Trunk, Front & Back Musculature

Muscle Regions of the Body:

	Head and neck
	Trunk, front and back
	Brachium, antibrachium & hand
	Thigh, leg & foot

Muscle Groups within this Region:

	Splenius Muscles
	Erector Spinae Muscles
	Transversospinal Muscles
	Segmental Muscles

Superficial Back Musculature

Trapezius

	Origin: external occipital protuberance along the medial sides of the superior nuchal line ligamentum nuchae (surrounding the cervical spinous processes) spinous processes of C1-T12
	Insertion: posterior, lateral 1/3 of clavicle acromion superior spine of scapula
	Action: elevates scapula upward rotation of the scapula (upper fibers) downward rotation of the scapula (lower fibers) retracts scapula
	Blood: transverse cervical artery
	Nerve: spinal Accessory (XI) (efferent or motor fibers) ventral ramii of C3 & C4 (afferent or sensory fibers)

Latissimus dorsi

	Origin: spinous process of T7-L5 upper 2-3 sacral segments iliac crest lower 3 or 4 Ribs
	Insertion: lateral lip of the intertubercular groove
	Action: adduction of humerus medial rotation of the humerus extension from flexed position downward rotation of the scapula
	Blood: thoracodorsal artery
	Nerve: thoracodorsal nerve, C6,7,8

Pectoral Musculature

Subclavius

	Origin: first rib about the junction of bone and cartilage
	Insertion: lower surface of clavicle
	Action: assists in stabilizing the clavicle
	Blood: clavicular branch of thoracoacromial artery
	Nerve: nerve to the subclavius, C5,6

Pectoralis major

	Origin: medial 1/3 of clavicle anterior aspect of manubrium & length of body of sternum cartilaginous attachments of upper 6 ribs external oblique's aponeurosis
	Insertion: lateral lip of bicipital groove to the crest of the greater tubercle clavicular fibers insert more distally; sternal fibers more proximally
	Action: adducts humerus medially rotates humerus flexion of the arm from extension (clavicular portion)
	Blood: pectoralis branch of thoracoacromial artery (runs with lateral pec. nerve) lateral thoracic artery (lesser supply, and runs with medial pectoral nerve)
	Nerve: lateral pectoral nerve, C5,6,7 to clavicular portion medial pectoral nerve, C8,T1 to sternal portion

Pectoralis minor

	Origin: outer surface of ribs 2-5 or 3-5 or 6
	Insertion: medial aspect of coracoid process of the scapula
	Action: depresses & downwardly rotates the scapula assists in scapular protraction from a retracted position stabilizes the scapula
	Blood: lateral thoracic artery
	Nerve: medial pectoral nerve, C8,T1

Shoulder Girdle Musculature

Levator scapulae

	Origin: transverse processes of C1-C3 or C4
	Insertion: superior angle of scapula toward the scapular spine
	Action: elevates the scapula extends and/or laterally flexes the head
	Blood: transverse cervical artery
	Nerve: nerves off cervical plexus, C3,4 dorsal scapular nerve, C5

Rhomboid minor

	Origin: spinous process of C7 & T1 ligamentum nuchae supraspinous ligament
	Insertion: medial margin of the scapula at the medial angle
	Action: retract scapula
	Blood: deep branch of transverse cervical artery, OR dorsal scapular artery
	Nerve: dorsal scapular nerve, C5, [C4]

Rhomboid major

	Origin: spinous processes of T2-T5 supraspinous ligament
	Insertion: medial scapula from the scapular spine to the inferior angle
	Action: retract scapula
	Blood: deep branch of transverse cervical artery, OR dorsal scapular artery
	Nerve: dorsal scapular nerve, C5

Serratus anterior

	Origin: fleshy slips from the outer surface of upper 8 or 9 ribs
	Insertion: costal aspect of medial margin of the scapula
	Action: protract scapula stabilize scapula assists in upward rotation
	Blood: lateral thoracic artery supplies the upper part thoracodorsal artery supplies the lower part
	Nerve: long thoracic nerve, C5,6,7

Deltoid

	Origin: lateral, anterior 1/3 of distal clavicle lateral boarder of the acromion scapular spine
	Insertion: deltoid tuberosity of humerus
	Action: abducts arm flexion and medial rotation (anterior portion) extension and lateral rotation (posterior portion)
	Blood: posterior humeral circumflex artery deltoid branch of thoracoacromial artery
	Nerve: axillary nerve, C5,6

Supraspinatus

	Origin: supraspinous fossa muscle fascia
	Insertion: uppermost of three facets of the greater tubercle of humerus
	Action: abduction of arm (first 15-20�) stabilizes glenohumeral joint
	Blood: suprascapular artery (poorly supplied)
	Nerve: suprascapular nerve, C5,6

Infraspinatus

	Origin: infraspinous fossa muscle fascia
	Insertion: middle facet of greater tubercle of humerus
	Action: external rotation of the humerus stabilizes the glenohumeral joint
	Blood: suprascapular artery scapular circumflex artery
	Nerve: suprascapular nerve, C5,6

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
	Blood: scapular circumflex artery
	Nerve: axillary nerve, C5,6

Teres major

	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
	Blood: thoracodorsal artery
	Nerve: lower subscapular nerve, C5,6

Subscapularis

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

Deep Back Musculature

Splenius Muscles:

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
	Blood: muscular branches of the aorta
	Nerve: dorsal rami of spinal nerves

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
	Blood: muscular branches of the aorta
	Nerve: dorsal rami of spinal nerves

Erector Spinae Muscles

Iliocostalis lumborum

	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
	Blood: muscular branches of the aorta
	Nerve: dorsal rami of spinal nerves

Iliocostalis thoracis

	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
	Blood: muscular branches of the aorta
	Nerve: dorsal rami of spinal nerves

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
	Blood: muscular branches of the aorta
	Nerve: dorsal rami of spinal nerves

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
	Blood: muscular branches of the aorta
	Nerve: dorsal rami of spinal nerves

Longissimus cervicis

	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
	Blood: muscular branches of the aorta
	Nerve: dorsal rami of spinal nerves

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
	Blood: muscular branches of the aorta
	Nerve: dorsal rami of spinal nerves

Spinalis thoracis

	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
	Blood: muscular branches of the aorta
	Nerve: dorsal rami of spinal nerves

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
	Blood: muscular branches of the aorta
	Nerve: dorsal rami of spinal nerves

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
	Blood: muscular branches of the aorta
	Nerve: dorsal rami of spinal nerves

Transversospinal Muscles

Semispinalis thoracis

	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
	Blood: muscular branches of the aorta
	Nerve: dorsal rami of spinal nerves

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
	Blood: muscular branches of the aorta
	Nerve: dorsal rami of spinal nerves

Semispinalis capitus

	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
	Blood: muscular branches of the aorta
	Nerve: dorsal rami of spinal nerves

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

Blood: muscular branches of the aorta

Nerve: dorsal rami of spinal nerves

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
	Blood: muscular branches of the aorta
	Nerve: dorsal rami of spinal nerves

Short rotators

	Origin: transverse process of one vertebra
	Insertion: base of spinous process of vertebra immediately above
	Action: rotate to opposite side bilateral extension
	Blood: muscular branches of the aorta
	Nerve: dorsal rami of spinal nerves

Segmental Muscles

Interspinalis

	Origin: spinous processes of each vertebra
	Insertion: to the spinous process of vertebra immediately above
	Action: extension of the vertebrae segments
	Blood: muscular branches of the aorta
	Nerve: dorsal rami of spinal nerves

Intertransversi

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)

Blood: muscular branches of the aorta

Nerve: dorsal rami of spinal nerves