MS anatomy: deep back and neck

this lecture covered the anatomy of the spine as well as the muscles of the deep back, head, and neck. the spine is made of 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae and a sacrum at the bottom which is made up of 5 fused vertebrae. notable differences between the three vertebral sections: cervical vertebrae have short, split spines, while thoracic vertebrae have long, downward sloping ones. lumbar vertebrae have extra processes next to the transverse processes called mamillary processes. range of movement is wide for cervical and lumbar sections but narrow for thoracic. the spine has two opposite curves, called kyphotic and lordotic. the sacrum and the thoracic spine are kyphotic, folding the body inwards, while the the lumbar and cervical spine have the lordotic curve which has the opposite shape.

some unique features about the top two vertebrae, the atlas (C1) and axis (C2). the atlas lacks a vertebral body and just has anterior and posterior arch. resting in the anterior arch, secured by the transverse ligament, is an upward protrusion from C2, called the "dens" of the axis, which is actually the fusion of the vertebral bodies of C1 and C2. the dens and the atlas form the atlanto-axis pivot joint and allow for rotational movement of the head. the joint between the atlas and the occiput is called the atlanto-occipital joint and is stabilized by a host of muscles that attach to the occiput around it (more to come) as well as the atlanto occipital membrane, a ligament that spans from the posterior occiput to the spinous process of C1. the joint itself is between the superior articular facets of the atlas and the condyles of the occiput.

we then look at the muscles of the back, neck, and head, starting with the muscles of the deep back. these include the erector spinae, the superficial and larger group of back muscles that span from the sacrum to the base of the skull. these include the spinalis, the longissimus, and the iliocostalis. the transversospinalis are a deeper and more intricate set of back muscles that lie in the groove between the transverse and spinous processes-- originating from transverse processes, inserting into spinous processes. the semispinalis covers the upper 1/3 of the spine and each muscle group has a span of 5-8 vertebrae, the multifidus is prominent near the sacrum and spans 3-4 vertebrae a piece, and the rotatores go all along the spine and cover 1-2 vertebrae each. in general, the erector spinae (the larger muscles) are more involved in extension and the transverospinalis muscles (smaller muscles) are more involved in lateral flexion and rotation.

the muscles that aid in movement of the head can be divided into three sections: suboccipital muscles, anterior neck muscles, and lateral neck muscles. suboccipital muscles include the rectus capitis posterior major and minor, and the inferior and superior oblique. for these muscles, when a muscle is oriented vertically, it is involved in extension, and when it is oriented diagonally or horizontally, it is involved in rotation. the anterior neck muscles include the rectus capitis anterior and longus colli and capitis. the lateral neck muscles are the scalenes and SCM. the suboccipital muscles are innervated by the posterior rami of C1, the anterior neck muscles are innervated by C1-4, and the lateral neck muscles are innervated by C2,3 and cranial nerve XI.


questions

vertebrae anatomy
1. spinous process is formed by...
2. transverse process is formed by...
3. mamillary processes...
4. vertebral canal is formed by...
5. zygapophyseal/facet joint is formed by...
6. what are the primary and secondary curves of the spine called?

cervical, thoracic, lumbar vertebrae:
7. body...
8. spines...
9. costotransverse foramen...
10. range of movement...
11. movements...

12. 5 sacral foramen fuse after...
13. sacral foarmina convey...
14. sacral promontory is...
15. what are the sacral crests and what are they made from?
16. sacral canal ends at...
17. what is the coccyx?

18. what is the sacralization of L5?
19. what is the lumbarization of S1?
20. what type of joint is the intervertebral joint?
21. describe the composition of the intervertebral joint.
22. what are the ligaments that support the intervertebral joints?
23. what is a herniated disc?
24. what type of joint is the facet joint?
25. supraspinous ligament...
26. interspinous ligament...
27. ligamentum flavum...

28. what are the anatomical features of C1?
29. what is unique about C2?
30. what is the atlanto-axis joint?
31. what is the transverse ligament?
32. alar and apical ligaments...
33. what is the atlanto-occipital joint and what movement does it allow?
34. what is the atlanto-occipital membrane penetrated by?

deep back muscles
35. what are the erector spinae muscles and where do they originate from?
36. spinalis...
37. longissimus...
38. iliocostalis...
39. what are the transverospinalis muscles?
40. semispinalis...
41. semispinalis capitis is...
42. multifidus...
43. rotatores...
44. what is the splenius and where do the two types attach?
45. describe the difference in action between the long and short deep back muscles.
46. what are deep back muscles innervated by?

suboccipital muscles- origins, insertions, actions
47. inferior oblique...
48. superior oblique...
49. rectus capitis posterior major...
50. rectus capitis posterior minor...
51. which nerve innervates the suboccipital muscles?

anterior neck muscles
52. rectus capitis anterior and lateralis...
53. longus colli and capitis...
54. which nerve innervates the anterior neck muscles?

lateral neck muscles
55. anterior scalenes...
56. posterior scalenes...
57. SCM...

58. flexion of head is mainly due to which muscles?
59. extension of head is mainly due to which muscles?

answers

1. fusion of two pedicles.
2. fusion of pedicles and laminae.
3. are on lumbar vertebrae and can be confused with transverse processes.
4. column of vertebral foramen and houses the spinal cord.
5. joining of superior and inferior articular facets.
6. primary = kyphotic in the thoracic spine and sacrum. secondary = lordotic in the cervical and lumbar spine.

7. oblong, heart shaped, oblong
8. short / bifid, long / downward sloping, intermediate / horizontal
9. transverse foramen, costotransverse, no foramen
10. wide, narrow, wide
11. flex/extend/abduct/some rotation, rotation, flex/extend/abduct/some rotation

12. 20 years
13. anterior and posterior rami of sacral nerves
14. prominent body of S1
15. median crest made from fused SP's, lateral crest from fused TVP's.
16. sacral hiatus
17. 4 small fused vertebrae at the bottom of the sacrum which serve as the origin for pelvic muscles and ligaments.

18. total or partial fusion of L5 to sacrum.
19. total or partial separation of S1 from sacrum.
20. symphysis joint.
21. outer layer is fibrous CT called annulus fibrosus, gelatinous center called nucleus pulposus.
22. anterior and posterior longitudinal ligaments.
23. when pressure between the vertebrae causes the nucleus pulposa to herniate out of the annulus fibrosus and potentially compress spinal nerves against the articular processes.
24. synovial joint.
25. joins tips of vertebral spines
26. spans between vertebral spines
27. elastic CT helps extend vertebral column

28. the "atlas" has an anterior and posterior arch and no vertebral body.
29. the "axis" has an upward protrusion called the "dens" which is the fusion of the bodies of the atlas and axis.
30. the joint that is formed by the dens and the anterior arch of the atlas which allows for the rotation of the head.
31. anchors the dens to the anterior arch.
32. anchor dens to margin of foramen magnum and limits rotational movement.
33. joint between the occipital condyles of the head and the superior articular facets of the atlas. permits flexion and extension of head.
34. C1, vertebral artery.

35. iliac crest and sacrum.
36. interconnects thoracic spinous processes.
37. runs along costovertebral region, also has a capitis portion.
38. goes from iliac crest to ribs.
39. semispinalis, multifidus, rotatores- muscles that span from sacrum to base of skull. lie within groove between transverse and spinous processes and go from TP's to SP's.
40. semispinalis spans 5-8 vertebrae, are in the upper 1/2 of vertebral column.
41. strongest extensor of the skull.
42. spans 3-4 vertebrae, thickest over sacrum
43. span 1-2 vertebrae throughout spine.

44. muscle that goes from spinous processes to TP's or to skull. capitis attaches to mastoid process, cervicis attaches to TP's.
45. long deep back muscles more extension, short deep back muscles more rotation and lateral flexion.
46. posterior rami of spinal nerves.

47. O: spine of axis I: TP of axis A: rotate
48. O: TP of axis I: occiput A: extend
49. O: spine of axis I: occiput A: extend and rotate
50. O: posterior tubercle of atlas I: occiput A: extend
51. posterior ramus of C1

52. O: TP of atlas I: occiput A: flexion and lateral flexion and stabilization of altantoocciptal joint.
53. O: body and TP's of cervical vertebrae I: same, plus occiput A: flexion
54. C1-4

55. O: upper TP's I: 1st rib A: flexion of head, raise ribs N: lower cervical nerves
56. O: upper TP's I: 2nd rib A: flexion of head, raise ribs N: lower cervical nerves
57. O: manubrium, clavicle I: mastoid process A: flexion, lateral flexion, rotation, raise ribs N: motor-spinal accessory (cranial nerve XI), C2,3

58. SCM, rectus capitis anterior, longus capitis / colli
59. trapezius, rectus capitis posterior, superior oblique