Trunk 2

Around the back

100

Teres minor: O: I: A; In:

What is: Teres minor Origin: middle half of the scapula’s lateral margin Insertion: lowest of three facets of the greater tubercle of humerus Action: lateral rotation of the humerus stabilizes the glenohumeral joint Nerve: axillary nerve, C5,6

200

Teres major: O; I: A: In:

What is: Origin: inferior, lateral margin of the scapula Insertion: crest of lesser tubercle (just medial to the insertion of latissimus dorsi) Action: assists in adduction of arm assists in medial rotation of arm assists in extension from an flexed position Nerve: lower subscapular nerve, C5,6

300

Subscapularis: O: I: A: In:

What is: Subscapularis Origin: subscapular fossa Insertion: lesser tubercle of humerus Action: medial rotation of the humerus stabilizes the glenohumeral joint Nerve: upper & lower subscapular nerves, C5,6

400

Splenius capitis: O: I: A: In:

What is: Splenius capitis Origin: lower portion of ligamentum nuchae spinous processes of C3-T3(4) Insertion: superior nuchal line mastoid process of temporal bone Action: bilateral contraction: extend head & neck unilateral contraction: rotate and laterally bend head & neck to the contracted (same) side Nerve: dorsal rami of spinal nerves

500

Splenius cervicis: O: I: A: In:

What is: Splenius cervicis Origin: spinous process of T3-T6 Insertion: posterior tubercles of transverse processes of C2-C4 Action: bilateral contraction: extend head & neck unilateral contraction: rotate and laterally bend head & neck to the contracted (same) side Nerve: dorsal rami of spinal nerves

Erector Spinae Muscles

100

Illiocostalis lumborum: O: I: A: In:

What is: Origin: common tendinous origin: (same for all lower erector spinae) sacrum iliac crest spinous processes of lower thoracic & most lumbar vertebrae Insertion: lower border of angles of ribs (5)6-12 Action: (same for all erector spinae) bilateral: extension of vertebral column maintenance of erect posture (pneumonic = I Like Standing) stabilization of vertebral column during flexion, acting in contrast to abdominal muscles and the action of gravity unilateral: lateral bend to same side rotation to same side opposite muscles contract eccentrically for stabilization Nerve: dorsal rami of spinal nerves

200

Iliocostalis thoracis: O: I: A: In:

What is: Origin: upper border of ribs 6-12 (medial to I. lumborum's insertion.) Insertion: lower border of angles of ribs 1-6 (sometimes transverse process of C7) Action: (same for all erector spinae) bilateral: extension of vertebral column maintenance of erect posture (pneumonic = I Like Standing) stabilization of vertebral column during flexion, acting in contrast to abdominal muscles and the action of gravity unilateral: lateral bend to same side rotation to same side opposite muscles contract eccentrically for stabilization Nerve: dorsal rami of spinal nerves

300

Iliocostalis cervicis: O: I: A: In:

What is: Iliocostalis cervicis Origin: angles of ribs 1-6 Insertion: transverse processes of C4-C6 Action: (same for all erector spinae) bilateral: extension of vertebral column maintenance of erect posture (pneumonic = I Like Standing) stabilization of vertebral column during flexion, acting in contrast to abdominal muscles and the action of gravity unilateral: lateral bend to same side rotation to same side opposite muscles contract eccentrically for stabilization Nerve: dorsal rami of spinal nerves

400

Longissimus thoracis: O: I: A: In:

What is: Longissimus thoracis Origin: common tendinous origin: (same for all lower erector spinae) sacrum iliac crest spinous processes of lower thoracic & most lumbar vertebrae Insertion: transverse processes of all thoracic vertebrae all ribs between tubercles and angles transverse processes of upper lumbar vertebrae Action: (same for all erector spinae) bilateral: extension of vertebral column maintenance of erect posture (pneumonic = I Like Standing) stabilization of vertebral column during flexion, acting in contrast to abdominal muscles and the action of gravity unilateral: lateral bend to same side rotation to same side opposite muscles contract eccentrically for stabilization Nerve: dorsal rami of spinal nerves

500

Longissimus cervicis: O: I: A: In:

What is: Origin: transverse processes of T1-T5(6) Insertion: transverse processes of C2-C6 Action: (same for all erector spinae) bilateral: extension of vertebral column maintenance of erect posture (pneumonic = I Like Standing) stabilization of vertebral column during flexion, acting in contrast to abdominal muscles and the action of gravity unilateral: lateral bend to same side rotation to same side opposite muscles contract eccentrically for stabilization Nerve: dorsal rami of spinal nerves

ES Muscles cont.

100

Longissimus capitis: O: I: A: In:

What is: Longissimus capitis Origin: transverse and articular processes of middle and lower cervical vertebrae transverse processes of upper thoracic vertebrae Insertion: posterior aspect of mastoid process of temporal bone Action: (same for all erector spinae) bilateral: extension of vertebral column maintenance of erect posture (pneumonic = I Like Standing) stabilization of vertebral column during flexion, acting in contrast to abdominal muscles and the action of gravity unilateral: lateral bend to same side rotation to same side opposite muscles contract eccentrically for stabilization Nerve: dorsal rami of spinal nerves

200

Spinalis thoracis: O: I: A: In:

What is: Origin: common tendinous origin: (same for all lower erector spinae) sacrum iliac crest spinous processes of lower thoracic & most lumbar vertebrae Insertion: spinous processes T3(4)-T8(9) Action: (same for all erector spinae) bilateral: extension of vertebral column maintenance of erect posture (pneumonic = I Like Standing) stabilization of vertebral column during flexion, acting in contrast to abdominal muscles and the action of gravity unilateral: lateral bend to same side rotation to same side opposite muscles contract eccentrically for stabilization Nerve: dorsal rami of spinal nerves

300

Spinalis cervicis: O: I: A: In:

What is: Spinalis cervicis Origin: spinous processes of C6-T2 Insertion: spinous processes of C2 (and possibly extend to C3 or C4) Action: (same for all erector spinae) bilateral: extension of vertebral column maintenance of erect posture (pneumonic = I Like Standing) stabilization of vertebral column during flexion, acting in contrast to abdominal muscles and the action of gravity unilateral: lateral bend to same side rotation to same side opposite muscles contract eccentrically for stabilization Nerve: dorsal rami of spinal nerves

400

Spinalis capitis: O: I: A: In:

What is: Spinalis capitis Origin: spinous processes of lower cervical & upper thoracic vertebrae Insertion: between superior & inferior nuchal lines of occipital bone Action: (same for all erector spinae) bilateral: extension of vertebral column maintenance of erect posture (pneumonic = I Like Standing) stabilization of vertebral column during flexion, acting in contrast to abdominal muscles and the action of gravity unilateral: lateral bend to same side rotation to same side opposite muscles contract eccentrically for stabilization Nerve: dorsal rami of spinal nerves

500

Semispinalis thoracis (starting transversospinal muscles): O: I: A: In:

What is: Origin: transverse processes of T6-T12 vertebrae Insertion: spinous processes of upper thoracic & lower cervical vertebrae Action: bilaterally extends vertebral column, especially head and neck controls lateral flexion to side opposite contraction (eccentric for stability) maintains head posture Nerve: dorsal rami of spinal nerves

Transverso-spinal muscles

100

Semispinalis cervicis: O: I: A: In:

What is: Semispinalis cervicis Origin: transverse processes of T1-T6 vertebrae and can go down to lower thoracic Insertion: spinous processes of C2-T5(6) Action: bilaterally extends vertebral column, especially head and neck controls lateral flexion to side opposite contraction (eccentric for stability) maintains head posture Nerve: dorsal rami of spinal nerves

200

Semispinalis capitus: O: I: A: In:

What is: Origin: transverse processes of T1-T6 articular processes of C4-C7 Insertion: between superior & inferior nuchal lines of occipital bone Action: bilaterally extends vertebral column, especially head and neck controls lateral flexion to side opposite contraction (eccentric for stability) maintains head posture Nerve: dorsal rami of spinal nerves

300

Multifidus: O: I: A: In:

What is: Multifidus Origin: cervical region: from articular processes of lower cervical vertebrae thoracic region: from transverse processes of all thoracic vertebrae lumbar region: lower portion of dorsal sacrum PSIS deep surface of tendenous origin of erector spinae mamillary processes of all lumbar vertebrae Insertion: spinous process of all vertebrae extending from L5 - C2 (skipping 1-3 segments) Action: bilaterally extends vertebral column controls lateral flexion to side opposite contraction (eccentric for stability) unilaterally rotate vertebral bodies (column) to opposite side Nerve: dorsal rami of spinal nerves

400

Long rotators: O: I: A: In:

What is: Long rotators Origin: transverse process of one vertebra Insertion: skips one vertebra to insert on the base of spinous process of vertebra above Action: rotate to opposite side bilateral extension Nerve: dorsal rami of spinal nerves

500

Short rotators: O: I: A: In:

What is: Short rotators Origin: transverse process of one vertebra Insertion: base of spinous process of vertebra immediately above Action: rotate to opposite side bilateral extension Nerve: dorsal rami of spinal nerves

Segmental Muscles

100

Interspinalis: O: I: A: In:

What is: Interspinalis Origin: spinous processes of each vertebra Insertion: to the spinous process of vertebra immediately above Action: extension of the vertebrae segments Nerve: dorsal rami of spinal nerves

200

Intertransversi: O: I: A: In:

What is: Origin: (A to A and B to B) cervical region: from the anterior tubercle of transverse process from the posterior tubercle of transverse process thoracic region: (poorly developed) lumbar region: lateral aspect of the transverse process mamillary process Insertion: cervical region: to the anterior tubercle immediately above to the posterior tubercle immediately above thoracic region: (poorly developed) lumber region: lateral aspect of the transverse process immediately above to the accessory process on the vertebra immediately above Action: laterally flexes each respective pair of vertebrae (also eccentric muscle contraction provides stability) Nerve: dorsal rami of spinal nerves