The Back and Thorax Flashcards
Trapezius
Origin: superior nuchal line, external occipital protuberance, ligament nuchae, and spinous process of T1-T12
Insertion: spine of the scapula, acromion process, and lateral 1/3 of the clavicle
Action: head rotation, elevation and retraction of the pelvic girdle, and superior rotation of the scapula
Innervation: spinal accessory nerve (Cranial Nerve XI)
Latissimus Dorsi
Origin: spinous process of T7 - L5, thoracolumbar fascia, sacrum, and iliac crest
Insertion: inter-tubercular sulcus of the humerus
Action: extension, adduction, and medial rotation of the humerus, depression and retraction of the pectoral girdle, and inferior rotation of the scapula
Innervation: thoracodorsal nerve
Rhomboid major
Origin: spinous process of T2-T5
Insertion: medial border of the scapula
Action: retraction and elevation of the pectoral girdle, and inferior rotation of the scapula
Innervation: dorsal scapular nerve
Rhomboid minor
Origin: spinous process of C7-T1
Insertion: medial border of the scapula
Action: retraction and elevation of the pectoral girdle, inferior rotation of the scapula
Innervation: dorsal scapular nerve
Levator scapulae
Origin: transverse process of C1-C4
Insertion: superior angle of the scapula
Action: elevation of the pectoral girdle and inferior rotation of the scapula
Innervation: dorsal scapular nerve
Serratus posterior superior
Origin: spinous process of C7 - T3
Insertion: ribs 2-5
Action: elevation of ribs 2-5
Innervation: ventral primary rami (intercostal nerves)
Serratus posterior inferior
Origin: spinous process of T11-L3
Insertion: ribs 9-12
Action: depression of ribs 9-12
Innervation: ventral primary rami (intercostal nerves)
Splenius capitis and cervicis
Origin: ligamentum nuchae and spinous process T1-T4
Insertion:
Capitis: superior nuchal line and mastoid process
Cervicis: transverse process of C1-C4
Action:
Unilateral: ipsilateral rotation of head and neck
Bilateral: extension of the head and neck
Erector spinae muscles
Origin: iliac crest, sacrum, and lumbar spinous process
Insertion:
Iliocostalis: ribs, spinous process of C1 and C7
Longissimus: cervical and thoracic transverse processes, ribs, and mastoid
process
Spinalis: thoracic spinous processes, ligamentum nuchae, and occipital bone
Action:
Unilateral: lateral flexion and ipsilateral rotation of trunk
Bilateral: extension of the trunk and head
Transversospinalis muscles
Origin: iliac crest, sacrum, and transverse process of C4 - L5
Insertion:
Semispinalis capitis: spans upper transverse processes to occipital bone
Semispinalis cervicis: spans upper thoracic transverse processes to upper
cervical spinous processes
Multifidus: spans 2-4 segments
Rotator: spans 1-2 segments
Action:
Unilateral: lateral flexion and contralateral rotation of the trunk
Bilateral: extension of the trunk
Intersegmental Muscles
Intertransverarii: spans the transverse processes
Interspinales: spans spinous processes
Levatores costarum
Origin: transverse processes of thoracic vertebrae
Insertion: ribs - 1-2 segments inferior to origin
Action: elevation of ribs
Rectus capitis posterior major
Origin: spinous process of C2
Insertion: inferior nuchal line
Action:
Unilateral: ipsilateral rotation of the head
Bilateral: extension of the head
Innervation: dorsal rami of C1
Rectus capitis posterior minor
Origin: posterior tubercle of C1
Insertion: inferior nuchal line
Action:
Unilateral: ipsilateral rotation of the head
Bilateral: extension of the head
Innervation: dorsal rami of C1
Obliquus capitis superior
Origin: transverse process of C1
Insertion: between nuchal lines
Action:
Unilateral: ipsilateral bending of the head
Bilateral: extension of the neck
Innervation: dorsal rami of C1
Obliquus capitis inferior
Origin: spinous process of C2
Insertion: transverse process of C1
Action:
Unilateral: ipsilateral rotation of the head
Bilateral: extension of the neck
Innervation: dorsal rami of C1
Blood supply to superficial muscles
Supplied by branches of axillary and subclavian
Transverse cervical artery : passes deep to the trapezius
Thoracodorsal artery: travels along deep surface of latissimus dorsi
Dorsal scapular: posteriorly in neck deep to levator scapulae and rhomboid
Blood supply to intrinsic muscles
Supplied by segmental arteries traveling with primary dorsal rami
Motor innervation
Scapular and superficial muscles of the back: branches of brachial plexus
Exception: trapezius - supplied by cranial nerve XI
Cutaneous innervation
Cutaneous branches of dorsal primary rami: skin overlaying intrinsic muscles
Cutaneous branches of ventral primary rami: skin of lateral margins of back
