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a tubular case or envelope.
arachnoid sheath the delicate membrane between the pial sheath and the dural sheath of the optic nerve.
carotid sheath a portion of the cervical fascia enclosing the carotid artery, internal jugular vein, vagus nerve, and sympathetic nerves supplying the head.
connective tissue sheath of Key and Retzius endoneurium.
crural sheath femoral sheath.
dural sheath the external investment of the optic nerve.
femoral sheath the fascial sheath of the femoral vessels.
Henle's sheath endoneurium.
lamellar sheath the perineurium.
medullary sheath myelin sheath.
myelin sheath (nerve sheath) the sheath surrounding the axon of myelinated nerve cells, consisting of concentric layers of myelin formed in the peripheral nervous system by the plasma membrane of Schwann cells, and in the central nervous system by the plasma membrane of oligodendrocytes. It is interrupted at intervals along the length of the axon by gaps known as nodes of Ranvier. Myelin is an electrical insulator that serves to speed the conduction of nerve impulses (see saltatory conduction).
pial sheath the innermost of the three sheaths of the optic nerve.
root sheath the epidermic layer of a hair follicle.
sheath of Schwann neurilemma.
synovial sheath synovial membrane lining the cavity of a bone through which a tendon moves.
tendon sheath a lubricated fibrous or synovial layer of tissue in which the tendon is housed and through which it moves.
A dense fibrous sheath that confines a tendon to an osseous groove, converting it into an osteofibrous canal. It is found principally in the wrist and ankle.See: synovial sheath
See also: sheath
A membrane covering a tendon.
Mentioned in: Trigger Finger
a sheet, cord or band of strong white fibrous tissue that connects a muscle to a bone or other structure. When the muscle contracts, or shortens, it pulls on the tendon. Tendons serve to convey an action to a remote site, change the direction of pull and focus the force. Sheetlike tendons (aponeuroses) serve to support and squeeze, cordlike ones to act on joints. See also cunean tendon.
chronic tendinitis of the superficial flexor tendons, usually of the front limbs, of a horse. The horse is lame or inclined to lameness, the tendon is thickened and is visibly enlarged. It may be painful on palpation in the early, acute stages.
see achilles tendon.
tendon cartilaginous metaplasia
focal metaplasia with the formation of cartilage in tendons causes no apparent harm and is considered to be normal.
common calcanean tendon
see achilles tendon.
congenital tendon contracture
an inherited contracture of multiple tendons is identified in cattle. The joints are fixed in extension or flexion and cause serious dystocia. See also akabane virus disease.
see tendon contracture (below).
permanent contraction of a tendon caused by chronic tendinitis. Most commonly of the flexor tendons of the digit in the horse. The action of the affected limb is restricted and the limb is not fully extended at rest causing the animal to stand up on its toe. Called also contracted tendons.
tendons of the superficial and deep flexor muscles of the digit. Commonly strained, lacerated and separated in the racing horse.
done in horses with badly torn or ruptured flexor tendons. Autologous grafts are taken from the lateral digital extensor tendon.
internal biceps tendon
a core of fibrous tissue within the biceps muscle of horses which serves a significant role in the stay apparatus.
suspensory ligament (1).
slipping of the superficial flexor tendon of the hindlimb of the horse off the tuber calcis, usually in the medial direction; also occurs rarely in dogs and ostriches. See also perosis.
tendon osseous metaplasia
a pathological abnormality and usually attended by abnormality of movement. See also tendon ossification (below).
occurs extensively in gallinaceous birds in the tendons of the legs and feet, the wings and the epaxial musculature. Although the ossification may be extensive the birds are normal and the reasons for the changes are unknown.
the tendon of insertion of the two abdominal recti muscles on to the pubis.
a fluid-filled sleeve that resembles a synovial bursa wrapped around the tendon so as to form a continuous sheath, except for the mesotendon.
performed by slitting the superficial flexor tendon (or the suspensory ligament) along its long axis and from lateral to medial sides as a treatment for tendinitis. The objective is to stimulate vascularization and hasten repair.
see tendon strain (below).
the injury caused to flexor tendons in the horse during racing. Most commonly affected is the superficial flexor tendon in the front limb. See also bowed tendon (above). Called also sprained tendon.
a vertical median sheet which hangs from the pubic symphysis and provides an origin for the medial thigh muscles.