44 Commentary on plates 17, 18, & 19.
All deep incisions made in the median line of the forepart of the wrist are liable to wound the median nerve B, Plate 17. When the thumb, together with its metacarpal bone, is being amputated, the radial artery E, Plate 19, which winds round near the head of that bone, may be wounded. It is possible, by careful dissection, to perform this operation without dividing the radial vessel.
DESCRIPTION OF PLATES 17, 18, & 19.
PLATE 17.
A. Radial artery.
B. Median nerve; b b b b, its branches to the thumb and fingers.
C. Ulnar artery, forming F, the superficial palmar arch.
D. Ulnar nerve; E e e, its continuation branching to the little and ring fingers, &c.
G. Pisiform bone.
H. Abductor muscle of the little finger.
I. Tendon of flexor carpi radialis muscle.
K. Opponens pollicis muscle.
L. Flexor brevis muscle of the little finger.
M. Flexor brevis pollicis muscle.
N. Abductor pollicis muscle.
OOOO. Lumbricales muscles.
P P P P. Tendons of the flexor digitorum sublimis muscle.
Q. Tendon of the flexor longus pollicis muscle.
R. Tendon of extensor metacarpi pollicis.
S. Tendons of extensor digitorum sublimis; P P P, their digital prolongations.
T. Tendon of flexor carpi ulnaris.
U. Union of the digital arteries at the tip of the finger.
Plate 17
PLATE 18.
A. Radial artery.
B. Tendons of the extensors of the thumb.
C. Tendon of extensor carpi radialis.
D. Annular ligament.
E. Deep palmar arch, formed by radial artery giving off e, the artery of the thumb.
F. Pisiform bone.
G. Ulnar artery, giving off the branch I to join the deep palmar arch E of the radial artery.
H. Ulnar nerve; h, superficial branches given to the fingers. Its deep palmar branch is seen lying on the interosseous muscles, M M.
K. Abductor minimi digiti.
L. Flexor brevis minimi digiti.
M. Palmar interosseal muscles.
N. Tendons of flexor digitorum sublimis and profundus, and the lumbricales muscles cut and turned down.
O. Tendon of flexor pollicis longus.
P. Carpal end of the metacarpal bone of the thumb.
Plate 18
PLATE 19.
AAA. Tendons of extensor digitorum communis; A*, tendon overlying that of the indicator muscle.
B. Dorsal part of the annular ligament.
C. End of the radial nerve distributed over the back of the hand, to two of the fingers and the thumb.
D. Dorsal branch of the ulnar nerve supplying the back of the hand and the three outer fingers.
E. Radial artery turning round the carpal end of the metacarpal bone of the thumb.
F. Tendon of extensor carpi radialis brevis.
G. Tendon of extensor carpi radialis longus.
H. Tendon of third extensor of the thumb.
I. Tendon of second extensor of the thumb.
K. Tendon of extensor minimi digiti joining a tendon of extensor communis.
Plate 19
COMMENTARY ON PLATES 20 & 21.
THE RELATIVE POSITION OF THE CRANIAL, NASAL, ORAL, AND PHARYNGEAL CAVITIES, &c.
On making a section (vertically through the median line) of the cranio-facial and cervico-hyoid apparatus, the relation which these structures bear to each other in the osseous skeleton reminds me strongly of the great fact enunciated by the philosophical anatomists, that the facial apparatus manifests in reference to the cranial structures the same general relations which the hyoid apparatus bears to the cervical vertebrae, and that these relations are similar to those which the thoracic apparatus bears to the dorsal vertebrae. To this anatomical fact I shall not make any further allusions, except in so far as the acknowledgment of it shall serve to illustrate some points of surgical import.
The cranial chamber, A A H, Plate 20, is continuous with the spinal canal C. The osseous envelope of the brain, called calvarium, Z B, holds serial order with the cervical spinous processes, E I, and these with the dorsal spinous processes. The dura-matral lining membrane, A A A*, of the cranial chamber is continuous with the lining membrane, C, of the spinal canal. The brain is continuous with the spinal cord. The intervertebral foramina of the cervical spine are manifesting serial order with the cranial foramina. The nerves which pass through the spinal region of this series of foramina above and below C are continuous with the nerves which pass through the cranial region. The anterior boundary, D I, of the cervical spine is continuous with the anterior boundary, Y F, of the cranial cavity. And this common serial order of osseous parts--viz., the bodies of vertebrae, serves to isolate the cranio-spinal compartment from the facial and cervical passages. Thus the anterior boundary, Y F D I, of the cranio-spinal canal is also the posterior boundary of the facial and cervical cavities.
Now as the cranio-spinal chamber is lined by the common dura-matral membrane, and contains the common mass of nervous structure, thus inviting us to fix attention upon this structure as a whole, so we find that the frontal cavity, Z, the nasal cavity, X W, the oral cavity, 4, 5, S, the pharyngeal and oesophageal passages 8 Q, are lined by the common mucous membrane, and communicate so freely with each other that they may be in fact considered as forming a common cavity divided only by partially formed septa, such as the one, U V, which separates to some extent the nasal fossa from the oral fossa.
As owing to this continuity of structure, visible between the head and spine, we may infer the liability which the affections of the one region have to pass into and implicate the other, so likewise by that continuity apparent between all compartments of the face, fauces, oesophagus, and larynx, we may estimate how the pathological condition of the one region will concern the others.
The cranium, owing to its comparatively superficial and undefended condition, is liable to fracture. When the cranium is fractured, in consequence of force applied to its anterior or posterior surfaces, A or B, Plate 20, the fracture will, for the most part, be confined to the place whereat the force has been applied, provided the point opposite has not been driven against some resisting body at the same time. Thus when the point B is struck by a force sufficient to fracture the bone, while the point A is not opposed to any resisting body, then B alone will yield to the force applied; and fracture thus occurring at the point B, will have happened at the place where the applied force is met by the force, or weight, or inertia of the head itself.