Back Muscles Flashcards
What are the superficial hypaxial muscles responsible for? Innervation?
-move the upper limb and pectoral girdle, innervated by branches of brachial plexus
What are the muscles in the superficial hypaxial muscles?
Layer 1:
- trapezius
- latissimus dorsi
Layer 2:
- levator scapulae
- rhomboid major
- rhomboid minor
Origin, insertion, actions, and innervation of TRAPEZIUS
origin: external occipital protuberance, nuchal ligament, spinous processes of C7-T12 vertebrae
insertion: lateral third of anterior clavicle and spine of scapula
actions: elevates, depresses, and retracts scapula, rotates glenoid fossa superiorly
innervation: motor -> accessory, sensory -> ventral rami C3 and C4
Origin, insertion, actions, and innervation of LATISSMUS DORSI
origin: spinous processes of inferior 6 thoracic vertebrae, thoracolumbar fascia, iliac crest, and inferior 3 ribs
insertion: floor of intertubercular sulcus of humerus
actions: extends, adducts, and medially rotates humerus, raises torso towards arms during climb
innervation: thoracodorsal nerve
Origin, insertion, actions, and innervation of RHOMBOID MAJOR and MINOR
origin:
- major: spinous processes of T2-T5
- minor: nuchal ligament, spinous processes of C7 and T1
insertion:
- major: medial border of scapula
- minor: medial end of scapular spine
actions: retract, elevate, and rotate scapula downward. Fix to thoracic wall
innervation: dorsal scapular nerve
Origin, insertion, actions, and innervation of LEVATOR SCAPULAE
origin: post. tubercles of transverse processes of first 4 cervical vertebrae
insertion: medial border of scapula, sup. part of scapular spine
actions: elevates scapula and tilts glenoid fossa inferiorly by rotating scapula (downward)
innervation: dorsal scapular nerve and ventral rami or cervical spinal nerves, C3 and C4 motor
What 3 muscles move the scapula?
- rhomboid major
- rhomboid minor
- levator scapulae
What are the extrinsic muscles of the back? third layer
- serratus posterior superior
2. serratus posterior inferior
Origin, insertion, actions, and innervation of SERRATUS POSTERIOR SUPERIOR
origin: nuchal ligament, spinous processes of C7-T3
insertion: sup. border of ribs 2-4
actions: elevates ribs
Innervation: T2-T5 intercostal nerves (ventral rami)
Origin, insertion, actions, and innervation of SERRATUS POSTERIOR INFERIOR
origin: spinous processes of T11-L2
insertion: inf. borders of ribs 8-12
actions: depress ribs
innervation: intercostal nerves and subcostal nerve (ventral rami)
What are the two groups of epaxial back muscles? What muscles belong in each?
- erector spinae group
- spinalis
- longissmus
- iliocostalis - transversospinalis group
- rotatores
- multifidus
- semispinalis
Origin, insertion, actions, and innervation of SPLENIUS
- cervicis
- capitis
origin: both arise from nuchal ligament and spinous processes of T1-T6
insertion:
- cervicis: tubercles of transverse processes of C1-C4
- capitis: lateral parts of mastoid processes and sup. nuchal lines
actions:
bilateral: extend head and neck
unilateral: laterally flex neck and rotate head to side of contracting muscle
innervation: dorsal rami of spinal nerves
Actions and innervation of iliocostalis, longissimus, adn spinalis
actions:
bilateral: extend vertebral column and head
unilateral: laterally flex vertebral column
innervation: dorsal rami of spinal nerves
Origin and insertion of ILIOCOSTALIS
origin: broad common tendon attaches to iliac crest, post. part of sacrum, sacroiliac ligaments, sacral and inf. lumbar spinous processes, and supraspinous ligament
insertions:
- lumborum: ribs 6-12
- thoracis: ribs 1-6
- cervicis: ribs 1-6 and post. tubercles of the transverse processes of cervical vertebrae 4-6
Origin and insertion for LONGISSIMUS
- thoracis
- cervicis
- capitis
thoracis
origin: same as iliocostalis
insertion: ribs and adjacent transverse processes or thoracic vertebrae
cervicis
origin and insertion: transverse processes of cervical vertebrae
capitis
origin: transverse processes of cervical vertebrae
insertion: mastoid processes
What portion of spinalis can be missing entirely?
capitis
Origin and insertion of SPINALIS THORACIS
origin: spinous process
insertion: spinous process superior to origin
What are the muscles in the deepest layer of back muscles? What are their common innervation?
- semispinalis
- rotatores
- multifidus
innervation: dorsal rami of spinal nerves
Origin, insertion, and actions of SEMISPINALIS
- thoracis
- cervicis
- capitis
cervis
-cervical transverse processes to spinous processes of second cervical vertebra
capitis
- superficial to cervicis
- transverse processes of 1-6 thoracic vertebare to nuchal line
thoracis
-transverse to spinous processes in thoracic region
action: extend head, thoracic and cervical regions, rotates them contrlaterally
Origin, insertion, actions, and innervation of MULTIFIDUS
- cover lamina and span vertebral segments from sacrum all the way to 2nd cervical vertebrae
- originate on transverse processes and insert on spinous processes
action: stabilizes vertebrae during localized movements of vertebral column
Origin, insertion, actions, and innervation of ROTATORES
- brevis
- longus
brevis
-transverse process of one vertebra to base of spinous process of next vertebra (1 intervertebral joint)
longus
-transverse process of one vertebra to spinous process of 2nd vertebra above (2 intervertebral joints)
action: extend head, thoracic and cervical regions, rotates them contralaterally
What are the segmental muscles and what are their innervations?
- interspinales -> dorsal rami
- intertransversari -> dorsal and ventral rami
- levator costarum -> dorsal rami of C8-T11
What muscles can be found in the suboccipital triangle? innervation? action?
-splenius and semispinalis overlie
- rectus capitis post. major
- rectus capitis post. minor
- obliquus capitis superior
- obliquus capitis inferior
- postural muscles and aid in extension and rotation
innervation: suboccipital nerve (dorsal rami of C1)
What are the nerves and vessels found in the suboccipital region?
- vertebral artery
- suboccipital nerve (motor to all muscles)
- greater occipital nerve (sensory fibers only)
- post. atlanto-occipital membrane (continuous with ligamentum flava)
