254 FASCIA AND MtrSCLBS OF THE HOESE 



pouches which act as bursse. The sjiiovial sheath is not to be confused with the 

 fibrous sheath of a tendon (Vagina fibrosa tendinis) . 



The student will note in dissection that intermediate forms of these sacs occur. A synovial 

 sheath may belong to two or more tendons in common; in such cases the synovial membrane is 

 reflected from one tendon to the other, forming a secondary mesotendon. In the normal state 

 these sacs cannot be recognized on external examination of the subject. It is only when they are 

 distended that their presence is evident. 



The fasciae are sheets of connective tissue, composed mainly of bundles of white 

 fibers, with a greater or less admixture of elastic fibers in some cases. At least two 

 layers may usually be distinguished. The superficial fascia (Fascia superficialis) 

 is subcutaneous, and is composed of loose connective tissue which usually contains 

 more or less fat. The deep fascia is composed of one or more layers of dense fibrous 

 tissue. Its deep face may be very slightly adherent to the underlying structures, 

 but in many places it is attached to the skeleton, ligaments, and tendons. In many 

 places laminae are given off from the deep face of the fascia, pass between muscles, 

 and are attached to bones or ligaments; such layers are termed intermuscular septa 

 (Septa intermuscularia) . The groove in which a tendon lies is converted into a 

 canal by a band or fascial sheet known as a vaginal or annular ligament (Lig. 

 vaginale). Many fasciae furnish origin or insertion to muscles and thus act as 

 tendons; such are tendinous in structure, so as to render the distinction between 

 fascia and aponeurosis in these cases arbitrary. Bursse occur in certain situations 

 between the fascia and underlying structures, and are distinguished as subfascial 

 bursse. Those between the fascia and the skin are subcutaneous bursae. 



FASCIA AND MUSCLES OF THE HORSE 



The cutaneous muscle or panniculus camosus (Musculus cutaneus) is a thin 

 muscular layer developed in the superficial fascia. It is intimately adherent in 

 great part to the skin, but has very little attachment to the skeleton. It does not 

 cover the entire body, and may be conveniently divided into facial, cervical, omo- 

 brachial, and abdominal parts. 



The facial part, m. cutaneus faciei, consists of a thin and usually incomplete 

 muscular layer, which extends over the mandibular space and the masseter muscle. 

 A distinct branch of it passes forward to the angle of the mouth and blends with the 

 orbicularis oris. This part, the m. cutaneus labiorum, retracts the angle of the 

 mouth, and has therefore been termed the retractor anguli oris. 



The cervical part, m. cutaneus colli, is situated on the ventral region of the neck. 

 It arises from the cariniform cartilage and a median fibrous raph6. The fibers are 

 directed forward and diverge from the raphe to the sides of the neck in pennate 

 fashion. It is thick at its sternal origin, but thins out in front and laterally. On 

 the side of the neck it is attached to the cervical fascia, which acts as its aponeurosis. 

 It is related deeply to the sterno-cephalicus, the brachio-cephalicus (in part) and 

 the jugular vein. Some bundles extend upon the parotid gland, and in well- 

 developed subjects it is continuous with the facial part. 



The omo-brachial part, m. cutaneus omo-brachialis, covers the lateral surface 

 of the shoulder and arm. Its fibers begin over the upper part of the scapula and 

 extend to the proximal part of the forearm. Most of its fibers are vertical, but 

 posteriorly they become oblique and are continued by the abdominal part. 



The abdominal part, m. cutaneus trunci, covers a large part of the body be- 

 hind the shoulder and arm. Its fibers are largely longitudinal. It is continuous 

 in front with the omo-brachial part, and a tendinous layer from it passes forward 



