System: Musculoskeletal

Lateral Head of Triceps Brachii

Lateral Head of Triceps Brachii The structure highlighted is the lateral head of the triceps brachii. The triceps brachii is the sole muscle in the posterior compartment of the arm. As the name suggests, the triceps brachii has three heads: Long head Medial head Lateral head These three heads converge to insert on the olecranon of the ulna. The lateral head and long head of the triceps brachii lie superficially, the medial head lies deep to these two heads. The triceps muscle serves to extend the forearm at the elbow joint and is an antagonist of the biceps and brachialis …

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triceps brachii lateral head


Acetabulum The structure indicated is the acetabulum of the pelvis. The acetabulum is formed from the point joining the three bones of the pelvis (ilium, ischium and pubis), and is the site of articulation with the head of the femur. The femoroacetabular articulation is known as the hip joint. The acetabulum consists of two parts: Articular part Non-articular part The non-articular part consists of the acetabular fossa and the acetabular notch inferiorly. The ligamentum teres attaches at one end to the acetabular notch, and at the other end to the fovea capitis of the femur. The articular part forms a …

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Tensor Fasciae Latae Muscle

Tensor Fasciae Latae Muscle The structure indicated is the tensor fasciae latae muscle. The tensor fasciae latae muscle is one of the muscles of the gluteal region. The muscles in the gluteal region are divided into a superficial and deep group. There are four muscles of the superficial group: Gluteus maximus Gluteus medius Gluteus minimus Tensor fasciae latae There are 5 muscles in the deep group: Gemellus superior Gemellus inferior Quadratus femoris Piriformis Obturator internus The tensor fasciae latae muscle is the most anteriorly situated muscle of the gluteal region and is continuous with the iliotibial tract (iliotibial band), which …

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tensor fasciae latae

Patellar ligament

Patellar Ligament The structure indicated is the patellar ligament. The quadriceps muscles of the thigh attach to and encapsulate the patella (the kneecap), via the quadriceps tendon. The patella ligament is essentially the continuation of the quadriceps tendon inferior to the patella, attaching it to the tibial tuberosity. Learn more about the muscles of the thigh in this tutorial.
Patellar ligament

Temporalis Muscle

Temporalis Muscle The structure indicated is the temporalis muscle. This muscle is one of the muscles of mastication. The muscles of mastication include: Masseter Temporalis Medial pterygoid Lateral pterygoid The temporalis muscle is a large fan-shaped muscle which lies in the temporal fossa above the zygomatic arch. Origin: temporal line of parietal bone. Temporal surface of sphenoid bone Insertion: coronoid process of mandible and ramus of mandible Innervation: mandibular branch of trigeminal nerve (cranial nerve V) Action: Elevation of the mandible and retraction of the mandible (via posterior horizontal fibres) To learn more about the muscles of mastication, check out …

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Obturator Foramen

Obturator Foramen The obturator foramen is indicated in this diagram. The obturator foramen lies inferior to the acetabulum of the pelvis and is an opening between the ischium and pubic bones. It is covered almost entirely by the obturator membrane. A small gap is left between the superior margin of the obturator membrane and the pelvic bone above, known as the obturator canal, which allows a few vessels and nerves to pass out from the pelvic cavity to communicate with the lower limb. There are three structures which pass through the obturator canal: Obturator artery Obturator vein Obturator nerve Learn …

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obturator foramen

Palmaris Longus

Palmaris Longus The structure indicated is the palmaris longus muscle of the forearm. The palmaris longus 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:  medial epicondyle of humerus Insertion: distal half …

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palmaris longus

Greater Tubercle of Humerus

Greater Tubercle of Humerus The structure indicated is the greater tubercle of the humerus. The greater tubercle lies lateral to the head of the humerus as serves as the point of attachment for three of the rotator cuff muscles. There are three flat facets to which these three muscles attach: Superior facet Middle facet Inferior facet The supraspinatus attaches to the superior facet. The infraspinatus attaches to the middle facet. The teres minor attaches to the inferior facet. Separating the greater tubercle from the lesser tubercle is the intertubercular sulcus, also known as the bicipital groove. The long head of …

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Greater Tubercle of Humerus

Biceps Femoris

Biceps Femoris The structure indicated is the biceps femoris muscle of the thigh. The biceps femoris muscle is one of three muscles in the posterior compartment of the thigh. The other muscles are the semimembranosus, and the semitendinosus. The muscles in the posterior compartment are often referred to as the “hamstrings” muscles. Collectively, these muscles are responsible for extending the hip joint, and flexing the knee joint. The biceps femoris lies laterally, and the semitendinosus and semimembranosus lie medially. Just like the biceps muscle in the arm, the biceps brachii , which is Latin for “two headed muscle (biceps) of …

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Biceps Femoris

Trapezium Bone

Trapezium Bone The structure indicated is the trapezium bone of the hand. There are three groups of bones in the hand: Carpal bones (8 in total) Metacarpal bones Phalanges The carpal bones are separated into two rows: Proximal row Distal row The trapezium bone is located in the distal row of carpal bones. There are four bones in the distal row: Trapezium Trapezoid Capitate Hamate The trapezium bone articulates with the 1st metacarpal of the thumb. It’s easy to confuse the location of the trapezium with the adjacent and similarly named trapezoid bone. A way to remember where the trapezium …

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