254 THE MUSCLES. 



mediate middle raphe of the two muscles, and, directing their course outwards and 

 upwards, soon become confounded with the aponeurosis. The latter, extremely 

 thin, is spread over the mastoido-humeralis, the superior cervical muscles, the 

 parotid region, and the cheeks, and is finally attached to the zygomatic crest. On 

 arriving near the commissure of the lips, it is united to the buccinator muscle by 

 a fleshy fasciculus named, in Man, the risorius Santorini (Fig. 163). 



The cervical panniculus braces the muscles it covers, during their contraction, 

 and pulls backwards the commissures of the Hps. We doubt very much whether 

 it has — in the cervical region at least — any action on the skin, for it adheres but 

 very slightly to its inner smface. 



2. Mastoido-humeralis (Levator Humeri) (Figs. 158, 160, 162, 163). 



Synonyms. — The muscle common to the arm, neck, and head — Bourgelat. Representing 

 the cleido-mastoid, and the clavicular portions of the trapezius and deltoid of Man, and the 

 trachelo-acromialis peculiar to quadruped Mammals ' — G. Cuvier, Lemons d'Anatomie Com- 

 par^e, 2iid edition. (This is the muscle which Percivall names the levator humeri. The 

 above is the designation given to it by Girard and Chauveau. Leyh gives it the same designa- 

 tion as Bourgelat.) 



Extent — Situation — Direction — Composition. — This muscle extends from the 

 summit of the head to the inferior part of the arm, and is applied to the scapulo- 

 humeral angle at the side of the neck, in an oblique direction downwards and 

 backwards. It is composed of two portions lying longitudinally, and somewhat 

 intimately united, and distinguished into anterior and posterior. 



Form — Structure — Attachments. — A. The anterior or superficial portion (Fig. 

 159, 6) constitutes a long fleshy band, which appears to be united, by its anterior 

 border, to the cuticular muscle of the neck. Its superior extremity, thin and wide, 

 is attached to the mastoid process and crest by an aponeurosis (Fig. 159, 71), which 

 is united, in front, to the tendon of the sterno-maxillaris by a very thin cellulo- 

 aponeurotic fascia. Its inferior extremity, thicker than the superior, is inserted 

 by means of a very short aponeurosis into the humerus, on the salient border 

 descending from the deltoid imprint, and which limits, in front, the musculo- 

 spiral groove on the body of that bone (Fig, 159, 7). 



panniculus the sternal band attributed until now to the mastoido-humeralis. These are the 

 consifierations which induce us to make this modification : 1. This band is not distinct from 

 the cervical panniculus ; a separation between the two muscles can only be artificially obtained. 

 2. In dissecting this band with care, we can see that its fibres, like those of the panniculus, are 

 not mixed with those of tlie mastoido-humeralis (superficial portion); they pass along the 

 external surface of that muscle, to which they intimately adhere, it is true, but they can easily 

 be separated, and are continuous with the aponeurosis of the first. 



' At first sight, we might hesitate to admit that this muscle is formed of such varied and 

 complicated elements as are enumerated above. Nevertheless, it is a scientific fact ; and we 

 will give a demonstration, as simple as it is clear, that such is the case — the idea we owe to 

 J. F. Mickel. If we take the Dnp-, for example, and suppose it to be possessed of a clavicle 

 extending from the anterior extremity of the sternum to the acromion, this clavicle would bisect, 

 transversely, the inferior portion of the mastoido-humeralis, which would thus be divided into 

 two portions— a superior and an inferior. The first, extending from the clavicle to the mastoiil 

 process, on this side, and on the other to the mastoid crest, as well as to the cervical ligament, 

 where it is confounded with the trapezius, would exactly represent the clavicular portion of the 

 latter muscle, and the cleido-mastoideus. With respect to the inferior portion, it perfectly 

 resembles, by its attachments, the clavicular portion of the deltoid. But, on the contrary, if 

 we suppose Man deprived of a clavicle, the three muscular fasciculi indicated, in becoming 

 confounded with each other, would form the mastoido-humeralis of the Dog, minus the posterior 

 portion, or the trachelo-acromialis, which is not represented in Man. 



