Proximal Attachment Of A Muscle

Introduction

The adductor grouping of thigh muscles occupies the medial myofascial compartment of the thigh. This group of muscles, in general, takes origin from the pelvis and inserts on the femur. Every bit is often the case, exceptions exist to the compartment generalizations; the gracilis, rather than attaching to the femur, attaches to the proximal medial tibia as part of the pes anserine group. The medial compartment muscles include pectineus, adductor longus, adductor brevis, gracilis, and the largest of the grouping, adductor magnus. These muscles all serve as adductors of the thigh and besides serve as important stabilizers of the pelvis and work to maintain the residue of the pelvis on the lower limb during gait. The nerve supply to nigh muscles in this compartment is the obturator nerve, which arises from the lumbar plexus from nerve roots L2-4. The adductor magnus is the largest of the medial compartment muscles; it is the most posterior of the group. Some consider information technology the virtually powerful and the well-nigh circuitous of the adductor grouping. Adductor magnus will be the focus of this commodity. This musculus's complexity is in part derived from the fact that information technology divides into an adductor (pubofemoral) portion and a hamstring (ischiocondylar) portion.[1]

Construction and Function

The adductor magnus is described as a large triangular musculus with a proximal tendinous attachment to the inferior ramus of the pubis, the ramus of the ischium, and the ischial tuberosity. The part of the muscle that is considered the adductor portion has its proximal zipper on the inferior ramus of the pubis and the ramus of the ischium. The part of the muscle considered the hamstring portion has its proximal attachment on the ischial tuberosity. Each portion of the muscle has separate and distinct distal attachment points.

The adductor portion of the adductor magnus can be divided into two parts, a more superior part that originates on the ramus of the pubis and the lower segment, which arises from the ramus of the ischium. The smaller, more than horizontal portion from the pubis inserts on the medial side of the gluteal tuberosity, medial to the zipper of gluteus maximus. This portion of the muscle is in a plane that lies more inductive to the rest of the muscle and has likewise been termed the adductor minimus muscle by some authors. The larger portion arises from the ramus of the ischium and extends laterally to insert into a broad aponeurosis on the linea aspera and the proximal portion of the medial supracondylar line of the femur. This larger portion of the musculus contains five fibrous openings that are maintained by tendinous arches. The more superior four openings, being pocket-sized, permit the perforating branches and the terminal portion of the profunda femoris artery to pass into the posterior compartment of the thigh. The larger fifth opening, known equally the adductor hiatus, allows for the passage of the femoral vessels from the adductor canal into the popliteal fossa. The distal attachment of the adductor portion of the adductor magnus on the linea aspera blends with the proximal attachment of the short head of the biceps femoris muscle. This blending creates the ability of the 2 muscles to work in a coordinated fashion as a stabilizer of the femur and pelvis. The adductor portion of the adductor magnus is innervated by the posterior partitioning of the obturator nerve (L2,3,4).

The hamstring portion of the adductor magnus is so named due to the similarity in construction, proximal zipper, and innervation to the hamstring muscles. This portion of the adductor magnus is near vertical in orientation every bit it extends from the ischial tuberosity to the adductor tubercle on the medial femoral condyle and through fibrous attachments to the supracondylar line of the femur. This portion of the muscle is innervated by the tibial portion of the sciatic nerve (L4).

The two parts of the musculus have similar and also differing deportment equally both portions of the muscle are adductors of the thigh. The adductor portion of the adductor magnus, likewise adduction, too flexes the thigh while the hamstring portion adducts only extends the thigh. The two portions of this musculus also office synergistically during the gait cycle and control the pelvis for posture.[2]

An commodity past Takizawa et al. examined the adductor magus of 10 limbs from embalmed cadavers. Based on the location of the perforating arteries, divided the musculus into 4 divisions rather than the three noted above. In their study, the authors noted that the function of the "adductor portion" that inserted on the inferior portion of the linea aspera and originated from the inferior ramus and ischial tuberosity (labeled AM3 in their report) received innervation from both the posterior division of the obturator nerve and the tibial portion of the sciatic nerve. In addition, the authors noted that the most proximal portion of the muscle has a different cobweb morphology than the residue of the muscle, making this uppermost segment of the muscle more suitable for stabilization activities. In dissimilarity, the residuum of the muscle with longer muscle fibers length is more functionally related to muscles such every bit semitendinosus and is suited for moving the lever arm of the thigh through a larger range of motility.[3] Furthermore, Takizawa et al. completed a secondary study that included 21 embalmed cadaveric limbs and found over 90% of the adductor portion (AM3) samples were supplied past both nerves. The authors besides demonstrated all parts of the adductor magnus, except for the uppermost segment of the adductor portion, had dual innervation in at least some specimens.[4]

Due to the depth of the adductor portion of the adductor magnus, surface EMG studies of this large portion of the muscle (approximately 70% of the muscle) are rare. Rather, nigh studies of the adductor magnus focus on the hamstring portion as it is accessible for surface EMG assay. This muscle can potentially affect postural control of the pelvis and lower extremity during the gait bike nevertheless is largely unstudied.

Embryology

The embryologic development of the adductor group is first evident in the proximal region of an xi mm embryo with separation into independent masses for the unlike muscles of the group, including the adductor portion of the adductor magnus. When the embryo reaches fourteen mm in length, the separate muscles are axiomatic, but their tendons are not clearly separable. Concurrently, the hamstring portion of the adductor magnus differentiates from the musculus blastema of the dorsal thigh closely associated with that from which the semimembranosus muscle develops. As the embryo reaches a length of 20 mm, the muscles of the adductor compartment and those in the posterior thigh compartment, forth with their tendinous skeletal attachments, are clearly discernable—the adductor and hamstring portions of the adductor magnus fuse at this point in development. The nerves to both portions of the adductor magnus develop from the anterior division of the lumbosacral plexus, which suggests that both developmentally have a primitive flexor origin.

Blood Supply and Lymphatics

The obturator artery, a branch of the internal iliac artery, passes from within the pelvis through the obturator foramen to enter the medial compartment of the thigh and supplies the muscles in this compartment, though the claret supply to the adductor magnus is derived from many additional vessels every bit well. As the perforating branches of the profunda femoris avenue pass through the adductor magnus, they also are the primary source of the blood supply to the musculus. As with the other adductor muscles, the medial femoral circumflex avenue supplies the superior portion of the muscle. The inferior portion of the musculus volition exist supplied via the femoral artery, the popliteal avenue, and the genicular arteries. Adductor magnus receives vascular supply from both its anterior and posterior surfaces.[5]

Lymphatic vessels from the adductor compartment muscles, including the adductor magnus, will drain into the deep inguinal lymph nodes located in the medial compartment of the femoral sheath of the femoral triangle.

Nerves

The fretfulness that supply the adductor magnus musculus have an embryologic origin from the anterior divisions of the lumbosacral plexus and include the obturator nerve, posterior partitioning (L2-4), and the tibial portion of the sciatic nervus (L4). Studies past Takizawa et al. accept challenged the long-held belief that the adductor portion is supplied by the posterior sectionalization of the obturator nerve, while the hamstring portion receives its supply from the tibial portion of the sciatic nerve.[iii][4]

Physiologic Variants

In a 2011 report past Tubbs RS et al., the authors dissected 20 developed cadavers and v fetuses looking for the presence of adductor minimus. The study revealed that approximately half of the adult (52.5%) and all fetal dissected limbs demonstrated an adductor minimus musculus separate from the adductor magnus muscle and five others where the adductor minimus was partially fused to the adductor magnus muscle. This study as well determined that when the adductor minimus was absent or underdeveloped, the quadratus femoris muscle extended more inferiorly, but a fascial layer maintained the separation of the two muscles.[3] In an earlier study, Tubbs et al. also noted that a vastoadductor membrane, part of the intermuscular septum, can exist between the vastus medialis and the adductor magnus. The femoral artery may undergo pinch by this membrane prior to the artery passing through the adductor canal.[6]

Equally previously indicated, a study by Takizawa et al. found that the adductor portion of the muscle that inserts most distally on the femur obtains innervation from the posterior segmentation of the obturator nervus and the tibial portion of the sciatic nerve.[iii] Other parts of the muscle may besides take dual innervation.[4]

Surgical Considerations

Obey et al.[7] studied the proximal attachments of the hamstrings and adductor magnus on the ischial tuberosity on cadaveric specimens. Avulsion injuries of the hamstrings tendon from the ischial tuberosity are increasingly recognized as injuries in athletic populations that do non respond well to conservative treatment, take poor outcomes, and are recommended for prompt surgical repair. An intact adductor magnus may mask a complete avulsion of the hamstring tendons on MRI evaluation as it appears to be an "intact but adulterate semimembranosus tendon." The authors state an intact adductor magnus may result in a misdiagnosis of patients as having only a fractional tear rather than a complete avulsion injury. They conclude that the adductor magnus is located medial to the hamstring origins on the ischial tuberosity. In some specimens, it was a sizable structure that may lead to some of the problems associated with MRI imaging of this surface area.[5]

Agreement the anatomical relationships between the adductor magnus and the hamstring tendons is crucial for appropriate diagnosis and surgical vs. bourgeois handling of injuries in this area. Cognition of the origin of the adductor on the ischial tuberosity tin can aid the surgeon in the appropriate anatomical repair of avulsion injuries of the hamstring muscles. As indicated in a study past Broski et al., radiologists likewise need to exist aware of the presence of the adductor magnus tendon on the ischial tuberosity when visualizing the ischial tuberosity on MRI to avoid confusion during diagnostic studies.[8]

Clinical Significance

A study past Arnold and Delp studied the contribution of the medial hamstrings and adductor muscles in the crouched, internally rotated gait of individuals with cerebral palsy to determine how these muscles contributed to the internal rotation seen with this gait pattern.[9] The medial hamstrings, adductor brevis/longus/hamstring portion of magnus muscles in upright standing, and normal femoral anteversion were found to have a slight internal rotation moment arm, the proximal adductor magnus and gracilis also had a minor medial rotation moment arm, and the middle and distal segment of the adductor portion of magnus had a negligible rotational moment arm. Yet, the study found that with hip anteversion greater than 20 degrees, or human knee flexion greater than approximately 30 degrees, the moment arms of these muscles inverse, and virtually became more externally biased. This finding is an of import consideration when assessing the strategies for the improvement of gait in these individuals. Intendance must be exercised when treating muscles around the hip, as positional differences can influence muscular function.[10]

Other Issues

The adductor magnus muscle is both a dynamic stabilizer of the pelvis and femur besides as a prime mover of the femur into adduction. The adductor magnus can be likened to the deltoid muscle; one portion flexes the thigh and works as a medial rotator while the other extends the thigh and is a lateral rotator, and both portions adduct the thigh. This is similar to the anterior (flexor/medial rotator/abductor) and posterior (extensor/lateral rotator/abductor) actions of the deltoid. The curvilinear attachment of the adductor magnus on the pelvis is also reminiscent of the curvilinear attachment of the deltoid on the spine of the scapula, acromion, and clavicle. Additionally, both muscles serve every bit dynamic stabilizers of the ball and socket joints with which they are associated, shoulder or hip, respectively. This comparison may aid students in making the correlations between the functions of the upper and lower extremities.

Review Questions

Figure

Medial Compartment of the Thigh, Pubis, Femur, Obturator Externus, Adductor Magnus; Brevis; Longus,. Contributed Past Gray's Beefcake Plates

References

1.: Ransom AL, Sinkler MA, Nallamothu SV. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): Oct half-dozen, 2021. Beefcake, Bony Pelvis and Lower Limb, Femoral Muscles. [PubMed: 29763184]
ii.: Benn ML, Pizzari T, Rath L, Tucker 1000, Semciw AI. Adductor magnus: An EMG investigation into proximal and distal portions and management specific activity. Clin Anat. 2018 May;31(iv):535-543. [PubMed: 29520841]
3.: Takizawa Thou, Suzuki D, Ito H, Fujimiya Chiliad, Uchiyama E. Why adductor magnus muscle is large: the role based on muscle morphology in cadavers. Scand J Med Sci Sports. 2014 Feb;24(1):197-203. [PubMed: 22537037]
4.: Takizawa Yard, Suzuki D, Ito H, Fujimiya M, Uchiyama E. The adductor part of the adductor magnus is innervated by both obturator and sciatic nerves. Clin Anat. 2014 Jul;27(v):778-82. [PubMed: 23813615]
v.: Kalinin RE, Suchkov IA, Klimentova ÉA, Shanaev IN. [Clinical beefcake of deep femoral vessels in the area of femoral triangle]. Angiol Sosud Khir. 2021;27(1):17-23. [PubMed: 33825724]
6.: Tubbs RS, Loukas M, Shoja MM, Apaydin N, Oakes WJ, Salter EG. Anatomy and potential clinical significance of the vastoadductor membrane. Surg Radiol Anat. 2007 Oct;29(7):569-73. [PubMed: 17618402]
7.: Obey MR, Broski SM, Spinner RJ, Collins MS, Krych AJ. Anatomy of the Adductor Magnus Origin: Implications for Proximal Hamstring Injuries. Orthop J Sports Med. 2016 Jan;4(1):2325967115625055. [PMC costless commodity: PMC4714133] [PubMed: 26798764]
8.: Broski SM, Murthy NS, Krych AJ, Obey MR, Collins MS. The adductor magnus "mini-hamstring": MRI appearance and potential pitfalls. Skeletal Radiol. 2016 Feb;45(two):213-9. [PubMed: 26554947]
9.: Arnold As, Delp SL. Rotational moment arms of the medial hamstrings and adductors vary with femoral geometry and limb position: implications for the treatment of internally rotated gait. J Biomech. 2001 Apr;34(4):437-47. [PubMed: 11266666]
x.: Hammond KE, Kneer L, Cicinelli P. Rehabilitation of Soft Tissue Injuries of the Hip and Pelvis. Clin Sports Med. 2021 Apr;40(2):409-428. [PubMed: 33673896]