OCCIPITAL AREA

From Big Medical Encyclopedia

OCCIPITAL AREA [regio occipitalis (PNA, JNA, BNA)] — the back department of the head corresponding to an upper half of scales of an occipital bone. In front borders on parietal area (regio parietalis), in front of and from sides — from mastoidal (regio mastoidea), from below — on back area of a neck (regio colli post.). Lower bound 3. islands carry out on an outside occipital ledge (protuberantia occipitalis externa) and upper nuchal lines (lineae nuchae sup.), side — on upper temporal lines of parietal bones (lineae temporales sup.); the front border is determined conditionally by lambdoid edge of an occipital bone.

Anatomy

Fig. 1. Scheme of layers of occipital area: 1 — the sebaceous gland falling into a hair follicle; 2 — epidermis of skin; 3 — hypodermic cellulose; 4 — a tendinous helmet; 5 — subgaleal cellulose; 6 — perikranium; 7 — an outside plate of an occipital bone; 8 — diploe; 9 and 18 — occipital emissarny veins; 10 — an internal plate of an occipital bone; 11 — a firm cover of a brain; 12 — an arachnoid membrane of a brain; 13 — a soft cover of a brain; 14 — a great brain; 15 — granulations of an arachnoid membrane; 16 — an upper sagittal bosom; 17 — Meningeal branches of an occipital artery; 19 — occipital branches of an occipital artery; 20 — connective tissue crossing points — retinaculums of skin; 21 — a sweat gland.

Skin within 3. the lake it is covered with hair, thick, dense, contains a large number of sweat and sebaceous glands. It is slow-moving since it is spliced by means of numerous connective tissue crossing points — retinaculums of skin (retinacula cutis) with the subject musculoaponeurotic layer (fig. 1). Hypodermic cellulose up to 3 mm thick contains vessels and nerves of area. Thanks to the retinaculums of skin located between skin and a musculoaponeurotic layer, hypodermic cellulose has a lobular structure. Therefore nadfastsialny purulent accumulations in 3. lakes have limited localization. Veins are fixed to connective tissue crossing points and at a section are not fallen down. Plentiful bleedings from the crossed vessels of soft tissues of Z.o are explained by it. The musculoaponeurotic layer consists of an occipital abdomen of a pair occipitofrontal muscle (venter occipitalis m. occipitofrontalis) and tendinous helmet (galea aponeurotica) of a nadcherepny aponeurosis (aponeurosis epicranialis). The occipital abdomen of an occipitofrontal muscle — the wide quadrangular lamina — begins from the upper nuchal line and ahead passes into a tendinous helmet. Between a musculoaponeurotic layer and the periosteum located more deeply throughout a calvaria there is a thin coat of friable not properly executed connecting fabric (subgaleal cellulose). Thereof a tendinous helmet at reduction of an occipitofrontal muscle can be displaced (together with skin), and at injuries it is easy to exfoliate therefore purulent processes and hematomas under a tendinous helmet can extend on all calvaria. The periosteum (pericranium) covers bones of the arch, growing together with them in the area of seams. Between a periosteum and bones there is also thin coat of friable connecting fabric, thanks to it subperiostal abscesses and hematomas can extend only within one bone, in particular occipital. An upper part of scales of an occipital bone is a part 3. the lake the so-called occipital platform (planum occipitale), edges is crossed cross by the highest nuchal line (linea nuchae suprema). The occipital platform develops by endesmalny bone formation (see. Bone ) separately from the bottom of scales of an occipital bone from two kernels to 3 — to the 6th year of life. In the conjunction of top and bottom occipital scales of parts to 3 — years the false seam of scales (sutura mendosa squamae) which can remain later would be defined. Occipital scales as well as other bones of a calvaria, consists of three layers: outside plate (lamina externa), diploe (diploe) and internal plate (lamina interna), or vitreous table (lamina vitrea). In diploe there are diploichesky channels (canales diploici) in which there passes the occipital diploichesky vein (v. diploica occipitalis). On an inner surface of occipital scales within 3. the lake the furrow of an upper sagittal sine is noticeable (sulcus sinus sagittalis sup.). K of an inner surface of occipital scales prilezhat meninx and occipital share of hemicerebrums.

Fig. 4. Blood vessels and nerves of occipital area: 1 — an occipital abdomen of an occipitofrontal muscle; 2 — an aponeurotic helmet; 3 — a big occipital nerve, occipital branches occipital arteries and veins; 4 — a belt muscle of the head; 5 — a back ear vein; 6 — a small occipital nerve; 7 — a trapezoid muscle.

Within 3. lakes pass branches of two arteries in hypodermic cellulose: occipital and back ear (tsvetn. fig. 4). The occipital artery (a. occipitalis) is located only in the most lower parts of area under an occipital abdomen of an occipitofrontal muscle where is divided into final branches: occipital branches (rr. occipitales), the pro-butting occipital abdomens and a tendinous helmet ascending on the arch and anastomosing with branches of a superficial temporal artery and an ear branch (r. auricularis) anastomosing with branches of a back ear artery. From a back ear artery (a. auricularis post.) behind an auricle the occipital branch (r. occipitalis) anastomosing with branches of an occipital and superficial temporal artery departs.

Outflow of blood happens in occipital and back ear veins. Their sources form the well-marked anastomosis creating in hypodermic cellulose together with the called veins a venous vascular texture. The occipital diploichesky vein forms in diploe more or less developed vascular venous network. Near an outside occipital ledge there is an occipital emissarium (emissarium occipitale) through which there passes the occipital emissarny vein (v. emissaria occipitalis) connecting a cross sine or a sinus drain with occipital diploichesky and to superficial veins 3. lake. Outflow of a lymph goes to 2 — to the 5th to occipital nodes (nodi lymphatici occipitales) located at the upper nuchal line; are available 1 — 5 subfascial and 1 — 3 deep occipital a node, lying respectively over and under a belt muscle of the head (m. splenius capitis).

Innervation of skin 3. the lake is carried out by generally big occipital nerve (n. occipitalis major) — a back branch of the 2nd cervical spinal nerve. Skin of lateral departments 3. the lake is innervated by a small occipital nerve (n. occipitalis minor). The sensitive innervation of other soft tissues also occurs at the expense of the specified nerves. The big occipital nerve leaves 3 under skin. the lake on 2 — 4 cm from a midline also ascends medialny occipital vessels. The small occipital nerve branches lateralny, approximately through continuation up of the rear edge grudino - a clavicular and mastoidal muscle. The occipital abdomen of an occipitofrontal muscle is innervated by a back ear nerve (n. auricularis post.), which is a branch of a facial nerve.

Pathology

Malformations. In 3. lakes are rather often localized inborn hernias of a brain (see. Brain, malformations ).

Fig. 2. A dermoid cyst (it is specified by an arrow) occipital area.

3. lakes — one of favourite places of localization of dermoid cysts (fig. 2) which on many signs stand close to atheromas and on the origin are a consequence of disturbance of formation of an ectoderm (see. Dermoid ).

Being located under a tendinous helmet, cysts in the started cases cause considerable impressions in a bone, and sometimes through (to a firm meninx) defects. Dermoid cyst 3. the lake should differentiate from brain hernia and an atheroma (see. Epidermoid cyst ).

Damages

as a result of use of obstetric nippers the brain of the child, and then because of the developed message between a cerebral cavity and hypodermic cellulose 3 is sometimes injured. the lake forms a so-called adventitious traumatic meningiozny cyst, it needs to be differentiated with inborn hernias of a brain.

Fig. 3. «An air tumor» (cyst) of occipital area.

As a result of some injuries of the head (at disturbance of an integrity of trellised, frontal bones) in 3. the lake can be observed accumulation of air between an occipital bone and a tendinous helmet. On looking alike tumors this education carries the name of an air tumor (cyst) of the head (fig. 3). The diagnosis is facilitated by the fact that the swelling with a pressure upon it decreases in sizes, and at a palpation is defined crepitation (see).

Bruises of soft tissues 3. lakes are characterized krovo-and limfoizliyaniye. Hemorrhage in hypodermic cellulose because of dense communication between skin, cellulose and an aponeurosis (fibrous crossing points) does not extend far in the parties, forming accurately outlined swelling. At hemorrhages under a tendinous helmet a swelling more diffuse.

Wounds owing to features of an anatomic structure 3. lakes often are degloved, gaping, strongly bleed because of existence of dense vascular network.

Changes of scales of an occipital bone can be followed by damage of anatomic formations of a back cranial pole. Fractures of an occipital bone outside 3 are especially dangerous. the lakes belonging to fractures of base of the skull (see. Craniocereberal injury ). Such is, e.g., change of a ring of a big occipital opening arising from antiblow during the falling from height on buttocks or the straightened legs.

Diseases

3. the lake — frequent localization anthrax (see). Owing to distribution it is purulent - necrotic process in depth it can be the cause of deep subgaleal phlegmons which recognition is complicated because of hypostasis and density of covers 3. lake.

Abscesses 3. lakes are formed in the field of an arrangement occipital limf, nodes at development in them a purulent infection. Abscesses and phlegmons can also develop at distribution of a purulent inflammation from the neighboring areas (more often from a mastoid at diseases of an ear, especially from the place of an attachment grudino - a clavicular and mastoidal muscle — Betsold's abscess) or to be result of osteomyelitis of an occipital bone with distribution of pus on a neck on intermuscular spaces.

Ligneous phlegmon 3 belongs to more rare diseases. the lake, edges has no clear boundary, is painless, proceeds without fervescence.

The inflammation occipital limf, nodes can be caused by syphilis of all forms, tubercular defeat and general diseases (a leukosis, a lymphogranulomatosis).

Erysipelatous inflammation 3. the lake, as well as on other pilar areas of the head, differs from an ugly face of other areas of a body in less noticeable redness and very big rarity of a violent form (see. Ugly face ). Rather seldom the neuritis of occipital nerves able meets to be the cause of persistent pains in 3. lakes

Tumours

In occipital area can arise benign tumors and opukholepodobny educations (neurinoma, an osteoma, papilloma).

Angiomas (see) 3. lakes are quite often connected with sine of a firm meninx. Danger of angiomas 3. the lake consists in a possibility of their damage with the subsequent bleeding and infection.

Lipomas (see) 3. lakes can reach the considerable sizes, sometimes grow into intermuscular intervals that complicates their removal. Accumulation of fatty tissue around limf, a node is called a periganglionarny lipoma, and around all limf, nodes 3. the lake «a fatty neck of Madelunga» (see. Madelunga syndrome ).

Fibromas 3. lakes can be from a pea to the considerable sizes, hanging down on a leg, single or multiple, can have inclusions of a pigment, contain elements of vascular and nervous tissue, get signs of malignant growth (see. Fibroma, fibromatosis ).

Malignant tumors 3. lakes are localized both in soft tissues, and in a bone. Sarcomas of soft covers meet seldom.

Osteosarcomas of an occipital bone meet more often and can have a different microscopic structure (see. Sarcoma ). Their wedge, manifestations depend generally on the direction of growth of a tumor in a head cavity or in soft tissues of covers 3. lake.

Cancer of covers 3. the lake on a structure treats planocellular, is more rare ferruterous and is even more rare to colloid forms (see. Cancer ) or pigmental (see. Melanoma ). Formation of the cancer ulcers destroying a bone is possible. The forecast depends on a form and a stage of a tumor. Limf, nodes 3. lakes can be the place of localization of metastasises of a malignant tumor of a thyroid gland, adrenal glands, is more rare than other bodies.

Operations

Cuts in 3. lakes do taking into account an arrangement of vessels and nerves. Through 3. lakes make trepanation of a back cranial pole for removal of tumors, cysts, the foreign bodys which are located in a cerebellum, the IV ventricle, a cerebellar corner in the cerebellar and brain tank, and also a puncture of a back horn of a side ventricle, the cerebellar and brain tank (see. Ventriculopuncture ), the draining operations at hydrocephaly (see), decompressive trepanation (see. Craniotrypesis ), resection occipital craniotomy. At phlegmon and abscesses 3. lakes make the wide cuts providing good drainage of a purulent cavity. Primary surgical treatment of wounds 3. the lake is made with economical excision of fabrics. Big rags process solutions of antiseptic agents and fix separate rare seams. Between seams enter drainages for ensuring outflow of wound separated or impose counteropenings. At small superficial wounds of soft tissues are limited to their toilet.



Bibliography: Dolinin V. A. and Bisenkov N. P. Wounds and injuries operations, L., 1972; Zolotareva T. V. and Axes G. N. Surgical anatomy of the head, M., 1968; 3olotko Yu. L. Atlas of topographical anthropotomy, p.1, page 6, M., 1964; And r of e r I. M. Neyrokhirurgiya, M., 1971; H about 1 1 i n s h e a d W. H. The head and neck, N. Y., 1968; Schmitt W. Allgemeine Chirurgie, Lpz., 1970; Speziel-le Chirurgie, hrsg. v. H. J. Serfling u. a., Lpz., 1971.

P. A. Kupriyanov, S. S. Mikhaylov, L. S. Taiinsky.

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