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Flashcards in Anatomy of the back Deck (27):

What are the superficial muscles of the back?

Where do they act?

1. Trapezius
2. Latissimus dorsi
3. Rhomboid major + Rhomboid minor
4. Levator scapulae

Appendicular muscles that act on the upper limb or its pectoral girdle (clavicle and scapula)


-blood supply

1. Origin
• External occipital protuberance
• Superior nuchal line (medial parts)
• Spinous processes of thoracic vertebrae (C7 – T12)

2. Insertion + action
• Superior part – attaches to the lateral 1/3rd of clavicle and elevates scapula
• Middle part – attaches to the acromion and spine of scapula; retracts scapula
• Inferior part – attaches near the medial end of spine of scapula; depresses the scapula
• When ALL 3 contract simultaneously, the scapula rotates in the coronal plane, causing the shoulder joint to angle upward

3. Innervation
Accessory nerve (CN XI)

4. Blood supply
Superficial branch of transverse cervical artery


Latissimus dorsi

1. Origin
• Spinous processes of lower thoracic vertebrae (T7 – T12)
• Thoracolumbar fascia
• Iliac crest
• Ribs 9 – 12 (lateral to their angles)

2. Action
• Extends, adducts and medially rotates the humerus at the shoulder joint
o Spins the anterior surface of the humerus around its long axis toward the midline at the shoulder joint
• Raises the body towards the hands when the arms are raised to grasp an object above one’s head through extension


Rhomboid (major and minor)

Rhomboid minor
1. Origin
• Nuchal ligament
• Spinous processes of vertebrae C7 and T1

2. Insertion
• Medial border of scapula at the level of its spine

Rhomboid major
1. Origin
• Spinous processes of vertebrae T2 – T5

2. Insertion
• Medial border of scapula inferior to its spine

-retract and rotate scapula
-hold scapula close to body wall

-dorsal scapular nerve

1. dorsal scapular artery if branch is from subclavian artery
2. Deep branch of transverse cervical artery if it arises from transverse cervical artery


Levator Scapulae Muscle

• Transverse processes of upper 4 cervical vertebrae

• Superior angle of scapula

• Elevates the scapula and rotates the scapula to depress the glenoid cavity

• Dorsal scapular nerve and artery
o Same as the rhomboids


Intermediate muscles of the back include?

1. Serratus posterior superior muscle

2. Serratus posterior inferior muscle


Serratus posterior superior muscle

1. Origin
• Nuchal ligament
• Spinous processes of upper thoracic vertebrae C7 – T3

2. Insertion
• Superior borders of upper ribs 2 – 5 lateral to their angles

3. Innervation
-intercostal nerves (ventral rami of thoracic spinal nerves)


2. Serratus posterior inferior muscle

1. Origin
• Spinous processes of thoracolumbar vertebrae T11 – L2

2. Insertion
• Inferior borders of lower ribs 9 – 12 lateral to their angles

3. Innervation
-intercostal nerves (ventral rami of thoracic spinal nerves)


Layers and contents of thoracolumbar (lumbodorsal) fascia

Deep investing membrane which covers the deep muscles of the back

3 layers - anterior, middle and posterior

• B/w anterior and middle lies the quadratus lumborum muscle
• B/w middle and posterior layers lies the erector spinae muscles
• Above, the T.F. passes in front of the serratus posterior superior muscle and is continuous w/ nuchal fascia


Triangle of auscultation

Boundaries are
-latissimus dorsi
-rhomboid major


Lumbar triangle (what can happen here?)

Boundaries are
-Latissimus dorsi
-external oblique
-iliac crest
-floor is internal oblique

Site of lumbar hernia (rare)


Anterior longitudinal ligament
location + action

-covers + connects anterior part of vertebral bodies and intervertebral disc
-runs from anterior tubercle of C1 vertebra to sacrum
-maintains stability of joints b/w vertebral bodies
-limits extension of vertebral column


Posterior longitudinal ligament
location + action

-attached to posterior aspect of intervertebral discs and posterior edges of vertebral bodies from C2 to sacrum
-resists flexion of vertebral column and posterior protrusion of discs


location + action

-cordlike band
-unites tips of spinous processes
-helps resist flexion


location + action

-membranous sheets
-unite spinous processes
-helps resist flexion


Ligamenta flava
location + action

-elastic bands uniting laminae of adjacent vertebrae
-helps preserve curvature of vertebral column
-supports joints b/w vertebral arches


Splenius muscle

PA + DA (both parts)

PA -> nuchal ligament and spinous processes of upper thoracic vertebrae (C7 - T6)

1. Splenius capitis m. -> mastoid process of the temporal bone and superior nuchal line of the occipital bone

2. Splenius cervicis m. -> transverse processes of the upper cervical vertebrae (C1 - C4)


Erector spinae muscles

3 muscles (inferior/superior attachment)

3 columns of muscles

Lateral to medial (ILS):
1. Iliocostalis
-inferior attachment -> ilium (iliac crest)
-superior attachment -> ribs

2. Longissimus
-inferior attachment -> sacrum
-superior attachment -> transverse processes of thoracic and cervical vertebrae

3. Spinalis
-inferior attachment -> spinous processes
-superior attachment -> spinous processes
-present at lumbar, thoracic and cervical levels

-extend vertebral column when both sides work together
-bend laterally if only one side is active towards the active side


Semispinalis capitis m.

-what class?
-inferior + superior attachments


-Action -> rotation and lateral bending movements b/w adjacent vertebrae and stabilize the vertebral column

-inferior attachment -> transverse processes of upper thoracic vertebrae
-superior attachment -> occipital bone b/w the superior and inferior nuchal lines

-Greater occipital nerve passes through this muscle as well as the traps


Spinal cord begins and terminates at?
what's found at the terminal point

begins at -> foramen magnum
terminates at -> L1/L2 intervertebral disc

Conus medullaris


Cervical enlargement

spinal cord segments C5 - T1


Lumbosacral enlargement

L1 - S3


How many spinal nerves + breakdown

31 pairs
-8 cervical
-12 thoracic
-5 lumbar
-5 sacral
-1 coccygeal


How are spinal nerves numbered?

-Most are numbered according to vertebrae above them as the pass through the intervertebral foramen

-EXCEPTION -> cervical region
Spinal nerves are numbered according to vertebra below
(C8 exits b/w C7 and T1)


CSF is contained within the?

Subarachnoid space


Filium terminale internum is continuous with?
ends at?

-pia mater



Characteristics of vertebral venous plexus
Implications in cancer

-valveless; blood flow up or down based on pressure gradients

-routes for mets of cancer from pelvis to vertebrae, vertebral canal and cranial cavity