Coracobrachialis muscle variants in human fetuses

Area of Science:

• Human Anatomy
• Embryology
• Surgical Anatomy

Background:

• The coracobrachialis muscle is a key component of the upper arm.
• Variations in its anatomy can impact surgical procedures and nerve function.
• Understanding embryological development aids in explaining anatomical anomalies.

Purpose of the Study:

• To investigate the variability of the coracobrachialis muscle in human fetuses.
• To analyze the embryological and phylogenetic origins of these variations.
• To compare fetal coracobrachialis muscle variations with those found in adult populations.

Main Methods:

• Gross anatomical dissection of 140 human fetal upper limbs.
• Assessment of coracobrachialis muscle anatomy, including head number and origins.
• Evaluation of the musculocutaneous nerve's course relative to the muscle.
• Documentation of coexisting neural and muscular variants and morphometric details.

Main Results:

• Four distinct coracobrachialis muscle variants were identified based on the number of heads.
• Typical two-headed muscles occurred in 60.7% of specimens.
• One-, three-, and four-headed variants were observed, along with 9.29% instances of musculocutaneous nerve absence where the median nerve innervated the muscle.

Conclusions:

• The study identified four coracobrachialis muscle variants in fetuses, differing from three variants noted in adult studies.
• The anatomical variations of the coracobrachialis muscle and associated nerves hold significant clinical relevance.