Back (24/4/18)
There are 2 superficial and 3 deep muscles
The 2 superficial muscles are Trapezius and Latissimus dorsi
The 3 deep muscles beneath (trapezius mostly) are levator scapulae, Rhomboids
major and minor
Landmarks of the back
1. External occipital protuberance - bony prominence in the median inferior occipital
bone
2. superior nuchal lines - two arches on the lateral sides of the External occipital
protuberance
3. vertebral prominens - Long spinous process of C7 vertebra
4. spine of scapula - arises at T3 vertebra
5. inferior angle of scapula - at 7th rib
6. posterior superior iliac crest - felt by the thumb when hands laterally placed on hip
bone
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Back (24/4/18)
Muscles
Superficial
1. Trapezius (O: External occipital protuberance, Medial 1/3rd of superior
nuchal line, ligmentum nuchae, spine of C7, spine T1 - T12 and
interspinous ligaments)(I: posterior border of later 1/3rd of clavicle,
Medial margin of acromial process, upper lip of spine of scapula)(N:
spinal accessory nerve)(A: [many] elevation of shoulder)
2. Latissimus Dorsi (O: posterior superior iliac crest, thoracolumbar fascia,
lower 4 ribs (9,10,11,12), inferior angle of scapula)(I: floor of Bicepital
groove)(N: Thoracodorsal Nerve aka Nerve to Latissimus Dorsi [C6-8])(A:
[swimming action] adduction, extension and a little lateral flexion, in
climbing actions the origin moves more)
Deep on medial side of the scapula
1. Levator Scapulae (O: 1-4th transverse process of cervical vertebrae)(I: superior
angle of scapula to medial border of spine of scapula)(N: Dorsal scapular Nerve)(A:
elevation of scapula)
2. Rhomboidus Minor (O: C7-T1 spine)(I: medial border of scapula at spine)(N: Dorsal
scapular nerve)(A: retraction of scapula)
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Back (24/4/18)
3. Rhomboidus Major (O: T2-T5 spine)(I: medial border of scapula below the spine to
the inferior angle)(N: Dorsal Scapular Nerve)(A: Retraction of scapula)
Lateral side of the scapula
1. Teres Major (O: above inferior angle of scapula)(I: medial lip of tubercular sulcus)(A:
medial rotator, adductor of arm)(N: subscapular Nerve [C5-6])
2. Teres Minor (O: superior portion of the lateral border of scapula beneath
infraglenoid tubercle)(I : lower impression on greater tubercle of humerus)(A: lateral
rotator of arm)(N: Axillary Nerve [C5-6])
Dorsal side of scapula
1. Supraspinatus (O: supraspinous fossa)(I: upper impression of greater tubercle of
humerus)(A: initiation of abduction)(N: Suprascapular Nerve [C5-6])
2. infraspinatus (O: infraspinous fossa)(I: middle impression of greater tubercle of
humerus)(A: Lateral rotator of arm)(N: suprascapular Nerve)
Ventral side of scapula
1. subscapularis (O: subscapular fossa)(I: lesser tubercle of Humerus)(N:Upper and
Lower Subscapular Nerve [C5-6])(A: medial rotator and adductor of arm)
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Back (24/4/18)
Triangles
1. Triangle of Auscultation
it is a triangular space in the back where deep muscles are absent
medially bordered by Trapezius, laterally by medial border of scapula and inferiorly
Latissimus Dorsi
in the right side triangle, lungs could be heard, in the left space stomach and
eosophagus
2. petit’s triangle
Posterior superior iliac makes the base, lateral and medial borders are by
Latissimus Dorsi and External oblique respectively
Herniation happens through this triangle (rarely)
3. intermuscular space
Quadrangular space: (structures passing through; Posterior Circumflex Humoral
Artery& Axillary Nerve,) superior border- Teres Minor, Inferior border- Teres major,
medial border - long head of triceps, lateral border- shaft of humerus (at surgical
neck)
upper triangle:(structures passing through; Circumflex scapular artery pierces the
Teres Minor and pass to the scapula in the middle of 2 heads of Teres Minor
) superior border- Teres Minor, inferior border: Teres Major, lateral border- long
head of triceps
lower triangle: (Structures passing through; Radial nerve and Profunda Brachial
Artery) superior border- Teres major, lateral border- shaft of humerus, medial
border- long head of triceps
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