The Journal of Bone and Joint Surgery (American). 2007;89:1293-1297.
doi:10.2106/JBJS.F.00343
© 2007 The Journal of Bone and Joint Surgery, Inc.
Brachialis Muscle AnatomyA Study in Cadavers
Domenic T. Leonello, MBBS1,
Ian J. Galley, MBchB2,
Gregory I. Bain, MBBS, FRACS(Orth)3 and
Christopher D. Carter, MBBS4
1 302/211 Grenfell Street, Adelaide SA 5000, Australia
2 Tauranga Hospital, Cameron Road, Private Bag 1204, Tauranga, New Zealand
3 196 Melbourne Street, North Adelaide SA 5006, Australia. E-mail address:
greg{at}gregbain.com.au
4 Level 1, 178 Fullarton Road, Dulwich SA 5065, Australia
Investigation performed at the University of Adelaide, Adelaide,
Australia
Disclosure: The authors did not receive any outside funding or
grants in support of their research for or preparation of this work. Neither
they nor a member of their immediate families received payments or other
benefits or a commitment or agreement to provide such benefits from a
commercial entity. No commercial entity paid or directed, or agreed to pay or
direct, any benefits to any research fund, foundation, division, center,
clinical practice, or other charitable or nonprofit organization with which
the authors, or a member of their immediate families, are affiliated or
associated.
Background: There have been conflicting descriptions of brachialis
muscle anatomy in the literature. The purpose of the present study was to
clarify brachialis muscle anatomy in order to refine surgical techniques
around the elbow.
Methods: Eleven cadaveric upper limbs were dissected under loupe
magnification. The gross morphological characteristics, relationships, and
nerve supply of the brachialis muscle were recorded. The nerve supply was
examined histologically to confirm the gross findings.
Results: In all specimens, the brachialis muscle had two heads. The
larger, superficial head originated from the anterolateral aspect of the
humerus, proximal to the smaller, deep head. The superficial head contained
longitudinal fibers, which inserted by means of a thick round tendon onto the
ulnar tuberosity. The deep head fibers were fan-shaped and converged to insert
by means of an aponeurosis onto the coronoid process. In all specimens, a
branch of the radial nerve supplied the inferolateral fibers of the deep
head.
Conclusions: Our observations of brachialis muscle anatomy differ
considerably from the descriptions in the current literature. The larger,
superficial head has the mechanical advantage of a more proximal origin and a
more distal insertion, which may enable it to provide the bulk of flexion
strength. The smaller, oblique, deep head has a more anterior insertion on the
coronoid, which may facilitate the initiation of elbow flexion from full
extension. The radial nerve-innervated inferolateral fibers of the deep head
run in a direction similar to the anconeus muscle, forming a muscular sling
around the elbow. This complex may act to dynamically stabilize the
ulnohumeral joint.
Clinical Relevance: This information may enhance surgical techniques
about the elbow. The identification of an internervous plane may allow for
improvement in the current anterior and anterolateral surgical approaches to
the humerus. The tendon of the superficial head is well positioned to allow
its transfer to the radial tuberosity, potentially improving supination
strength in the absence of a distal biceps tendon. It is possible that the
tendon of the superficial head might also be used to reconstruct the anular
ligament or the medial collateral ligament of the elbow.

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