The document describes the various muscles of the back, thoracic wall, abdominal wall, and pelvic wall. It discusses the superficial and deep back muscles, including their origins, insertions, innervations, and actions. It also details the external and internal intercostal muscles of the thoracic wall, as well as the abdominal wall muscles like the external oblique, internal oblique, transversus abdominis, rectus abdominis, and pyramidalis. Finally, it briefly outlines some of the posterior abdominal wall and pelvic wall muscles.

1. Muscles of body wall
Muscles of the back
Muscles of thoracic wall
Muscles of abdominal wall
Muscles of pelvic wall
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2. Muscles of the back
• There are two major groups of muscles in the back:
 The extrinsic back muscles include:
 Superficial muscles that produce and control limb movement
 Intermediate back muscles: produce & control respiratory
movements
The intrinsic (deep) back muscles include muscles that specifically act
on the vertebral column, producing its movements and maintaining
posture.
2

3. Superficial group of back muscles
• The muscles in the superficial group are
immediately deep to the skin and superficial
fascia.
• They attach the superior part of the appendicular
skeleton (clavicle, scapula, and humerus) to the
axial skeleton (skull, ribs, and vertebral column).
• Because these muscles are primarily involved
with movements of this part of the appendicular
skeleton, they are sometimes referred to as the
appendicular group.
3

4. Trapezius: is flat and triangularly shaped muscle
 Origin- skull and upper portion of the vertebral
column
 Insertion-attach to the lateral third of the clavicle
and to the acromion of the scapula
 Innervation- the spinal accessory nerve (CN
XI).
 Action-assists in rotating the scapula during
abduction of humerus; upper fibers elevate,
middle fibers adduct, and lower fibers depress
scapula 4

5. As a result, movements associated with this
muscle include extension, adduction, and
medial rotation of the upper limb.
• Latissimus dorsi can also depress the shoulder,
preventing its upward movement
• The thoracodorsal nerve innervates the
latissimus dorsi muscle
5
Latissimus dorsi: is a large, flat triangular muscle that
attaches the back and to the humerus

6. • It elevates the scapula and may assist
other muscles in rotating the scapula
inferiorly
• Innervation; from the anterior rami
of spinal nerves C3, C4 and the dorsal
scapular nerve
6
Levator scapulae; descends from the transverse processes
of the upper cervical vertebrae to the upper portion of the
scapula.

7. Rhomboid minor and major are inferior to
levator scapulae .
 arises from the ligamentum nuchae of the neck
and the spinous processes of vertebrae CVII & TI
and attaches to the medial scapular border
 The two rhomboid muscles work together to
retract or pull the scapula toward.
• Innervation- dorsal scapular nerve,
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8. Intrinsic Back Muscles
• The intrinsic back muscles (muscles of back proper, deep back
muscles) are innervated by the posterior rami of spinal nerves and
act to maintain posture and control movements of the vertebral
column.
• The intrinsic back muscles are grouped into superficial,
intermediate, and deep layers according to their relationship to the
surface.
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9. Superficial layer of intrinsic back muscles
• The splenius muscles are thick and
flat and lie on the lateral and
posterior aspects of the neck
• The splenii arise from the midline
and extend superolaterally to the
cervical vertebrae (splenius
cervicis) and cranium (splenius
capitis)
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10. Intermediate layer of intrinsic back muscles
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The erector spinae muscles lie
in a groove on each side of the
vertebral column centrally and the
angles of the ribs laterally.
 The iliocostalis forms the
lateral column, the longissimus
forms the intermediate column,
and the spinalis forms the
medial column.

11. Deep layer of intrinsic back muscles
• Deep to the erector spinae is an obliquely disposed group of
much shorter muscles called the transversospinal muscle
group, consisting of the semispinalis, multifidus, and rotators
• These muscles originate from transverse processes of
vertebrae & pass to spinous processes of more superior
vertebrae
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12. Deep layer of intrinsic back muscles,,,
Semispinalis
• the superficial member of the group
• as its name indicates, it arises from approximately half of the vertebral
column (spine)
• it is divided into three parts according to the superior attachments:
semispinalis capitis, semispinalis thoracis, and semispinalis cervicis
Multifidus
• the middle layer of the group
• consists of short, triangular muscular bundles that are thickest in the lumbar
region
Rotatores, or rotator muscles
• the deepest of the three layers of transversospinal muscles
• best developed in the thoracic region 12

13. 13
Deep layer of intrinsic back muscles,,,

14. Principal muscles producing movement of cervical intervertebral joints
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15. Principal muscles producing movements of thoracic and lumbar intervertebral joints.
15

16. 16
Principal muscles producing movements of thoracic and lumbar intervertebral joints.

17. Muscles of thoracic wall
Pectoralis major and pectoralis minor.
Subclavius.
Serratus anterior muscles anteriorly.
Latissimus dorsi muscles posteriorly.
Anterolateral abdominal muscles and.
Some back and neck muscles. 17
 Several upper limb (thoracoappendicular) muscles attach to the thoracic
cage – including:

18. Muscles of thoracic wall,,,
 Axio-appendicular, neck &
anterolateral abdominal muscles
overlying thoracic wall.
 Muscles act primarily on the upper
limbs
 The pectoralis major has been
removed on the left side to expose
the pectoralis minor, subclavius, and
external intercostal muscles.
18

19. Intercostal muscles
The Extercostal muscles occupy the
intercostal spaces.
Originate from the inferior border of one
rib, course infero-medially and insert to
the superior border of the immediate rib
below.
Anteriorly, the muscle fibers are replaced
by the external intercostal membranes at
the costochondral junctions.
19

20. Intercostal muscles,,,
Intercostal muscles 20

21. Intercostal muscles,,,
The internal intercostal muscles
(11 pairs) run deep to and at right
angles to the external
intercostals.
Their fibers run inferoposteriorly
from the floors of the costal
grooves to the superior borders of
the ribs inferior to them.
21

22. Intercostal muscles,,,
 Between the ribs posteriorly,
medial to the angles, the internal
intercostals are replaced by the
internal intercostal
membranes.
 The external intercostals are
most active during inspiration.
 The internal intercostals are
most active during expiration
22

23. Intercostal muscles,,,
The innermost intercostal muscles are
similar to the internal intercostals.
The innermost intercostal muscle forms the
deepest layer
The innermost intercostals are separated
from the internal intercostals by intercostal
nerves and vessels.
Actions innermost intercostals are the
same as those of the internal intercostal
muscles.
23

24. Intercostal muscles,,,
The subcostal muscles are variable in size
and shape, usually being well developed
only in the lower thoracic wall..
 They extend from the internal surfaces of
one rib to the internal surface of the second
(next) or third rib below.
Crossing one or two intercostal spaces, the
subcostals run in the same direction as the
internal intercostals and blend with them. 24

25. Muscles of anterolateral abdominal wall
• There are five (bilaterally paired)muscles in the anterolateral group
of abdominal wall muscles:
The 3 flat muscles are; external oblique, internal oblique, and
transversus abdominis muscles
Two vertical muscles, near the midline, which are enclosed within a
tendinous sheath formed by the aponeuroses of the flat muscles-
Rectus abdominus and pyramidalis
25

26. • All three flat muscles are continued anteriorly and
medially as strong, sheet-like aponeuroses.
• B/n the midclavicular line & the midline, the
aponeuroses form the tough, aponeurotic, tendinous
rectus sheath enclosing the rectus abdominis
muscle
• The aponeuroses then interweave with their
fellows of the opposite side, forming a midline
raphe the linea alba which extends from the
xiphoid process to the pubic symphysis.
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27. External oblique muscle
• The external oblique muscle is the largest &
most superficial of the 3 flat anterolateral
abdominal muscles
• Its muscle fibers pass in an inferomedial
direction,
• The aponeuroses then interweave with their
fellows of the opposite side, forming a midline
raphe, the linea alba
27

28. External oblique muscle,,,
• Origin: Muscular slips from the outer surfaces of the lower
8 ribs(5th–12th ribs)
• Insertion: Lateral lip of iliac crest; aponeurosis ending in
midline (linea alba),pubic tubercle
• Nerve supply: Thoraco-abdominal nerves (T7–T11 spinal
nerves) and subcostal nerve
• Main Action: Compress abdominal contents; both muscles
flex trunk; each muscle bends trunk to same side, turning
anterior part of abdomen to opposite side
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29. Internal oblique muscle
• The intermediate of the three flat abdominal muscles.
• Its fleshy fibers run perpendicular to those of the
external oblique, running superomedially
• Origin: Thoracolumbar fascia; iliac crest & lateral
2/3rd of inguinal ligament
• Insertion: Inferior border of the lower three or four
ribs; linea alba; pubic crest
• Nerve supply: anterior rami of T6–T12 and first
lumbar nerves
• Main Action: Compress abdominal contents; both
muscles flex trunk; each muscle bends trunk 29

30. Transversus abdominis muscle
• The innermost of the 3 flat abdominal
muscles
• Its fibers run transversally, except for the
inferior ones.
• This muscle is ideal for compressing the
abdominal contents, increasing intra-
abdominal pressure.
• B/n the internal oblique & the transversus
abdominis muscles is a neurovascular plane,
30

31. Origin: Thoracolumbar fascia; medial lip of iliac
crest; lateral one-third of inguinal ligament;
internal surfaces of 7th–12th costal cartilages,
Insertion: Aponeurosis ending in linea alba; pubic
crest and pectineal line via conjoint tendon
Nerve supply: Thoraco-abdominal nerves
(anterior rami of T6–T12 spinal nerves) and first
lumbar nerves
• Main action: Compresses and supports
abdominal viscera 31

32. 32

33. Rectus abdominis muscle
• A long, broad, strap-like muscle, the rectus
abdominis is the principal vertical muscle
• Is a paired muscle, separated by the linea alba
• The rectus abdominis is 3 times as wide
superiorly as inferiorly; it is broad and thin
superiorly and narrow and thick inferiorly..
• Most of the rectus abdominis is enclosed in the
rectus sheath.
• Along its course, it is intersected by 3 or 4
transverse fibrous bands or tendinous
intersections
33

34. Origin: Pubic crest, pubic tubercle, and
pubic symphysis
Insertion: Xiphoid process and 5th– 7th
costal cartilages
• Nerve supply:
• Anterior rami of lower seven thoracic
spinal nerves (T7 to T12)
Main Action: Compress abdominal
contents; flex vertebral column; tense
abdominal wall
34

35. Pyramidalis muscle
• Is small, triangular-shaped muscle
• Which may be absent in some individuals
• Is anterior to the rectus abdominis
• Has its base on the pubis, and its apex is
attached superiorly and medially to the linea
alba
• Origin: Front of pubis and pubic symphysis
• Insertion: Into linea alba
• Nerve supply: Anterior ramus of T12
• Action: Tenses the linea alba
35

36. Muscles of anterolateral abdominal wall,,,
D. Anterior View E. Lateral View
36

37. Functions and actions of anterolateral abdominal muscles
 Form a strong expandable support for the anterolateral abdominal wall.
 Support the abdominal viscera & protect them from injuries.
 Compress the abdominal contents to maintain/increase the intra-
abdominal pressure & in so doing, oppose the diaphragm
 Move the trunk and help to maintain posture.
37

38. Posterior abdominal wall muscles
Muscles of Posterior abdominal wall
includes:
 The psoas(minor & major)
 Quadratus lumborum
 Iliacus
 Transversus abdominis
 Oblique muscles (laterally).
38

39. Psoas major and minor
• Medially, the psoas major muscles cover the anterolateral surface of the
bodies of the lumbar vertebrae, filling in the space between the vertebral
bodies and the transverse processes
• Each of these muscles arises from the bodies of vertebra TXII and all five
lumbar vertebrae, from the intervertebral discs between each vertebra, and
from the transverse processes of the lumbar vertebrae
• Passing inferiorly along the pelvic brim, each muscle continues into the
anterior thigh, under the inguinal ligament, to attach to the lesser trochanter
of the femur 39

40. Quadratus lumborum
Laterally, the quadratus lumborum muscles fill the space between
ribs XII and the iliac crest on both sides of the vertebral column
They are overlapped medially by the psoas major muscles; along
their lateral borders are the transversus abdominis muscles
The quadratus lumborum muscles arise from the transverse process
of vertebra LV, the iliolumbar ligament, and the adjoining part of
the iliac crest
40

41. Quadratus lumborum,,,
• The quadratus lumborum muscles depress
and stabilize rib XII and contribute to lateral
bending of the trunk. Acting together, the
muscles may extend the lumbar part of the
vertebral column
• They are innervated by anterior rami of T12
and L1 to L4 spinal nerves
41

42. Diaphragm
• The diaphragm is a double-domed musculotendinous sheet, located at the
inferior-most aspect of the rib cage.
It serves two main functions:
1. Separates the thoracic cavity from the abdominal cavity
Note: the word diaphragm is derived from the Greek ‘diáphragma’, meaning partition.
2. Undergoes contraction and relaxation, altering the volume of the thoracic
cavity and the lungs, producing inspiration and expiration.
It is the principal muscle of respiration.
The pericardium, containing the heart, lies on the central part of the
diaphragm.
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43. Diaphragm,,,
43

44. Muscles of the pelvic wall,,,
Medial view of hemisected pelvis
Posterior view
44

45. Muscles of the pelvic wall,,,
Obturator internus muscle
 Origin - Pelvic surfaces of ilium and
ischium; obturator membrane
 Insertion - greater trochanter of the
femur
 Action - Rotates thigh laterally;
assists in holding head of femur in
acetabulum
 Nerve supply - nerve to obturator
internus (L5, S1, S2) 45

46. Muscles of the pelvic wall,,,
Piriformis muscle: is triangular muscle.
• It originates in the bridges of bone and passes
through the greater sciatic foramen.
 Origin-Pelvic surface of S2 - S4 segments
-superior margin of greater sciatic notch and
sacrotuberous ligament
 Insertion - greater trochanter of femur
 Nerve supply – nerve to piriformis from sacral
plexus (S1 and S2)
 Action – Rotates thigh laterally; abducts
thigh; assists in holding head of femur in
acetabulum 46

47. Muscles of the pelvic wall,,,
47

48. 48
Muscles of the pelvic wall,,,

49. 49