Muscles

Question 1

How many abdominal wall muscles are there

Answer 1

8 muscles - 4 on each side
Rectus abdominis
External Oblique 
Internal oblique
Transversus abdominis

Question 2

What’s the function of the abdominal muscles as a group

Answer 2

Trunk Movement

Sitting up from lying, getting out of bed.

Protection of the abdominal viscera

Spinal stabilisation

Raising intra-abdominal pressure for:
○ Forced expiration
○ Micturition (urination;1) - Combined with appropriate sphincter relaxation, increased pressure on the bladder aids micturition
○ Defecation (2) - Combined with appropriate sphincter relaxation, increased pressure aids on the rectum, it assists defecation
○ Parturition (childbirth)- In the final stages of childbirth, the compressive force produced helps to expel the fetus from the uterus
○ Vomiting - Combined with appropriate sphincter relaxation, increased pressure aids on the stomach, it helps in vomiting

Question 3

How is raising intra-abdominal pressure achieved

Answer 3

This is achieved by the ‘sheet’ muscles pulling on the rectus sheath via their aponeuroses, flattening the abdomen, compressing the abdominal viscera. If the diaphragm maintains its tone and resists upward displacement, the increase in intra-abdominal pressure is important in producing the ‘expulsive’ acts.

When the diaphragm is relaxed, the increased intra-abdominal pressure presses the abdominal viscera against its lower surface, pushing the diaphragm upwards, increasing intrathoracic pressure so that, when the glottis is opened, air is forced from the lungs in a violent, explosive cough or sneeze. The coughing action is reinforced by the abdominal muscles acting on the lower ribs, pulling them downwards. Pain resulting from surgical incision of the abdominal wall frequently causes inhibition of these muscles, making coughing very difficult.

The combined action of the abdominal muscles, together with the diaphragm, also produces a ‘muscular corset’ (valsalva manoeuvre) holding the abdominal viscera in place. This action can be increased during activities such as lifting, in which a form of pneumatic cushion is formed in front of the vulnerable lumbar spine. This action is frequently seen when people hold their breath, anchoring the diaphragm, prior to and when moving a heavy object.

Question 4

What is the Thoracolumbar fascia (TLF)

Answer 4

Non-contractile extensive fascial sheet enclosing deep back muscles

Composed of 3 layers enclosing erector spinae & quadratus lumborum; unite laterally to give origin via conjoint tendon to internal oblique (IO) & transversus abdominis (TA)

TLF leaves a free posterior edge for external obliques

Lumbar region - thick & strong, between 12th rib and iliac crest
○ Important to fill gap between 12th rib and iliac crest, acting as a protective membrane; it is considered by some to function as a large ligament

Thoracic region – thin & transparent
○ Sandwiched between erector spinae and latissimus dorsi, and the rhomboids

Question 5

Describe the posterior layer of TLF

Answer 5

a. Superficial to erector spinae & attached medially to spinous processes of the thoracic, lumbar and sacral vertebrae and associated supraspinous ligaments
b. It extends from the sacrum and iliac crest to the angles of the ribs, lateral to iliocostalis; latissimus dorsi partly arises from the strong membranous part of this layer in the lower part of the back

Question 6

Describe the middle layer of TLF

Answer 6

a. Medially attached to the tips of the lumbar transverse processes and the intertransverse ligaments
b. Sandwiched between erector spinae and quadratus lumborum, joining the posterior layer at the lateral border of erector spinae
c. It extends from the lower border of the 12th rib and the lumbocostal ligament above to the iliac crest and iliolumbar ligament below

Question 7

Describe the anterior layer of TLF

Answer 7

a. Thinnest of the three layers
b. Deep to QL, attached to anterior aspect of lumbar TPs medially; laterally, it fuses with the middle layer at the lateral border of QL
c. It extends from the iliac crest and iliolumbar ligament below to the lower border of the 12th rib
d. Superiorly, it is thickened between the 12th rib and TP of L1, forming the lateral arcuate ligament

Question 8

What are the muscles of the anterolateral wall and their action and innervation

Answer 8

All muscles associated with rectus sheath
4 muscles
Layers:
	• External oblique - most superficial 
	• Internal oblique - middle layer
	• Transversus abdominis- most deep
Vertical muscle = rectus abdominis

Rectus abdominis = Anterior primary rami of the lower six or seven thoracic nerves ( T6/T7–T12 )

EO, IO, TA = Anterior rami of the lower six thoracic and first lumbar nerves (T7–T12, L1)

Action (excluding TA) - mainly trunk/hip flexion or posterior pelvic tilt; contralateral rotation (RA/EO)/ ipsilateral rotation (IO) and ipsilateral side flexion

Question 9

Give attachments for rectus abdominis

Answer 9

Origin: Anterior aspect of the pubic symphysis and pubic crest, via two tendons

Insertion: Passes vertically superiorly and widens to attaches to anterior surfaces of the xiphoid process and costal cartilages of the 5-7 ribs

Question 10

Give position of rectus abdominis

Answer 10

Superficial muscles situated vertically on the left and right sides of anterior abdominal wall, enclosed within the rectus sheath; two muscles are separated by the linea alba

Intermediately anchored by transverse tendinous intersections (usually three) to give ‘6-pack’ appearance

Slightly convex lateral border presents as a groove, the linea semilunaris , on lean individuals

Question 11

Give action of rectus abdominis

Answer 11

Trunk/hip flexion - bilateral

Trunk fixed (bilateral) - posterior pelvic tilt

Contralateral rotation (trunk on pelvis)- unilateral

Lateral flexion - ipsilaterally; reversed action: hip hitching

Compression of abdominal viscera

Question 12

Give innervation of rectus abdominis

Answer 12

Anterior primary rami of the lower six or seven thoracic nerves ( T6/T7–T12 )

Question 13

Give Palpation of rectus abdominis

Answer 13

On the anterior abdominal wall when the trunk is flexed against resistance.

In an athletic subject, possible to palpate the three transverse tendinous intersections, linea alba and semilunaris at the sides of each muscle

Question 14

Give position of external oblique

Answer 14

Superficial muscle situated on left and right sides of the anterolateral abdominal wall, the fibres run inferomedially from the ribs towards the midline

most superficial of the three sheets of muscle forming the anterolateral abdominal wall; lateral to rectus abdominis

Question 15

Give attachments of external oblique

Answer 15

Origin: Fleshy slips to the outer borders of the lower eight ribs (5-12) and their costal cartilages; interdigitating with serratus anterior above and latissimus dorsi below

Insertion:
Outer lip of the anterior 2/3 of the iliac crest, forming a large aponeurosis fusing with that of the opposite side at the linea alba; lower free border of the aponeurosis stretches between the pubic tubercle and ASIS forming the inguinal ligament.

Question 16

Give action of external oblique

Answer 16

Trunk/hip flexion - bilateral; work w/ rectus abdominis & IO

Trunk (shoulder) fixed (bilateral) - posterior pelvic tilt

Contralateral rotation (trunk on pelvis)- unilateral; often w/ some trunk flexion

Lateral flexion - ipsilaterally; reversed action: hip hitching

Question 17

Give innervation of external Oblique

Answer 17

Anterior rami of the lower six thoracic and first lumbar nerves (T7–T12, L1)

Question 18

Give palpation of external oblique

Answer 18

Flat hand placed over the lower lateral aspect of the ribs may allow the contraction of external oblique to be felt on resisted flexion.

Question 19

Give position of internal oblique

Answer 19

Muscles situated on left and right of anterolateral abdominal wall, deep to external oblique internal oblique and superficial to transversus abdominis

Fibres run supero-medially; continuous with angle fibres of EO on the contralateral side

Question 20

Give attachments of internal oblique

Answer 20

Origin: Lateral ⅔ of inguinal ligament, anterior ⅔ of iliac crest, thoracolumbar fascia

Insertion:
Posterior fibres: pass almost vertically to inferior borders of lower 4 ribs (8-12) and costal cartilages

Anterior and inferior fibres: pass superomedially forming an aponeurosis fusing with that of the opposite side at the Linea alba; fibres arising from the inguinal ligament passes inferomedially, blending with the lower part of TA to form the conjoint tendon - attaching to the pubic crest and pecten pubis

Question 21

Give action of internal oblique

Answer 21

Trunk/hip flexion - bilateral; work w/ rectus abdominis, EO

Trunk fixed (bilateral) - posterior pelvic tilt

Ipsilateral rotation (trunk on pelvis)- unilateral

Lateral flexion - ipsilaterally; reversed action: hip hitching

Question 22

Give innervation of internal oblique

Answer 22

Anterior rami of the lower six thoracic and first lumbar nerves (T7–T12, L1)

Question 23

Give palpation of internal oblique

Answer 23

Flat hand is placed over the lower abdomen just above the anterior half of the iliac crest and felt on resisted flexion

Question 24

Give position of transversus abdominis

Answer 24

Deep to rectus abdominis, EO and IO

Fibres pass horizontally from TLF to midline anteriorly via rectus sheath

Question 25

Give attachments of transversus abdominis

Answer 25

Origin: Lateral 1/3 inguinal ligament, anterior 2/3 inner lip of the iliac crest inferiorly; TLF posteriorly; inner surface of the costal cartilages of the lower 5-6 ribs superiorly (6/7-12), where it interdigitates with the attachment of the diaphragm Insertion: Fibres pass horizontally around the abdominal wall, forming a aponeurosis fusing to its fellow at the linea alba; fibres arising from inguinal ligament arch downwards to join those from IO forming the conjoint tendon - attaching to the pubic crest and pecten pubis

Question 26

Give action of transversus abdominis

Answer 26

Raises intra-abdominal pressure for all expulsive acts Compression and support of abdominal viscera Stabilising muscle of lumbar spine - prevents lumbar instability

Question 27

Give innervation of transversus abdominis

Answer 27

Anterior rami of the lower six thoracic and first lumbar nerves (T7–T12, L1)

Question 28

Give palpation of transversus abdominis

Answer 28

Few cm medial to ASIS - soft squidgy area. Feel contraction by asking to tighten rectum

Question 29

Give functional activity of these anterolateral abdominal muscles

Answer 29

Side flexion reverse action = ipsilateral pelvis lifted, i.e. in walking Trunk Movement Sitting up from lying, getting out of bed. Protection of the abdominal viscera Spinal stabilisation Raising intra-abdominal pressure

Question 30

Describe the rectus sheath

Answer 30

complex - formation differs at different levels: ○ Above the costal margin, it is only present anteriorly, formed entirely by the aponeurosis of external oblique; posterior layer is deficient so that rectus abdominis lies directly on the thoracic wall ○ superior band - it is formed anteriorly by the aponeuroses of external and internal oblique, and posteriorly by the aponeuroses of internal oblique and transversus abdominis; anterior and posterior layers interlace at linea alba ○ Inferior band - the aponeuroses of all three muscles pass in front of rectus abdominis so that the posterior wall of the sheath is deficient hence suggesting for weakening of linea alba ○ Inferior limit of the posterior layer is marked by a crescentic border - the arcuate line ○ Below the arcuate line, rectus abdominis lies directly on the transversalis fascia, separating it from extraperitoneal fat

Question 31

Describe the linea alba

Answer 31

fibrous band running from the tip of the xiphoid process of the sternum to the pubic symphysis It is vulnerable in the latter stages of pregnancy - linea alba stretches to increase the distance between the two rectus abdominis muscles, a condition called rectus diastasis - Separation of 5 or more centimetres can occur; postpartum, it returns to normal providing undue strains are avoided Rectus diastasis also occurs in obesity

Question 32

What are the muscles of the posterior abdominal wall

Answer 32

``` 5 muscles all associated with thoracolumbar fascia (TLF): Iliacus Psoas major Psoas minor Quadratus Lumborum (QL) Diaphragm Also includes: Posterior aspect of TA and Obliques Lumbar vertebrae and intervertebral discs ```

Question 33

Give position of iliacus

Answer 33

fan-shaped muscle that is situated inferiorly on the posterior abdominal wall. It combines with the psoas major to form the iliopsoas – the major flexor of the thigh.

Question 34

Give attachments of iliacus

Answer 34

Origin:Upper and posterior 2/3 iliac fossa, ASIS Insertion: Conjoint tendon (psoas major) into lesser trochanter of femur

Question 35

Give position of psoas major

Answer 35

Situated near the midline of the posterior abdominal wall, immediately lateral to the lumbar vertebrae

Question 36

Give attachments psoas major

Answer 36

Origin: Vertebral bodies of T12-L4 and TPs of L1-5 Insertion: Conjoint tendon (iliacus) into lesser trochanter of femur

Question 37

Give actions of iliopsoas

Answer 37

Hip/trunk flexion

Question 38

Give innervation of iliopsoas

Answer 38

Iliacus: femoral nerve L2-3 | Psoas major: anterior rami of lumbar plexus L1-4

Question 39

Position of psoas minor

Answer 39

Weak muscle, not always present (only in 60% of population)

Question 40

Give position quadratus lumborum (QL)

Answer 40

Large, flat, quadrilateral muscle situated laterally in the posterior abdominal wall running between the pelvis and the 12th rib deep to erector spinae; enclosed by the anterior and middle layers of the TLF; superficial to psoas major

Question 41

Give attachments of QL

Answer 41

Origin: Iliolumbar lig, adjacent post 1/2 iliac crest Insertion: Fibres run superiorly and slightly medially to apices (tips) of TPs of each lumbar vertebrae and medial 1/2 of the lower border of the 12th rib;

Question 42

Give action of QL

Answer 42

Muscle of inspiration - steadies the 12th rib during deep inspiration so that the origin of the diaphragm is fixed Ipsilateral side flexion (Unilateral); Reversed action: when standing on one leg acts strongly on the non-weight-bearing side to stop the pelvis dropping downwards Lumbar extension - bilateral

Question 43

Give innervation of QL

Answer 43

Anterior primary rami of the subcostal nerve and the upper three or four lumbar nerves (T12, L1-L4)

Question 44

What is the major extensor muscle of the back

Answer 44

Erector spinae

Question 45

Give position of erector spinae

Answer 45

Large, complex, powerful, superficial mass of muscle consisting of several parts running the length of the vertebral column - from sacrum to external occipital protuberance Broad belly in lumbar region with a well-defined lateral border, but as it extends upwards, it divides into three columns, each column further divided into 3 parts: Iliocostalis = Most lateral of the three columns, divided into lumborum, thoracis and cervicis parts; attached rib angles and cervical TPs Longissimus = Intermediate column of muscle and is the longest and thickest, it divides into thoracis, cervicis and capitis parts; attaches to TPs Spinalis = most medial muscular column, it divides into thoracis, cervicis and capitis parts; attaches to SPs

Question 46

Give attachments of erector spinae

Answer 46

Origin: SP T11-L5 adjacent supraspinous ligs, post sacral crests, sacrotuberous lig, posterior part iliac crest Insertion: The fibres pass upwards, deep to the TFL and Lat. Dorsi dividing into 3 columns: iliocostalis - (Lumborum) via six slips into the inferior border of the lower six ribs (6-12) near their angles, (Thoracis) near the angles of the upper six ribs and TP C7, (Cervicis) TPs of C4 – C6 longissimus - (Thoracis) via two sets of slips to TPs of all lumbar and thoracic vertebrae and adjacent regions of the lower 10 ribs, (Cervicis) from TPs of T1–T5 to TPs C2–C6, (Capitis) from TPs C4-T5 to mastoid process spinalis - Thoracis: SPs of T11-L2 to SPs of T1-T6, (cervices often absent) lower part ligamentum nuchae, SP C7 to SP C2, (Capitis) blends with semispinalis capitis

Question 47

Give actions of erector spinae

Answer 47

Bilateral: spinal and head on neck extension (concentric), control of flexion (eccentric) Unilateral: Spinal and head on neck Ipsilateral Lateral flexion/ contralateral rotation

Question 48

Give functional activity of erector spinae

Answer 48

Maintenance of Lumbar lordosis during sitting/standing - because main mass of muscle is situated in the lumbar region (particularly longissimus thoracis) Standing on one leg - lower part of erector spinae on the non-weight-bearing side prevents the pelvis from dropping During walking, erector spinae contracts, alternately steadying the vertebral column on the pelvis

Question 49

Give innervation of erector spinae

Answer 49

Dorsal rami of adjacent thoracolumbar nerves

Question 50

How to palpate of erector spinae

Answer 50

Each erector spinae can be felt and seen as a column of muscle on either side of the lumbar region, particularly during extension. Each muscle mass can also be felt contracting when alternately standing on one and then the other leg

Question 51

Give transversospinalis muscles and function and innervation

Answer 51

5 muscles all innervated by Posterior primary rami of adjacent spinal nerves: ``` Semispinalis Rotatores Multifidus Interspinales Intertransversarii ``` Stability muscles - mainly thought of as one group of muscles that provide stability at an individual spinal unit, summing up to gross spinal stability Individually each muscle has a degree of physiological movement Each muscle has several layers

Question 52

Give position of semispinalis

Answer 52

Consists of thoracis, cervicis, capitis parts extending from the lower thoracic region to the base of the skull

Question 53

Give attachments of semispinalis

Answer 53

Thoracis: TPs T6-T10 to SPs of C6–T2 Cervicis: (larger than thoracis) from TPs T1-T6 to SPs C2-C6 Capitis: largest; TPs T1-T6 and articular processes C4-7 inserting to medial impression between the superior and inferior nuchal lines on the base of the skull; most medial part may be separate = spinalis capitis

Question 54

Give action of semispinalis

Answer 54

Bilateral: thoracic, cervical extension Unilateral: ipsilateral trunk, neck and head on neck side flexion and contralateral rotation Stabilisation: adjusting their length to stabilize adjacent vertebrae irrespective of the position of the vertebral column

Question 55

Give rotatores position

Answer 55

Best developed in the thoracic region; represented by variable bundles in the lumbar and cervical regions; deep to multifidus

Question 56

Give attachments of rotatores

Answer 56

Origin: TP process of each vertebrae Insertion: Run supero-medially to lamina of adjacent verterbrae one level above

Question 57

Give action of rotatores

Answer 57

Stabilisation: adjusting their length to stabilize adjacent vertebrae irrespective of the position of the vertebral column Contralateral rotation of thoracic vertebrae

Question 58

Give position of multifidus

Answer 58

Lies deep to semispinalis and erector spinae in the gutter between the spinous and transverse processes of the vertebrae at all levels

Question 59

Give attachments of multifidus

Answer 59

Origin: Post sacrum, mamillary processes (lumbar vertebrae), TPs of all thoracic vertebrae, articular processes of lower 4-5 cervical vertebrae Insertion: Muscle fibres are arranged in three layers passing superomedially to SPs of all vertebrae from the L5 - axis (C2) Deepest layer: SP of vertebrae 1 level superior Middle layer: SP of vertebrae 2/3 levels superior Superficial layer: SP of vertebrae 3/4 levels superior

Question 60

Give actions of multifidus:

Answer 60

Stabilisation: adjusting their length to stabilize adjacent vertebrae irrespective of the position of the vertebral column Unilateral: assists Contralateral rotation of all vertebral column, Ipsilateral lateral side flexion of all vertebral column Bilateral: assists Spinal extension of all vertebral column

Question 61

Give position of interspinales

Answer 61

Short insignificant muscles of the back ;best developed in the cervical and lumbar regions = muscle fibres within interspinous ligaments; thoracic region, they are poorly developed or absent

Question 62

Give attachments of interspinales

Answer 62

Origin: SP of each vertebrae Insertion: SP of adjacent vertebrae

Question 63

Give actions of interspinales

Answer 63

Stabilisation: adjusting their length to stabilize adjacent vertebrae irrespective of the position of the vertebral column Extension of cervical and lumbar spine

Question 64

Give position of intertransversarii

Answer 64

Small slips of muscle within intertransversus ligaments in lumbar and cervical regions

Question 65

Give attachments of intertransversarii

Answer 65

Cervical: well-developed, consisting of up to four slips between adjacent TPs from the atlas ( C1 ) to T1 Lumbar: lateral slip passing between adjacent TPs; medial slip passing between accessory process of one vertebra to mamillary process of vertebra one level superior

Question 66

Give actions of intertransversarii

Answer 66

Stabilisation: adjusting their length to stabilize adjacent vertebrae irrespective of the position of the vertebral column Ipsilateral side flexion in lumbar and cervical spine

Question 67

Give innervation of transversospinalis

Answer 67

Posterior primary rami of adjacent spinal nerves