System: Musculoskeletal

Abductor Pollicis Brevis

Abductor Pollicis Brevis The structure indicated is the abductor pollicis brevis muscle of the hand. The abductor pollicis brevis muscle is one of the intrinsic muscles of the hand that belongs to the thenar group. The thenar group of intrinsic hand muscles consist of three muscles: Abductor pollicis brevis Flexor pollicis brevis Opponens pollicis All the intrinsic muscles of the hand, except the thenar muscles and the lateral two lumbrical muscles are innervated by the deep branch of the ulnar nerve. The thenar muscles and the lateral two lumbrical muscles are innervated by the median nerve.  A useful mnemonic for …

Abductor Pollicis Brevis Read More »

Abductor Pollicis Brevis

Omohyoid

Omohyoid The structure indicated is the omohyoid muscle. The omohyoid muscle is one of four infrahyoid muscles which lie in the anterior triangle of the neck. The infrahyoid muscles, as the name suggests, attach to the hyoid bone and lie below it. Contraction of the infrahyoid muscles then causes depression of the hyoid bone. The infrahyoid muscles are often referred to as the strap muscles due to their strap-like appearance. The four infrahyoid muscles are: Omohyoid Sternohyoid Thyrohyoid Sternothyroid The omohyoid muscle sits lateral to the sternohyoid muscle and is comprised of two muscle bellies (superior and inferior) connected by …

Omohyoid Read More »

Omohyoid Muscle

Calcaneus

Calcaneus The structure indicated is the calcaneus bone of the foot. The foot contains three groups of bones: Tarsals Metatarsals Phalanges The calcaneus is one of seven tarsal bones. There are three groups of tarsal bones: Proximal group Intermediate group Distal group There are two bones in the proximal group of tarsal bones: the talus and the calcaneus. The calcaneus is the largest tarsal bone and forms the heel through its posterior projection. Anteriorly, the calcaneus articulates with the cuboid bone, and superiorly it articulates with talus. Three muscles insert onto the calcaneus: Gastrocnemius Soleus Plantaris Learn more about the …

Calcaneus Read More »

Calcaneus

Genioglossus

Genioglossus The structure indicated is the genioglossus muscle of the tongue. The genioglossus muscle is one of the extrinsic muscles of the tongue. The muscles involved with the tongue consist of intrinsic muscles which lie within the tongue itself, and the extrinsic muscles which attach to the tongue and are responsible for depression, elevation, protraction and retraction of the tongue. There are four sets of extrinsic tongue muscles: Genioglossus Hyoglossus Palatoglossus Styloglossus The genioglossus is a large muscle which extends anteriorly from the chin, to the tongue. The genioglossus is involved in depression and protrusion of the tongue. Origin: Superior …

Genioglossus Read More »

Genioglossus

Calcaneofibular Ligament

Calcaneofibular Ligament The structure indicated is the calcaneofibular ligament of the foot. The calcaneofibular ligament is one of three ligaments found on the lateral aspect of the ankle. The lateral ligaments of the ankle joint consists of: Anterior talofibular ligament Posterior talofibular ligament Calcaneofibular ligament The calcaneofibular ligament has its superior attachment on the malleolar fossa on the lateral malleolus, and its inferior attachment on the lateral surface of the calcaneus. Running across the calcaneofibular ligament are the tendons of the peroneus longus and peroneus brevis. Learn more about the anatomy of the ankle joint in this tutorial.
Calcaneofibular Ligament

Central Tendon of Diaphragm

Central Tendon of Diaphragm The structure indicated is the central tendon of the diaphragm. The diaphragm is a musculotendinous structure which seals the inferior thoracic aperture and separates the abdominal cavity from the thoracic cavity. When it contracts, it flattens, increasing the intrathoracic volume and thereby allowing air to enter the lungs. The central tendon is an aponeurosis which forms the top of the dome-shaped diaphragm. It blends with the fibrous pericardium above, helping to maintain it in place. The inferior vena cava passes through the central tendon at the level of the 8th vertebra.
Central Tendon of Diaphragm

Lateral Head of Gastrocnemius Muscle

Lateral Head of Gastrocnemius Muscle The structure indicated is the lateral head of the gastrocnemius muscle. The gastrocnemius muscle is the most superficial muscle of the posterior compartment of the leg. The muscles in the posterior compartment of the leg are separated into a superficial group and a deep group. The superficial group consists of the following leg muscles: Gastrocnemius Plantaris Soleus The deep group consists of the following leg muscles: Popliteus Flexor hallucis longus Flexor digitorum longus Tibialis posterior The gastrocnemius is one of the largest muscles in the leg and has two heads which form its origin, the …

Lateral Head of Gastrocnemius Muscle Read More »

Lateral Head of Gastrocnemius Muscle

Eccentric Muscle Contraction

Eccentric Muscle Contraction This diagram is illustrating eccentric muscle contraction. When muscles generate tension, they can either lengthen, shorten, or stay the same length. Muscle contraction is therefore classified into three main types: Concentric muscle contraction – muscle shortens Eccentric muscle contraction – muscle lengthens Isometric muscle contraction – muscle remains the same length
Eccentric Muscle Contraction

Inversion of the Foot

Inversion of the Foot This diagram indicates inversion of the foot. Inversion is a movement of the foot which causes the soles of the feet to face inwards, and eversion is the opposite movement. Inversion and eversion occur primarily at: Talocalcaneonavicular joint Subtalar (talocalcaneal) joint The muscles which cause inversion of the foot are: Tibialis anterior Tibialis posterior The muscles which cause eversion of the foot are: Peroneus longus Peroneus brevis Inversion injuries of the ankle are common, and result in ankle sprain affecting the ligaments on the lateral aspect of the ankle. Most commonly, the anterior talofibular ligament (70-85% …

Inversion of the Foot Read More »

Inversion of the Foot

Radial Collateral Ligament of Elbow

Radial Collateral Ligament of Elbow The structure indicated is the radial collateral ligament of the elbow. The fibrous joint capsule which surrounds the elbow joint is reinforced medially and laterally, where it thickens to form the collateral ligaments – the radial collateral ligament and the ulnar collateral ligament. Surrounding the radial head is the annular ligament, the fibres of which blend with the fibres of the radial collateral ligament. Because of the way the joint capsule is thickened to form ligaments with blended fibres, the elbow ligaments on the lateral aspect of the elbow are often referred to collectively as …

Radial Collateral Ligament of Elbow Read More »

Radial Collateral Ligament of Elbow