Back Muscles Flashcards
OIA
Trapezius
O: superior nuchal line, external occipital protuberance, nuchal ligament, spinous processes of C7-T12
I: lateral third of clavicle, acromion, spine of scapula
N: Spinal accessory n. (CN XI), Cervical anterior rami (C3-4)
A: elevate, retract, depress scapula; glenoid-up rotation of scapula
Latissimus dorsi
O: lower thoracic spinous processes, thoracolumbar fascia, iliac crest
I: intertubercular groove of humerus (anterior)
N: Thoracodorsal n.
A: adduct, medial rotate, extend arm
Levator scapulae
O: upper cervical transverse processes
I: medial border of scapula superior to root of spine
N: Dorsal scapular n., Cervical anterior rami (C3-4)
A: elevate scapula; glenoid-down rotation of scapula
Rhomboid major
O: spinous processes of upper thoracic vertebrae
I: medial border of scapula inferior to root of spine
N: Dorsal scapular n.
A: retract, glenoid-down rotation of scapula; fix scapula to thoracic wall
Rhomboid minor
O: nuchal ligament and spinous processes of C7-T1
I: medial border of scapula near spine
N: Dorsal scapular n.
A: retract, glenoid-down rotation of scapula; fix scapula to thoracic wall
Pectoralis major
O: clavicular head (medial half of clavicle) and sternocostal head (sternum, superior costal cartilages)
I: intertubercular groove of humerus (lateral lip)
N: Medial pectoral n. and Lateral pectoral n.
A: adduct, medially rotate arm; clavicular head flexion
Pectoralis minor
O: ribs 3-5
I: coracoid process of scapula
N: Medial pectoral n.
A: stabilize scapula
Serratus anterior
O: ribs 1-8
I: inferior angle and medial border of scapula (anterior surface)
N: Long thoracic n.
A: primary glenoid-up rotator of scapula; anchors scapula to thoracic wall by protracting and depressing scapula
Subclavius
O: rib 1
I: subclavian groove on inferior clavicle
N: Subclavian n.
A: depress clavicle
Deltoid
O: spine of scapula, acromion, lateral third of clavicle
I: deltoid tuberosity of humerus
N: Axillary n.
A: spinal part: extension and lateral rotation; acromion part: abduction of arm; clavicular part: flexion and medial rotation of arm
Teres minor (rotator cuff muscle)
O: middle part of lateral border of scapula
I: greater tubercle of humerus
N: Axillary n.
A: lateral rotation of arm; stabilizes glenohumeral joint
Teres major
O: posterior surface of inferior angle of scapula
I: intertubercular groove of humerus (medial lip)
N: Lower subscapular n.
A: adduction and medial rotation of arm
Supraspinatus
O: supraspinous fossa of scapula
I: greater tubercle of humerus
N: Suprascapular n.
A: initiates abduction of arm up to 15 degrees; stabilizes glenohumeral joint
Infraspinatus
O: infraspinous fossa of scapula
I: greater tubercle of humerus
N: Suprascapular n.
A: lateral rotation of arm; stabilizes glenohumeral joint
Rectus capitis posterior major
O: spinous process of C2
I: lateral inferior nuchal line
N: Suboccipital n. (posterior ramos of C1)
A: head extension; postural
Rectus capitis posterior minor
O: posterior tubercle of C1
I: medial inferior nuchal line
N: Suboccipital n. (posterior ramos of C1)
A: head extension; postural
Obliquus capitis superior
O: transverse process of C1
I: above the lateral inferior nuchal line
N: Suboccipital n. (posterior ramos of C1)
A: head extension; postural
Obliquus capitis inferior
O: spinous process of C2
I: transverse process of C1
N: Suboccipital n. (posterior ramos of C1)
A: head rotation; postural
Splenius capitis
O: nuchal ligament, spinous processes of C7-T6
I: mastoid process, lateral 1/3 of superior nuchal line
N: Posterior rami of spinal nerves
A: bilateral: head and neck extension; unilateral: ipsilateral head rotation and lateral flexion of neck
Splenius cervicis
O: nuchal ligament, spinous processes of C7-T6
I: transverse processes of upper cervical vertebrae
N: Posterior rami of spinal nerves
A: bilateral: neck extension; unilateral: lateral flexion of neck
Iliocostalis
O: common tendon from iliac crest, vertebrae of the sacral and lumbar spine, thoracolumbar fascia that surrounds the sacral and lumbar vertebrae
I: angles of lower ribs and cervical transverse processes
A: bilateral: back extension; unilateral: lateral flexion of vertebral column
Longissimus
O: common tendon from iliac crest, vertebrae of the sacral and lumbar spine, thoracolumbar fascia that surrounds the sacral and lumbar vertebrae
I: ribs, transverse processes of thoracic and cervical vertebrae, mastoid process
N: Posterior rami of spinal nerves
A: bilateral: back extension and head extension; unilateral: lateral flexion of vertebral column
Spinalis
O: common tendon from iliac crest and sacrum, cervical, thoracic and lumbar spinous processes
I: spinous processes of sacrum/lumbar to higher vertebrae (usually thoracic and sometimes cervical)
N: Posterior rami of spinal nerves
A: bilateral: back extension; unilateral: lateral flexion of vertebral column
What are the three muscles of the Erector Spinae group?
Iliocostalis, Longissimus, and Spinalis
Semispinalis
O: transverse processes of most thoracic vertebrae and lower cervical vertebrae
I: spinous processes of vertebrae 4-6 levels superior; superior nuchal line of occipital bone (only S. capitis)
N: Posterior rami of spinal nerves
A: stabilizes vertebral column; bilateral: assists in vertebral column extension; unilateral: assists with contralateral rotation and ipsilateral lateral flexion
Multifidus
O: common tendon of erector spinae from iliac crest and sacrum/transverse processes
I: spinous processes of vertebrae 2-4 levels superior
N: Posterior rami of spinal nerves
A: stabilizes vertebral column; bilateral: assists in vertebral column extension; unilateral: assists with contralateral rotation and ipsilateral lateral flexion
Rotatores
O: transverse processes (mostly thoracic)
I: spinous processes of vertebrae 1-2 levels superior
N: Posterior rami of spinal nerves
A: stabilizes vertebral column; bilateral: assists in vertebral column extension; unilateral: assists with contralateral rotation and ipsilateral lateral flexion
What are the three muscles of the Transversospinalis group?
Semispinalis, Multifidus, and Rotatores
