Trunk Structures Flashcards
What are the four cutaneous muscles of the trunk?
- Platysma
- Cutaneous trunci
- Cutaneous omobrachialis
- Preputial muscles
What are the characteristics of the Platysma muscle?
- Platysma
Covers the neck and face
Draws lips caudally
Innervated by the facial nerve
What are the characteristics of the Cutaneous trunci?
- Cutaneous trunci
Covers the side of the trunk
Innervated by the lateral thoracic nerve
What are the characteristics of the Cutaneous omobrachialis?
- Cutaneous omobrachialis
Continuation of the cutaneous trunci muscle over the shoulder
Present in horses and ruminants
What are the characteristics of the Preputial muscles?
- Preputial muscles
Extends down to the prepuce
Present in carnivores, ruminants, and pigs
What is the difference between hypaxial and epaxial muscles?
Hypaxial muscles:
> Ventral to the transverse processes of
the vertebrae
> Innervated by the ventral branches of the
spinal nerves
> Flexors of the spine
Epaxial muscles:
> Dorsal to the transverse processes of
the vertebrae
> Innervated by the dorsal branches of the
spinal nerves
> Extensor of the spine
What are the structures in the first three layers of epaxial musculature, especially the ones involved in respiration?
1st layer: trapezius, cleidocephalicus
2nd layer: latissimus dorsi, rhomboideus
3rd layer: cranial and caudal serratus dorsalis
How do the ribs and diaphragm move during inspiration and expiration?
Inspiration
> Ribs pull cranially
> Diaphragm is displaced caudally
Expiration
> Ribs are drawn caudally
> Diaphragm is displaced cranially
> Decreases the transverse diameter and
volume of the thorax
What is the location of the dorsal intercostal artery and intercostal nerves in relation to the ribs?
Dorsal intercostal artery and intercostal nerves run along the caudal aspect of the ribs.
What nerve (and cranial nerve) innervate the diaphragm?
Diaphragm is innervated by the phrenic nerve.
Cranial nerve: Vagus (CN 10)
What are the three openings of the diaphragm?
- Aortic hiatus (dorsal)
- Esophageal hiatus
- Caval foramen (ventral)
What structures pass through the aortic hiatus?
Aorta, azygous vein, thoracic duct
What structures pass through the esophageal hiatus?
Esophagus, dorsal/ventral vagal trunks
What structure passes through the caval foramen?
Caudal vena cava
Name the four abdominal muscles.
- External abdominal oblique
- Internal abdominal oblique
- Transversus abdominis
- Rectus abdominis
What are the characteristics of the external abdominal oblique?
Flat muscle
> Most superficial of the abdominal muscles
> Fibers orient caudoventrally
> Extends from the ribs/thoracolumbar fascia to the ventral midline by a wide aponeurosis
What are the characteristics of the internal abdominal oblique?
Flat muscle
> Deep to the external abdominal oblique
> Fibers orient cranioventrally
> Arises from the tuber coxae and thoracolumbar fascia
> Inserts on the last rib and the linea alba via an aponeurosis
> Cremaster muscle (caudal slip of the internal abdominal oblique)
What are the characteristics of the transversus abdominis?
Flat muscle
> Deepest abdominal muscle
> Arises from the inner surface of the last ribs and transverse processes of the lumbar vertebrae
> Fibers run transversely
> Terminates in an aponeurosis on the linea alba
What are the characteristics of the rectus abdominis?
Paired, long straight muscles extending from the sternum on either side of the linea alba to the pubis
> Lies between the aponeurotic sheaths of the oblique and transverse abdominal muscles
> “Six pack” in humans
Which of the four abdominal muscles includes the cremaster muscle?
Internal abdominal oblique
What is the holding layer when closing the abdominal wall during surgery?
External rectus sheath
What structures form the superficial inguinal rings?
Define: A slit in the aponeurosis of the external abdominal oblique muscle
> Lateral wall - aponeurosis of the external abdominal oblique
> Medial wall - transversalis fascia and a little of the internal abdominal oblique muscle
What structures form the deep inguinal rings?
> Cranial boundary - caudal border of the internal abdominal oblique
> Caudolateral boundary - inguinal ligament (external abdominal ligament)
> Medial boundary - lateral border of the rectus abdominis muscle
What 5 structures pass through the inguinal canal?
- External pudendal artery/vein
- Genitofemoral nerve
- Vaginal process (female)
- Spermatic cord (male)
- Cremaster muscle (male)
