Muscles Flashcards
How many abdominal wall muscles are there
8 muscles - 4 on each side Rectus abdominis External Oblique Internal oblique Transversus abdominis
What’s the function of the abdominal muscles as a group
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
How is raising intra-abdominal pressure achieved
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.
What is the Thoracolumbar fascia (TLF)
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
Describe the posterior layer of TLF
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
Describe the middle layer of TLF
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
Describe the anterior layer of TLF
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
What are the muscles of the anterolateral wall and their action and innervation
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
Give attachments for rectus abdominis
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
Give position of rectus abdominis
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
Give action of rectus abdominis
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
Give innervation of rectus abdominis
Anterior primary rami of the lower six or seven thoracic nerves ( T6/T7–T12 )
Give Palpation of rectus abdominis
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
Give position of external oblique
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
Give attachments of external oblique
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.
Give action of external oblique
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
Give innervation of external Oblique
Anterior rami of the lower six thoracic and first lumbar nerves (T7–T12, L1)
Give palpation of external oblique
Flat hand placed over the lower lateral aspect of the ribs may allow the contraction of external oblique to be felt on resisted flexion.
Give position of internal oblique
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
Give attachments of internal oblique
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
Give action of internal oblique
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
Give innervation of internal oblique
Anterior rami of the lower six thoracic and first lumbar nerves (T7–T12, L1)
Give palpation of internal oblique
Flat hand is placed over the lower abdomen just above the anterior half of the iliac crest and felt on resisted flexion
Give position of transversus abdominis
Deep to rectus abdominis, EO and IO
Fibres pass horizontally from TLF to midline anteriorly via rectus sheath
Give attachments of transversus abdominis
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
Give action of transversus abdominis
Raises intra-abdominal pressure for all expulsive acts
Compression and support of abdominal viscera
Stabilising muscle of lumbar spine - prevents lumbar instability
Give innervation of transversus abdominis
Anterior rami of the lower six thoracic and first lumbar nerves (T7–T12, L1)
Give palpation of transversus abdominis
Few cm medial to ASIS - soft squidgy area. Feel contraction by asking to tighten rectum
Give functional activity of these anterolateral abdominal muscles
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
Describe the rectus sheath
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
Describe the linea alba
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
What are the muscles of the posterior abdominal wall
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
Give position of iliacus
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.
Give attachments of iliacus
Origin:Upper and posterior 2/3 iliac fossa, ASIS
Insertion: Conjoint tendon (psoas major) into lesser trochanter of femur
Give position of psoas major
Situated near the midline of the posterior abdominal wall, immediately lateral to the lumbar vertebrae
Give attachments psoas major
Origin: Vertebral bodies of T12-L4 and TPs of L1-5
Insertion: Conjoint tendon (iliacus) into lesser trochanter of femur
Give actions of iliopsoas
Hip/trunk flexion
Give innervation of iliopsoas
Iliacus: femoral nerve L2-3
Psoas major: anterior rami of lumbar plexus L1-4
Position of psoas minor
Weak muscle, not always present (only in 60% of population)
Give position quadratus lumborum (QL)
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
Give attachments of QL
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;
Give action of QL
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
Give innervation of QL
Anterior primary rami of the subcostal nerve and the upper three or four lumbar nerves (T12, L1-L4)
What is the major extensor muscle of the back
Erector spinae
Give position of erector spinae
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
Give attachments of erector spinae
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
Give actions of erector spinae
Bilateral: spinal and head on neck extension (concentric), control of flexion (eccentric)
Unilateral: Spinal and head on neck Ipsilateral Lateral flexion/ contralateral rotation
Give functional activity of erector spinae
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
Give innervation of erector spinae
Dorsal rami of adjacent thoracolumbar nerves
How to palpate of erector spinae
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
Give transversospinalis muscles and function and innervation
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
Give position of semispinalis
Consists of thoracis, cervicis, capitis parts extending from the lower thoracic region to the base of the skull
Give attachments of semispinalis
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
Give action of semispinalis
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
Give rotatores position
Best developed in the thoracic region; represented by variable bundles in the lumbar and cervical regions; deep to multifidus
Give attachments of rotatores
Origin: TP process of each vertebrae
Insertion: Run supero-medially to lamina of adjacent verterbrae one level above
Give action of rotatores
Stabilisation: adjusting their length to stabilize adjacent vertebrae irrespective of the position of the vertebral column
Contralateral rotation of thoracic vertebrae
Give position of multifidus
Lies deep to semispinalis and erector spinae in the gutter between the spinous and transverse processes of the vertebrae at all levels
Give attachments of multifidus
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
Give actions of multifidus:
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
Give position of interspinales
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
Give attachments of interspinales
Origin: SP of each vertebrae
Insertion: SP of adjacent vertebrae
Give actions of interspinales
Stabilisation: adjusting their length to stabilize adjacent vertebrae irrespective of the position of the vertebral column
Extension of cervical and lumbar spine
Give position of intertransversarii
Small slips of muscle within intertransversus ligaments in lumbar and cervical regions
Give attachments of intertransversarii
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
Give actions of intertransversarii
Stabilisation: adjusting their length to stabilize adjacent vertebrae irrespective of the position of the vertebral column
Ipsilateral side flexion in lumbar and cervical spine
Give innervation of transversospinalis
Posterior primary rami of adjacent spinal nerves
