EXAM III The Back Flashcards
What are the components of the 3 layers of the hypaxial/superficial/extrinsic back muscles?
Layer I: (superficial to layer 2)
Trapezius
Latissimus Dorsi
Layer 2:
Rhomboid major/minor (major is inferior to minor)
Levator scapulae
Layer 3:
Serratus posterior superior - deep to rhomboids
Serratus posterior inferior
What nerve innervates the trapezius muscle?
Spinal Accessory Nerve (motor)
CN XI
ONLY back muscle that is innervated by part of a CN; whereas the others come off the brachial plexus
Sensory = ventral rami
What nerve innervates the rhomboids?
Dorsal Scapular Nerve
via roots, one of the first branches off of the brachial plexus
What nerve innervates the latissimus dorsi?
Thoracodorsal
A long branch off of the posterior cord of the brachial plexus
What is the action of the trapezius?
Elevates, depresses, retracts scapula
Rotates glenoid fossa superiorly during abduction of the arm (raising arm in front)
What are the actions of the latissimus dorsi?
Raises torso towards arms when climbing (i.e. pullups)
Extends, Adducts, Medially rotates humerus
What are the actions of the rhomboid muscles?
Retracts, Elevate, and Rotate Scapula
Fix scapula to thoracic wall
What nerve innervates the levator scapulae muscle? (2)
Dorsal scapular nerve
Ventral rami of cervical spinal nerves
What are the actions of the levator scapula muscle?
Elevates scapula
Downward rotation of scapula by tilting glenoid fossa inferiorly
What are the segmental muscles of the back?
Interspinales
Intertransversari
Levator costarum
What muscle lies beneath the rhomboid muscles?
Serratus posterior superior
What are the actions of the serratus posterior superior?
Elevates ribs
Breathing muscles
What nerve innervates the serratus posterior superior muscle?
Intercoastal nerves via ventral rami
What nerve innervates the serratus posterior inferior muscle and what is its function?
Depresses the ribs
Intercostal nerves
Subcostal nerve (ventral rami)
What are the 2 major groups of the epaxial back muscles?
Erector Spinae Group:
Spinalis
Logissimus
Iliocostalis
Transversospinalis Group:
Rotatores
Multifidus
Semispinalis
Which section of the erector spinae muscle group has lumbar insertions?
Iliocostalis lumborum
What back muscle lies deep to the splenius capitis?
Semispinalis capitis
What nerves innervate the segmental back muscles? What is the one exception?
Dorsal rami of spinal nerves innervate all
Ventral rami innervate Intertransversari group
What muscles lie superior to the suboccipital triangle muscles?
Splenius
Semispinalis
What nerve innervates the suboccipital triangle muscles?
(motor and sensory)
Motor: Suboccipital nerve
Sensory: Greater Occipital nerve
What are the functions of the suboccipital triangle muscles?
Mainly Postural muscles
Aid in extension and rotation at atlantoaxial joint
What artery supplies the suboccipital triangle?
Vertebral artery
What nerve supplies all of the epaxial muscles? Name one exception
Dorsal Rami of Spinal Nerves
Exception: Intertransversari is innervated by both dorsal and ventral rami
What muscles does the transverse cervical artery supply?
Trapezius - superficial + deep branch
Levator scapula - deep branch
Rhomboids - deep branch
What is the action of the splenius capitis and splenius cervicis muscles
Bilaterally - elevate head and neck
Unilaterally - flex neck, epsilateral rotation of the head
What are the breathing muscles of the back?
Serratus posterior superior
Serratus posterior inferior
Which muscles are apart of the erector spinae group?
Iliocostalis (most lateral) - contains a lumborum portion
Longissimus (middle)
Spinalis (medial)
Superficial to Transversospinalis group
Which muscles are apart of the transversospinalis group?
Multifidus
Rotatores
Semispinalis Capitis
Deep to erector spinae group
What are the actions of the Iliocostalis portion of the erector spinae group?
Bilaterally - Extend vertebral column, head, and neck
Unilaterally - Laterally flex vertebral column
What are the actions of the longissimus muscle of the erector spinae group? (capitis, cervicis, thoracis)
Capitis - extend head
Cervicis - extend and laterally bend the neck
Thoracis - extend spine
What are the actions of the multifidus muscle?
Stabilizes vertebrae during localized movements of vertebral column
What are the actions of the rotatores muscle of the transversospinalis group?
Extend head
Rotate cervical and thoracic contralaterally
Longus and brevis portion
What are the actions of the semispinalis capitis muscle of the transversospinalis group?
Extend head, cervical and thoracic
Rotates head, cervical, thoracic contralaterally
Bends neck laterally
What muscles are involved in elevating the scapula?
Trapezius
Levator scapulae
Rhomboids
What muscles rotate scapula downwards?
Levator scapulae
Rhomboids major and minor
What muscles are involved in extending the head? (5)
Splenius capitis and cervicis
Iliocostalis cervicis region
Longissimus capitis
Rotatores
Semispinalis capitis
What muscles are involved in extending the spine? (2)
Longissiumus thoracis
Spinalis
