Anterior inferior iliac spine
The anterior inferior iliac spine is a bony eminence on the anterior border of the hip bone, or, more the wing of the ilium. The upper portion of the spine gives origin to the straight head of the rectus femoris muscle, while a teardrop-shaped lower portion gives origin to the iliofemoral ligament of the hip joint and borders the rim of the acetabulum. Antero-medially and inferiorly to the AIIS is the iliopsoas groove, the passage for the iliopsoas muscle as it passes down to the lesser trochanter of the femur. A vague line, the inferior gluteal line, might run from the AIIS to the greater sciatic notch which delineates the inferior extent of the gluteus minimus origin; the AIIS is formed from a separate apophysis. Anatomy figure: 12:01-04 at Human Anatomy Online, SUNY Downstate Medical Center Anatomy photo:17:st-0202 at the SUNY Downstate Medical Center Anatomy photo:17:os-0104 at the SUNY Downstate Medical Center
In human anatomy, a hamstring is one of the three posterior thigh muscles in between the hip and the knee. The hamstrings are quite susceptible to injury. In quadrupeds, the hamstring is the single large tendon found behind comparable area; the common criteria of any hamstring muscles are: Muscles should originate from ischial tuberosity. Muscles should be inserted in the tibia or in the fibula. Muscles will be innervated by the tibial branch of the sciatic nerve. Muscle will participate in flexion of the knee extension of the hip joint; those muscle which fulfill all of the four criteria are called true hamstrings. The adductor magnus reaches only up to the adductor tubercle of the femur, but it is included amongst the hamstrings because the tibial collateral ligament of the knee joint morphologically is the degenerated tendon of this muscle; the ligament is attached to two millimeters from the adductor tubercle. The three muscles of the posterior thigh flex the knee, while all but the short head of biceps femoris extend the hip.
The three'true' hamstrings cross both the hip and the knee joint and are therefore involved in knee flexion and hip extension. The short head of the biceps femoris crosses only one joint and is therefore not involved in hip extension. With its divergent origin and innervation it is sometimes excluded from the'hamstring' characterization. A portion of the adductor magnus is sometimes considered a part of the hamstrings; the hamstrings cross and act upon two joints - the hip and the knee, as such are termed biarticular muscles. Semitendinosus and semimembranosus extend the hip; the long head of the biceps femoris extends the hip, as. The hamstrings play a crucial role in many daily activities such as walking, running and controlling some movement in the trunk. In walking, they are most important as an antagonist to the quadriceps in the deceleration of knee extension. Imaging the hamstring muscles is performed with an ultrasound and/or MRI; the biceps femoris is most injured, followed by semitendinosus.
Semimembranosus injury is rare. Imaging is useful in differentiating the grade of strain if the muscle is torn. In this setting, the level and degree of retraction can be determined, serving as a useful roadmap prior to any surgery; those with a hamstring strain of greater than 60mm in length have a greater risk of recurrence. The distal semitendinosus tendon is one of the tendons that can be used in the surgical procedure ACL reconstruction. In this procedure, a piece of it is used to replace the anterior cruciate ligament; the ACL is one of the four major ligaments in the knee. The word "ham" is derived from the Old English ham or hom meaning the hollow or bend of the knee, from a Germanic base where it meant "crooked", it gained the meaning of the leg of an animal around the 15th century. String refers to tendons, thus, the hamstrings are the string-like tendons felt on either side of the back of the knee. Hamstringing Hamstring curl Lombard's Paradox Popliteal fossa Pulled hamstring MRI Images demonstrating avulsion fracture of the hamstring muscle origin
Anatomical terms of muscle
Muscles are described using unique anatomical terminology according to their actions and structure. There are three types of muscle tissue in the human body: skeletal and cardiac. Skeletal striated muscle, or "voluntary muscle" joins to bone with tendons. Skeletal muscle maintains posture. Smooth muscle tissue is found in parts of the body; the majority of this type of muscle tissue is found in the digestive and urinary systems where it acts by propelling forward food and feces in the former and urine in the latter. Other places smooth muscle can be found are within the uterus, where it helps facilitate birth, the eye, where the pupillary sphincter controls pupil size. Cardiac muscle is specific to the heart, it is involuntary in its movement, is additionally self-excitatory, contracting without outside stimuli. As well as anatomical terms of motion, which describe the motion made by a muscle, unique terminology is used to describe the action of a set of muscles. Agonist muscles and antagonist muscles refer to muscles that inhibit a movement.
Agonist muscles cause a movement to occur through their own activation. For example, the triceps brachii contracts, producing a shortening contraction, during the up phase of a push-up. During the down phase of a push-up, the same triceps brachii controls elbow flexion while producing a lengthening contraction, it is still the agonist, because while resisting gravity during relaxing, the triceps brachii continues to be the prime mover, or controller, of the joint action. Agonists are interchangeably referred to as "prime movers," since they are the muscles considered responsible for generating or controlling a specific movement. Another example is the dumbbell curl at the elbow; the "elbow flexor" group is the agonist. During the lowering phase the "elbow flexor" muscles lengthen, remaining the agonists because they are controlling the load and the movement. For both the lifting and lowering phase, the "elbow extensor" muscles are the antagonists, they shorten during the dumbbell lowering phase.
Here it is important to understand that it is common practice to give a name to a muscle group based on the joint action they produce during a shortening contraction. However, this naming convention does not mean; this term describes the function of skeletal muscles. Antagonist muscles are the muscles that produce an opposing joint torque to the agonist muscles; this torque can aid in controlling a motion. The opposing torque can slow movement down - in the case of a ballistic movement. For example, during a rapid discrete movement of the elbow, such as throwing a dart, the triceps muscles will be activated briefly and to accelerate the extension movement at the elbow, followed immediately by a "burst" of activation to the elbow flexor muscles that decelerates the elbow movement to arrive at a quick stop. To use an automotive analogy, this would be similar to pressing your gas pedal and immediately pressing the brake. Antagonism is not an intrinsic property of a particular muscle group. During slower joint actions that involve gravity, just as with the agonist muscle, the antagonist muscle can shorten and lengthen.
Using the example above of the triceps brachii during a push-up, the elbow flexor muscles are the antagonists at the elbow during both the up phase and down phase of the movement. During the dumbbell curl, the elbow extensors are the antagonists for both the lifting and lowering phases. Antagonist and agonist muscles occur in pairs, called antagonistic pairs; as one muscle contracts, the other relaxes. An example of an antagonistic pair is the triceps. "Reverse motions" need antagonistic pairs located in opposite sides of a joint or bone, including abductor-adductor pairs and flexor-extensor pairs. These consist of an extensor muscle, which "opens" the joint and a flexor muscle, which does the opposite by decreasing the angle between two bones. However, muscles don't always work this way. Sometimes during a joint action controlled by an agonist muscle, the antagonist will be activated, naturally; this occurs and is not considered to be a problem unless it is excessive or uncontrolled and disturbs the control of the joint action.
This serves to mechanically stiffen the joint. Not all muscles are paired in this way. An example of an exception is the deltoid. Synergist muscles help perform, the same set of joint motion as the agonists. Synergists muscles act on movable joints. Synergists are sometimes referred to as "neutralizers" because they help cancel out, or neutralize, extra motion from the agonists to make sure that the force generated works within the desired plane of motion. Muscle fibers can only contract up to 40% of their stretched length, thus the short fibers of pennate muscles are more suitable where power rather than range of contraction is required. This limitation in the range of contraction affects all muscles, those that act over several joints may be unable to shorten sufficiently to produce
The iliopsoas refers to the joined psoas and the iliacus muscles. The two muscles are separate in the abdomen, but merge in the thigh; as such, they are given the common name iliopsoas. The iliopsoas muscle joins to the femur at the lesser trochanter, acts as the strongest flexor of the hip; the iliopsoas muscle is supplied by parts of the femoral nerve. The iliopsoas muscle is a composite muscle formed from the psoas major muscle, the iliacus muscle; the psoas major originates along the outer surfaces of the vertebral bodies of T12 and L1-L3 and their associated intervertebral discs. The iliacus originates in the iliac fossa of the pelvis; the psoas major unites with the iliacus at the level of the inguinal ligament and crosses the hip joint to insert on the lesser trochanter of the femur. The iliopsoas is classified as an "anterior hip muscle" or "inner hip muscle"; the psoas minor does contribute to the iliopsoas muscle. The inferior portion below the inguinal ligament forms part of the floor of the femoral triangle.
The psoas major is innervated by direct branches of the anterior rami off the lumbar plexus at the levels of L1-L3, while the iliacus is innervated by the femoral nerve. The iliopsoas is the prime mover of hip flexion, is the strongest of the hip flexors; the iliopsoas is important for standing and running. The iliacus and psoas major perform different actions; the iliopsoas muscle is covered by the iliac fascia, which begins as a strong tube-shaped psoas fascia, which surround the psoas major muscle as it passes under the medial arcuate ligament. Together with the iliac fascia, it continues down to the inguinal ligament where it forms the iliopectineal arch which separates the muscular and vascular lacunae, it is a typical posture muscle dominated by slow-twitch red type 1 fibers. Since it originates from the lumbar vertebrae and discs and inserts onto the femur, any structure from the lumbar spine to the femur can be affected directly. A short and tight iliopsoas presents as externally rotated legs and feet.
It can cause pain in the low or mid back, SI joint, groin, knee, or any combination. The iliopsoas gets innervation from the L2-4 nerve roots of the lumbar plexus which send branches to the superficial lumbar muscles; the femoral nerve passes through the muscle and innervates the quadriceps and sartorius muscles. It comprises the intermediate femoral cutaneous and medial femoral cutaneous nerves which are responsible for sensation over the anterior and medial aspects of the thigh, medial shin, arch of the foot nerves; the obturator nerve passes through the muscle, responsible for the sensory innervation of the skin of the medial aspect of the thigh and motor innervation of the adductor muscles of the lower extremity and sometimes the pectineus. Any of these innervated structures can be affected. Psoas abscess Iliopsoas tendonitis Muscles of the hip Muscles/Iliopsoas at exrx.net Cross section image: pelvis/pelvis-e12-15—Plastination Laboratory at the Medical University of Vienna
Vastus lateralis muscle
The vastus lateralis called the"vastus externus" is the largest and most powerful part of the quadriceps femoris, a muscle in the thigh. Together with other muscles of the quadriceps group, it serves to extend the knee joint, moving the lower leg forward, it arises from a series of flat, broad tendons attached to the femur, attaches to the outer border of the patella. It joins with the other muscles that make up the quadriceps in the quadriceps tendon, which travels over the knee to connect to the tibia; the vastus lateralis is the recommended site for intramuscular injection in infants less than 7 months old and those unable to walk, with loss of muscular tone. The vastus lateralis muscle arises from several areas of the femur, including the upper part of the intertrochanteric line; these form a broad flat tendon that covers the upper three-quarters of the muscle. From the inner surface of the aponeurosis, many muscle fibers originate; some additional fibers arise from the tendon of the gluteus maximus muscle, from the septum between the vastus lateralis and short head of the biceps femoris.
The fibers form a large fleshy mass, attached to a second strong aponeurosis, placed on the deep surface of the lower part of the muscle. This lower aponeurosis becomes contracted and thickened into a flat tendon that attaches to the outer border of the patella, subsequently joins with the quadriceps femoris tendon, expanding the capsule of the knee-joint; the vastus lateralis muscle is innervated by the muscular branches of the femoral nerve. Notes This article incorporates text in the public domain from page 470 of the 20th edition of Gray's Anatomy Cross section image: pembody/body18b—Plastination Laboratory at the Medical University of Vienna Cross section image: pelvis/pelvis-e12-15—Plastination Laboratory at the Medical University of Vienna PTCentral
A nerve is an enclosed, cable-like bundle of nerve fibres called axons, in the peripheral nervous system. A nerve provides a common pathway for the electrochemical nerve impulses called action potentials that are transmitted along each of the axons to peripheral organs or, in the case of sensory nerves, from the periphery back to the central nervous system; each axon within the nerve is an extension of an individual neuron, along with other supportive cells such as Schwann cells that coat the axons in myelin. Within a nerve, each axon is surrounded by a layer of connective tissue called the endoneurium; the axons are bundled together into groups called fascicles, each fascicle is wrapped in a layer of connective tissue called the perineurium. The entire nerve is wrapped in a layer of connective tissue called the epineurium. In the central nervous system, the analogous structures are known as tracts; each nerve is covered on the outside by a dense sheath of the epineurium. Beneath this is a layer of flat cells, the perineurium, which forms a complete sleeve around a bundle of axons.
Perineurial septae subdivide it into several bundles of fibres. Surrounding each such fibre is the endoneurium; this forms an unbroken tube from the surface of the spinal cord to the level where the axon synapses with its muscle fibres, or ends in sensory receptors. The endoneurium consists of an inner sleeve of material called the glycocalyx and an outer, meshwork of collagen fibres. Nerves are bundled and travel along with blood vessels, since the neurons of a nerve have high energy requirements. Within the endoneurium, the individual nerve fibres are surrounded by a low-protein liquid called endoneurial fluid; this acts in a similar way to the cerebrospinal fluid in the central nervous system and constitutes a blood-nerve barrier similar to the blood-brain barrier. Molecules are thereby prevented from crossing the blood into the endoneurial fluid. During the development of nerve edema from nerve irritation, the amount of endoneurial fluid may increase at the site of irritation; this increase in fluid can be visualized using magnetic resonance neurography, thus MR neurography can identify nerve irritation and/or injury.
Nerves are categorized into three groups based on the direction that signals are conducted: Afferent nerves conduct signals from sensory neurons to the central nervous system, for example from the mechanoreceptors in skin. Efferent nerves conduct signals from the central nervous system along motor neurons to their target muscles and glands. Mixed nerves contain both afferent and efferent axons, thus conduct both incoming sensory information and outgoing muscle commands in the same bundle. Nerves can be categorized into two groups based on where they connect to the central nervous system: Spinal nerves innervate much of the body, connect through the vertebral column to the spinal cord and thus to the central nervous system, they are given letter-number designations according to the vertebra through which they connect to the spinal column. Cranial nerves innervate parts of the head, connect directly to the brain, they are assigned Roman numerals from 1 to 12, although cranial nerve zero is sometimes included.
In addition, cranial nerves have descriptive names. Specific terms are used to describe their actions. A nerve that supplies information to the brain from an area of the body, or controls an action of the body is said to "innervate" that section of the body or organ. Other terms relate to whether the nerve affects the same side or opposite side of the body, to the part of the brain that supplies it. Nerve growth ends in adolescence, but can be re-stimulated with a molecular mechanism known as "Notch signaling". If the axons of a neuron are damaged, as long as the cell body of the neuron is not damaged, the axons would regenerate and remake the synaptic connections with neurons with the help of guidepost cells; this is referred to as neuroregeneration. The nerve begins the process by destroying the nerve distal to the site of injury allowing Schwann cells, basal lamina, the neurilemma near the injury to begin producing a regeneration tube. Nerve growth factors are produced causing many nerve sprouts to bud.
When one of the growth processes finds the regeneration tube, it begins to grow towards its original destination guided the entire time by the regeneration tube. Nerve regeneration is slow and can take up to several months to complete. While this process does repair some nerves, there will still be some functional deficit as the repairs are not perfect. A nerve conveys information in the form of electrochemical impulses carried by the individual neurons that make up the nerve; these impulses are fast, with some myelinated neurons conducting at speeds up to 120 m/s. The impulses travel from one neuron to another by crossing a synapse, the message is converted from electrical to chemical and back to electrical. Nerves can be categorized into two groups based on function: An afferent nerve fiber conducts sensory information from a sensory neuron to the central nervous system, where the information is processed. Bundles of fibres or axons, in the peripheral nervous system are called nerves, bundles of afferent fibers are known as sensory nerves.
An efferent nerve fiber conducts signals from a motor neuron in the central nervous system to muscles. Bundles of these fibres are known as efferent nerves; the nervous system is the part of an animal that coordinates its actions by transmitting signals to and from different parts of its body. In vertebrates it consists of two main par
The gluteus medius one of the three gluteal muscles, is a broad, radiating muscle, situated on the outer surface of the pelvis. Its posterior third is covered by the gluteus maximus, its anterior two-thirds by the gluteal aponeurosis, which separates it from the superficial fascia and integument; the gluteus medius muscle starts, or "originates," on the outer surface of the ilium between the iliac crest and the posterior gluteal line above, the anterior gluteal line below. The fibers of the muscle converge into a strong flattened tendon that inserts on the lateral surface of the greater trochanter. More the muscle's tendon inserts into an oblique ridge that runs downward and forward on the lateral surface of the greater trochanter. A bursa separates the tendon of the muscle from the surface of the trochanter; the posterior border may be more or less united to the piriformis, or some of the fibers end on its tendon. The posterior fibres of gluteus medius contract to produce hip extension, lateral rotation and abduction.
During gait, the posterior fibres help to decelerate internal rotation of the femur at the end of swing phase. • The anterior part acting alone helps to flex and internally rotate the hip. • The posterior part acting alone helps to extend and externally rotate the hip. • The anterior and posterior parts working together abduct the hip and stabilize the pelvis in the coronal plane. Dysfunction of the gluteus medius or the superior gluteal nerve can be indicated by a positive Trendelenburg's sign. Trendelenburg gait This article incorporates text in the public domain from page 474 of the 20th edition of Gray's Anatomy Anatomy photo:13:st-0404 at the SUNY Downstate Medical Center Cross section image: pelvis/pelvis-e12-15—Plastination Laboratory at the Medical University of Vienna