Left Clavicle Inferior Surface

Left Clavicle Inferior Surface. The posterior or cervical surface is smooth, flat, and looks backward toward the root of the neck. It is limited, above, by the superior border; below, by the subclavian border; internally, by the margin of the sternal extremity; externally, it is continuous with the posterior border of the flat portion. It is concave from within outward, and is in relation, by its lower part, with the suprascapular vessels. This surface, at about the junction of the inner and outer curves, is also in close relation with the brachial plexus and subclavian vessels. It gives attachment, near the sternal. extremity, to part of the Sterno-hyoid muscle; and presents, at or near the middle, a foramen, directed obliquely outward, which transmits the chief nutrient artery of the bone. Sometimes there are two foramina on the posterior surface, or one on the posterior, the other on the inferior surface The inferior or subclaviansurface is bounded, in front, by the anterior border; behind, by the subclavian border. It is narrow internally, but gradually increases in width externally, and  is continuous with the under surface of the flat portion. Commencing at the sternal extremity may be seen a small facet for articulation with the cartilage of the first rib. This is continuous with the articular surface at the sternal end of the bone. External to this is a broad, rough surface, the rhomboid impression, rather more than an inch in length, for the attachment of the costo-clavicular (rhomboid) ligament. The remaining part of this surface is occupied by a longi­tudinal groove, the subclavian groove, broad and smooth externally, narrow and more uneven internally; it gives attachment to the Subclavius muscle, and by its margins to the costo-coracoid membrane, which splits to enclose a muscle. Not infrequently this groove is subdivided into two parts by a longitudinal line, which gives attachment to the intermuscular septum of the Subclavius muscle.

The Lesser or Anterior

The Lesser or Anterior.

The Lesser or Anterior Sacro-sciatic Ligament, much shorter ano. smaller than the preceding, is thin, triangular in form, attached by its apex to the spine of the ischium, and internally, by its broad base, to the lateral margin of the sacrum and coccyx, anterior to the attachment of the great sacro-sciatic ligament with which its fibres are intermingled.  It is in relation, anteriorly, with the Coccygeus muscle; poste1'iorly, it is covered   by the great sacro-sciatic ligament and crossed by the internal pudic vessels and nerve. Its superior border forms the lower boundary of the great sacro-sciatic foramen; its inferi01' border, part of the lesser sacro-sciatic foramen.

Base Of The External Surface

Base Of The External Surface.

External to the stylo-mastoid foramen is the auricular fissure, for the auricular branch of the pneumogastric, bounded behind by the mastoid process. Upon the inner side of the mastoid proc­ess is a deep groove, the digastric fossa; and a little more internally the occipital groove, for the occipital artery. At the base of the internal pterygoid plate is a large and somewhat triangular aperture, the foramen lacerum medium, bounded in front by the great wing of the sphenoid, behind by the apex of the petrous portion of the temporal bone, and internally by the body of the sphenoid and basilar proc­ess of the occipital bone: it presents in front the posterior orifice of the Vidian canal; behind, the aperture of the carotid canal. The basilar surface of this open­ing is filled in the recent state by fibro-cartilaginous substance f across its upper or cerebral aspect passes the internal carotid artery. External to this aperture the petro-sphenoidal suture is observed, at the outer termination of which is seen the orifice of the canal for the Eustachian tube and tLat for the Tensor tympani muscle. Behind this suture is seen the under surface of the petrous portion of the temporal bone, presenting, from within outward, the quadrilateral, rough surface, part of which affords attachment to the Levator palati and Tensor tympani muscles; exter­nal to this surface the orifices (If the carotid canal and the aqureductus cochlere, the former transmitting the internal carotid artery and the ascending branches of the superior cervical ganglion of the sympathetic, the latter serving for the passage of a small artery and vein to the cochlea. Behind the carotid canal is a large aperture, the Jugular foramen. formed in front by the petrous portion of the tem­poral, and behind by the occipital; it is generally larger on the right than on the left side, and is divided into three compartments by processes of dura mater. The anterior is for the passage of the inferior petrosal sinus; the posterior, for the lateral sinus and some meningeal branches from the occipital and ascending phar­yngeal arteries; the central one, for the glosso-pharyngeal, pneumogastric, and spinal accessory nerves. On the ridge of bone dividing the carotid canal from the jugular foramen is the small fora.men for the transmission of Jacobson's nerve; and on the wall of the jugular foramen, near the root of the styloid process, is the small aperture for the transmission of Arnold's nerve. 

Development Of The Foot

Development Of The Foot.

Surface Form.-On the dorsum of the foot the individual bones are not to be distinguished with the exception of the head of the astragalus, which forms a rounded projection in front of the   ankle-joint when the foot is forcibly extended, The whole surface forms a smooth convex outline, the summit of which is the ridge formed by the head of the astragalus, the navicular, the middle cuneiform, and the second metatarsal bones; from this it gradually inclines outward and more rapidly inward. On the inner side of the foot, the internal tuberosity of the os calcis and the   ridge separating the inner from the posterior surface of the bone may be felt most pos­teriorly. In front of this, and below the internal malleolus, may be felt the projection of the sustentaculum tali. Passing forward is the well-marked tuberosity of the navicular bone, situ­ated about an inch or an inch and a quarter in front of the internal malleolus. Further toward the front, the ridge formed by the base of t.he first metatarsal bone can be obscurely felt, and from this the shaft of the bone can be traced to the expanded head articulating with the base of the first phalanx of the great toe. Immediately beneath the base of this phalanx, the internal sesamoid bone is to be felt. Lastly, the expanded ends of the bones forming the last joint of the great toe are to be felt. On the outer side of the foot the most posterior bony point is the outer tuberosity of the os calcis, with the ridge separating the rosterior from the outer surface of the bone. In front of this the greater part of the externa surface of the 08 calcis is subcutaneous; on it, below and in front of the external malleolus, may be felt the pero­neal ridge, when this process is present.. Farther forward, the base of the fifth metatarsal bone forms a prominent and well-defined landmark, and in front of this the shaft of the bone, with its expanded head, and the base of the first phalanx may be defined. The sole of the foot is almost entirely covered by soft parts, so that but few bony parts are to be made out, and these somewhat obscurely. The hinder part of the under surface of the os calcis and the heads of the metatarsal bones, with the exception of the first, which is concealed by the sesamoid bones, may be recofnized.

The utero-extemal border

The Utero-extemal

The utero-extemal border commences above in front of the head, runs verti- cally downward to a little below the middle of the bone, and then, curving some­what outward, bifurcates so as to embrace the triangular subcutaneous surface immediately above the outer surface of the external malleolus. This border gives attachment to an intermuscular septum, which separates the extensor muscles on the anterior surface of the leg from the Peroneus longus and brevis muscles on the outer surface. The antero-internal border, or interoBBeous ridge, is situated close to the inner side of the preceding, and runs nearly parallel with it in the upper third of its extent, but diverges from it so as to include a broader space in the lower two-thirds. It commences above, just beneath the head of the bone (sometimes it is quite indistinct for about an inch below the head), and terminates below at the apex of a rough triangular surface immediately above the articular facet of the external malleolus. It serves for the attachment of the interosseous membrane, which sepa­rates the extensor muscles in front from the flexor muscles behind. The postero-extemal border is prominent; it commences above at the base of the styloid process, and terminates below in the posterior border of the outer malleolus. It is directed outward above, backward in the middle of its course, backward and a little inward below, and gives attachment to an aponeurosis which separates the Peronei muscles on the outer surface of the shaft from the flexor muscles on its posterior surface.

The Mastoid Portion

The Mastoid Portion.

The superior border is thin, bevelled at the expense of the internal surface, so as .to overlap the lower border of the parietal bone, forming the squam­ous suture. 

 The position and size of this foramen are very variable. It is not always present; sometimes it is situated in the occipital bone or in the suture between the temporal and the occipital. The mastoid portion is continued below into a conical projection, the mastoid process, the size and form of which vary somewhat. This process serves for the attachment of the Sterno-mastoid, ~Jllenius capitis, and 'rl'achelo-mastoid muscles. On the inner side of the mastoid process is a deep groove, the digastric fossa, for the attachment of the Diga"tric muscle; and, running parallel with it, but more in­ternal, the occipital gronee. which lodges the occipital artery.

 

The Costal Cartilages

The Costal Cartilages

The Costal Cartilages are bars of white, hyaline cartilage, which serve to prolong the ribs forward to the front of the chest, and contribute very materially to the elasticity of its walls. The first seven are connected with the sternum, the next three with the lower border of the cartilage of the preceding rib. The cartilages of the last two ribs have pointed extremities, which terminate in free ends in the walls of the abdomen. Like the ribs, the costal cartilages vary in their length, breadth, and direction. They increase in .length from the first to the seventh, then gradually diminish to the last. They diminish in breadth, as well as the intervals between them, from the first to the last. They are broad at their attachment to the ribs, and taper toward their sternal extremities, excepting the first two, which are of the same breadth throughout, and the sixth, seventh, and eighth, which are enlarged where their margins are in contact. In direction they also vary: the first descends a little, the second is horizontal, the third ascends slightly, while all the rest follow the course of the ribs for a short extent, and then ascend to the sternum or preceding cartilage. Each costal carti­lage presents two surfaces, two borders, and two extremities. The anterior surface is convex, and looks forward and upward: that of the first gives attachment to the costo-clavicular ligament and the Subclavius muscle; that of the second, third, fourth, fifth, and sixth, at their sternal ends, to the Pectoralis major.! The others are covered by, and give partial attachment to, some of the great fiat muscles of the abdomen. The posterior surface is concave, and directed backward and downward, the first giving attachment to the Sterno-thyroid, the third to the sixth inclusive to the rrriangularis sterni, and the six or seven inferior ones to the Tranversalis muscle and the Diaphragm. Of the two borders, the superior is concave, the inferior convex: they afford attachment to the internal Intercostal muscles, the upper border of the sixth giving attachment to the Pectoralis major muscle. The contiguous borders of the sixth, seventh, and eighth, and sometimes the ninth and tenth, costal cartilages present small, smooth, oblong-shaped facets at the points where they articulate. Of the two extremities, the outer one is continuous with the osseous tissue of the rib to which it belongs. The inner extremity of the first is continuous with the sternum; the six succeeding ones have rounded extremities,which are received into shallow concavities on the lateral margins of the sternum. The inner extremities of the eighth, ninth, and tenth costal cartilages are pointed, and are connected with the cartilage above.