Cranial nerves are the nerves that emerge directly from the brain, of which there are conventionally considered twelve pairs. Cranial nerves relay information between the brain and parts of the body, primarily to and from regions of the head and neck, including the special senses of vision, taste, smell, and hearing.
A head injury is any injury that results in trauma to the skull or brain. The terms traumatic brain injury and head injury are often used interchangeably in the medical literature. Because head injuries cover such a broad scope of injuries, there are many causes—including accidents, falls, physical assault, or traffic accidents—that can cause head injuries.
The abducens nerve or abducent nerve, also known as the sixth cranial nerve, cranial nerve VI, or simply CN VI, is a cranial nerve in humans and various other animals that controls the movement of the lateral rectus muscle, one of the extraocular muscles responsible for outward gaze. It is a somatic efferent nerve.
A bruise, also known as a contusion, is a type of hematoma of tissue, the most common cause being capillaries damaged by trauma, causing localized bleeding that extravasates into the surrounding interstitial tissues. Most bruises occur close enough to the epidermis such that the bleeding causes a visible discoloration. The bruise then remains visible until the blood is either absorbed by tissues or cleared by immune system action. Bruises which do not blanch under pressure can involve capillaries at the level of skin, subcutaneous tissue, muscle, or bone.
Epidural hematoma is when bleeding occurs between the tough outer membrane covering the brain and the skull. Often there is loss of consciousness following a head injury, a brief regaining of consciousness, and then loss of consciousness again. Other symptoms may include headache, confusion, vomiting, and an inability to move parts of the body. Complications may include seizures.
Battle's sign, also known as mastoid ecchymosis, is an indication of fracture of middle cranial fossa of the skull. These fractures may be associated with underlying brain trauma. Battle's sign consists of bruising over the mastoid process as a result of extravasation of blood along the path of the posterior auricular artery. The sign is named after William Henry Battle.
Facial nerve paralysis is a common problem that involves the paralysis of any structures innervated by the facial nerve. The pathway of the facial nerve is long and relatively convoluted, so there are a number of causes that may result in facial nerve paralysis. The most common is Bell's palsy, a disease of unknown cause that may only be diagnosed by exclusion of identifiable serious causes.
The crown is the top portion of the head behind the vertex. The anatomy of the crown varies between different organisms. The human crown is made of three layers of the scalp above the skull. The crown also covers a range of bone sutures, and contains blood vessels and branches of the trigeminal nerve.
A skull fracture is a break in one or more of the eight bones that form the cranial portion of the skull, usually occurring as a result of blunt force trauma. If the force of the impact is excessive, the bone may fracture at or near the site of the impact and cause damage to the underlying structures within the skull such as the membranes, blood vessels, and brain.
A basilar skull fracture is a break of a bone in the base of the skull. Symptoms may include bruising behind the ears, bruising around the eyes, or blood behind the ear drum. A cerebrospinal fluid (CSF) leak occurs in about 20% of cases and may result in fluid leaking from the nose or ear. Meningitis occurs in about 14% of cases. Other complications include injuries to the cranial nerves or blood vessels.
The cranial cavity, also known as intracranial space, is the space within the skull that accommodates the brain. The skull minus the mandible is called the cranium. The cavity is formed by eight cranial bones known as the neurocranium that in humans includes the skull cap and forms the protective case around the brain. The remainder of the skull is called the facial skeleton. Meninges are protective membranes that surround the brain to minimize damage to the brain in the case of head trauma. Meningitis is the inflammation of meninges caused by bacterial or viral infections.
Sixth nerve palsy, or abducens nerve palsy, is a disorder associated with dysfunction of cranial nerve VI, which is responsible for causing contraction of the lateral rectus muscle to abduct the eye. The inability of an eye to turn outward, results in a convergent strabismus or esotropia of which the primary symptom is diplopia in which the two images appear side-by-side. Thus, the diplopia is horizontal and worse in the distance. Diplopia is also increased on looking to the affected side and is partly caused by overaction of the medial rectus on the unaffected side as it tries to provide the extra innervation to the affected lateral rectus. These two muscles are synergists or "yoke muscles" as both attempt to move the eye over to the left or right. The condition is commonly unilateral but can also occur bilaterally.
Subgaleal hemorrhage, also known as subgaleal hematoma, is bleeding in the potential space between the skull periosteum and the scalp galea aponeurosis.
Cavernous sinus thrombosis (CST) is the formation of a blood clot within the cavernous sinus, a cavity at the base of the brain which drains deoxygenated blood from the brain back to the heart. This is a rare disorder and can be of two types–septic cavernous thrombosis and aseptic cavernous thrombosis. The most common form is septic cavernous sinus thrombosis. The cause is usually from a spreading infection in the nose, sinuses, ears, or teeth. Staphylococcus aureus and Streptococcus are often the associated bacteria.
The occipital condyles are undersurface protuberances of the occipital bone in vertebrates, which function in articulation with the superior facets of the atlas vertebra.
An orbital blowout fracture is a traumatic deformity of the orbital floor or medial wall that typically results from the impact of a blunt object larger than the orbital aperture, or eye socket. Most commonly this results in a herniation of orbital contents through the orbital fractures. The proximity of maxillary and ethmoidal sinus increases the susceptibility of the floor and medial wall for the orbital blowout fracture in these anatomical sites. Most commonly, the inferior orbital wall, or the floor, is likely to collapse, because the bones of the roof and lateral walls are robust. Although the bone forming the medial wall is the thinnest, it is buttressed by the bone separating the ethmoidal air cells. The comparatively thin bone of the floor of the orbit and roof of the maxillary sinus has no support and so the inferior wall collapses mostly. Therefore, medial wall blowout fractures are the second-most common, and superior wall, or roof and lateral wall, blowout fractures are uncommon and rare, respectively. They are characterized by double vision, sunken ocular globes, and loss of sensation of the cheek and upper gums from infraorbital nerve injury.
Periorbital puffiness, also known as puffy eyes, or swelling around the eyes, is the appearance of swelling in the tissues around the eyes, called the orbits. It is almost exclusively caused by fluid buildup around the eyes, or periorbital edema. Minor puffiness usually detectable below the eyes only is often called eye bags. Such transient puffiness is distinct from the age related and gradual increase in the size of the fat pad lying below the lower eyelids which can also be colloquially referred to as eye bags.
Cerebrospinal fluid rhinorrhoea refers to the drainage of cerebrospinal fluid through the nose (rhinorrhoea). It is typically caused by a basilar skull fracture, which presents complications such as infection. It may be diagnosed using brain scans, and by testing to see if discharge from the nose is cerebrospinal fluid. Treatment may be conservative, but usually involves neurosurgery.
Dislocations occur when two bones that originally met at the joint detach. Dislocations should not be confused with subluxation. Subluxation is when the joint is still partially attached to the bone.
Orbital emphysema is a medical condition that refers to the trapping of air within the loose subcutaneous around the orbit that is generally characterized by sudden onset swelling and bruising at the impacted eye, with or without deterioration of vision, which the severity depends on the density of air trapped under the orbital soft tissue spaces.
