System: Musculoskeletal

Hamate Bone

Hamate Bone The structure indicated is the hamate 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 hamate bone is one of four bones in the distal row of carpals (hamate, capitate, trapezium, trapezoid). It is named after its small hook-like process (“hamulus” comes from the Latin meaning hook). Several structures attach to the hook of the hamate bone. The hamate bone has the following articulations: Radial: capitate Ulnar: pisiform Proximal: lunate Distal: metacarpals of …

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hand - hamate

Medial Femoral Condyle

Medial Femoral Condyle The structure indicated is the medial condyle of the femur. The distal end of the femur forms two rounded condyles which articulate with the tibia below and the patella anteriorly – the medial condyle and the lateral condyle. The linea aspera is a roughened crest of bone on the posterior aspect of the femur. Distally the linea aspera forms two ridges known as the lateral supracondylar line and the medial supracondylar line which as the name suggests, terminate just superiorly to the lateral and medial femoral condyles respectively. At the end of the medial supracondylar line is …

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femur - medial condyle

Abductor Hallucis

Abductor Hallucis The structure indicated is the abductor hallucis muscle of the foot. The intrinsic muscles on the plantar aspect of the foot are divided into four layers. The abductor hallucis muscle is found in the first layer of muscles. There are three muscles in the first layer: Abductor hallucis Flexor digitorum brevis Abductor digiti minimi The abductor hallucis muscle is located in the medial border of the foot and is responsible for the palpable bulk of muscle that you can feel on the inside of the foot. It inserts via a common tendon, together with the flexor hallucis brevis, onto …

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abductor hallucis

Fibularis Longus

Fibularis Longus The structure indicated is the fibularis (peroneus) longus muscle of the leg. The fibularis longus muscle is one of the muscles of the lateral compartment of the leg. The leg consists of three muscular compartments: anterior, posterior and lateral. The lateral compartment consists of two muscles: Fibularis (peroneus) longus Fibularis (peroneus) brevis The lateral muscles are responsible for eversion of the foot and are innervated by the superficial fibular (peroneal) nerve, which is a branch of the common fibular nerve. The common fibular nerve is a branch of the sciatic nerve and divides into the superficial fibular nerve …

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Fibularis longus

Levator Palpebrae Superioris

Levator Palpebrae Superioris The structure indicated is the levator palpebrae superioris muscle. The levator palpebrae superioris muscle is located in the upper eyelid and is responsible for raising the eyelid. Just like the rectus muscles, and oblique muscles of the eyeball, the levator palpebrae superioris muscle is innervated by the oculomotor nerve (cranial nerve III). The eyelids themselves are supported by the tarsus – in the upper eyelid the superior tarsus, and in the lower eyelid, the inferior tarsus. These structures consist of dense connective tissue. Origin: Roof of the orbit on sphenoid bone, above the optic foramen Insertion: Anterior …

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levator palpebrae superioris

Rectus Capitis Posterior Minor

Rectus Capitis Posterior Minor The structure indicated is the rectus capitis posterior minor muscle. The rectus capitis posterior minor is one of 4 muscles which make up the suboccipital group of back muscles. This group of small muscles are located at the base of the occipital bone in the superior cervical region posteriorly. The four suboccipital muscles are: Rectus capitis posterior major Rectus capitis posterior minor Obliquus capitis inferior Obliquus capitis superior Origin:  spinous process of atlas vertebrae CI Insertion: occipital bone inferior to nuchal line Innervation: posterior ramus of CI Action: Extension of head   Learn more about the …

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Rectus Capitis Posterior Minor

Abductor Pollicis Longus

Abductor Pollicis Longus The structure indicated is the abductor pollicis longus muscle of the posterior forearm. The abductor pollicis longus muscle is one of the muscles located in the deep layer of muscles in the posterior compartment of the forearm. There are 5 muscles in the deep layer of the posterior forearm: Supinator Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus Extensor indicis The abductor pollicis longus muscle, as the name suggests abducts the thumb. Origin: Posterior surface of proximal ulna, radius and interosseous membrane Insertion: Base of 1st metacarpal Innervation: Posterior interosseous nerve Action: Abduction and extension of …

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abductor pollicis longus

Nasal Bone

Nasal Bone The structure indicated is the nasal bone of the facial skeleton. The skull consists of the calvaria (the part which contains the brain), and the facial skeleton (viscerocranium) which forms the anterior and inferior part of the skull. The facial skeleton consists of the following bones: Nasal bones Lacrimal bones Palatine bones Zygomatic bones Maxillae bones Inferior nasal conchae Vomer There are two paired nasal bones. The nasal bone has four articulations: Frontal bone (superiorly) Ethmoid bone (posteriorly) Maxillae (laterally) Nasal bone (medially) Learn more about the anatomy of the facial skeleton in this tutorial.
skull - nasal bone

Occiptofrontalis

Occipitofrontalis The structure indicated is the frontal belly of the occipitofrontalis muscle. The occipitofrontalis muscle is involved in facial expression and is comprised of two muscle bellies: Frontal belly Occipital belly Contraction of the frontal belly causes wrinkling of the forehead and raising of the eyebrows. Contraction of the occipital belly pulls the scalp back posteriorly. As a muscle of facial expression, the occipitofrontalis muscle is innervated by the facial nerve (cranial nerve VII). In between the frontal and occipital bellies, is an aponeurotic tendon which connects two bellies. Learn more about the muscles of facial expression in this tutorial.
occipitofrontalis - frontal belly

Iliopsoas Muscle

Iliopsoas Muscle The structure indicated is the iliopsoas muscle. The iliopsoas muscle collectively refers to the distal ends of the psoas major and iliacus muscles which exit the pelvis to enter the anterior compartment of the thigh and insert onto the lesser trochanter of the femur. The iliopsoas muscle is the strongest hip flexor. Origin: Iliac fossa and vertebral bodies of T12 to L5 Insertion: Lesser trochanter of femur Innervation: anterior rami of lumbar plexus (L2-L4) Action: Hip flexion, lateral rotation of femur Learn more about the muscles of the anterior compartment of the thigh in this tutorial.
iliopsoas