Podcast
Questions and Answers
Which of the following is NOT a function of the abdominal wall muscles?
Which of the following is NOT a function of the abdominal wall muscles?
- Aiding in defecation
- Regulation of body temperature (correct)
- Assistance with breathing
- Protection of internal organs
Which spinal nerves innervate the anterior abdominal wall muscles?
Which spinal nerves innervate the anterior abdominal wall muscles?
- S2 to S5
- T7 to L1 (correct)
- T1 to T6
- L2 to S1
What is the primary action of the rectus abdominis muscle?
What is the primary action of the rectus abdominis muscle?
- Extension of the vertebral column
- Flexion of the vertebral column (correct)
- Lateral flexion of the trunk
- Rotation of the trunk
The Linea Alba is formed by the aponeuroses of which muscles?
The Linea Alba is formed by the aponeuroses of which muscles?
Where does the pyramidalis muscle insert?
Where does the pyramidalis muscle insert?
Which muscles form the rectus sheath?
Which muscles form the rectus sheath?
If only the right side of the external oblique muscle contracts, what movement will occur?
If only the right side of the external oblique muscle contracts, what movement will occur?
In which direction do the fibers of the internal oblique muscle run?
In which direction do the fibers of the internal oblique muscle run?
Flashcards
Functions of Abdominal Muscles
Functions of Abdominal Muscles
Protect internal organs and aid in breathing, defecation, and childbirth.
Rectus Abdominis
Rectus Abdominis
Paired muscle along the midline, flexes the vertebral column.
Innervation of Anterior Abdominal Muscles
Innervation of Anterior Abdominal Muscles
Supplied by the anterior rami of spinal nerves T7 to L1.
Linea Alba
Linea Alba
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External Oblique Muscle
External Oblique Muscle
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Internal Oblique Muscle
Internal Oblique Muscle
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Rectus Sheath
Rectus Sheath
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Pyramidalis Muscle
Pyramidalis Muscle
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Study Notes
Abdominal Wall Muscles
- Abdominal wall muscles protect internal organs and aid in breathing, defecation, urination, and childbirth.
- Muscle contractions alter thoracic cavity volume for breathing.
- Abdominal muscle contraction increases intra-abdominal pressure, aiding in bodily functions.
Anterior Abdominal Wall Muscles
- Anterior abdominal wall muscles are innervated by spinal nerves T7 to L1.
- Rectus Abdominis:
- Paired muscle along the midline, separated by the Linea Alba.
- Originates on the pubic symphysis and pubic tubercle.
- Inserts on the costal margin and xiphoid process.
- Action: Flexes the vertebral column.
- Linea Alba: White line formed by abdominal muscle aponeuroses.
- Linea Semilunaris: White line on the lateral rectus abdominis.
- Tendinous Intersections: Horizontal divisions within the rectus abdominis.
- Pyramidalis:
- Small, triangular muscle (not always present).
- Originates on the pubis, inserts on the Linea Alba.
- Innervation: Anterior ramus of T12.
- Rectus Sheath:
- Tendinous sheath surrounding rectus abdominis and pyramidalis.
- Formed by aponeuroses of external oblique, internal oblique, and transversus abdominis.
- Upper three-quarters fully enclosed; lower quarter only anteriorly covered.
- Lateral Muscles:
- External Oblique:
- Origin: Ribs 5 to 12.
- Insertion: Iliac crest, pubic crest, pubic tubercle, Linea Alba, and xiphoid process.
- Action: Trunk flexion (both sides), lateral flexion (one side).
- Fiber Direction: Inferomedially (downward and inward).
- Inferior margin forms the inguinal ligament.
- Internal Oblique:
- Origin: Iliac crest and inguinal ligament.
- Insertion: Lower ribs (9-12), Linea Alba, and pubic crest.
- Action: Trunk flexion (both sides), lateral flexion (one side).
- Fiber Direction: Superomedially (upward and inward).
- Mnemonic: "Hands in pockets (external oblique) - Hands on tits (internal oblique)".
- Transversus Abdominis:
- Origin: Iliac crest, inguinal ligament, and costal cartilages.
- Insertion: Linea Alba and pubic crest.
- Action: Compresses the abdomen.
- Fiber Direction: Transversely (horizontally).
- External Oblique:
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