*Anatomy: Anterior and Lateral Abdominal Wall, Inguinal Region, and Hernias Flashcards
Identify the four quadrants in the abdomen, as well as the lines/planes which delimit each quadrant.
Right upper
Right lower
Left upper
Left lower
Transumbilical plane (through L3/L4 disc) Median (sagittal) plane (through xiphoid process, pubic symphysis)
Identify the nine regions in the abdomen, as well as the lines/planes which delimit each region.
R Hyponchondrial L Hyponchondrial Epigastric R lumbar region (flank, loin) Umbilical region L lumbar region (flank, loin) R iliac/inguinal region (groin) Hypogastric region (pubic, suprapubic) L iliac/inguinal region
- Midclavicular lines
- Subcostal plane (L3 vertebra, lowest point of the costal margins, 10th CC)
- Transtubercular/Intertubercular plane (L5 vertebrae, iliac tubercles)
Identify the main layers of the abdominal wall.
- Skin (attached to SC tissue loosely except at umbilicus)
- SC tissue/fascia (including SC fatty layer i.e. Camper’s fascia + deep membraneous layer i.e. Scarpa’s fascia)
- Abdominal muscles within investing fascia
- Transversalis fascia
- Extraperitoneal fat
- Parietal peritoneum
What direction do the skin cleavage lines run in the trunk ?
The natural lines of cleavage of skin (Langer’s lines) are constant running downwards and forways almost horizontally around the trunk
What is the clinical significance of Langer’s lines ?
Incisions made (or wounds) across the lines of skin tension promote hypertrophic scarring (hence oblique or S shaped incisions may be preferred)
Define perineum.
Space between the anus and scrotum in the male and between the anus and the vulva in the female.
Identify structures of the abdominal wall which are continuous with the perineum wall.
Abdominal muscles NO
Skin, subcutaneous tissue, and superficial fascia are continuous from abdominal wall to perineum wall.
Camper’s fascia (ab wall) is continuous with the Cruveilher’s fascia (aka SC tissue of the perineum)
Scarpa’s fascia (ab wall) is continuous with Colles’ (perineal) fascia and dartos fascia
How many abdominal muscles are there ?
3 flat muscles (external oblique, internal oblique, tranversus abdominis), and 1 strap-like vertical muscle (rectus abdominis)
What are the functions common to all the abdominal muscles ?
- Support ab contents
- Raises intra-ab P
- Withstand P from descent of the diaphragm
- Respiration
- Support vertebral column
- Flex, laterally flex, and rotate the trunk
What is the innervation of the abdominal muscles ?
Thoraco-abdominal (7th-11th intercostal) n
Subcostal n
RECTUS ABDOMINIS
- Origin
- Insertion
- Action
- Other special feature
RECTUS ABDOMINIS
-Origin: pubic crest, pubic symphysis
-Insertion: 5th-7th CC, xiphoid process
-Action: stabilises pelvis during gait
-Other special feature: Each rectus abdominis is enclosed within rectus sheath, formed by the aponeuroses of the flat muscles
Rectus abdominis also crossed by three firbous bands called tendinous intersections
Describe the main features of rectus abdominis.
ABOVE ARCUATE LINE:
-Internal oblique, external oblique, and traversus abdominis all become tendinous around here, before approaching side of
RA.
-These are aponeuroses of the three flat muscles
-EO: all of its aponeurosis passes anterior to RA and merge with the internal oblique in the midline.
-IO: its aponeurosis divides into two layers,
one passes anterior to RA whereas the other passes posterior to RA. Between two recti, they come together and re-attach.
-TA: all of it aponeurosis passes posterior to RA and merge with the internal oblique and external oblique aponeurosis in the midline.
-Transversalis fascia and parietal peritoneum both posterior to RA (TF anterior to PP)
BELOW ARCUATE LINE:
- EO (same): all of its aponeurosis passes anterior to RA and merge with the internal oblique in the midline.
- IO: posterior layer of aponeurosis now also passes anteriorly to RA (both layers), although it also has a layer that passes posterior to RA.
- TA: aponeurosis passes anteriorly to RA now
- Transversalis fascia and parietal peritoneum both posterior to RA (TF anterior to PP)
Define linea albla and linea semilunaris.
- Linea alba= region in the midline where the aponeurosis of the three muscles fuse
- Linea semilunaris = “Lateral border of Rectus Abdominis, formed by the aponeurosis of the internal oblique at its line of division to enclose the rectus, reinforced anteriorly by the external oblique and posteriorly by the transversus abdominis above the arcuate line”
Define arcuate line.
The inferior epigastric vessels enter the rectus sheath, passing anterior to the arcuate line.
Also “the demarcation where the internal oblique and transversus abdominis aponeuroses of the rectus sheath start to pass anteriorly to the rectus abdominis muscle, leaving only the transversalis fascia posteriorly”
EXTERNAL OBLIQUE
- Origin
- Insertion
- Action
- What direction do fibers run ?
EXTERNAL OBLIQUE
- Origin: lower 8 ribs
- Insertion: iliac crest, linea alba, xiphoid process, pubic tubercle, anterior superior iliac spine
- What direction do fibers run ? infero-medially
Define and describe the inguinal, and lacunar ligament.
♦ Inguinal ligament is the lower border of the aponeurosis of the external oblique muscle.
It attaches to and extends between anterior superior iliac spine and pubic tubercle
♦ Some of the fibers from medial end of inguinal ligament turn posterolaterally and attach to pubic pecten (=lacunar ligament, forming medial border of the femoral canal)
Define superficial inguinal ring.
Defect of the aponeurosis of the external oblique, just above the pubic tubercle is called superficial inguinal ring (i.e. superficial (medial) opening of inguinal canal)
Describe the location, and role of the thoraco-lumbar fascia.
THORACO-LUMBAR FASCIA
- Location: passes from the iliac crest to the 12th rib in 3 layers
- Role: surrounds back muscles + the three layers fuse and provide the origin to tranversus abdominis and internal oblique muscles (but NOT to external obliques)
What is the clinical implication of the following: “the three layers of the thoraco-lumbar fascia fuse and provide the origin to tranversus abdominis and internal oblique muscles (but NOT to external obliques)”
There is a weak area through which there can be lumbar hernia.
INTERNAL OBLIQUE MUSCLES
- Origin
- Insertion
- Nerve supply
- Direction of the fibers
INTERNAL OBLIQUE MUSCLES
- Origin: Thoracolumbar fascia, iliac crest (anterior 2/3), lateral 2/3 of inguinal ligament
- Insertion: Inferior 3-4 ribs, linea alba, xiphoid process, pubic crest
- Nerve supply: T7-T12 + Iliohypogastric (L1) nerve (latter especially for lower fibers)
- Direction of the fibers: supero-medially and inferiorly to conjoint tendon
TRANSVERSUS ABDOMINIS
- Origin
- Insertion
- Nerve supply
TRANSVERSUS ABDOMINIS
- Origin: Thoracolumbar fascia, iliac crest, lateral 1/3 of inguinal ligament, inferior 6 ribs + CC
- Insertion: Linea alba, xiphoid process, pubic crest
- Nerve supply: T7-T12 + Iliohypogastric (L1) nerve (latter especially for lower fibers)
Define and describe conjoint tendon, including its location and role.
=Inguinal falx
The fibers of internal oblique arising from the inguinal ligament arch medially over the spermatic cord and unite with the transverse abdominis aponeurosis to form the conjoint tendon.
- Location: Attaches to the pubic crest and pectineal line behind the superficial inguinal ring
- Role: Support the superficial inguinal ring
Identify the location of tranversalis fascia.
Thin layer of CT that lines the tranversus abdominis muscle internally
INGUINAL CANAL
- Location
- What it connects
- Openings
- Contents
-Location: passage through the anterior abdominal wall
-What it connects: connects abdominal cavity to scrotum in males, to labia majora in females
-Openings: Deep inguinal ring, superficial inguinal ring
-Contents:
Ductus deferens (m)
Testicular artery (m)
Round ligament of the uterus (= ligamentum teres) (f)
Genital branch of the genitofemoral nerve (L1/2)
Ilioinguinal nerve (L1)
Define deep inguinal ring, giving its location.
Opening in the tranversalis fascia.
Location: Found in lateral inguinal fossa, lateral to the lateral umbilical fold (covering inferior epigastric vessels), about 1 cm above the midway between anterior superior iliac spine and pubic symphysis (mid-inguinal point)
Define superficial inguinal ring, giving its location, and stating any sources of support.
Triangular opening in the external oblique aponeurosis.
Supported from behind by the conjoint tendon.
Identify the anterior, posterior borders, roof, and floor of the inguinal canal.
ANTERIOR
- External oblique
- Internal oblique laterally
POSTERIOR
- Conjoint tendon medially
- Transversalis fascia laterally
ROOF
-Arching inferior edges of internal oblique and transversus abdominis
FLOOR
- Inguinal ligament
- Lacunar ligament medially
Define hernia. Where does an inguinal hernia appear ? Where does a femoral hernia appear ?
A condition in which part of an organ is displaced and protrudes through the wall of the cavity containing it (appears as a lump)
Especially occurs in weaker areas
Inguinal hernias usually appears above and medial to the pubic tubercle
Femoral hernias pass through the femoral canal and appears below and lateral to the pubic tubercle
Explain how direct inguinal hernias occur, referring to the anatomy behind it.
Area on the posterior wall of inguinal canal, medial to the inferior epigastric vessels is called Hesselbach’s (inguinal) triangle. On the medial side of triangle is the Conjoint tendon.
Direct inguinal hernias are usually caused by weaker conjoint tendons (usually in adult males).
Results in small bowel, or fat pushing the peritoneum and tranversalis fascia.
May notably pass through the superficial inguinal ring to enter the scrotum, parallel to the spermatic cord and covered by peritoneum, transversalis fascia, and conjoint tendon
Explain how indirect inguinal hernias occur.
Abdominal contents pass through deep inguinal ring
Involves a persistant processes vaginalis
Contents are covered by all the layers of the spermatic cord
Explain the mechanics of hernias during straining effort.
-On coughing and straining (e.g. micturition, defecation, parturition), the arching lowest fibers of the IO and TA muscles contract flattening out the arched roof of the inguinal canal so that it is lowered toward the floor. The floor may actually compress the contents of the inguinal canal against the floor so that the canal is virtually closed.
-When great straining effort is required (e.g. defecation and parturition), the person naturally tends to assume the squatting position. The hip joints are flexed and the anterior surfaces of the thighs are brought up against the anterior abdominal wall. By tis means, the lower part of the anterior abdominal wall is protected by the thighs.
However, particularly in males, the inguinal region is susceptible to the development of hernias.
What often happens to hernias when:
- coughing/straining
- relaxed/supine
- When coughing/straining, hernias often increase in size
- When relaxed/supine, hernias reduce in size or disappear (examination may show a hernia to have a cough impulse and to be reducible)
What happens upon strangulation of a hernia lump ? How is diagnosis of hernia performed ?
Lump becomes red and tender
Diagnosis is performed based on clinical features
What is the difference between obstructed irreducible and non-obstructed irreducible hernias ?
- Irreducible but non-obstructed hernias may cause little pain
- If a hernia causes obstruction (colicky abdominal pain, distension and vomiting may occur), it will be tense, tender, and irreducible
