Anat- Back Muscles
Terms
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- levator scapulae: origin
- posterior tubercles of transverse processes of C1-C4 vertebrae
- levator scapulae: insertion
- medial border of scapula superior to root of spine
- levator scapulae: innervation
- dorsal scapular (C5) and cervical (C3,4) nerves
- rhomboid minor: origin
- nuchal ligament; spinous processes of C7 and T1 vertebrae
- rhomboid major: origin
- spinous processes of T2-T5 vertebrae
- rhomboid minor: insertion
- triangular area at medial end of scapular spine
- rhomboid major: insertion
- medial border of scapula from level of spine to inferior angle
- rhomboid major and minor: innervation
- dorsal scapular nerves (C4,5)
- rhomboid major and minor: action
- retracts scapula and rotates it to depress glenoid cavity; fixes scapula to thoracic wall
- levator scapulae: action
- elevates scapula and tilts its glenoid cavity inferiorly by rotating scapula
- trapezius: origin
- medial third of superior nuchal line, external occipital protuberance, nuchal ligament, spinous processes of C7-T12 vertebrae
- trapezius: insertion
- lateral third of clavicle, acromion and spine of scapula
- trapezius: innervation
- spinal accessory nerve, C3 & C4 nerves
- whole trapezius: action
- elevates, retracts, and rotates scapula
- trapezius, descending part: action
- elevate pectoral girdle, maintain level of shoulders against gravity or resistence
- trapezius, middle part: action
- retract scapula
- trapezius, ascending part: action
- depress shoulders
- trapezius, ascending and descending parts: action
- rotates scapula upward with shoulders fixed, bilateral contraction extends neck; unilateral contraction produces lateral flexion to same side
- serratus anterior: origin
- external surfaces of lateral parts of 1st-8th ribs
- serratus anterior: insertion
- anterior surface of medial border of scapula
- serratus anterior: innervation
- long thoracic nerve
- serratus anterior: action
- protracts scapula and holds it against thoracic wall, rotates scapula
- serratus anterior: blood supply
- lateral thoracic artery and vein
- pectoralis minor: origin
- 3rd-5th ribs near their costal cartilages
- pectoralis minor: insertion
- medial border and superior surface of coracoid process of scapula
- pectoralis minor: innervation
- medial pectoral nerve
- pectoralis minor: action
- stabilizes scapula by drawing it inferiorly and anteriorly against thoracic wall
- pectoralis minor: blood supply
- pectoral branches of thoracoacromial artery and pectoral veins
- latissimus dorsi: origin
- spinous processes of inferior 6 thoracic vertebrae, thoracolumbar fascia, iliac crest, and inferior 3 or 4 ribs
- latissimus dorsi: insertion
- floor of intertubercular groove of humerus
- latissimus dorsi: innervation
- thoracodorsal nerve (C6, 7, or 8)
- latissimus dorsi: action
- extends, adducts, and medially rotates humerus; raises body toward arms during climbing
- teres major: origin
- posterior surface of inferior angle of scapula
- teres major: insertion
- medial lip of intertubercular groove of humerus
- teres major: innervation
- lower subscapular nerve (C5, C6)
- teres major: action
- adducts and medially rotates arm
- teres minor: origin
- middle part of lateral border of scapula
- teres minor: insertion
- inferior facet of greater tubercle of humerus
- teres minor: innervation
- axillary nerve (C5, C6)
- teres minor: action
- laterally rotates arm; helps hold humeral head in glenoid cavity of scapula
- infraspinatus: origin
- subscapular fossa (most of anterior surface of scapula)
- subscapularis: origin
- subscapular fossa (most of anterior surface of scapula)
- infraspinatus: insertion
- middle facet of greater tubercle of humerus
- infraspinatus: innervation
- suprascapular nerve (C5, C6)
- infraspinatus: action
- laterally rotates arm; help hold humeral head in glenoid cavity of scapula
- subscapularis: insertion
- lesser tubercle of humerus
- subscapularis: innervation
- upper and lower subscapular nerves (C5, C6, C7)
- subscapularis: action
- medially rotates and adducts arm; helps hold humeral head in glenoid cavity
- supraspinatus: origin
- suprospinous fossa of scapula
- supraspinatus: insertion
- superior facet of greater tubercle of humerus
- supraspinatus: innervation
- suprascapular nerve (C4, C5, C6)
- supraspinatus: action
- initiates and assists deltoid in abduction of arm and acts with rotator cuff muscles
- deltoid: origin
- lateral third of clavicle; acromion and spine of scapula
- deltoid: insertion
- deltoid tuberosity of humerus
- deltoid: innervation
- axillary nerve (C5, C6)
- deltoid: action
- clavicular part flexes and medially rotates arm; acromial part abducts arm; spinal part extends and laterally rotates arm
- pectoralis major: origin
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clavicular head: anterior surface of medial half of clavicle
sternalcostal head: anterior surface of sternum, superior six costal cartilages, aponeurosis of external oblique muscles - pectoralis major: insertion
- lateral lip of intertubercular groove of humerus
- pectoralis major: innervation
- medial and lateral pectoral nerves
- pectoralis major: action
- adducts and medially rotates humerus, draws scapula anteriorly and inferiorly
- pectoralis major: blood supply
- thoracoacromial artery, pectoral veins
- serratus posterior superior: origin
- nuchal ligament, spinous processes of C7-T3 vertebrae
- serratus posterior superior: insertion
- superior borders of 2nd-4th ribs
- serratus posterior superior: innervation
- 2nd-5th intercostal nerves
- serratus posterior superior: action
- elevates ribs
- serratus posterior inferior: origin
- spinous processes of T11-L2 vertebrae
- serratus posterior inferior: insertion
- inferior borders of 8th-12th ribs near their angles
- serratus posterior inferior: innervation
- 9th-11th intercostal nerves & subcostal (T12) nerve
- serratus posterior inferior: action
- depresses ribs
- splenius: origin
- arises from nuchal ligament and spinous processes of C7-T3 or T4 vertebrae
- splenius capitis: insertion
- fibers run superolaterally to mastoid process of temporal bone and lateral third of superior nuchal line of occipital bone
- splenius cervicis: insertion
- tubercles of transverse processes of C1-C3 or C4 vertebrae
- splenius: innervation
- posterior rami of spinal nerves
- splenius: action
- laterally flex neck and rotate head to side of active muscles, extend head and neck
- iliocostalis lumborum, thoracis, cervicis: origin
- arises by broad tendon from posterior part of iliac crest, posterior surface of sacrum, sacroiliac ligaments, sacral and inferior lumbar spinous processes, and supraspinous ligament
- iliocostalis lumborum, thoracis, & cervicis
- fibers run superiorly to angles of lower ribs and cervical transverse processes
- iliocostalis: innervation
- posterior rami of spinal nerves
- iliocostalis: action bilaterally
- extends vertebral column & head; as back is flexed, control movement by gradually lengthening their fibers
- iliocostalis: action unilaterally
- laterally flexes vertebral column
- longissimus thoracis, cervicis, capitis: origin
- arises by broad tendon from posterior part of iliac crest, posterior surface of sacrum, sacroiliac ligaments, sacral and inferior lumbar spinous processes, and supraspinous ligament
- longissimus thoracis, cervicis, capitis: insertion
- fibers run superiorly to ribs between tubercles and angles to transverse processes in thoracic and cervical regions and to mastoid process of temporal bone
- longissimus thoracis, cervicis, capitis: innervation
- posterior rami of spinal nerves
- longissimus thoracis, cervicis, capitis: action bilaterally
- extend vertebral column and head; as back is flexed, control movement by gradually lengthening their fibers
- longissimus thoracis, cervicis, capitis: action unilaterally
- laterally flex vertebral column
- spinalis thoracis, cervicis, capitis: origin
- arises by broad tendon from posterior part of iliac crest, posterior surface of saccrum, sacroiliac ligaments, sacral and inferior lumbar spinous processes, and supraspinous ligament
- spinalis thoracis, cervicis, capitis: insertion
- fibers run superiorly to spinous processes in upper thoracic region and to cranium
- spinalis thoracis, cervicis, capitis: innervation
- posterior rami of spinal nerves
- spinalis thoracis, cervicis, capitis: action bilaterally
- extends vertebral column and head; as back is flexed, control movement by gradually lengthening their fibers
- spinalis thoracis, cervicis, capitis: action unilaterally
- laterally flexes vertebral column
- semispinalis thoracis, cervicis, capitis: origin
- arises from transverse processes of C4-T10 vertebrae
- semispinalis thoracis, cervicis, capitis: insertion
- fibers run superomedially to occipital bone and spinous processes in upper thoracic and cervical regions, spanning 4-6 segments
- semispinalis thoracis, cervicis, capitis: innervation
- posterior rami of spinal nerves
- semispinalis thoracis, cervicis, capitis: action
- extends head and thoracic and cervical regions of vertebral column and rotates them contralaterally
- quadratus lumborum: origin
- medial half of inferior border of 12th rib and tips of lumbar transverse processes
- quadratus lumborum: insertion
- iliolumbar ligament and interal lip of iliac crest
- quadratus lumborum: innervation
- anterior branches of T12 and L1-L4 nerves
- quadratus lumborum: action
- extends and laterally flexes vertebral column, fixes 12th rib during inspiration
- intertransversarii: origin
- transverse processes of cervical and lumbar vertebrae
- intertransversarii: insertion
- transverse processes of adjacent vertebrae
- intertransversarii: innervation
- posterior and anterior rami of spinal nerves
- intertransversarii: action
- aid in lateral flexion of vertebral column; acting bilaterally, stabilize vertebral column
- multifidi: origin
- arises from posterior sacrum, posterior superior iliac spine of ilium, aponeurosis of erector spinae, sacroiliac ligaments, mammillary processes of lumbar vertebrae, transverse processes of T1-T3, and articular processes of C4-C7
- multifidi: insertion
- thickest in lumbar region, fibers pass obliquely superomedially to entire length of spinous processes of vertebrae located 2-4 segments superior to origin
- multifidi: innervation
- posterior rami of spinal nerves
- multifidi: action
- unilateral contraction rotates contralateral side; stabilizes vertebrae during local movements of vertebral column
- rotators: origin
- arises from transverse processes of vertebrae; are best developed in thoracic region
- rotators: insertion
- fibers pass superiomedially to attach to junction of lamina and transverse process or spinous process of vertebra immediately (brevis) or segments (longus) superior to vertebrae of origin
- rotators: innervation
- posterior rami of spinal nerves
- rotators: action
- may funciton as organs of proprioception; possibly stabilize vertebrae and assist w/ local extension and rotatory movements of vertebral column
- interspinalis: origin
- superior surfaces of spinous processes of cervical and lumbar vertebrae
- interspinalis: insertion
- inferior surfaces of spinous processes of vertebrae superior to vertebrae of origin
- interspinalis: innervation
- posterior rami of spinal nerves
- interspinalis: action
- aid in extension and rotation of vertebral column
- levator scapulae: blood supply
- suprascapular a, v; thyrocervical trunk, jugular v
- rhomboid: blood supply
- cervical neurovascular bundles; branches and tributaries from scapular anastomoses
- trapezius: blood supply
- transverse cervical a, v; thoracic neurovascular bundles
- latissimus dorsi: blood supply
- thoracodorsal a,v
- teres major: blood supply
- scapular anastomoses
- teres minor: blood supply
- scapular anastomoses
- infraspinatus: blood supply
- suprascapular a, v
- subscapularis: blood supply
- subscapular a, v
- supraspinatus: blood supply
- suprascapular a, v
- deltoid: blood supply
- thoracoacromial a, v; circumflex humeral aa, axillary v
- serratus posterior superior: blood supply
- cervical neurovascular bundles
- serratus posterior inferior: blood supply
- lumbar neurovascular bundles