BIOS 252 Week 1 Case Study: Muscle

Student Name

Chamberlain University

BIOS-252: Anatomy & Physiology II with Lab

Prof. Name:

Date

Muscles Severed During Amputation

The muscles severed during an amputation involving the wrist or forearm 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 crucial for wrist and finger movements, and their severance significantly impacts motor functionality and rehabilitation prospects.

Compromised Muscles Affecting Pronation

If a patient can no longer properly pronate the arm following an injury, the most likely compromised muscles are the Pronator Teres and the Pronator Quadratus. These muscles facilitate the inward rotation of the forearm, essential for various functional activities like turning a doorknob or using utensils.

Differences in Replantation Timeframes: Limbs vs. Fingers

A severed limb has a shorter window for successful replantation than a finger. This disparity arises from differences in tissue composition and metabolic demands. Fingers primarily consist of smaller muscles and fewer bones, typically one to three per digit. Conversely, an arm or wrist amputation involves larger muscles, a greater number of bones (e.g., the eight carpal bones), more nerve endings, and a larger surface area to repair. These factors result in higher metabolic demands, requiring more energy and resources for healing and replantation, which limits the viable time for surgical success.

Tissue Bridging Severed Muscle Bellies

When muscles are severed, ligaments and connective tissues often play a crucial role in bridging the gap between muscle bellies. Ligaments are strong, fibrous structures that connect bones and provide stability. In cases of muscle regrowth, two mechanisms—hypertrophy and hyperplasia—contribute to tissue repair. Hypertrophy involves an increase in the size of existing cells, while hyperplasia entails the proliferation of new cells. Together, these processes support the restoration of severed muscles and their attachment to surrounding anatomical structures (Leversedge, 2018; Luna, 2021).

Table Summary

Heading	Details	Examples
Muscles Severed During Amputation	Muscles affected include wrist and finger flexors and extensors.	Flexor Carpi Ulnaris, Extensor Carpi Ulnaris, Extensor Pollicis Longus.
Compromised Muscles for Pronation	Inability to pronate results from damage to pronator muscles.	Pronator Teres, Pronator Quadratus.
Tissue Repair and Growth	Ligaments and connective tissue bridge severed muscle bellies. Muscle repair occurs via hypertrophy and hyperplasia.	Ligaments stabilize bone connections. Hypertrophy increases cell size; hyperplasia increases cell count (Leversedge, 2018; Luna, 2021).

References

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