BIOS 252 Week 1 Case Study: Muscle

Student Name

Chamberlain University

BIOS-252: Anatomy & Physiology II with Lab

Prof. Name

Date

Case Study Questions

Question 1: Name the muscles severed during the amputation event.

During the amputation, several muscles in the forearm and hand region were severed. These include the Flexor Carpi Ulnaris, Extensor Carpi Ulnaris, Extensor Digiti Minimi, Extensor Digitorum, Extensor Carpi Radialis Brevis, Extensor Pollicis Brevis, Extensor Pollicis Longus, and Extensor Indicis Proprius. These muscles are essential for wrist flexion, extension, and fine finger movements. Damage to these structures significantly impairs hand and wrist mobility, highlighting the severity of the injury.

Question 2: If the patient were no longer able to properly pronate his arm, which muscle do you think has been compromised?

If the patient is unable to pronate the arm effectively, it indicates potential damage to the Pronator Teres and the Pronator Quadratus. Both of these muscles play a critical role in forearm rotation. The Pronator Teres assists with quick pronation during forceful movements, while the Pronator Quadratus is essential for stabilizing and maintaining pronation during routine forearm motion. Injury to either or both can cause weakness and limited range of motion.

Question 3: Why does a patient with a severed limb have a smaller window of time for successful replantation compared to finger replantation surgery?

A complete limb amputation has a shorter viable timeframe for replantation than a finger amputation due to the greater anatomical and metabolic complexity. Limbs consist of larger muscles, more extensive bone structures, and higher numbers of blood vessels and nerve endings compared to fingers. The metabolic demands of an entire limb are significantly greater, causing ischemic tissues to deteriorate more rapidly. Therefore, the critical window for successful reattachment is smaller than for fingers, where tissue survival time is longer due to lower oxygen and nutrient demands.

Question 4: What tissue type can be found bridging the two halves of the once severed muscle bellies? Why?

When muscle bellies are severed, the tissue bridging them during the healing process primarily consists of scar tissue (fibrous connective tissue) rather than ligaments. Ligaments specifically connect bones, not muscle fibers. In muscle repair, fibroblasts produce collagen fibers that form scar tissue, which bridges the gap between severed ends. Over time, muscle regeneration occurs through hypertrophy (enlargement of muscle fibers) and limited hyperplasia (formation of new fibers). However, scar tissue often reduces elasticity and functional strength compared to original muscle tissue, which is why rehabilitation is essential after such injuries.

Case Study Questions in Table Format

Question	Answer
Name the muscles severed during the amputation event.	The severed muscles include: Flexor Carpi Ulnaris, Extensor Carpi Ulnaris, Extensor Digiti Minimi, Extensor Digitorum, Extensor Carpi Radialis Brevis, Extensor Pollicis Brevis, Extensor Pollicis Longus, and Extensor Indicis Proprius.
If the patient were no longer able to properly pronate his arm, which muscle do you think has been compromised?	The muscles likely compromised are the Pronator Teres and Pronator Quadratus, both essential for forearm pronation and stabilization.
Why does a patient with a severed limb have a smaller window of time for successful replantation compared to finger replantation surgery?	Limb replantation has a shorter timeframe due to larger muscles, complex vascular and neural structures, and higher metabolic demands, which increase the risk of tissue necrosis compared to finger tissues.
What tissue type can be found bridging the two halves of the once severed muscle bellies? Why?	Fibrous connective tissue (scar tissue) bridges severed muscle bellies. It forms as fibroblasts produce collagen during healing, while muscles attempt regeneration through hypertrophy and limited hyperplasia.

References

Leversedge, F. J. (2018). Wrist sprains. OrthoInfo. https://orthoinfo.aaos.org/en/diseases–conditions/wrist-sprains

Luna, D. (2021). Muscle hypertrophy vs hyperplasia: The difference explained. Inspire Us Foundation. https://www.inspireusafoundation.org/muscle-hypertrophy-vs-hyperplasia

BIOS 252 Week 1 Case Study: Muscle

Snyder, C. M., & Moore, K. L. (2020). Clinically oriented anatomy (8th ed.). Wolters Kluwer.