System: Musculoskeletal

Mandibular Notch

Mandibular Notch The structure indicated is the mandibular notch. The ramus of the mandible forms the lateral portion of the mandible. It has two processes: Coronoid process Condyloid process These processes extend superiorly from the ramus of the mandible. The coronoid process is located anteriorly, and the condyloid process is located posteriorly. In between these two processes is a concave notch, known as the mandibular notch. Passing through this notch are the following structures: Masseteric nerve Masseteric artery Masseteric vein Learn more about the anatomy of the mandible in this tutorial.
Mandibular Notch

Squamous Suture

Squamous Suture The structure indicated is the squamous suture of the skull. Sutures are junctions between the bones of the skull – they are a type of fibrous joint, bound together by Sharpey’s fibres. The squamous suture forms the joint of the skull between the squamous part of the temporal bone and the inferior aspect of the parietal bone. Posteriorly, the squamous suture becomes the parietomastoid suture where the mastoid process articulates with the parietal bone. Anteriorly, the squamous suture extends towards pterion. Learn more about the sutures of the skull in this tutorial.
Sqaumous Suture

Teres Major

Teres Major The structure indicated is the teres major muscle. The teres major muscle is located in the posterior scapular area. It originates on the inferior angle of the scapula and inserts anteriorly on the humerus on the intertubercular sulcus. Contraction of the teres major causes extension and medial rotation of the humerus at the glenohumeral joint. Origin:  Inferior angle of scapula Insertion: Medial portion of intertubercular sulcus of humerus Action: Adduction, medial rotation, extension of humerus Innervation: Lower subscapular nerve The pectoralis major inserts on the lateral part of the intertubercular sulcus and the latissimus dorsi inserts on the …

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Teres Major

Pronator Teres

Pronator Teres The structure indicated is the pronator teres muscle. The pronator teres is one of four muscles in the superficial layer of muscles in the anterior compartment of the forearm. The anterior compartment of the forearm consists of three layers of muscles: Superficial layer Intermediate layer Deep layer Four muscles are located in the superficial layer (from lateral to medial): Flexor carpi ulnaris Palmaris longus Flexor carpi radialis Pronator teres All four muscles of the superficial layer have a common origin on the medial epicondyle of the humerus. Origin:  humeral head – medial epicondyle of humerus; ulnar head – …

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Pronator Teres

Anterior Inferior Tibiofibular Ligament

Anterior Inferior Tibiofibular Ligament The structure indicated is the anterior inferior tibiofibular ligament. The distal ends of the tibia and the fibula are held together by the inferior portion of the interosseous membrane. The interosseous membrane is the membrane which joins the tibia to the fibula along its entire length, separating the leg into anterior and posterior compartments. There are two apertures within the interosseous membrane proximally and distally which allow vessels to pass from one compartment to the other. In addition to the attachment of the interosseous membrane inferiorly between the distal tibia and fibula, this inferior articulation is …

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Anterior Inferior Tibiofibular Ligament

Z-Line

Z-Line The structure indicated is the Z-disc/Z-line formed between adjacent sarcomeres. A sarcomere is the name given to the basic unit of muscle, composed of sliding protein filaments of actin and myosin. Myosin filaments are thick, actin filaments are thin. These two filaments overlap each other, and their ability to slide past each other forms the basis of the theory of muscle contraction and relaxation. Under electron microscopy, the overlapping pattern of these thick and thin protein filaments gives rise to darker and lighter areas (bands), as well as distinct lines. The thinner actin filaments are all bound to the …

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Z-Line

Infraorbital Foramen

Infraorbital Foramen The structure indicated is the infraorbital foramen of the skull. The infraorbital foramen are a pair of external foramina of the skull which are visible anteriorly on the skull. Foramen (foramina is plural), are holes in the human body which allow other structures to pass through. In the case of the skull, foramina permit the passage of arteries, veins and nerves. There are three pairs of foramina visible from an anterior view of the skull: Infraorbital foramen Supraorbital foramen Mental foramen The infraorbital foramen is located in the maxillary bone of the skull just below the inferior margin …

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Infraorbital Foramen

Pterion

Pterion The structure indicated is known as pterion. Pterion is the name given to the region on the lateral aspect of the skull where four bones are joined: Parietal bone Squamous part of temporal bone Front bone Greater wing of sphenoid bone Pterion is a point of clinical significance – the skull is very thin at this point. In addition to being structurally weak due to being the point of union between several bones, it also lies over the anterior division of the middle meningeal artery. Fracture of the skull at this point can therefore disrupt the middle meningeal artery, …

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Pterion

Head of Fibula

Head of Fibula The structure indicated is the head of the fibula. The two bones of the leg are the tibia and the fibula. The fibula is the smaller of the two bones and lies laterally. The head of the fibula is an expansion of the fibula at the proximal end, and is flattened superiorly and medially forming a surface for articulation with the lateral condyle of the tibia. The head of the fibula provides the point of attachment for several muscles and ligaments, including the biceps femoris and the lateral collateral ligament (fibular collateral ligament). Just below the head …

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Head of Fibula

Infraspinous Fossa

Infraspinous Fossa The structure indicated is the infraspinous fossa of the scapula. It is called the infraspinous fossa because it lies below (infra) the spine of the scapula (-spinous). Accordingly, the fossa that lies superior to the spine of the scapula is the supraspinous fossa. The scapula consists of two surfaces – the costal surface and the posterior surface. The infraspinous fossa is significantly larger than the supraspinous fossa and comprises the majority of the posterior surface of the scapula. The infraspinatus muscle, one of the rotator cuff muscles, originates in the infraspinous fossa. Learn all about the anatomy of …

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Infraspinous Fossa