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Iliocostalis Lumborum
- Erector Spinae
- Origin: Common origin from anterior surface of broad tendon attached to medial crest of the sacrum, spinous processes of lumbar and 11th and 12th thoracic vertebrae, posterior part of medial lip of iliac crest, suporaspinous ligament, and lateral crests of sacrum
- Insertion: By tendons into inferior borders of angles of lower six or seven ribs
- Action: Extension of vertebral column in lower thoracic area; draws ribs downward
- Innervation: Spinal nn.
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Iliocostalis Thoracis
- Erector Spinae
- Origin: By tendons from upper borders of angles of lower six ribs
- Insertion: Cranial borders of angles of upper six ribs and dorsum of transverse process of seventh cervical vertebra
- Action: Extension and lateral flexion of vertebral column in upper thoracic area; draws ribs downward
- Innervation: Spinal nn.
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Iliocostalis Cervicis
- Erector Spinae
- Origin: Angles of third through sixth ribs
- Insertion: Posterior tubercles of transverse processes of fourth through sixth cervical vertebrae
- Action: Extension of vertebral column in upper thoracic and lower cervical areas
- Innervation: Spinal nn.
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Longissimus Thoracis
- Erector Spinae
- Origin: In lumbar region, blended with iliocostalis lumborum posterior surfaces of transverse and accessory processes of lumbar vertebrae, and anterior layer of thoracolumbar fascia
- Insertion: By tendons into tips of transverse processes of all thoracic vertebrae and by leshy digitations into lower 9 or 10 ribs between tubercles and angles
- Action: Extension and lateral flexion of vertebral column in thoracic area; draws ribs downward
- Innervation: Spinal nn.
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Longissimus Cervicis
- Erector Spinae
- Origin: By tendons from transverse processes of upper four or five thoracic vertebrae
- Insertion: By tendons into posterior tubercles of transverse processes of second through sixth cervical vertebrae
- Action: Extension and lateral flexion of vertebral column in cervical area; draws ribs downward
- Innervation: Spinal nn.
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Longissimus Capitis
- Erector Spinae
- Origin: By tendons from transverse processes of upper four or five thoracic vertebrae and articular processes of lower three or four cervical vertebrae
- Insertion: Posterior margin of masoid process deep to splenius capitis and sternocleidomastoid
- Action: Extension, lateral flexion, ipsilateral rotation of cervical spine
- Innervation: Cervical nn.
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Spinalis Thoracis
- Erector Spinae
- Origin: By tendons from spinous processes of first two lumbar and last two thoracic vertebrae
- Insertion: Spinous processes of upper four to eight thoracic vertebrae
- Action: Extension of vertebral column in thoracic area
- Innervation: Spinal nn.
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Spinalis Cervicis
- Erector Spinae
- Origin: Ligamentum nuchae, lower part; spinous process of seventh cervical vertebra and, sometimes, from spinous process of first and second thoracic vertebrae
- Insertion: Spinous process of axis and, occasionally, into the spinous processes of C3 and 4
- Action: Extension of vertebral column in upper cervical area
- Innervation: Spinal nn.
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Spinalis Capitis
- Erector Spinae
- (Inseparably connected with Semispinalis Capitis)
- Origin: Tips of transverse processes of upper six or seven thoracic and seventh cervical vertebrae and articular processes of fourth through sixth cervical vertebrae
- Insertion: Between superior and inferior nuchal lines of occipital bone
- Action: Extension, contralateral rotation of neck
- Innervation: Spinal nn.
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Semispinalis Thoracis
- Transversospinalis, first layer
- Origin: Transverse processes of lower 6 to 10 thoracic vertebrae
- Insertion: By tendons into spinous processes of first four thoracic and last two cervical vertebrae
- Action: Extension, contralateral rotation of thoracic spine
- Innervation: Spinal nn.
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Semispinalis Cervicis
- Transversospinalis, first layer
- Origin: Transverse processes of upper five or six thoracic vertebrae
- Insertion: Cervical spinous processes of second through fifth cervical vertebrae
- Action: Extension , contralateral rotation of upper thoracic and cervical vertebrae
- Innervation: Spinal nn.
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Semispinalis Capitis
- Transversospinalis, first layer
- Origin: Tips of transverse processes of upper six or seven thoracic and seventh cervical vertebrae and articular processes of fourth through sixth cervical vertebrae
- Insertion: Between superior and inferior nuchal lines of occipital bone
- Action: Extension, contralateral rotation of neck
- Innervation: Spinal nn.
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Multifidi
- Transversospinalis, second layer
- Origin:
- Sacral Region - Posterior surface of sacrum, medial surface of posterior iliac spine and posteropsacroiliac ligaments
- Lumbar, thoracic, and cervical regions - Transverse processes of L5-C4
- Insertion: Spanning 2-4 vertebrae, inserted into spinous process of one of vertebra above from last lumbar to C2
- Action: Extension, contralateral rotation of vertebral column
- Innervation: Spinal nn.
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Rotatores
- Transversospinalis, third layer
- Origin: Transverse processes of vertebrae
- Insertion: Base of spinous process of vertebra above
- Action: Extension, contralateral rotation of vertebral column
- Innervation: Spinal nn.
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Interspinales
- Origin and Insertion: Placed in pairs between spinous processes of contiguous vertebrae. Cervical - 6 pairs; Thoracic - 2-3 pairs between 1st and 2nd, sometimes 2nd and 3rd, and 11th and 12th vertebrae; Lumbar - 4 pairs
- Action: Extension of vertebral column
- Innervation: Spinal nn.
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Intertransversarii Anterior and Posterior
- Origin and Insertion: Small muscles placed between transverse processes of contiguous vertebrae in cervical, thoracic, and lumbar regions
- Action: Lateral flexion of vertebral column
- Innervation: Spinal nn.
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Splenius Cervicis
- Origin: Spinous processes of third through sixth thoracic vertebrae
- Insertion: Posterior tubercles of transverse processes of first two or three cervical vertebrae
- Action: Extension, lateral flexion, ipsilateral rotation of neck
- Innervation: Cervical nn.
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Splenius Capitis
- Origin: Caudal 1/2 of ligamentum nuchae, spinous process of seventh cervical vertebrae, and spinous process of first three or four thoracic vertebrae
- Insertion: Occipital bone inferior to lateral 1/3 of superior nuchal line; mastoid process of temporal bone
- Action: Extension, lateral flexion, ipsilateral rotation of neck
- Innervation: Cervical nn.
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Rectus Abdominis
- Origin: Pubic crest and symphysis
- Insertion: Costal cartilages of fifth through seventh ribs and xiphoid process of sternum
- Action: Flexes the vertebral column by approximating the thorax and pelvis anteriorly
- Innervation: T5, 6, T7-11, T12, Ventral rami
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External Oblique, Anterior fibers
- Origin: External surfaces of ribs five through eight interdigitating with the serratus anterior
- Insertion: Into a braod, flat aponeurosis, terminating in the linea alba, wihich is a tendinous raphe that extends from the xiphoid
- Action: Acting bilaterally, the anterior fibers flex the vrtebral column, support and compress abdominal vixerca, depress the thorax and assist in respiration. Acing unilaterally (with anterior fibers of internal oblique on opposite side), anterior fibers create contralateral rotation of vertebral column
- Innervation: (T5, 6) T7-11, T12
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External Oblique, Lateral Fibers
- Origin: External surface of ninth rib, interdigitating with the serratus anterior; and external surfaces of the 10th through 12th ribs, interdigitating with the latissimus dorsi
- Insertion: As the inguinal ligament, into the anterosuperior spine and pubic tubercle and into the external lip of the anterior 1/2 of the iliac crest
- Action: Acting bilaterally, the lateral fibers flex the vertebral column with a major influence on the lumbar spine, tilting the pelvis posteriorly. Acting unilaterally (with lateral fibers of internal oblique on same side), these fibers laterally flex the vertebral column. Also act with internal oblique on opposite side to create contralateral rotation of the vertebral column.
- Innervation: (T5, 6) T7-11, T12
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Internal Oblique, Lower Anterior Fibers
- Origin: Lateral 2/3 of inguinal ligament and short attachment on iliac crest near the anterosuperior spine
- Insertion: With the transverse abdominis into crest of pubis, medial part of the pectineal line and into the linea alba by means of an aponeurosis
- Action: Compress and support abdominal viscera in conjunction with the transversus abdominis
- Innervation: T7, 8, T9-12, L1, Iliohypogastric and Ilioinguinal, Ventral rami
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Internal Oblique, Upper Anterior Fibers
- Origin: Anterior 1/3 of intermediate line of iliac crest
- Insertion: Linea alba by means of an aponeurosis
- Action: Acting bilaterally, flex vertebral column, support and compress abdominal viscera, depress the thorax and assist in respiration. Acting unilaterally (with anterior fibers of external oblique on opposite side), ipsilateral rotation of vertebral column.
- Innervation: T7, 8, T9-12, L1, Iliohypogastric and Ilioinguinal, Ventral rami
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Internal Oblique, Lateral Fibers
- Origin: Middle 1/3 of intermediate line of iliac crest and thoracolumbar fascia
- Insertion: Inferior borders of 10th through 12th ribs and linea alba by means of an aponeurosis
- Action: Acting bilaterally, flex vertebral column and depress thorax. Acting unilaterally (with lateral fibers of external oblique on same side), laterally flex vertebral column. Also act with external oblique on opposite side for ipsilateral rotation of vertebral column.
- Innervation: T7, 8, T9-12, L1, Iliohypogastric and Ilioinguinal, Ventral rami
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Trasnversus Abdominis
- Origin: Inner surfaces of cartilages of lower six ribs, interdigitating with the diaphragm; thoracolumbar fascia; anterior 3/4 of internal lip of the iliac crest; and lateral 1/3 of inguinal ligament
- Insertion: Linea alba by means of a braod aponeurosis, pubic crest, and pecten pubis
- Action: Acts like girdle to flatten abdominal wall and compress abdominal viscera; upper portion helps to decrease infrasternal angle of ribs, as in expiration; stabilizes linea alba, permitting better action by anterolateral trunk muscles.
- Innervation: T7-12, L1, iliohypogastric and ilioinguinal, ventral divisions
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Diaphragm
- Origin:
- Sternal part - Two fleshy slips from dorsum of xiphoid process
- Costal part - Inner surface of lower six costal cartilages and lower six ribs on either side, interdigitating with the transversus abdominis
- Lumbar part - By two muscular crura from the bodies of the upper lumbar vertebrae and by two fibrous arches on either side, known as the medial and lateral arcuate ligaments, which span from the vertebrae to the transverse processes and from the latter to the 12th rib
- Insertion: Into the central tendon, a thin, strong aponeurosis with no bony attachments, situated closer to ventral than dorsal part of thorax
- Action: Separates thoracic and abdominal cavities, is principal muscle of respiration. During inspiration, muscle contracts and dome descends, increasing the volume and decreasing pressure of thoracic cavity while decreasing volume and increasing pressure of thoracic cavity. Descent is limited by abdominal viscera; further contraction results in central tendon becoming origin and vertical fibers attached to ribs elevating and everting the costal margin. Expiration relaxes the muscle and reverses this process.
- Innervation: Phrenic: C3, 4, 5
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External Intercostals
- Origin: Lower borders of ribs
- Insertion: Upper borders of ribs below
- Action: Stabilize and maintain the shape and integrity of the rib cage, assist with inspiration and posture
- Innervation: Thoracic nn.
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Internal Intercostals
- Origin: Inner surfaces of ribs and costal cartilages
- Insertion: Upper borders of adjacent ribs below
- Action: Stabilize and maintain the shape and integrity of the rib cage, assist with expiration and posture
- Innervation: Thoracic nn.
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