Back Flashcards
3 basic layers to back muscles and what they act on
- Superficial extrinsic muscles - act on upper limb
- Intermediate extrinsic muscles - accessory muscles of respiration
- Intrinsic back muscles (divided into superficial, intermediate, and deep) - act on vertebral column and skull
Trapezius - superficial Origin? Insertion? Innervation? Action?
Origin - superior nuchal line, external occipital protuberance, ligamentum nuchae, and spinous processes of C7-T12
Insertion - lateral 1/3 of clavicle, and acromion, and spine of scapula
Innervation - accessory nerve and ventral rami of C3 and C4
Action - elevates, retracts, superiorly rotates and depresses scapula
Lats - superficial Origin? Insertion? Innervation? Action?
Origin: Spinous processes of lower 6 thoracic vertebrae and of the lumbar and sacral vertebrae,
iliac crest, lower 3 or 4 ribs
~attach to vertebrae and iliac crest via thoracolumbar fascia
Insertion: tendon inserts into floor of intertubercular (bicipital) groove of humerus
Innervation: thoracodorsal nerve
Action: extends, abducts, and medially rotates arm
Levator Scapulae - superficial
Origin
Insertion
Innervation
Action
Origin: transverse process of upper 4 cervical vertebrae
Insertion: medial border of scapula
Innervation: ventral rami of C3 and C4 and dorsal scapular nerve
Action: elevates and rotates scapula inferiorly
Rhomboid minor - superficial
Origin
Insertion
Innervation
Action
Origin: lower part of ligamentum nuchae and spinous processes of C7 and T1
Insertion: medial border of scapula (at level of scapular spine)
Innervation: dorsal scapular nerve
Action: retract and help rotate scapula inferiorly
Rhomboid major - superficial
Origin
Insertion
Innervation
Action
Origin- spinous processes from T2-T5
Insertion: medial border of scapula (from spine to inferior angle)
Innervation: dorsal scapular nerve
Action: retract and help rotate scapula inferiorly
Serratus posterior superior muscle - intermediate
Origin
Insertion
Innervation
Action
Origin- ligamentum nuchae and C7-T2/T3 spinous processes
Insertion- ribs 2-5
Innervation - ventral rami of T2-T5
Action - elevates ribs 2-5
Serratus posterior inferior - intermediate
Origin
Insertion
Innervation
Action
Origin- T11- L2/L3 spinous processes
Insertion - lower 4 ribs
Innervation - ventral rami of T9-T12
Action - depresses ribs 8-12
Where is thoracolumbar fascia thickest?
In this region, there are 3 layers: name them what where they attach
Thickest in lumbar region (surrounds intrinsic back muscles); thinner in thoracic region
In lumbar region there are 3 layers:
Posterior layer- attaches to spinous processes
Intermediate layer - attaches to transverse processes
Anterior layer - attaches to transverse processes and forms quadratus lumborum fascia
Intrinsic back muscles:
Location?
Function?
Innervation?
Subdivided into 3 layers (what muscles in each?)
Intrinsic back muscles extend form the pelvis to the skull
Maintain posture and control movements of the vertebral column
Innervated by dorsal rami of spinal nerves
Superficial layer- consists of splenius capitis and splenius cervicis
Intermediate layer- erector spinae muscle
Deep layer- transversospinalis muscle
Splenius capitis - superficial intrinsic muscle
Origin
Insertion
Innervation
Action
Origin- lower part of ligamentum nuchae and spinous processes of C7-T3 vertebrae
Insertion: superior nuchal line and mastoid process
Innervation: dorsal rami of cervical spinal nerves
Action: bilateral contraction-extension of head and neck; unilateral contraction-lateral flexion and rotation of head and neck to the same side of contracting muscle
Splenius cervicis - superficial intrinsic muscle (usually never on practical)
Origin
Insertion
Innervation
Action
Origin: spinous process of T3-T6
Insertion: transverse process C1-C3
Innervation: dorsal rami of cervical spinal nerves
Action: bilateral contraction-extension of head and neck; unilateral contraction-lateral flexion and rotation of head and neck to the same side of contracting muscle
Erector spinae - intermediate intrinsic muscle
What 3 muscles make up this group?
Origin
Insertion
Innervation
Action
Iliocostalis, longissimus, spinalis
Origin&Insertion- from a broad tendon attaching to the iliac crest, sacrum, sacroiliac ligaments, and inferior lumbar spinous processes
Innervation- dorsal rami of spinal nerves
Action- bilateral contraction extension
of spine
unilateral contraction lateral flexion of spine to same side of contracting muscle
also contracts during flexion of spine to control movement against gravity
Transversospinalis muscles - deep intrinsic muscle
What 3 muscles make up this group?
Origin
Insertion
Innervation
Action
(From superficial to deep) Semispinalis, multifidus, rotatores (muscle span gets smaller as you get deeper)
Origin- transverse processes
Insertion- spinous processes of higher vertebrae
Innervation- dorsal rami of spinal nerves
Action- bilateral contraction extension of
spine
unilateral contraction lateral flexion of spine to same side of contracting muscle; AND, rotation of spine to opposite side of contracting muscle also, shorter muscles’ main function is to stabilize vertebral column
~ so basically same action as erector spinae except deep muscles stabilize the vertebral column more
semispinalis has 3 parts, what are they?
Two things to look for when trying to identify semispinalis capitis muscle
Capitis, Cervicis, Thoracic
Capitis is pierced by occipital nerve and is superior to sub occipital triangle
