Middle meningeal artery
Encyclopedia
The middle meningeal artery (Latin arteria meningea media) is typically the third branch of the first part (retromandibular part) of the maxillary artery, one of the two terminal branches of the external carotid artery
External carotid artery
In human anatomy, the external carotid artery is a major artery of the head and neck. It arises from the common carotid artery when it bifurcates into the external and internal carotid artery.-Course:...

. After branching off the maxillary artery in the infratemporal fossa
Infratemporal fossa
The infratemporal fossa is an irregularly shaped cavity, situated below and medial to the zygomatic arch.* anteriorly, by the infratemporal surface of the maxilla and the ridge which descends from its zygomatic process...

, it runs through the foramen spinosum
Foramen spinosum
The foramen spinosum is one of several foramina located in the base of the skull, on the sphenoid bone, situated lateral to the foramen ovale, in a posterior angle.-Contents:It permits the passage of certain arteries, veins and/or other structures:...

 to supply the dura mater
Dura mater
The dura mater , or dura, is the outermost of the three layers of the meninges surrounding the brain and spinal cord. It is derived from Mesoderm. The other two meningeal layers are the pia mater and the arachnoid mater. The dura surrounds the brain and the spinal cord and is responsible for...

 (the outermost meninges
Meninges
The meninges is the system of membranes which envelopes the central nervous system. The meninges consist of three layers: the dura mater, the arachnoid mater, and the pia mater. The primary function of the meninges and of the cerebrospinal fluid is to protect the central nervous system.-Dura...

) and the calvaria
Calvaria (skull)
The calvaria is the upper part of the cranium and surrounds the cranial cavity containing the brain.The calvaria is made up of the frontal, occipital and right and left parietals....

. The middle meningeal artery is the largest of the three (paired) arteries which supply the meninges, the others being the anterior meningeal artery and the posterior meningeal artery.

In approximately half of subjects it branches into an accessory meningeal artery.

The middle meningeal artery runs beneath the pterion
Pterion
The pterion is the point corresponding with the posterior end of the sphenoparietal suture.-Location:It is situated about 3 cm. behind, and a little above the level of the zygomatic process of the temporal bone.It marks the junction between four bones:...

. It is vulnerable to injury at this point, where the skull is thin. Rupture of the artery may give rise to an epidural hematoma
Epidural hematoma
Epidural or extradural hematoma is a type of traumatic brain injury in which a buildup of blood occurs between the dura mater and the skull. The dura mater also covers the spine, so epidural bleeds may also occur in the spinal column...

. In the dry cranium, the middle meningeal, which runs within the dura mater surrounding the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...

, makes a deep indention in the calvarium.

The middle meningeal artery is intimately associated with the auriculotemporal nerve
Auriculotemporal nerve
The auriculotemporal nerve is a branch of the mandibular nerve that runs with the superficial temporal artery and vein, and provides sensory innervation to various regions on the side of the head.-Origin:...

 which wraps around the artery making the two easily identifiable in the dissection
Dissection
Dissection is usually the process of disassembling and observing something to determine its internal structure and as an aid to discerning the functions and relationships of its components....

 of human cadavers
Cadaver
A cadaver is a dead human body.Cadaver may also refer to:* Cadaver tomb, tomb featuring an effigy in the form of a decomposing body* Cadaver , a video game* cadaver A command-line WebDAV client for Unix....

 and also easily damaged in surgery
Surgery
Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...

.

Before entering cranium

It ascends between the sphenomandibular ligament
Sphenomandibular ligament
The sphenomandibular ligament is a flat, thin band which is attached above to the spina angularis of the sphenoid bone, and, becoming broader as it descends, is fixed to the lingula of the mandibular foramen...

 and the Pterygoideus externus, and between the two roots of the auriculotemporal nerve
Auriculotemporal nerve
The auriculotemporal nerve is a branch of the mandibular nerve that runs with the superficial temporal artery and vein, and provides sensory innervation to various regions on the side of the head.-Origin:...

 to the foramen spinosum
Foramen spinosum
The foramen spinosum is one of several foramina located in the base of the skull, on the sphenoid bone, situated lateral to the foramen ovale, in a posterior angle.-Contents:It permits the passage of certain arteries, veins and/or other structures:...

 of the sphenoid bone
Sphenoid bone
The sphenoid bone is an unpaired bone situated at the base of the skull in front of the temporal bone and basilar part of the occipital bone.The sphenoid bone is one of the seven bones that articulate to form the orbit...

, through which it enters the cranium; it then runs forward in a groove on the great wing of the sphenoid bone
Sphenoid bone
The sphenoid bone is an unpaired bone situated at the base of the skull in front of the temporal bone and basilar part of the occipital bone.The sphenoid bone is one of the seven bones that articulate to form the orbit...

, and divides into two branches, anterior and posterior.

The anterior branch, the larger, crosses the great wing of the sphenoid, reaches the groove, or canal, in the sphenoidal angle of the parietal bone
Parietal bone
The parietal bones are bones in the human skull which, when joined together, form the sides and roof of the cranium. Each bone is roughly quadrilateral in form, and has two surfaces, four borders, and four angles. It is named from the Latin pariet-, wall....

, and then divides into branches which spread out between the dura mater and internal surface of the cranium, some passing upward as far as the vertex
Vertex (anatomy)
In arthropod and vertebrate anatomy, the vertex refers to the upper surface of the head.In humans, the vertex is formed by four bones of the skull: the frontal bone, the two parietal bones, and the occipital bone...

, and others backward to the occipital
Occiput
The occiput is the anatomical term for the posterior portion of the head, in insects the posterior part of those head capsule.-Clinical significance:Trauma to the occiput can cause a basilar skull fracture....

 region.

The posterior branch curves backward on the squamous part
Squama temporalis
The squama of the temporal bone forms the anterior and upper part of the bone, and is scale-like, thin, and translucent.- Surfaces :Its outer surface is smooth and convex; it affords attachment to the temporalis muscle, and forms part of the temporal fossa; on its hinder part is a vertical groove...

 of the temporal bone
Temporal bone
The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebrum.The temporal bone supports that part of the face known as the temple.-Parts:The temporal bone consists of four parts:* Squama temporalis...

, and, reaching the parietal bone some distance in front of its mastoid angle, divides into branches which supply the posterior part of the dura mater and cranium.

The branches of the middle meningeal artery are distributed partly to the dura mater, but chiefly to the bones; they anastomose with the arteries of the opposite side, and with the anterior and posterior meningeal arteries. The very smallest distal branches anastomose
Anastomosis
An anastomosis is the reconnection of two streams that previously branched out, such as blood vessels or leaf veins. The term is used in medicine, biology, mycology and geology....

 through the skull
Human skull
The human skull is a bony structure, skeleton, that is in the human head and which supports the structures of the face and forms a cavity for the brain.In humans, the adult skull is normally made up of 22 bones...

 with small arterioles from the scalp
Scalp
The scalp is the anatomical area bordered by the face anteriorly and the neck to the sides and posteriorly.-Layers:It is usually described as having five layers, which can conveniently be remembered as a mnemonic:...

.

Very rarely the ophthalmic artery
Ophthalmic artery
The ophthalmic artery is the first branch of the internal carotid artery distal to the cavernous sinus. Branches of the OA supply all the structures in the orbit as well as some structures in the nose, face and meninges...

 may arise as a branch of the middle meningeal artery.

Branches upon entering cranium

On entering the cranium, the middle meningeal artery gives off the following branches:
  • (1) Numerous small vessels supply the semilunar ganglion and the dura mater
    Dura mater
    The dura mater , or dura, is the outermost of the three layers of the meninges surrounding the brain and spinal cord. It is derived from Mesoderm. The other two meningeal layers are the pia mater and the arachnoid mater. The dura surrounds the brain and the spinal cord and is responsible for...

     in this situation.
  • (2) A superficial petrosal branch enters the hiatus of the facial canal
    Hiatus of the facial canal
    A shallow groove, sometimes double, leading lateralward and backward to an oblique opening, the hiatus for greater petrosal nerve , for the passage of the greater superficial petrosal nerve and the petrosal branch of the middle meningeal artery....

    , supplies the facial nerve
    Facial nerve
    The facial nerve is the seventh of twelve paired cranial nerves. It emerges from the brainstem between the pons and the medulla, and controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue and oral cavity...

    , and anastomoses with the stylomastoid branch of the posterior auricular artery
    Posterior auricular artery
    The posterior auricular artery is a small artery and arises from the external carotid artery, above the Digastric muscle and Stylohyoid muscle, opposite the apex of the styloid process....

    .
  • (3) A superior tympanic artery
    Superior tympanic artery
    The superior tympanic artery, a branch of the middle meningeal on entering the cranium, runs in the canal for the Tensor tympani, and supplies this muscle and the lining membrane of the canal....

     runs in the canal of the tensor tympani
    Tensor tympani
    The tensor tympani, the larger of the two muscles of the tympanic cavity, is contained in the bony canal above the osseous portion of the auditory tube...

     muscle, and supplies this muscle and the lining of the canal.
  • (4) Orbital branches pass through the superior orbital fissure or through separate canals in the great wing of the sphenoid, to anastomose with the lacrimal
    Lacrimal artery
    The lacrimal artery arises close to the optic foramen, and is one of the largest branches derived from the ophthalmic artery: not infrequently it is given off before the artery enters the orbit....

     or other branches of the ophthalmic artery
    Ophthalmic artery
    The ophthalmic artery is the first branch of the internal carotid artery distal to the cavernous sinus. Branches of the OA supply all the structures in the orbit as well as some structures in the nose, face and meninges...

    .
  • (5) Temporal branches pass through foramina in the great wing of the sphenoid, and anastomose in the temporal fossa
    Temporal fossa
    The temporal fossa is a shallow depression on the side of the skull bounded by the temporal lines and terminating below the level of the zygomatic arch.-Boundaries:...

     with the deep temporal arteries
    Deep temporal arteries
    The deep temporal arteries, two in number, anterior and posterior, ascend between the Temporalis and the pericranium.They supply the muscle, and anastomose with the middle temporal artery....

    .

Clinical relevance

An injured middle meningeal artery is the cause of an epidural hematoma
Epidural hematoma
Epidural or extradural hematoma is a type of traumatic brain injury in which a buildup of blood occurs between the dura mater and the skull. The dura mater also covers the spine, so epidural bleeds may also occur in the spinal column...

. A head injury (e.g. from a road traffic accident or sports injury) is required to rupture the artery. Emergency treatment requires decompression of the haematoma, usually by craniotomy
Craniotomy
A craniotomy is a surgical operation in which a bone flap is temporarily removed from the skull to access the brain. Craniotomies are often a critical operation performed on patients recording, brain imaging, and for neurological manipulations such as electrical stimulation and chemical...

. Subdural bleeding
Subdural hematoma
A subdural hematoma or subdural haematoma , also known as a subdural haemorrhage , is a type of haematoma, a form of traumatic brain injury. Blood gathers within the outermost meningeal layer, between the dura mater, which adheres to the skull, and the arachnoid mater, which envelops the brain...

 is usually venous in nature, rather than arterial.

The middle meningeal artery runs in a groove on the inside of the cranium. This can clearly be seen on a lateral skull X-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...

, where it may be mistaken for a fracture of the skull. On a dry specimen the groove is easy to see. This means that the artery is easy to study, even in specimens centuries old, and several classifications of the branches have been proposed, e.g. Adachi's classification of 1928.

External links

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