42 Questions
What is the origin of the external abdominal oblique muscle?
Ribs 4-13 and thoracolumbar fascia
What is the action of the external abdominal oblique muscle in relation to the vertebral column?
Flexion of the vertebral column
What is the insertion of the external abdominal oblique muscle?
Linea alba by a wide aponeurosis
What is the direction of the fibers of the internal abdominal oblique muscle?
Cranioventrally
What is the origin of the internal abdominal oblique muscle?
Tuber coxae, thoracolumbar fascia and inguinal ligament
What is the common innervation of the muscles of the abdominal walls?
Ventral branches of thoracic and lumbar spinal nerves
What is the fiber orientation of the external abdominal oblique m?
Caudoventrally
What is the function of the external abdominal oblique muscle in relation to respiration?
Aids in expiration
What is the main function of the abdominal muscles?
To facilitate breathing and defecation
Which of the following structures is NOT part of the abdominal wall layers?
Scapula
What is the purpose of the inguinal canal (for males specifically).
To house the spermatic cord in males
What is the name of the structure that forms the boundary of the inguinal canal?
Superficial inguinal ring
What is the primary function of the cremaster muscle?
To pull the testis closer to the body in response to cold
What is the origin of the cremaster muscle?
Caudal border of the internal abdominal oblique
What is the innervation of the cremaster muscle?
Genitofemoral nerve
What is the significance of the inguinal canal in clinical importance?
Neutering, cryptorchidism, and inguinal hernias
What is the structure that contains the spermatic cord in males?
Vaginal tunic
What is the feminine counterpart of the vaginal tunic?
Vaginal process
What is the anatomical structure that courses through the superficial inguinal ring? (Hint: noted in males)
Cremaster muscle
Which of the following structures is NOT present in the inguinal canal (for both males and females)?
Pudendal nerve
What forms the rectus sheath?
Aponeuroses of the external and internal abdominal oblique muscles and transversus abdominis muscle
What is the clinical importance of the rectus sheath?
It is the holding layer when closing the abdomen
What is the linea alba?
A midventral raphe where the aponeuroses of the left and right abdominal muscles meet
What is the inguinal ligament?
A ligament that separates the inguinal canal from the vascular lacuna
What is the caudal limit of the aponeurosis of the external abdominal oblique muscle?
The inguinal ligament
What is the prepubic tendon?
A tendon that attaches the abdominal muscles to the pelvis
What is the function of the aponeuroses of the external and internal abdominal oblique muscles and transversus abdominis muscle?
They form the rectus sheath
What is the superficial inguinal ring?
The opening of the inguinal canal
The abdomen is divided into three main regions. What are they? (State in order)
Cranial, middle and caudal abdominal regions
What region(s) make up the cranial abdomen?
Xiphoid and hypochondriac region
What regions make up the middle abdominal topographic region?
Umbilical and lateral abdominal region
What regions make up the caudal abdominal region?
Pubic region and Inguinal region
Match the direction of the fibers to it’s correct muscle
External abdominal oblique m = Caudoventrally Internal Abdominal oblique m. = Cranioventrally Transversus abdominis m. = Transversely Rectus abdominis m. = Longitudinally
Match insertion to correct muscles
External abdominal oblique m. = Linda alba by a wide aponeurosis Internal abdominal oblique muscle = Costal arch, rectus abdominus, linea alba, and pre pubic tendon Transversus abdominis m. = Linea alba Rectus abdominis m. = First costal cartilage and sternum and pelvis by way of pre pubic tendon
Match the origins to correct muscle
External abdominal oblique = Ribs 4-13 and thoracolumbar fascia Internal abdominal oblique muscle = Tuber coxae, thoracolumbar fascia and Inguinal ligament Transversus abdominis m = Medial surfaces of rib 9-13 and transverse process of the lumbar vertebrae Rectus abdominis m. = First costal cartilage and sternum and pelvis by way of pre pubic tendon
Which muscle of the abdominal wall is the deepest abdominal muscle?
Transversus abdominis m.
What 3 borders make up the deep Inguinal ring?
The cranial, medial and latero-caudal border make up the deep Inguinal ring.
What muscle participates/contributes to the cranial border of the deep Inguinal ring?
Caudal border of internal abdominal oblique m.
The ___________ m. is the muscle considered to be the medial border that contributes to forming the deep Inguinal ring
Rectus abdominus
The _____________ is considered the latero-caudal border that participates in forming the deep Inguinal ring.
Inguinal ligament
What 3 structures make up the deep Inguinal ring?
The rectus abdominis m. , the internal abdominal oblique m and the Inguinal ligament
What feature/characteristic makes the superficial Inguinal ring distinct?
It’s covered by thoracolumbar fascia
Study Notes
Abdominal Wall and Muscles
- The abdominal wall consists of four layers: external abdominal oblique muscle, internal abdominal oblique muscle, transversus abdominis muscle, and rectus abdominis muscle.
- The muscles of the abdominal wall function to compress the abdominal viscera, aid in expiration, urination, and defecation, and flex the vertebral column.
External Abdominal Oblique Muscle
- Origin: ribs 4-13 and thoracolumbar fascia
- Insertion: linea alba by a wide aponeurosis
- Innervation: ventral branches of thoracic and lumbar spinal nerves
- Action: compression of the abdominal viscera, aids in expiration, urination, defecation, parturition, and flexion of the vertebral column
Internal Abdominal Oblique Muscle
- Location: medial to the external abdominal oblique muscle
- Fiber direction: cranioventrally
- Origin: tuber coxae, thoracolumbar fascia, and inguinal ligament
- Insertion: costal arch, rectus abdominis, linea alba, and prepubic tendon
- Innervation: ventral branches of thoracic and lumbar spinal nerves
- Action: compression and support of the abdominal viscera
Rectus Sheath
- Formed by aponeuroses of the external abdominal oblique muscle, internal abdominal oblique muscle, and transversus abdominis muscle
- Clinical importance: the holding layer when closing the abdomen
Linea Alba
- Midventral raphe (seam) where the aponeuroses of the left and right abdominal muscles meet
- A thick, white, fibrous structure that runs from the xiphoid process to the pubic symphysis
Inguinal Ligament
- Separates the inguinal canal from the vascular lacuna
- Caudal limit of the aponeurosis of the external abdominal oblique muscle
Superficial Inguinal Ring
- Formed by the aponeurosis of the external abdominal oblique muscle
- Contains the spermatic cord, cremaster muscle, and vaginal process
Prepubic Tendon
- Strong attachment of abdominal muscles to the pelvis
- Contains several structures: external pudendal artery and vein, genitofemoral nerve, lymphatics, and the vaginal process (in females)
Inguinal Canal
- Clinical importance: neutering, cryptorchidism, and inguinal hernias
Cremaster Muscle
- Origin: caudal border of the internal abdominal oblique muscle
- Innervation: genitofemoral nerve
- Action: pulls the testis closer to the body in response to cold
This quiz covers the external and internal abdominal oblique muscles in canine anatomy, including their location and functions.
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