System: Musculoskeletal

Temporomandibular Joint

Temporomandibular Joint The structure indicated is the temporomandibular joint. The temporomandibular joint is commonly referred to as the TMJ and is a synovial joint formed between the condyles of the mandible and the articular fossa and articular tubercle of the temporal bones of the skull. The articular surfaces of the temporomandibular joint are covered with fibrocartilage, and the joint is divided into two parts by the presence of a fibrous articular disc: The inferior part of the TMJ allows depression and elevation. The superior part of the TMJ allows protrusion and retraction. Temporomandibular joint dysfunction (TMJD) is an umbrella term which …

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Temporomandibular Joint

Epimysium

Epimysium The structure indicated in this diagram is the epimysium. Skeletal muscle fibres are organised into bundles, called fascicles. Each fibre within the fascicle is surrounded by connective tissue called endomysium. Surrounding each fascicle (bundle), is the perimysium. Extensions of the perimysium project into the fascicles to blend with the endomysium. Surrounding the groups of fascicles is the epimysium, which covers the outer surface of the muscle. The epimysium is composed of dense irregular connective tissue. The epimysium can extend beyond the fleshy muscle fibres to form tendons or aponeuroses, which then form attachments to the periosteum of bones.
Epimysium

Prepatellar Bursa

Prepatellar Bursa The structure indicated is the prepatellar bursa of the knee joint. The synovial membrane of the knee joint forms bursae to protect the structures of the knee joint and to provide low friction surfaces to allow tendons and structures of the knee joint to glide smoothly over one another. In addition there are several other bursae which do not communicate with the joint cavity, located in and around the knee joint. The prepatellar bursa is found anteriorly, and as the name suggests, in front of the patella. There are several other bursae located laterally and medially. Anterior bursae: Suprapatellar …

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Prepatellar Bursa

Median Sacral Crest

Median Sacral Crest The structure indicated is the median sacral crest. The median sacral crest is located on the dorsal surface of the sacrum. The median sacral crest possesses three to four tubercles which are essentially the equivalent of the spinous processes of the upper sacral vertebrae. Either side of the median sacral crest on the dorsal surface of the sacrum, are the posterior sacral foramina (four pairs). Inferiorly, the sacrum forms two horns, or cornua, which articulate with the cornua of the coccyx. To learn more about the anatomy of the bones of the pelvis watch this video.
Median Sacral Crest

Epiphyseal Line

Epiphyseal Line The structure indicated is the epiphyseal line. The epiphyseal plate is a plate of hyaline cartilage found in children and adolescents, located in the metaphysis at the ends of each long bone. Long bones consist of a diaphysis, metaphysis and epiphysis. The diaphysis is the main long section of the bone, the epiphysis is the rounded end of the long bone, and the metaphysis is the section of bone between the diaphysis and metaphysis.  In adults, the epiphyseal plate is replaced with the epiphyseal line and marks the point of union were the epiphysis meets the diaphysis. The …

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Epiphyseal Line

Iliocostalis Lumborum

Iliocostalis Lumborum The muscle indicated is the iliocostalis lumborum muscle, one of the erector spinae group of back muscles. The back muscles can be divided into three groups of muscles: Superficial Intermediate Deep group The erector spinae muscles belong to the deep (intrinsic) group of back muscles and are the largest group of intrinsic back muscles. There are three main erector spinae muscles, from lateral to medial: Iliocostalis Longissimus Spinalis Each of these three muscles is further subdivided into separate parts: Lumborum Thoracis Cervicis Capitis Origin: sacrum, iliac crest, spinous processes of lumbar vertebrae and thoracic vertebrae T11 and T12 …

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Iliocostalis Lumborum

Major alar cartilage

Major alar cartilage The structure indicated is the major alar cartilage (greater alar cartilage). The lateral walls of the external nose are comprised from three cartilages: Lateral process of septal cartilage Major alar cartilage Minor alar cartilage The major alar cartilage is located directly below the lateral process of the septal cartilage. It is structured such that it is bent in on itself to form both the medial and lateral walls of the nose. The crus laterale forms the lateral wall, whereas the crus mediale forms the medial wall.
Major Alar Cartilage

Iliacus Muscle

Iliacus Muscle The muscle indicated is the iliacus muscle. The iliacus originates in the iliac fossa on the inside of the pelvic bone. The iliacus combines with the psoas major to enter the anterior compartment of the thigh and insert via a common tendon on the lesser trochanter of the femur. The iliacus and psoas are thus collectively referred to as the iliopsoas muscle – they act synergistically to flex the thigh at the hip joint, as well as acting to cause lateral rotation of the thigh. The iliopsoas muscles are the strongest hip flexors. Origin: Iliac fossa Insertion: Base …

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Iliacus

Orbicularis Oris Muscle

Orbicularis Oris The muscle indicated is the orbicularis oris muscle. The orbicularis oris muscle is one of the muscles of facial expression belonging to the oral group. The muscles of facial expression can be organised into functional groups to provide a more structured approach to understanding the muscles. The functional groups include the following: Orbital group Nasal group Oral group Other The oral group of muscles includes muscles that are responsible for moving the lips and the cheek. There are 11 muscles included in this functional group: orbicularis oris, depressor anguli oris, depressor labi inferioris, mentalis, risorius, buccinator, zygomaticus major, …

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Orbicularis Oris

Superior Oblique Muscle

Superior Oblique Muscle The structure indicated is the superior oblique muscle. The superior oblique muscle is one of the extra-ocular muscles. The extra-ocular muscles include the medial, lateral, superior and inferior recti muscles, and the superior and inferior oblique muscles. Origin: Annulus of Zinn Insertion: Outer posterior quadrant of the eyeball Innervation: Trochlear nerve Action: Moves the eyeball down and out (depression, abduction, medial rotation). The superior oblique muscle inserts onto the eyeball via a long tendon which loops around a pulley (the trochlea of the superior oblique) on the medial aspect of the orbital roof, just lateral to the …

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Superior Oblique Muscle