The venous circle of Trolard.

A venous anastomotic network is occasionally found at the base of the brain, which closely resembles the vicinal arterial circle of Willis. When present, this venous polygon is composed of the anterior cerebral and communicating veins, the basal vein of Rosenthal and the posterior communicating and lateral mesencephalic veins. We propose that this anastomotic ring be termed the venous circle of Trolard. This venous circle might cause bleeding with such procedures as an endoscopic third ventriculostomy. We believe that information regarding this venous circle may be useful to neuroradiologists or neurosurgeons operating at the base of the brain (Fig. 1, Ref. 10). Full Text (Free, PDF) www.bmj.sk.

Indirect inguinal hernia of the urinary bladder through a persistent canal of Nuck: case report.

We report a 79-year-old female cadaver found to harbor an indirect inguinal hernia involving the urinary bladder. Further investigation revealed a patent canal of Nuck. The authors describe this rare finding in an adult and review the pertinent literature regarding such herniation. We believe this to be the first report of an indirect inguinal hernia involving the urinary bladder in a cadaver. This also seems to be the first description of such a hernia via a patent canal of Nuck in an adult.

An unusual muscular variation of the infratemporal fossa.

The infratemporal fossa is often the site of pathology or surgical intervention. We describe an unusual muscle found during the routine dissection of the right infratemporal fossa. The literature germane to this variable muscle, best described as a variant of the pterygoideus proprius, is reviewed. The clinician may contemplate the wide array of muscular anomalies within the infratemporal fossa when considering unexplained neurological symptoms attributed to branches of V3 and pursue appropriate diagnostic testing.

The subanconeus muscle.

There is a paucity of information in the extant literature regarding the detailed anatomy of the subanconeus (articularis cubiti) muscle. Our current study seeks to elucidate further the presence, morphology, and potential function of this muscle. Eighteen cadaveric upper extremities underwent dissection of their posterior elbow joint capsule with special attention to any fibres attaching to it from the triceps brachii muscle. We found that all specimens had various amounts of muscular attachment of the medial head of the triceps into the posterior joint capsule. It was noted that the highest concentration of fibres was into the joint capsule near the groove for the ulnar nerve. No specimen was found to have a distinct muscle belly associated with these connections to the joint capsule. On all sides these fibres were simply deeper attachments of the medial head of the triceps brachii muscle. Following tension on these deeper fibres retraction of the joint capsule was not noted but rather compression of the capsule. We would speculate on the basis of our study that these fibres of the medial head of the triceps brachii muscle do not represent a separate muscle per se and do not retract the posterior elbow joint capsule with extension of the forearm as has been theorised. It is possible that compression of the posterior elbow joint capsule from these deeply placed fibres of the triceps brachii restricts the elbow fat pad from being displaced and allows it to cushion the contact made between the olecranon process and the olecranon fossa.

Klippel-Feil anomaly with associated rudimentary cervical ribs in a human skeleton: case report and review of the literature.

Anomalies of the cervical spine are intriguing anatomically and often come to clinical attention. Fusion of one or more cervical vertebral segments, the Klippel- Feil anomaly (KFA), often causes increased motion at the vertebral segments superior to and inferior to the fused level with a resultant premature wear of these joints. We report an adult male skeleton with fusion of his C6 and C7 vertebral bodies (Type II KFA). A remnant of the intervertebral disc space was noted and bilateral rudimentary cervical ribs were observed emanating from the C7 vertebrae. Excessive joint degeneration was noted between the vertebral bodies of C5 and C6. Following our review of the literature and case report, it appears that there is an increased incidence of the presence of cervical ribs in KFA. We review the literature for coexistent KFA and cervical ribs and discuss their dysembryology.

An unusual muscle of the wrist with potential compression of the ulnar nerve.

During routine cadaveric dissection of the upper extremity an unusual muscle was discovered arising from the tendon of the flexor carpi ulnaris and inserting into the muscle belly of the flexor digiti minimi. The muscle's course was superficial to the ulnar nerve and artery in Guyon's canal. We review the literature regarding such muscle variations and discuss the potential for compression of the ulnar nerve by such muscles.

Bilateral accessory middle cerebral arteries associated with an aneurysm of the anterior circulation.

An accessory middle cerebral artery is one variation of the intracranial vasculature that may be a source of misinterpretation by clinicians dealing with cerebrovascular diseases. We report a case of an elderly female found to have bilateral accessory middle cerebral arteries, who presented with the rupture of an aneurysm of the anterior part of the circle of Willis. Accessory middle cerebral arteries are rare anatomical findings and the bilateral occurrence is exceedingly rare. We believe this to be the first report of bilateral accessory middle cerebral arteries associated with an aneurysm of the anterior cerebral-anterior communicating arteries. The anatomical and clinical relevance of this variation is described.

Does a third head of the rectus femoris muscle exist?

Current anatomical texts describe only two tendinous origins of the rectus femoris muscle. The authors identified one older reference in which a third head of the rectus femoris muscle was briefly described. In order to confirm the existence of this head, 48 adult cadavers (96 sides) underwent detailed dissection of the proximal attachments of the rectus femoris muscle. Of these sides 83% were found to harbour a recognised third head of the rectus femoris muscle. This additional head was found to attach deeply to the iliofemoral ligament and superficially with the tendon of the gluteus minimus muscle as it attached into the femur. This tendon attached to the anterior aspect of the greater trochanter in an inferolateral direction compared to the straight head. The mean length and width of the third head was 2 cm and 4 cm, respectively. The mean thickness was found to be 3 mm. Most commonly this third head was bilaterally absent or bilaterally present. However, 4.2% were found only on left sides and 5.2% were found only on right sides. The angle created between the reflected and third heads was approximately 60 degrees. Two sides (both left sides with one female and one male specimen) were found to have third heads that were bilaminar. These bilaminar third heads had a distinct layer attaching to the underlying iliofemoral ligament and a superficial layer blending with the gluteus minimus tendon to insert onto the greater trochanter. Although the function of such an attachment is speculative, the clinician may wish to consider this structure in the interpretation of imaging or in surgical procedures in this region, as in our study it was present on the majority of sides.

The morphology and function of the quadrate ligament.

There is a paucity of information in the literature regarding the quadrate ligament and the information that does exist is extremely conflicting. We dissected 30 cadavers (60 sides) to determine the morphology and function of this enigmatic ligament. A quadrate ligament (thickening of the elbow joint capsule) was found in all specimens. In all specimens this band was distinct from the circumferential fibres of the annular ligament. The length, width, and thickness of the quadrate ligament were found to be 11 mm, 8 mm, and 1 mm respectively. This ligament not only aided in securing the neck of the radius to the ulna but also resisted excessive supination and, to a lesser degree, pronation of the forearm. Following transection of the quadrate ligament, the head of the radius was secured to the ulna considerably less firmly and supination and pronation increased by 10 to 20 degrees and 5 to 8 degrees respectively. The quadrate ligament contributes to proximal radioulnar stability, limits the "spin" of this joint, and should be considered in manipulation, surgery, or imaging of the proximal forearm.

Quantitative anatomy of the posterior cricoid region.

The anatomy of the posterior cricoid cartilage region was examined to obtain a better quantitative understanding of this region. The mean height and width of the posterior cricoid cartilage in the midline measured 24.5 mm and 25 mm respectively. The mean distance between the fibres for the left and right posterior cricoarytenoid muscles was 5 mm at the midpoint of the posterior cricoid cartilage. The height of these muscles averaged 19 mm for left sides and 20 mm for right sides. The mean distances from the midpoint and superior midline of the posterior cricoid cartilage to the inferior laryngeal nerve were 14 mm and 15 mm respectively for left sides and 17 mm and 18 mm respectively for right sides. It is hoped that these data will be of use to clinicians performing invasive procedures in this area.

The results of compression forces applied to the isolated human calvaria.

Data for the force necessary to fracture the isolated calvaria (skull cap) are not available in the extant literature. Twenty dry adult calvaria were tested to failure quasistatically at the vertex using a 15-kN load cell. The forces necessary to fracture or cause diastasis of calvarial sutures were then documented and gross examination of the specimens made. Failure forces had a mean measurement of 2772 N. Initial fractures did not cross suture lines. Prior to complete destruction of the calvaria there were 7 specimens in which all sutures of the calvaria became diastatic, 6 specimens in which the calvaria became diastatic along only the coronal sutures, 2 specimens in which the calvaria became diastatic along only the sagittal suture and 5 specimens in which there were diagonal linear parietal bone fractures. Our hopes are that these data may contribute to the structural design of more safer protective devices for use in our society, assist in predicting injury and aid in the construction of treatment paradigms.

Anatomical observations on the acromioclavicular joint and supporting ligaments.

An anatomical study of the acromioclavicular (AC) joint and its supporting ligaments was performed using both macroscopic and microscopic methods. The project used 63 cadaver shoulders of unknown ages. Fifty-three joints were used for macroscopic and 10 for microscopic study. The data consisted of micrometer measurements of the dimensions of the extrinsic and intrinsic ligaments of the AC joint; measurement and description of the intraarticular meniscus and the superior and inferior capsular ligaments of the AC joint; and the anatomical course and relationship of the coracoacromial (CA) ligament to the supporting ligaments of the AC joint and a description of its insertion on the acromion process. The following observations were made: The coracoclavicular ligament, especially the trapezoid ligament, provides significant soft tissue restraints to upward displacement of the clavicle. A complete AC joint disc was found in only one, meniscoid discs in 25, remnants of discs in 16, and no discs in 11 of the 53 joints studied macroscopically. (No age correlation was made since the ages of the cadavers were unknown). The CA ligament interconnects with the inferior capsular ligament of the AC joint as well as with the coracoclavicular and coracohumeral ligaments. It also has a broad area of insertion on the inferior acromial surface. The CA ligament appears to function as a buffer between the acromion and the rotator cuff, and to provide support for the AC joint. Transection of the CA ligament may result in loss of this buffering function.

Hyoid bone syndrome: a degenerative injury of the middle pharyngeal constrictor muscle with photomicroscopic evidence of insertion tendinosis.

This article describes the condition known as hyoid bone syndrome, its diagnosis by exclusion, and the histopathologic evidence of focal, degenerative muscle injury. The injury involves the origin fibers of the middle pharyngeal constrictor muscle on the greater cornu of the hyoid bone. The importance of the dentist and physician in recognizing the condition is emphasized, because dental and nondental pain reference sites make up the syndrome.

Photomicrographic evidence of insertion tendonosis: the etiologic factor in pain for temporal tendonitis.

A patient with the classic signs and symptoms of temporal tendonitis was treated with excisional surgery of the temporal tendon and its respective mandibular coronoid process. The excised tissue was submitted to pathology for microscopic analysis, and the results were confirmed by two pathologists. Degenerative signs of focal atrophy and tissue necrosis were evident and served to describe the focal nature of the painful condition of temporal tendonitis. The description for the pain pattern is given, along with the recommended method for diagnostic testing. The current method of surgical management using radiofrequency thermal ablation is described, which replaces the more tissue-destructive, excisional approach.