254 FASCLH AND MUSCLES OF THE HORSE 
pouches which act as burse. The synovial 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 fasciz 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, igaments, and tendons. In many 
places laminz 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 les is converted into a 
‘canal by a band or fascial sheet known as a vaginal or annular ligament (Lig. 
vaginale). Many fascize 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. Bursee occur in certain situations 
between the fascia and underlying structures, and are distinguished as subfascial 
bursa. Those between the fascia and the skin are subcutaneous bursa. 
FASCIZ AND MUSCLES OF THE HORSE 
The cutaneous muscle or panniculus carnosus (Musculus cutaneus) is a thin 
muscular layer developed in the superficial fascia. It is intimately adherent in 
ereat 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 raphé. The fibers are 
directed forward and diverge from the raphé 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 1s 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 
