vertebrae occur.
Contraction of all three muscle columns on
one side will result in combined lateral flexion
and rotation to the same side.
Step 5– Trapezius
The trapezius muscle, commonly
known as the traps, is named due to
its trapezoidal shape (four sides, with
no two sides parallel).
The upper part of this muscle
retracts (adducts) the scapula,
elevates the pectoral girdle, laterally
flexes the head and neck and
extends the head. The middle part
retracts and slightly elevates or
depresses the scapula. The lower
part is used to rotate the scapula
superiorly and assist in keeping the
spine erect.
The origin of this muscle is in processes of the spine. The points of insertion are
the clavicle and the spine of the scapula.
May 2015
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Advanced Anatomy and Physiology
Lesson 2.2 Posterior muscles of the body
Step 6 – Latissimus dorsi
The latissimus dorsi is a Latin name
meaning broad (latus) back
(dorsum) and is usually shortened
to Lats.
The latissimus dorsi extends,
adducts and medially rotates the
shoulder joint.
The muscle originates in the
processes of the middle and lower
spine and ilium, and inserts onto the
inner edge of the humerus.
Step 7 – Rhomboids
The rhomboids get their name from their shape (rhomboid is a four-sided figure
with opposite sides and angles equal), these muscles elevate, retract (adductpulling the scapula towards the spine) and stabilise the scapulae. They originate
on the spine and insert on the scapula.
Step 8 – Activity
Correctly select the following muscles on the diagram.



Gluteus maximus
Latissimus dorsi
Trapezius
May 2015
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Advanced Anatomy and Physiology
Lesson 2.2 Posterior muscles of the body
Step 9 – Activity
Which of these four muscles adducts and slightly lifts the scapula?




Gluteus maximus
Latissimus dorsi
Trapezius
Erector spinae
Step 10 – Activity
Which of these four muscles extends the hip and laterally rotates it?




Gluteus maximus
Latissimus dorsi
Trapezius
Erector spinae
Step 11 – Activity
Which of these four muscles medially rotates and extends the shoulder joint?




Gluteus maximus
Latissimus dorsi
Trapezius
Erector spinae
May 2015
© Future Fit Training, 2015
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Advanced Anatomy and Physiology
Lesson 2.2 Posterior muscles of the body
Step 12 – Activity
Which of these four muscles extends the spine?




Gluteus maximus
Latissimus dorsi
Trapezius
Erector spinae
Step 13 – Summary
Now that you have completed this lesson you should have a better understanding
of the following:
The gluteus maximus is located at the top of the leg and is responsible for
extending and abducting the hip and laterally rotating the thigh.
The erector spinae is located on the back, along the spine and is responsible for
extending the spine.
The trapezius is located on the upper back, stretching across the shoulder area. It
is responsible for retracting and rotating the scapula superiorly, elevating the
shoulder girdle and laterally flexing the neck. It is also responsible for elevating or
depressing the scapula.
The latissimus dorsi is located on the middle and lower portions of the back and is
responsible for extending and adducting the shoulder and rotating it medially.
The rhomboids are located on the upper back and are responsible for retracting,
adducting and elevating the scapulae.
May 2015
© Future Fit Training, 2015
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