This section is from the book "Applied Anatomy: The Construction Of The Human Body", by Gwilym G. Davis. Also available from Amazon: Applied anatomy: The construction of the human body.
Bleeding may occur from the sinuses of the base as well as from those of the vault. In severe injuries of the vault detached fragments frequently penetrate the superior longitudinal and lateral sinuses. In these cases profuse bleeding occurs as soon as attempts are made to remove the loose pieces of bone, and it is necessary to use a packing of gauze to control it. Fractures passing through the petrous portion of the temporal bone wound the petrosal sinus and this no doubt contributes to the blood which flows from the ear.
Emphysema is most likely to occur if the frontal air sinuses are involved, particularly if the patient blows his nose in the attempt to relieve it of blood clots. Emphysema is not so liable to occur in cases of fracture involving the mastoid cells.
Cerebrospinal fluid may escape whenever the meninges are torn and the subarachnoid space is opened. It is most frequently seen in the fractures involving the middle fossa and passing through the internal auditory meatus. The meninges are prolonged into the internal meatus, and the clear fluid is not infrequently seen coming from the ear of the injured side. Although the normal amount of cerebrospinal fluid is only about two ounces, much greater quantities can escape. A serous discharge, perhaps of several ounces, is indicative of a rupture into the subarachnoid space.
The nerves most often disturbed in injuries of the skull are the first, second, third, seventh, and eighth.
The first or olfactory nerve may be injured directly in the line of fracture, or by concussion. I have had under my care two such cases in women who struck the occiput on an asphalt pavement in getting off backward from a moving trolley car. These patients left the hospital after several weeks with the sense of smell still lacking.
Injuries to the second or optic nerve are apt to be accompanied by such severe injuries to other parts as to cause the death of the patient before the loss of sight is discovered. If the optic nerve is injured at the optic foramen, there may be impairment of sight without any intra-ocular changes to be seen with the ophthalmoscope. Inside of two weeks, however, the pinkish color of the disk gives way to the gray-white color of atrophy, and this progresses until complete. The nerve never resumes its functions and the patient remains blind.
Injury of the third or oculomotor nerve has also come under my notice. In this the pupil of the affected eye is moderately dilated and does not respond to light. The ciliary muscle is supplied by the third nerve, as well as the circular fibres of the iris, so that the accommodation is paralyzed and, if the eye has been normal in its refraction, the patient will be unable to read or see objects clearly at close distances. The extrinsic muscles of the eye, with the exception of the superior oblique and external rectus, are also supplied by this nerve and the eye is therefore pulled outward and slightly downward, and diplopia, or double vision, may be produced. The patient is unable to move the eye either upward, inward, or downward. The levator palpebral muscle is also paralyzed and there is ptosis or drooping of the upper lid. The orbicularis palpebrarum muscle, being supplied by the seventh nerve, has its functions unimpaired, and the eyelids can be closed.
Fig. 26 - Paralysis of the facial nerve from fracture of base of skull (author's case).
The fourth or pathetic nerve is almost never injured. It supplies the superior oblique muscle, which turns the eyeball down and slightly outward. Paralysis of it causes diplopia, with the image of the injured eye below that of the sound eye and tilted to the right, if the right eye is affected, and to the left, if the left is affected.
The fifth or trifacial nerve is very rarely injured. If it is completely paralyzed there will be loss of motion in the muscles of mastication and loss of sensation over the side of the face, of one-half of the interior of the mouth, of the side and front of the tongue, and of the eye.
The sixth or abducent nerve supplies the external rectus muscle of the eye, and if paralyzed causes internal strabismus, the eye looking inward. While more often paralyzed than the fourth and fifth, it is not so frequently paralyzed as are the two following nerves.
The seventh ox facial nerve is the one most frequently injured in fractures of the skull. It enters the internal auditory meatus with the auditory nerve, being above it. Reaching the end of the meatus internus, it enters the canal of Fallopius and emerges from the temporal bone at the stylomastoid foramen. When paralyzed, the face on that side remains motionless, the eye cannot be closed, and food accumulates between the teeth and cheek. The corner of the mouth is drawn to the opposite side when the muscles of the face are contracted.
The internal auditory meatus contains a prolongation of the dura mater and arachnoid, so that a fracture through it would open the subarachnoid space and allow the cerebrospinal fluid to escape. In these cases there is also usually bleeding from the ear. Escape of cerebrospinal fluid is to be distinguished from a flow of serum by its greater quantity, sometimes many ounces escaping.
The eighth or auditory nerve is injured with moderate frequency, but perhaps hardly so often as supposed, for the deafness which sometimes follows injuries to the head may not be caused by an injury to the auditory nerve itself, but is rather due to the injury done by concussion of the brain in the region of the first temporal convolution, or possibly to the tympanum. The eighth nerve is embraced in the same extension of the meninges into the internal meatus as is the seventh, and injuries to it may also be accompanied with loss of cerebrospinal fluid. The seventh and eighth are said to be more often paralyzed than any of the other nerves.
Injuries to the remaining four nerves - the glossopharyngeal, vagus, spinal accessory, and hypoglossal - have been observed too rarely to require any extensive attention here.