Anatomy of the back Flashcards
MUSCLES 1. classify the back muscles as superficial, intermediate or deep 2. Provide the nerve and blood supply 3. Provide the origin and insertion 4. Describe the action performed LIGAMENTS CLINICAL NOTES
What are the superficial muscles of the back?
Where do they act?
- Trapezius
- Latissimus dorsi
- Rhomboid major + Rhomboid minor
- Levator scapulae
Appendicular muscles that act on the upper limb or its pectoral girdle (clavicle and scapula)
Trapezius
- origin
- insertion
- innervation
- blood supply
- action
- Origin
• External occipital protuberance
• Superior nuchal line (medial parts)
• Spinous processes of thoracic vertebrae (C7 – T12) - 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)
- Blood supply
Superficial branch of transverse cervical artery
Latissimus dorsi
- origin
- action
1. Origin • Spinous processes of lower thoracic vertebrae (T7 – T12) • Thoracolumbar fascia • Iliac crest • Ribs 9 – 12 (lateral to their angles)
- 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
- Insertion
• Medial border of scapula at the level of its spine
Rhomboid major
1. Origin
• Spinous processes of vertebrae T2 – T5
- Insertion
• Medial border of scapula inferior to its spine
ACTION
- retract and rotate scapula
- hold scapula close to body wall
INNERVATION
-dorsal scapular nerve
BLOOD SUPPLY
- dorsal scapular artery if branch is from subclavian artery
- Deep branch of transverse cervical artery if it arises from transverse cervical artery
Levator Scapulae Muscle
ORIGIN
• Transverse processes of upper 4 cervical vertebrae
INSERTION
• Superior angle of scapula
ACTION
• Elevates the scapula and rotates the scapula to depress the glenoid cavity
INNERVATION AND BLOOD SUPPLY
• Dorsal scapular nerve and artery
o Same as the rhomboids
Intermediate muscles of the back include?
- Serratus posterior superior muscle
2. Serratus posterior inferior muscle
Serratus posterior superior muscle
- origin
- insertion
- innervation
- Origin
• Nuchal ligament
• Spinous processes of upper thoracic vertebrae C7 – T3 - Insertion
• Superior borders of upper ribs 2 – 5 lateral to their angles - Innervation
- intercostal nerves (ventral rami of thoracic spinal nerves)
- Serratus posterior inferior muscle
- origin
- insertion
- innervation
- Origin
• Spinous processes of thoracolumbar vertebrae T11 – L2 - Insertion
• Inferior borders of lower ribs 9 – 12 lateral to their angles - 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
- trapezius
- 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
Suprapsinatus
location + action
- cordlike band
- unites tips of spinous processes
- helps resist flexion
Interspinous
location + action
- membranous sheets
- unite spinous processes
- helps resist flexion