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Superficial muscles related to the upper limb
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Trapezius (m. trapezius /трапециевидная мышца)
· Origin. From the superior nuchal line, the ligamentum nuchae and the spines of all the thoracic vertebrae.
· Insertion. Into the spine of the scapula, the lateral edge of the acromion and the lateral third of the clavicle.
· Actions. Fxtends the head on looking upwards, raises the tips of the shoulders, braces the shoulders back, and helps serratus anterior to rotate the scapula during abduction of the arm.
· Nerve supply. Spinal accessory nerve.
Latissimus dorsi (m. latissimus dorsi /широчайшая мышца спины)
· Origin. From the spines of the lower six thoracic vertebrae, the lumbar spines via the thoracolumbar fascia and the medial part of the iliac crest.
· Insertion. To the floor of the intertubercular sulcus. curving round teres major.
· Actions. Adduction and medial rotation of the arm. Can hold up the lower limb girdle as in crutch walking.
Nerve supply. Thoracodorsal nerve.
Levator scapulae (m. levator scapulae /мышца, поднимающая лопатку)
· Origin. From the transverse processes of the upper cervical vertebrae.
· Insertion. To the medial border of the scapula above the spine.
· Action. Elevates the scapula.
· Nerve supply. C3 and 4.
Rhomboids (mm. rhomboidei /ромбовидные мышцы)
· Origin. From spines of thoracic vertebrae.
· Insertion. To the medial border of the scapula.
· Action. Bracing back the scapula.
· Nerve supply. Dorsal scapular nerve.
Superficial muscles related to the ribs
Serratus posterior superior (m. serratus posterior superior /верхняя задняя зубчатая мышца)
· Origin. From the spinous processes of the lower two cervical and upper two thoracic vertebrae.
· Insertion. The posterior surface of the 2-5 ribs laterally of their angles.
· Actions. Raises the ribs.
· Nerve supply. Intercostal nerves (Th1-4).
Serratus posterior inferior (m. serratus posterior inferior /нижняя задняя зубчатая мышца)
· Origin. From the thoracolumbal fascia in the region of the spinous processes of the lower two thoracic and upper two lumbar vertebrae.
· Insertion. The posterior surface of the 9-12 ribs.
· Actions. Pulls the ribs downwards.
· Nerve supply. Intercostal nerves (Th9-12).
The deep (autochtonous) muscles
· The autochtonous muscles of the back form on each side two longitudinal (lateral and medial) muscular tracts which are lodged in the groove between the vertebral columne and the angles of the ribs.
· In the deep parts, nearest to the skeleton, they are made up of short muscles arranged in segments between the vertebrae (medial tract); the long muscles are closer to the surface (lateral tract).
· In addition the splenius muscles cover both tracts in the posterior cervical region.
Splenius capitis and splenius cervicis (mm. splenius capitis et cervicis /ременная мышца головы, шеи)
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· Origin. From the spinous processes of the lower five and the upper thoracic six vertebrae.
· Insertion. Splenius capitis to the superior nuschal line and mastoid process, the splenius cervicis to the transverse processes of the 2-3 cervical vertebrae.
· Actions. In contraction of one muscle the head turns in its direction; bilateral contraction bends the head and neck backwards.
Lateral tract
This muscle is attached to the vertebral transverse processes and the ribs or their rudiments.
Erector spinae (m. erector spine /мышца, выпрямляющая позвоночник)
· Origin. From the sacrum, spinous processes of the lumbar vertebrae, iliac crest and the thoracolumbar fascia and extends to the skull.
· Insertion. It forms three divisions according to the insertion
- The lateral division is iliocostalis (m. iliocostalis /подвдошно-рёберная мышца). It is attached to the transverse processes of the lumbar and cervical vertebrae and the angles of the ribs.
- The intermediate division is longissimus (m. longissimus /длиннейшая мышца). It is attached to the transverse processes of the thoracic and cervical vertebrae, the ribs and the mastoid process.
- The medial division is spinalis (m. spinalis /остистая мышца). It is attached to the spinous processes of the thoracic and cervical vertebrae.
Intertransversarii (mm. intertransversarii /межпоперечные мышцы)
They pass between the transverse processes of two adjacent vertebrae and related to the lateral tract.
Medial tract
Transversospinales (mm. transversospinales /поперечно-остистые мышцы)
The muscle extends from the sacrum to the occipital bone.
· Origin. From the transverse processes of the vertebrae.
· Insertion. To the spinous processes of the vertebra above.
· It has three layers that are distinguished by their depth and by the mumber of vertebrae they overlap:
- The superficial layer is semispinalis (m. semispinalis /полуостистая мышца). Its bundles overlap 5-6 vertebrae.
- The middle layer is multifidus (mm. multifidi /многораздельные мышцы). Their bundles overlap 3-4 vertebrae.
- The deep layer is rotatores (mm. rotatores /мышцы-вращатели). Their bundles overlap 1-2 vertebrae.
Interspinales (mm. interspinales /межостистые мышцы)
They pass between the spinous processes of adjacent vertebrae and related to the medial tract.
Suboccipital muscles
Obliquus capitis superior (m. obliquus capitis superior /верхняя косая мышца головы)
· Origin. The transverse process of the atlas.
· Insertion. The inferior nuchal line.
Obliquus capitis inferior (m. obliquus capitis inferior /нижняя косая мышца головы)
· Origin. The spinous process of the axis.
· Insertion. The transverse process of the atlas.
Rectus capitis posterior major (rectus capitis posterior major /большая задняя прямая мышца головы)
· Origin. The spinous process of the axis.
· Insertion. The inferior nuchal line.
Rectus capitis posterior minor (rectus capitis posterior minor /малая задняя прямая мышца головы)
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· Origin. The posterior tubercle of the atlas.
· Insertion. The inferior nuchal line.
Action of deep muscles consists in holding the trunk erect.
- Contraction of all parts of these muscles on both sides effects general extension of the spine, while contraction of separate parts effects extension between the separate vertebrae.
- Contraction of these muscles on one side causes lateral flexion of the spine and the trunk to this side.
- The multifundi and rotatores accomplish rotation of the spine.
- The muscles take part in the respiratory excursions. The upper part of iliocostal muscle raises ribs, while its lower part lowers them.
- The erector spinae contracts also in flexion of the trunk to counteract the backward pull of gravitational force.
Actions of suboccipital muscles. Contraction of the muscles on one side contributes to turning of the head to the corresponding side. Bilateral contraction pulls the head backwards.
Nerve supply of the deep muscles. The posterior branches of the spinal nerves (cervical, thoracic and lumbar).
Fasciae of the back
The superficial fascia covers the uoter surface of the trapezius and latissimus dorsi.
The thoracolumbar fascia (fascia thoracolumbalis /пояснично-грудная фасция) has two layer.
· The superficial layer:
- It separates the deep muscles of the back from the muscles lying more superficially.
- It stretches from pelvis to the head.
- This layer is attached to the spinous processes medially and continuous with the ribs laterally.
- Its lower part is continuous with the aponeurosis of the latissimus dorsi.
· The deep layer:
- It originates from the transverse processes of the lumbar vertebrae and stretches only between the twelfth rib and the iliac crest.
- The deep layer covers the anterior surface of the erector spinae and on the lateral border of this muscle fuses with the superficial layer.
The deep muscles are thus invested in an osteofibrous sheath, with the initial part of the erector spinae being enclosed in a fibrous sheath.
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