The skull consists of three parts: the skull top, the skull base and the skull cavity. The cranial top is divided into frontoparietal occipital region and temporal region, including its deep cranial top bone. (1) Frontoparietal occipital region
1. Realm: anterior orbital margin, posterior occipital protuberance and superior nuchal line, with both sides separated by superior temporal line.
2. Level: The soft tissue covering this area is divided into five layers from shallow to deep, namely: skin, superficial fascia, cap aponeurosis and cranial parietal muscle (frontoccipital muscle), loose connective tissue under aponeurosis and periosteum. Among them, the superficial three layers are closely related and difficult to separate. So these three layers are often called "scalp". The connection between the deep two layers is loose and easy to separate.
(1) Skin: The skin in this area is thick and dense, with two remarkable features. First, it contains a large number of hair follicles, sweat glands and sebaceous glands, which is the prone site of furuncle or sebaceous cyst; Second, the blood vessels are rich, and there is much bleeding during trauma, but the wound heals quickly. The hair root inclines through the dermis to reach the superficial fascia and attaches to the hair follicle. Surgical incision should be consistent with the direction of hair to reduce the damage to hair follicles.
(2) Superficial fascia
Fascia: composed of dense connective tissue and adipose tissue, there are many thick and vertical fiber bundles, which make the skin closely connected with the aponeurosis, and divide this layer into many small cells, which are full of fat and have blood vessels and nerves running through them. When infected, the exudate is not easy to spread, so the swelling is limited, which can compress the nerve endings in the early stage and cause severe pain. In addition, the blood vessel wall of the compartment is tightly fixed by the surrounding connective tissue, so it is not easy to contract and close when the blood vessel is injured, and there is more bleeding, so it is often necessary to compress or suture to stop bleeding.
(3) Scalp aponeurosis
Aponeurosis: It is a thick and tough aponeurosis, which is connected with the frontalis muscle of the occipital frontalis muscle at the front and with the occipital abdomen at the rear. The middle protrudes backward and attaches to the occipital protuberance. As the starting point of the supraauricular muscle and preauricular muscle, it gradually becomes thinner, continues with the superficial temporal fascia, and attaches to the zygomatic arch, just like a hat buckled on the top of the head.
The frontalis and ventralis of occipital frontalis muscle stop at the subfrontal skin, and some fibers are mixed with orbicularis oculi muscle; The posterior part is connected with the membranous aponeurosis slightly in front of the coronal suture, and horizontal stripes are produced on the forehead during contraction.
The occipital abdomen of the occipital frontalis muscle starts from the outer side of the dorsal line of the upper neck, goes forward and upward, and ends at the posterior edge of the cap aponeurosis, and pulls the scalp backwards during contraction.
The cap aponeurosis is closely connected with the skin through the fibrous membrane of superficial fascia. Clinically, the skin, superficial fascia and cap aponeurosis are collectively called scalp. When the scalp is injured, if the cap aponeurosis is not injured, the wound dehiscence is not obvious; If the cap aponeurosis is injured at the same time, the wound will split, especially the transverse wound, due to the contraction and traction of the anterior occipital muscle. When sewing the scalp, be sure to sew this layer well, which can reduce the tension of the skin and help the wound heal and stop bleeding.
(4) Subfascial loose connective tissue (Subfascial space)
Space): It is a thin layer of loose connective tissue between the aponeurosis of cap and the periosteum of skull. This space has a wide range, reaching the superior orbital margin, the supranuchal line and the zygomatic arch on both sides. The scalp is loosely connected with the skull adventitia through this layer, so it has great fluidity. During craniotomy, the flap can be turned up after passing through this gap, and the scalp avulsion injury is mostly separated along this layer. When aponeurosis space is bleeding or suppurating, it can quickly spread to the whole skull top, forming a large hematoma, and scars can appear in the subcutaneous layer of nose root and upper eyelid. The vein in this space is connected with the barrier vein of skull and the cranial dural vein sinus through the guide vein. If infection occurs, it can cause osteomyelitis of the skull or spread to the skull through the above channels, so this layer is clinically considered as a "dangerous area" at the top of the skull.
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(5) Pericranium: It is composed of dense connective tissue, which is connected with the cranial surface through a small amount of connective tissue, and the two are easy to peel off. However, the periosteum closely healed with the cranial suture, formed the periosteum deep into the suture, and fused with the outer layer of intracranial dura mater. Therefore, subperiosteal hematoma is often confined to a skull, which is easily distinguished from subperiosteal hematoma. The scalp is severely avulsed, and the scalp can be avulsed together with some periosteum.
The adventitia of skull has little effect on the nutrition of skull. Skinning does not affect skull growth. (2) Time region
1. Realm: It is located on both sides of the skull top, between the upper line and the upper edge of zygomatic arch, reaching the frontal process of zygomatic bone and zygomatic process of frontal bone in front, and reaching the base of mastoid process and the external auditory meatus in the back.
2. Level: There are five layers of soft tissue in this area from shallow to deep, followed by skin, superficial fascia, temporal fascia, temporal muscle and scalp.
(1) skin: The skin in front of the temporal region is thin and movable, and the longitudinal or transverse incision is easy to suture during operation, and the scar is not obvious after healing.
(2) Superficial fascia: contains less adipose tissue and fibrous septa. There are superficial temporal vessels and ototemporal nerves in front of the auricle, and posterior auricular vessels and occipital nerves behind the auricle, which run radially from bottom to top along the temporal area to the frontoparietal occipital area. When performing craniotomy through this area, the base of the flap should be below, including the blood vessels and nerves above, to ensure the survival and feeling of the flap.
(3) Temporal fascia Temporal fascia:
1) Superficial temporal fascia: It is a continuation of the hat-shaped aponeurosis, which is weak and gradually continues with the deep temporal fascia. The preauricular muscle and supraauricular muscle start from membranous aponeurosis, the posterior auricular muscle starts above the mastoid root, and all three muscles stop at the ear root.
2) Deep temporal fascia: it is attached to the superior temporal line from above, and attached to the medial surface of zygomatic arch in two layers from below, with fat and blood vessels sandwiched between the two layers, and the middle temporal artery (originating from the superior temporal artery) and the middle temporal vein pass through. Because this fascia is very dense, fingers can touch the hard fascia edge when examining the wound, which may be mistaken for skull injury.
(4) temporal muscle
Muscle: Fan-shaped, starting from the deep surface of temporal fossa and temporal fascia, the anterior muscle fibers are vertically downward, the posterior muscle fibers are almost horizontally forward, and the muscle fibers are gradually concentrated, passing through the deep surface of zygomatic arch and ending in the mandibular coronoid process. Temporal muscle and temporal fascia can protect meninges and brain tissue after removing part of temporal bone scales through temporal craniotomy, so temporal approach is often used for closed epidural hematoma removal and subtemporal decompression. There are deep temporal vessels and nerves in the deep part of temporal muscle. The deep temporal artery comes from the maxillary artery, and the deep temporal nerve comes from the mandibular nerve which innervates the temporal muscle.
(5) Periosteum: It is thin and clings to the skull surface, so subperiosteal hematoma rarely occurs in this part. Between the periosteum and the temporal muscle, there is a large amount of adipose tissue, called the loose connective tissue under the temporal fascia, which communicates with the infratemporal space through the deep surface of the zygomatic arch and then continues with the buccal fat body of the face. Therefore, when bleeding or inflammation occurs in the loose connective tissue under the temporal fascia, it can spread downward to the face, forming hematoma or abscess in the deep part of the face, and facial inflammation such as odontogenic infection can also spread to the loose connective tissue under the temporal fascia.
(3) The blood vessels and nerves at the top of the skull run in the superficial fascia, which can be divided into pre-auricular group and post-auricular group. 1. Cranial parietal vessels: there are three pairs in the preauricular group and two pairs in the retroauricular group.
(1) superior trochlear artery and vein. Five: about 2cm from the center line. The superior trochlear artery is one of the last branches of ophthalmic artery, which runs with the superior trochlear nerve and goes around the frontal notch to the forehead.
(2) Superior orbital artery and vein. About 2.5 from the center line
Cm. The supraorbital artery is a branch of the ophthalmic artery, which runs with the supraorbital nerve. Walk between the levator palpebrae superioris and the upper orbital wall, reach the supraorbital foramen (notch), bypass the upper orbital margin and reach the forehead. The accompanying conditions of the above two groups of arteries and nerves are usually that the supratrochlear artery is inside the supratrochlear nerve and the supraorbital artery is outside the supraorbital nerve.
(3) superficial temporal artery and vein
A.& ampv: Accompanied by ototemporal nerve, it passes through the upper margin of parotid gland and zygomatic arch to reach the temporal region. Superficial temporal artery is one of the two terminal branches of external carotid artery, which starts from the back of mandibular neck, goes up to the deep surface of parotid gland, and touches its pulse in front of ototemporal nerve and tragus. About above the zygomatic arch
The superficial temporal artery is divided into frontal branch and parietal branch at 2~3 cm. The frontal branch is thick, with an outer diameter of about 1.8 mm, usually at a distance of 15~900 from the vertical.
The anteversion angle inclines forward and upward, reaching the upper angle near the extraorbital or frontal tubercle and reaching the cranial top. During the journey, there are 2~5 frontoparietal branches distributed in the cranial top, covering an area of about 99.
Cm2, and the diameter of more than one branch exceeds 1.0 cm2(82%). The outer diameter of the top support is about 1.7 mm, and it is about 300 from the vertical.
Posterior oblique, from the upper back to the parietal tubercle, branches are distributed in the cranial top, with a distribution area of about 53.
Square centimeter. The superficial temporal artery has a constant position, large diameter and strong expansibility, which is an ideal feeding artery for intracranial and extracranial artery anastomosis under the condition of internal carotid artery system ischemia. The superficial temporal vein empties into the posterior mandibular vein.
(4) Arteriovenous behind ear
A.& ampv: The posterior auricular artery is small, which starts from the external carotid artery in the depth of parotid gland, goes back and up along the upper edge of the posterior abdomen of the digastric muscle, goes up through the back of the auricle, and is distributed on the side of the auricle and its skin. Because of its small diameter, this artery is not suitable for intracranial and extracranial anastomosis, but is more anastomosed with superficial temporal artery and occipital artery. It is an axial blood vessel with pedicle free flap in the posterior ear area and a supplementary blood vessel for the whole flap. The posterior auricular vein empties into the external jugular vein.
(5) Occipital artery and vein
A.& ampv: The occipital artery is thick, which starts from the external carotid artery, goes backward along the lower edge of the posterior abdomen of the digastric muscle, passes through the groove of the mastoid occipital artery of the temporal bone to the back of the neck, and finally passes through the trapezius muscle and the lateral deep fascia of the greater occipital nerve on the upper line of the back of the neck, and is distributed in the occipital skin. External diameter of occipital artery >: 1. 1
Mm, the body surface projection is 2~3cm below the occipital protuberance and 3~4 cm away from the midline.
Location. Because the position of occipital artery is constant and the diameter of its trunk and branches is relatively large, the occipital artery is often anastomosed with the inferior posterior cerebellar artery in vertebrobasilar artery ischemia. Occipital artery has abundant anastomosis with contralateral homonymous artery, superficial temporal artery and posterior auricular artery, and the external diameter of anastomosis point is 0.3~0.6, accounting for more than 60%.
Therefore, the occipital scalp can also be used as a donor site for free flap transplantation. The occipital vein is injected into the external jugular vein. The greater occipital nerve is thicker and is the cutaneous branch of the posterior branch of the second cervical nerve, which is about 2.5 cm away from the lateral occipital protuberance.
It passes through the aponeurosis and deep fascia of trapezius muscle, and then reaches the cranial top together with occipital artery, and is distributed in most skin behind the head. Occipital artery is outside the greater occipital nerve, and there is a certain distance between them.
The blood vessels in the cranial top radiate from the periphery to the cranial top, so when the flap is made here during craniotomy, the pedicle of the flap should be below, and the pedicle should be where the blood vessels and nerve trunks are located to ensure the nutrition of the flap. Generally, the scalp incision should be radial to avoid damaging the vascular nerve trunk. The arteries at the top of the skull are anastomosed widely, not only the left and right sides are anastomosed with each other, but also the internal carotid artery system and the external carotid artery system are interrelated, so it is not easy to die when the scalp is torn in large pieces. Similarly, when the scalp bleeds due to injury, annular compression should be used to stop bleeding.
The vein at the top of the skull runs with the artery of the same name, forming a vein network under the skin. In addition, there is a guiding vein in the head, which forms the communication between the extracranial vein and the intracranial dural sinus. The dominant veins are: ① the top wall and the top dominant vein.
The guide v passes through the parietal foramen on both sides of the posterior sagittal line at the midpoint of the cranial top and connects the superficial temporal vein with the superior sagittal sinus; ② Mastoid messenger of mastoid vein
Verb (abbreviation of verb) passes through mastoid foramen and connects posterior auricular vein, occipital vein and sigmoid sinus; ③ Condylar conduction of condylar vein.
Verb (abbreviation of verb) passes through condyle and connects suboccipital venous plexus with sinoatrial node; Sometimes a occipital vein passes through the occipital protuberance to connect the occipital vein with the sinus confluence. There is no valve in the guide vein, and the direction of venous blood flow is generally outside the skull, but it can also flow into the skull reversibly under certain circumstances, so the infection inside and outside the skull can spread directly to each other; Minor scalp injuries, if not treated in time or improperly, sometimes cause serious intracranial infections, such as venous sinus thrombosis and meningitis.
2. Cranial parietal nerves There are ten pairs of nerves on the cranial parietal, five pairs in front of the ear and five pairs behind the ear, including one pair of motor nerves and four pairs of sensory nerves. (1) Preauricular group 1) On the trochlear nerve.
Noun: it is the terminal branch of frontal nerve from the first branch of trigeminal nerve, which goes up through the superior orbital margin at a distance of 2.0 mm from the midline and distributes in the skin near the midline. 2) supraorbital nerve
Noun: It is the other terminal branch of the frontal nerve, which reaches the forehead and cranial top through the supraorbital notch, reaches the skin at the herringbone suture, and also sends out small branches to the frontal sinus.
Both the supratrochlear nerve and the supraorbital nerve are branches of the oculomotor nerve, so patients with trigeminal neuralgia have tenderness at the medial and medial orbital margin 1/3. 3) zygomatic temporal nerve
Branches: tiny, originating from the zygomatic branch of the intraorbital maxillary nerve, passing through the temporal fascia behind the frontal process of the zygomatic bone and distributed in the skin in front of the temporal area. 4) temporal branch of facial nerve
Facial nerve: it passes through the anterior upper part of parotid gland, and sends out tiny branches to the frontalis muscle, supraauricular muscle, preauricular muscle and the upper part of orbicularis oculi muscle, and there are anastomotic branches connected with the zygomatic temporal nerve of trigeminal nerve.
5) the ototemporal side of the ototemporal nerve
Noun: It is a branch of the third mandibular nerve of trigeminal nerve. From the infratemporal fossa, it passes through the upper end of parotid gland and goes up near the front of auricle, and is distributed in the upper skin of auricle, the external auditory canal, the front of tympanic membrane, the temporal region and the head side. Local anesthesia can be performed before the foot of the helix.
(2) The posterior auricular nerve in the posterior auricular group (1)
Noun (abbreviation for Noun): It is a small branch of facial nerve immediately after coming out of stylomastoid foramen. It bends upward immediately after the root of the ear and distributes in occipital muscle, posterior auricular muscle and part of supraauricular muscle. 2) Great auricular nerve
Noun: It comes from the second and third psychological scenes and is distributed behind the auricle, before and after the lower auricle and on the surface skin of parotid gland. 3) Occipital minor nerve N: from the 2nd and 3rd.
The cervical nerve is a branch of the cervical plexus, which is distributed in the upper part of the neck, behind the auricle and adjacent skull skin. 4) greater occipital nerve
Noun: thick, which is the cutaneous branch of the posterior branch of the second cervical nerve, about 2.5 cm away from the lateral occipital protuberance.
It penetrates trapezius muscle and deep fascia and is distributed in most of the skin at the back of the head. The greater occipital nerve block can be performed at the lower transverse finger of occipital protuberance, about 2.5 cm outward. 5) the third occipital nerve
Noun: tiny, it is the cutaneous branch of the posterior branch of the third cervical nerve, which passes through trapezius muscle and is distributed in the skin near the upper nape of the neck and occipital protuberance.
The cranial parietal nerve runs in the superficial fascia, anastomosing with each other, and the distribution areas overlap with each other. Therefore, local anesthesia often fails to achieve satisfactory results, and it is necessary to inject anesthetics in many places to expand the scope of nerve block. At the same time, it should be noted that anesthetic must be injected into superficial fascia during local anesthesia, because there are thick fiber bundles in subcutaneous tissue, so the resistance will be greater when injecting. If you mistakenly enter the aponeurosis space, you will not achieve anesthesia effect.
(4) The structural characteristics and clinical significance of the skull cap bone, which is an endosperm during embryonic development, has not been completely ossified at birth. Therefore, in some parts, such as the front fontanel and the back fontanel, the membrane structure still remains.
All the bones in the skull belong to the flat bone. Frontal bone at the front and occipital bone at the back. Between the forehead and occipital bone are the left and right parietal bones. both wings
The small part in front is the butterfly wing; Most of the back is temporal bone scale. When intracranial pressure increases, the suture of children can be slightly separated. Adult skulls are connected by zigzag cranial sutures, which firmly connect the skulls into a whole. With the increase of age, the suture gradually forms bone healing from the inside out. Therefore, the healing degree of bone suture can be used as an index to judge age.
The thickness of skull cap varies with gender, age, individual and location. The average thickness of adults is about 5 mm, the thickest part (occipital protuberance) can reach 10 mm, and the thinnest part (temporal region) is only 1~2.
Well, due to the different thickness of the skull, we should pay attention to drilling when opening the skull. The thickness can be measured by x-ray or CT before operation.
Cranial parietal bone is dome-shaped and elastic. External force is often concentrated at one point, and the adult fracture line radiates around the stress point. However, children's cranial parietal bone is thin, soft and elastic, so concave fractures often occur after trauma.
The skull is divided into three layers: the outer plate, the barrier and the inner plate. The outer plate is thicker, with an average thickness of 1~2 mm, which is stronger than the inner plate in tensile strength and smaller in radian. The inner plate is thin, with an average thickness of about 0.5.
Mm, the texture is also brittle, so it is called glass sample. Therefore, the outer plate can remain intact during trauma, while the inner plate is fractured. Or linear fracture of outer plate and comminuted fracture of inner plate. Fracture fragments can stab intracranial blood vessels, venous sinuses, meninges and brain tissues, and lead to serious complications.
The barrier is cancellous bone between the inner and outer plates, which contains bone marrow, and there are barrier veins in the barrier tube. The barrier tube is on the x axis.
X-ray shows cracks, which are sometimes mistaken for fracture lines, so attention should be paid to differentiation. Because the vein of the plate barrier is located in the bone, it can not be ligated during operation, and bone wax is often used to stop bleeding. Plateau veins can usually be divided into four groups: ① Frontofrontal veins.
The barrier vein is located in the forehead and communicates with the superior sagittal sinus and the superior ophthalmic vein. ② Anterior temporoparietal vein in the anterior temporoparietal barrier.
Communicate with sphenoid sinus and communicate with temporal muscle vein outward; ③ Posterior temporal plate barrier vein.
From top to bottom to the mastoid part of the baffle, communicating with the transverse sinus; ④ Occipital diploid vein in occipital-occipital barrier vein.
Located in the occipital part, it communicates with the transverse sinus and communicates with the occipital vein outward. Besides communicating with the sinus of intracranial vein, the vein of plank barrier also communicates with the vein of soft tissue at the top of skull, so it is also the way for extracranial infection to spread to skull.
Thinking: 1. The significance of skull mark and the body surface projection of important intracranial structures are briefly described. 2. Briefly describe the structural characteristics of the cranial top level and the blood vessels and nerves distributed in the cranial top.