Exam 2 (Lecture 1) - Thoracic Cavity Flashcards
What does the thoracic region correspond to?
Where the ribs are located.
Describe the shape of the vertebral bodies as we move cranially.
They are directed ventrally as we move cranially.
Describe the orientation of the spinous processes as we move cranially.
The spinous processes get longer as we move cranially.
Why do the spinous processes get longer as we move cranially?
There needs to be more surface area for epaxial muscle attachment and this orientation provides that surface area.
Does the thoracic limb cover any of the thoracic cavity?
Yes, a fair amount cranially.
What does the point of elbow (olecranon process) correspond to?
The 5th rib or 5th intercostal space.
In large animals, what is the muscle attachment called that attaches the thoracic limb to the body wall?
Muscles of synsarcosis.
What percentage of body weight is carried on the thoracic limb? Provide and example.
About 60% of their body weight is carried on the thoracic limb (and 40% on the pelvic limb).
If a cow weighs 1500 lbs, she’s carrying 900 lbs on her front end; or 450 pounds on each thoracic limb
What are the EXTRINSIC muscles of synsarcosis?
1) Trapezius cervicis
2) Trapezius thoracic
3) Omotransversarius
4) Cleidooccipitalis
5) Cleidomastoideus
6) Latissimus dorsi
What are the INTRINSIC muscles of synsarcosis?
1) Subclavius (largest in the pig and the horse; thin in cattle)
2) Pectoral muscles
- Ascending (deep) pectoral
- Superficial pectorals (transverse and descending)
3) Serratus ventralis cervicis
4) Serratus ventralis thoracis
5) Rhomboideus cervicis
6) Rhomboideus thoracis
What is the superficial vein on the thoracic cavity (caudal to the olecranon process) and what is its clinical significance?
1) In cattle, it’s called the superficial thoracic vein
2) In horses, it’s called the spur vein
3) We utilize it as a site for blood draws in horses (not so much in cattle)
Which INTRINSIC muscle of snysarcosis are the most significant in the attachment of the thoracic limb to the body wall?
1) Pectoral muscles
2) Serratus ventralis
What happens to the shape of the thoracic cavity as we move cranially?
It gets narrow (so, the thoracic cavity is triangular shaped)
What are the boundaries of the thoracic cavity?
1) Dorsal Boundary: thoracic vertebrae
2) Lateral Boundaries: ribs and costal cartilage (each pair of ribs will articulate with a different vertebrae)
3) Ventral Boundary: sternum
In the newborn animal, what is the sternum comprised of? Are any still visible in the adult?
1) Sternebrae (fuse to form the sternum)
2) Yes; in the adult we have the manubrium sterni and the xyphoid process of the sternum
What are true ribs?
True ribs are the sternal ribs; they join the coastal cartilage ventrally and is then connected to the sternum.
What are false ribs?
False ribs are the asternal ribs; the costal cartilage from multiple asternal ribs forms the costal arch (so the rib is connected to the costal arch, NOT the sternum).
How many cervical vertebrae are there?
7 in ALL species.