Class notes Anatomy and physiology Snell's Clinical Anatomy by Regions, ISBN: 9781975107024

Point of Boundaries
a. External occipital protuberance
❖ Superior nuchal line
b. Spine of the scapula
❖ Acromion process
c. Iliac crest
d. Sacrum
e. Vertebral spines

Deep Fascia of the Back (Thoracolumbar fascia)
● or Lumbodorsal fascia.
● Ensheaths the primary muscle of the back (Erector
spinae) and dorsum of the neck..
● This fascial sheath attaches:
Medially to the Ligamentum nuchae to the tips of the
spinous process and to the supraspinous ligament of
the entire column into the medial crest of the sacrum.
● To the cervical and lumbar region, it is attached to the
transverse process of the vertebra
● In the thoracic region, it joins the angles of the ribs,
which is lateral to the iliocostalis muscle to the
intercostal fascia..

Lumbar part
➔ Lies in the interval between the iliac crest and 12th rib.
➔ Medially, split into three lamellae.
1. Posterior - covers deep muscles and attached to the
I. GENERAL AND SPECIFIC OBJECTIVES spinous process of the lumbar vertebral and laterally
1. To study and understand the gross anatomy of the serves as attachment of latissimus dorsi, serratus
back. posterior and serratus inferior.
a. Boundaries of the back & thoracolumbar fascia. 2. Middle - lies deep and immediately anterior to the

b. Neurovascular supply of the back. sacrospinalis but posterior to the quadratus lumborum;

c. Layers of the muscle of the back with their origin, medially it is attached to tip of the transverse process
of lumbar vertebrae and laterally it becomes continuous
insertion and nerve innervation.
with the aponeurosis of the transverse abdominis
d. Triangle of auscultation and the lumbar triangle of
muscle.
Petit.
3. Anterior - anterior to the quadratus lumborum and
e. Structures in suboccipital triangle.
attached to anterior surface of transverse process of
the lumbar spines.

Allora, MD 2025 |
of
1 5

, Blood supply of the Back ● Most are attached to the Scapula and one is attached to the
The chance of ischemia in the back is very small. Humerus.
A. Cervical region
Trapezius
1. Occipital artery - branch of external carotid artery.
➔ 2nd largest skeletal muscles of the back.
2. Vertebral artery - branch of the subclavian artery located in
O: Occipital bone, Ligament of nuchae, C7 to T12 spines.
the root of the neck.
I: Upper fibres- lateral ⅓ of the clavicle,
3. Deep cervical artery - branch of costocervical trunk (a branch
Middle fibres - acromion process of the scapula,
of subclavian artery).
Lower fibres - spinous process of scapula.
4. Ascending cervical - branch of thyrocervical trunk (a branch of
N: motor nuclei of C3 & C4 of the Spinal accessory nerve (CN XI).
subclavian artery.
A: 1. upper fibres elevate the clavicle. 2. Middle fibres pull scapula
B. Thoracic region
medially. 3. Lower fibres pull the scapula down.
➔ 12 pairs of posterior intercostal arteries -
Upper 2 are branches of the superior thoracic artery. Latissimus dorsi
Lower 10 are direct branches of the thoracic aorta. ➔ Largest of the skeletal muscles of the back.
C. Lumbar region O: Iliac crest, Lumbar fascia, T7-T12 spines, inf. angle of scapula.
1. Subcostal artery (12 superior intercostal arteries) - direct I: Floor of bicipital groove of humerus.
branches of thoracic aorta. N: Thoracodorsal nerve (posterior cord of the brachial plexus).
2. 4 pairs of Lumbar arteries - direct branches of abdominal A: 1. extend. 2. adduct 3. medially rotate the arm.
aorta.
3. Iliolumbar artery - branch of posterior division of internal iliac Levator scapula
O: transverse process of C1 - C4.
artery.
D. Sacral region I: Medial border of scapula.
1. Iliolumbar artery - branch of posterior division of internal iliac N: anterior rami of C3, C4 and dorsal scapular nerve (a branch of the
brachial plexus)
artery.
A: raise medial border of scapula.
2. Lateral sacral artery - branch of posterior division of internal
iliac artery. Rhomboid Minor
O: Ligamentum nuchae, C7 and T1 spines.
Veins of the Back
I: Medial border of scapula.
*the veins that drains the back has the same name as the artery that it accompanies*
Form communicating plexuses, extending along the vertebral column N: Dorsal scapular nerve (branch of anterior rami of C5)

from the skull to the coccyx. A: Raise medial border of the scapula upward and medially.

1. External vertebral venous plexus
2. Internal vertebral venous plexus
Rhomboid Minor
O: T1 - T5 spine.
Nerve Supply of the Back I: Medial border of scapula.
● Posterior/Dorsal rami of the 31 pairs of spinal nerves N: Dorsal scapular nerve (branch of anterior rami of C5)
supply the skin and deep muscles of the back. A: Raise medial border of the scapula upward and medially.
*Never form the plexuses of nerve unlike anterior rami which forms cervical, brachial,
lumbar, and sacral plexuses* Triangle of Auscultation
Boundaries:
a. Medially - Trapezius
II. MUSCLES OF THE BACK
b. Inferiorly - Latissimus dorsi
1. Superficial
2. Intermediate c. Laterally - Medial border of scapula
3. Deep Significance:
Site where breath sounds are best heard.
Superficial Muscles of the Back
● Muscles that are inserted to bones of the upper extremities Lumbar Triangle of Petit
(shoulder/arm bones). Boundaries:
● Hence assist in moving the upper extremities. A. Laterally - External oblique abdominis muscle
B. Medially - Latissimus dorsi


Allora, MD 2025 |
of
2 5