:Acta . Ndurochlrurgica

Acta Neurochir (Wien) (1994) 130:144-146

9 Springer-Verlag 1994 Printed in Austria

Hypophyseal Ligaments J. Lang Department of Anatomy, University of Wiirzburg, Federal Republic of Germany

Summary

Results

Described are for the first time: a. Posterolateral hypophyseal ligament which is seen in most dissections b. Anterolateral ligament which is always developed c. A middle superior ligament d. Inferior anterior and e. inferior posterior hypophyseal ligament

Histological sections as well as microanatomical observations show, that the hypophyseal ligaments consist of collagen fibre bundles which connect the hypophyseal capsule with the endocranium of the hypophyseal fossa at the anterior and posterior side of the inferior intercavernous sinuses. Other ligaments connect the capsule with the connective tissue around the internal carotid arteries (ICA) in the syphon area and with other parts of the internal carotid arteries. Further ligaments extend at the transition area between these anterior and posterior sinusoideal loopes and extend posterolaterally to the connective tissue around the I C A and the sphenoid bone. The ligaments can be classified according to the place of their localisation:

Keywords: Hypophyseal ligaments; surgical anatomy. Introduction In 1985 the Hypophyseal Region was extensively described in " A n a t o m y of the Operative Approaches ''3. At this time and for this question the hypophyseal capsule and the endocranium of the pituitary fossa were emphasized. During the last year some additional hypophyses have been dissected from medially to have a look at structures at the inferior and lateral side of the hypophyseal capsule. To our astonishment some ligaments of the hypophyseal capsule could be found. These ligaments have been demonstrated at the Neurosurgical Course in Hannover, December 1993. Since these ligaments were unknown to most of the neurosurgeons and since they have not yet been described in the neurosurgical or anatomical literature, it seems to be worthwhile to present a description.

Material and Technique Dissections have been made in three cadavers from the medial side in median saginal sections. The hypophysis was at first freed from the lower side, then at the anterolateral and at the posterolateral and at the lateral side. Afterwards it was mooved upwards into the area of the subarachnoid space. All connections between the hypophyseal capsuleand the neighbouring structures have been noticed and documented. In addition, previous material of our laboratory was studied again with special regard to these ligaments.

1. Posterolateral Ligament The ligament arises from the transition between the anterior and posterior lobes and extends posterolaterally. Its length was measured with 2-4 mm, its thickness with 1-2ram (Fig. 1). The course of the ligament is mostly behind the inferior hypophyseal artery.

2. Anterolateral Ligament (Fig. 2) The ligament connects the anterior part of the hypophyseal capsule around the inner side of the anterior intercavernous sinus with the connective tissue around the internal carotid artery. It is 1-2 m m long.

3. Middle Superior Ligament (Fig. 1) The ligament connects the middle part of the hypophyseal capsule and the endocranium with the sagittal cavernous part of the internal carotid artery. It

J. Lang: Hypophyseal Ligaments

Fig. 1. Hypophyseal ligaments at a transverse section from below. i Mm-paper at the apertures of the sphenoid sinus; 2 optic nerve, dissected; 3 dura mater of planum sphenoidale, removed; 4 syphon of ICA; 5 hypophyseal capsule, mm-paper, and anterior intercavernous sinus; 6 anterolateral and middle superior hypophyseal ligaments and posterior lobe of hypophysis; 7 posterolateral ligament of hypophysis; 8 sphenoid bone

measures as a rule 1 . 5 m m in length and 1 1/amm in thickness.

4. Inferior Anterior Hypophyseal Ligament (Fig. 3) This ligament connects the hypophyseal capsule with the e n d o c r a n i u m below the anterior intercavernous sinus. It measures 2-3 m m in length and 1 m m in width.

5. Inferior Posterior Ligament (Fig. 3) The ligament extends between the hypophyseal capsule and the e n d o c r a n i u m posterior to the inferior intercavernous sinus area and to the endocranium.

145

Fig. 2. Coronal section through the anterior lobe (50 y, male, Ladewig). Anterolateral ligament; internal carotid artery, intracavernous and first subarachnoid part. 1 Anterior clinoid process, mmpaper; 2 IIIrd nerve; 3 IVth nerve; 4 ophthalmic nerve; 5 VIth nerve; 6 maxillary nerve; 7 blood spaces of cavernous sinus; 8 ant. cavern. bend of ICA; 9 lat. recess of sphenoid sinus; 10 fixation of ICA on transition zone (connective tissue); 11 endocranium (dislocated) and anterolateral ligament; 12 adenohypophysis and sphenoid sinus

Discussion Dolenc in 19891 described f.e. the proximal and distal rings in the cavernous sinus. In 1993 1 demonstrated (Figs. 2.43 and 2.44 in K o o s et al}) a ligament lateral to the internal carotid artery between the proximal ring and the apex area o f the petrous part of the temporal bone< These ligaments are connected with the ligaments, described in the present paper, by connective tissue strands. In the transnasal-transsphenoidal a p p r o a c h to the hypophysis, following removal o f the anterior b o n y wall o f the sella and before opening the capsule of the hypophysis, the inferior anterior and the inferior posterior ligaments have to be dissected. I f the inferior b o n y wall is removed also the other ligaments m a y be

146

J. Lang: Hypophyseal Ligaments

Fig. 3. Hypophysis, viewed from medial, dissected and removed upwards, inferior ligaments dissected. I Sphenoid sinus and tuberculnm sellae; 2 hypophyseal fossa and diaphragma sellae; 3 inferior anterior hypophyseal ligament, cut; 4 hypophysis displaced, inferior hypophyseal artery and ICA; 5 inferior posterior ligament and rampaper; 6 posterior lobe of hypophysis, displaced upwards and posterior communicating artery; 7 oculomotor nerve; 8 basilar artery

dissected. It should be n o t e d t h a t the a n t e r i o r lateral, the m i d d l e superior a n d the posterior lateral ligaments are c o n n e c t e d with the connective tissue a r o u n d the i n t e r n a l carotid artery a n d therefore also with the medial wall of the c a v e r n o u s sinus.

Acknowledgement Professor Dr. H.-D. Herrmann for the literature search and the relevant discussions.

References 1. Dolenc VV (1989) Anatomy and surgery of the cavernous sinus. Springer, Wien New York 2. Koos WT, Spetzler RF, Lang J (1993) Color atlas of microneurosurgery, vol 1. Intracranial tumors. Thieme, Stuttgart 3. Lang J (1985) Hypophyseal region-anatomy of the operative approaches in neurosurgical review, de Gruyter, pp 93-124 Correspondence: J. Lang, M.D., Koelliker-Strasse 6, D-97070 Wiirzburg, Federal Republic of Germany.