Muscles of the back Flashcards
What are the 2 major groups of muscles in the back and what muscles compose these? What are the main functions of each group?
Extrinsic: superficial and intermediate muscles (produce and control limb and respiratory movements)
Intrinsic: deep back muscles (act on vertebral column, produce movements and maintain posture)
Which muscles compose the superficial extrinsic back muscle group?
Trapezius, latissimus dorsi, levator scapulae, and rhomboids; they attach the upper limbs to the trunk
What is the innervation of the extrinsic back muscles?
Anterior rami of cervical nerves; act on the upper limb
- Trapezius receives its motor fibers from the spinal accessory nerve (CNXI)
Which muscles compose the intermediate extrinsic back muscle group?
Serratus posterior superior and inferior; designated superficial respiratory muscles but are more likely proprioceptive rather than motor in function
Extension of intrinsic back muscles
From pelvis to cranium
Where does the deep fascia that encloses the intrinsic back muscles attach?
- Medially to the nuchal ligament
- Tips of spinous processes
- Supraspinous ligament, and median crest of sacrum
-Laterally to the cervical and lumbar transverse `processes and to the angle of the ribs
How are the deep back muscles grouped?
Superficial, intermediate, and deep layers (according to relationship to their surface)
Which muscles constitute the superficial layer of intrinsic back muscles?
Splenius muscles
What is the extension of the splenii muscles?
Midline and extend superolaterally to the cervical vertebrae and cranium
What types of splenii muscles are there and how can we differentiate them?
Cervicis and capitis; we can tell them apart, based on where they attach
Where are the splenius muscles located?
Lie on the lateral and posterior aspects of the neck, covering the vertical muscles (bandage)
Which muscles constitute the intermediate layer of the intrinsic back muscles?
Erector spinae muscles
Where are the erector spinae muscles located?
Lie in a groove on each side of the vertebral column, between spinous processes and the angles of the ribs
What is the erector spinae and how is this divided?
Chief extensor of the VC, divides into 3 muscle columns:
- Iliocostalis: lateral column
- Longissimus: intemediate column
- Spinalis: medial column
How are the columns of the erector spinae divided?
Divided regionally into 3 parts, named depending on their superior attachments.
- Lumborum, thoracis, and cervicis
What is the common origin of the three erector spinae columns?
Arise from a broad tendon that attaches inferiorly to:
- Posterior part of the iliac crest
- Posterior aspect of the sacrum
- Sacro-iliac ligaments
- Sacral and inferior lumbar spinous processes
- Supraspinous ligament
What is the origin of the splenius muscles?
Arises from nuchal ligament and spinous processes of C7-T6 vertebrae
What is the insertion of the splenius capitis?
Fibers run superolaterally to mastoid process of temporal bone and lateral third of superior nuchal line of occipital
What is the insertion of the splenius cervicis?
Tubercles of transverse processes of C1-C3 or C4 vertebrae
What is the nerve supply of the splenius muscles?
Posterior rami of spinal nerves
What are the main actions of the splenius muscles?
Acting alone: laterally flexes neck and rotates head to side of active muscles
Acting together: extend head and neck
What is the insertion of the iliocostalis (lumborum, thoracis, and cervicis) of the erector spinae?
Fibers run superiorly to angles of lower ribs and cervical tranverse processes
What is the insertion of the longissimus (lumborum, thoracis, and capitis) of the erector spinae?
Fibers run superiorly to ribs between tubercles and angles to transverse processes in thoracic and cervical regions and mastoid process of temporal
What is the insertion of the spinalis muscles (thoracis, cervicis, and capitis) of the erector spinae?
Fibers run superiorly to spinous processes in upper thoracic region and cranium
What is the nerve nerve supply of the three columns that compose the erector spinae?
Posterior rami of spinal nerves
What are the main functions of the columns of the erector spinae?
Acting bilaterally: extend vertebral column and head; as back is flexed, control movement by gradually lengthening their fibers
Acting unilaterally: laterally flex vertebral column
Which muscles constitute the deep layer of the intrinsic back muscles?
Transversospinales muscle group
The transversospinales muscle group is composed of…
Semispinalis, multifidus, and rotatores
Where are the transversospinales muscle group located?
Deep to erector spinae; these obliquely disposed group of muscles, ocuppy the “gutter” between the transverse and spinous processes; these originate from transverse processes and pass to spinous processes of more superior vertebrae
Where are the semispinalis, multifidus, and rotatores located in relation to the other?
Semispinalis: superficial
Multifidus: intermediate
Rotatores: deepest
How many parts are the semispinalis divided into? Name them
Three parts; according to vertebral level of its superior attachments
Capitis, thoracis, and cervicis
Where are the semispinalis capitis located? What is their extension?
This form the longitudinal bulge on each side in the back of the neck near the median plane
- Extension: ascend from cervical and thoracic transverse processes to the occipital bone
What is the extension of the semispinalis thoracis and cervicis?
Pass superomedially from the transverse processes to the thoracic and cervical spinous processes of superior vertebrae
What are the characteristics of the multifidus muscles?
- Short, triangular muscular bundles
- Thickest in lumbar region
- Each bundle passes obliquely, superiorly, and medially and attaches along the whole length of the spinous process of adjacent superior vertebra
What are the characteristics of the rotatores?
- Best developed in thoracic region
- Deepest of three layers of transversospinales muscles
- Arise from transverse process of one vertebra and insert into the root of spinous processes of the next one or two vertebrae superiorly
Which are the smallest deep back muscles?
Interspinales (connect spinous), intertransversarii (connect transverse), and levatores costarum
What is the origin of the semispinalis muscles?
Arise from transverse processes of C4-T10
What is the insertion of the semispinalis muscles?
Fibers run superomedially to occipiral bone and spinous processesin upper thoracic and cervical regions, spanning 4-6 segments
What is the nerve supply of the semispinalis muscles?
Posterior rami of spinal nerves
What are the main actions of the semispinalis?
Extends head and thoracic and cervical regions of vertebral column and rotates them contralaterally
What is the origin of the multifidius?
Arises from:
- Posterior sacrum
- Posterior superior iliac spine of ilium
- Aponeurosis of erector spinae
- Sacro-iliac ligaments
- Mammillary processes of lumbar vertebrae
- Transverse processes of thoracic vertebrae
- Articular processes of C4-C7
What is the insertion of the multifidius?
Fibers pass obliquely superomedially to entire length of spinous processes of vertebrae located 2 - 4 segments superior to origin
What is the nerve supply of the multifidus?
Posterior rami of spinal nerves
What are the main actions of multifidus?
Unilateral contraction rotates to contralateral side; stabilizes vertebrae during local movements of the vertebral column
What is the origin of the rotatores (brevis and longus)?
Arise from transverse proceses of vertebrae
What is the insertion of the rotatores?
Fibers pass superomedially to attach to junction of lamina and transverse process or spinous process of vertebra immediately (brevis) or 2 segments (longus) superior to the vertebra of origin
What is the nerve supply of the rotatores?
Posterior rami of spinal nerves
What are the main actions of the rotatores?
Mainly act as organs of proprioception; possible stabilize vertebrae and assist with local extension and rotatory movements of vertebral column
What does sensors of proprioception refer to?
Sense of one’s position
What is the suboccipital region?
Superior part of the back of the neck; the triangular are inferior to the occipital region of the head, including posterior aspects of C1 and 2
Where is the suboccipital region located?
Loes deep to the trapezius and semispinalis capitis muscles
Which muscles can be found in the suboccipital region?
Rectus capitis posterior major and minor and obliquus capitis superior and inferior
What is the nerve supply for the 4 muscles in the suboccipital region?
Posterior ramus of C1 (suboccipital nerve)
What is the origin of the rectus capitis posterior major?
Arises from the spinous process of C2
What is the insertion of the rectus capitis posterior major?
Lateral part of the inferior nuchal line of occipital
What is the origin of the rectus capitis posterior minor?
Arises from posterior tubercle on the posterior arch of the C1
What is the insertion of the rectus capitis posterior minor?
Medial third of the inferior nuchal line
What is the origin of the obliquus capitis inferior?
Arises from the spinous process of C2
What is the insertion of the obliquus capitis inferior?
Transverse process of C1
What is the origin of the obliquus capitis superior?
Arises from the transverse process of C1
What is the insertion of the obliquus capitis superior?
Occipital bone beterrn the superior and inferior nuchal lines
What are the boundaries of the suboccipital region?
Superomedially: rectus capitis posterior major
Superolaterally: obliquus capitis superior
Inferolaterally: obliquus capitis inferior
Floor: posterior atlanto-occipital membrane and posterior arch of C1
Roof: semispinalis capitis
What are the main functions of the suboccipital group of muscles?
Extend the head on C1 and rotate the head and the C1 on C2
What are the movements that can be produced at the cervical intervertebral joints?
Flexion, extension, lateral bending, rotation
Which are the principal muscles producing “flexion” of the cervical intervertebral joints?
Bilateral action of:
- Longus colli
- Scalene
- Sternocleidomastoid
Which are the principal structures limiting/opposing “flexion” of the cervical intervertebral joints?
Ligaments
- Posterior atlanto-axial
- Posterior longitudinal
- Ligamenta flava
- Tectorial membrane
Posterior neck nuscles
Anulus fibrosus (tension posteriorly)
Which are the principal muscles producing “extension” of the cervical intervertebral joints?
Bilateral action of deep neck muscles
- Semispinalis cervicis and iliocostalis cervicis
- Splenius cervicis and levator scapulae
- Splenius capitis
- Multifidus
- Longissimus capitis
- Semispinalis capitis
- Trapezius
Which are the principal structures limiting/opposing “extension” of the cervical intervertebral joints?
Ligaments
- Anterior longitudinal ligament
- Anterior atlanto-axial
Anterior neck muscles
Anulus fibrosus (tension anteriorly)
Spinous processes (contact between adjacent processes)
Which are the principle muscles producing “lateral bending” of the cervical intervertebral joints?
Unilateral action of:
- Iliocostalis cervicis
- Longissimus capitis and cervicis
- Splenius capitis
- Splenius cervicis
- Intertransversarii and scalenes
Which are the main structures limiting/opposing movement of the cervical interverteral joints
Ligaments
- Alar ligaments tension limits movement to contralateral side
Anulus fibrosus (tension anteriorly)
Zygapophysial (facet) joints
Which are the principle muscles producing “rotation” of the cervical intervertebral joints?
Ipsilateral action of:
- Rotatores
- Semispinalis capitis and cervicis
- Multifidus
- Splenius cervicis
Contralateral action of
- Sternocleidomastoid
Which are the main structures limiting/opposing movement of the cervical intevertebral joints?
Ligaments
- Alar ligaments tension limits movement to ipsilateral side
Anulus fibrosus
What are the movements that can be produced at the thoracic and lumbar intervertebral joints?
Flexion, extension, lateral bending, and rotation
Which are the principle muscles that produce “flexion” of the thoracic and lumbar intervertebral joints?
Bilateral action of:
- Rectus abdominis
- Psoas major
- Gravity
Which are the principle structures limiting/opposing “flexion” of the thoracic and lumbar intervertebral joints?
Ligaments
- Supraspinous
- Interspinous
- Ligamenta flava
Capsule of zygapophysial (facet) joints
Extensor muscles
Vertebral bodies (apposition anteriorly)
IV disc (compression anteriorly)
Annulus fibrosus (tension posteriorly)
Which are the principle muscles that produce “extension” of the thoracic and lumbar intervertebral joints?
Bilateral action of:
- Erector spinae
- Multifidus
- Semispinalis thoracis
Which are the principle structures limiting/opposing “extension” of the thoracic and lumbar intervertebral joints?
Ligaments
- Anterior longitudinal ligament
Capsule of zygapophysial joints
Abdominal muscles
Spinous processes (contact between adjacent processes)
Anulus fibrosus (tension anteriorly)
IV discs (compression posteriorly)
Which are the principle muscles that produce “lateral bending” of the thoracic and lumbar intervertebral joints?
Unilateral action of:
- Iliocostalis thoracis and lumborum
- Longissimus thoracis
- Multifidus
- External and internal oblique
- Quadratus lumborum
- Rhomboids
- Serratus anterior
Which are the principle structures limiting/opposing “lateral bending” of the thoracic and lumbar intervertebral joints?
Ligaments
- Contralateral side
Contralateral muscles that laterally bend trunk
Contact between iliac crest and thorax
Anulus fibrosus (tension of contralateral fibers)
IV discs (compression ipsilaterally)
Which are the principle muscles that produce “rotation” of the thoracic and lumbar intervertebral joints?
Unilateral action of:
- Rotatores
- Multifidus
- Iliocostalis
-Longissimus
- External oblique acting synchronously with opposite internal oblique
- Splenius thoracis
Which are the principle structures limiting/opposing “rotation” of the thoracic and lumbar intervertebral joints?
Ligaments
- Costovertebral
Ipsilateral external oblique, contralateral internal oblique
Articular facets (apposition)
Anulus fibrosus
Which are the principle muscles that produce “flexion” of the atlanto-occipital joint?
- Longus capitis
- Rectus capitis anterior
- Anterior fibers of sternochleidomastoid
- Suprahyoid and infrahyoid muscles
Which are the principle muscles that produce “extension” of the atlanto-occipital joint?
- Rectus capitis posterior major and minor
- Obliquus capitis superior
- Splenius capitis
- Longissimus capitis
- Trapezius (ascending part)
Which are the principle muscles that produce “lateral bending” of the atlanto-occipital joint?
- Sternocleidomastoid
- Rectus capitis lateralis
- Longissimus capitis
- Splenius capitis
Which are the principle muscles that produce “rotation” of the atlanto-axial joint?
Right:
- Sternocleidomastoid
- Semispinalis capitis
Left:
- Obliquus capitis inerior
- Rectus capitis posterior, major and minor
- Longissumus capitis
- Splenius capitis
