The present disambiguation page holds the title of a primary topic , and an article needs to be written about it. It is believed to qualify as a broad-concept article . It may be written directly at this page or drafted elsewhere and then moved over here. Related titles should be described in Trochlea, while unrelated titles should be moved to Trochlea (disambiguation).
|Look up trochlea in Wiktionary, the free dictionary.|
Trochlea (Latin for pulley) is a term in anatomy. It refers to a grooved structure reminiscent of a pulley's wheel.
A pulley is a wheel on an axle or shaft that is designed to support movement and change of direction of a taut cable or belt, or transfer of power between the shaft and cable or belt. In the case of a pulley supported by a frame or shell that does not transfer power to a shaft, but is used to guide the cable or exert a force, the supporting shell is called a block, and the pulley may be called a sheave.
Anatomy is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science which deals with the structural organization of living things. It is an old science, having its beginnings in prehistoric times. Anatomy is inherently tied to developmental biology, embryology, comparative anatomy, evolutionary biology, and phylogeny, as these are the processes by which anatomy is generated over immediate (embryology) and long (evolution) timescales. Anatomy and physiology, which study (respectively) the structure and function of organisms and their parts, make a natural pair of related disciplines, and they are often studied together. Human anatomy is one of the essential basic sciences that are applied in medicine.
In joinery, a groove is a slot or trench cut into a member which runs parallel to the grain. A groove is thus differentiated from a dado, which runs across the grain.
Most commonly, trochleae bear the articular surface of saddle and other joints:
In a saddle joint the opposing surfaces are reciprocally concave-convex.
In the human arm, the humeral trochlea is the medial portion of the articular surface of the elbow joint which articulates with the trochlear notch on the ulna in the forearm.
The femur or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with the tibia and kneecap forming the knee joint. By most measures the femur is the strongest bone in the body. The femur is also the longest bone in the human body.
In humans, the calcaneus or heel bone is a bone of the tarsus of the foot which constitutes the heel. In some other animals, it is the point of the hock.
It also can refer to structures which serve as a guide for muscles:
The trochlea of superior oblique is a pulley-like structure in the eye. The tendon of the superior oblique muscle passes through it. Situated on the superior nasal aspect of the frontal bone, it is the only cartilage found in the normal orbit. The word trochlea comes from the Greek word for pulley.
The superior oblique muscle, or obliquus oculi superior, is a fusiform muscle originating in the upper, medial side of the orbit which abducts, depresses and internally rotates the eye. It is the only extraocular muscle innervated by the trochlear nerve.
The trochlear nerve, also called the fourth cranial nerve or CN IV, is a motor nerve that innervates only a single muscle: the superior oblique muscle of the eye, which operates through the pulley-like trochlea.
|disambiguation page lists articles associated with the title Trochlea. This |
If an internal link led you here, you may wish to change the link to point directly to the intended article.
The ulna is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. It runs parallel to the radius, the other long bone in the forearm, and is the larger and longer of the two.
The humerus is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a rounded head, a narrow neck, and two short processes. The body is cylindrical in its upper portion, and more prismatic below. The lower extremity consists of 2 epicondyles, 2 processes, and 3 fossae. As well as its true anatomical neck, the constriction below the greater and lesser tubercles of the humerus is referred to as its surgical neck due to its tendency to fracture, thus often becoming the focus of surgeons.
The extraocular muscles are the six muscles that control movement of the eye and one muscle that controls eyelid elevation. The actions of the six muscles responsible for eye movement depend on the position of the eye at the time of muscle contraction.
The superior orbital fissure is a foramen in the skull, although strictly it is more of a cleft, lying between the lesser and greater wings of the sphenoid bone.
The talus, talus bone, astragalus, or ankle bone is one of the group of foot bones known as the tarsus. The tarsus forms the lower part of the ankle joint through its articulations with the lateral and medial malleoli of the two bones of the lower leg, the tibia and fibula. Within the tarsus, it articulates with the calcaneus below and navicular in front within the talocalcaneonavicular joint. Through these articulations, it transmits the entire weight of the body to the foot.
The popliteal fossa is a shallow depression located at the back of the knee joint. The bones of the popliteal fossa are the femur and the tibia. Like other flexion surfaces of large joints, it is an area where blood vessels and nerves pass relatively superficially, and with an increased amount of lymph nodes.
Trochleitis is inflammation of the superior oblique tendon trochlea apparatus characterized by localized swelling, tenderness, and severe pain. This condition is an uncommon but treatable cause of periorbital pain. The trochlea is a ring-like apparatus of cartilage through which passes the tendon of the superior oblique muscle. It is located in the superior nasal orbit and functions as a pulley for the superior oblique muscle. Inflammation of the trochlear region leads to a painful syndrome with swelling and exquisite point tenderness in the upper medial rim of the orbit. A vicious cycle may ensue such that inflammation causes swelling and fraying of the tendon which then increases the friction of passing through the trochlea which in turn adds to the inflammation. Trochleitis has also been associated with triggering or worsening of migraine attacks in patients with pre-existing migraines.
In human cranial neuroanatomy, the supratrochlear nerve is a branch of the frontal nerve, which itself comes from the ophthalmic division of the trigeminal cranial nerve. It is smaller than the nearby supraorbital nerve. It passes above the pulley of the superior oblique muscle, and gives off a descending filament that joins the infratrochlear branch of the nasociliary nerve.
The infratrochlear nerve is given off from the nasociliary nerve just before it enters the anterior ethmoidal foramen.
The lower extremity of the humerus is flattened from before backward, and curved slightly forward; it ends below in a broad, articular surface, which is divided into two parts by a slight ridge.
The humeroulnar joint, is part of the elbow-joint. It is composed of two bones, the humerus and ulna, and is the junction between the trochlear notch of ulna and the trochlea of humerus. It is classified as a simple hinge-joint, which allows for movements of flexion, extension and circumduction. Owing to the obliquity of the trochlea of the humerus, this movement does not take place in the antero-posterior plane of the body of the humerus.
Fourth cranial nerve palsy also known as Trochlear nerve palsy, is a condition affecting Cranial Nerve 4 (IV), the Trochlear Nerve, which is one of the Cranial Nerves that causes weakness or paralysis to the Superior Oblique Muscle that it innervates. This condition often causes vertical or near vertical double vision as the weakened muscle prevents the eyes from moving in the same direction together.
Brown's syndrome is a rare form of strabismus characterized by limited elevation of the affected eye. The disorder may be congenital, or acquired. Brown syndrome is caused by a malfunction of the superior oblique muscle, causing the eye to have difficulty moving up, particularly during adduction. Harold W. Brown first described the disorder in 1950 and initially named it the "superior oblique tendon sheath syndrome".
The following outline is provided as an overview of and topical guide to human anatomy:
The Parks–Bielschowsky three-step test, also known as Park's three-step test or Bielschowsky head tilt test, is a method used to isolate the paretic extraocular muscle, particularly superior oblique muscle and trochlear nerve, in acquired vertical double vision. It was originally described by Marshall M. Parks.