Muscles

Anconeus

Anconeus The structure indicated is the anconeus muscle of the forearm. The anconeus muscle is one of the muscles of the posterior compartment of the forearm. The posterior compartment consists of a superficial layer of muscles comprised of 7 muscles. The deep layer is comprised of 5 muscles. Origin: lateral epicondyle of humerus Insertion: olecranon, proximal surface of ulna Innervation: Radial nerve Action: assists elbow extension, stabilises the elbow joint, abducts ulna during pronation Learn about the muscles of the forearm in this tutorial.

anconeus

Flexor Digitorum Brevis

Flexor Digitorum Brevis The structure indicated is the flexor digitorum brevis muscle of the foot. The intrinsic muscles on the plantar aspect of the foot are divided into four layers. The flexor digitorum brevis muscles 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 flexor digitorum brevis muscle lies above the  central part of the plantar aponeurosis and just below the tendons of flexor digitorum longus. Origin: medial process of calcaneal tuberosity and plantar aponeurosis. Insertion: Plantar sides of middle phalanges of lateral four …

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flexor digitorum brevis

Brachioradialis

Brachioradialis The structure indicated is the brachioradialis muscle of the forearm. The brachioradalis muscle is one of the muscles of the posterior compartment of the forearm. The posterior compartment consists of a superficial layer of muscles comprised of 7 muscles. The deep layer is comprised of 5 muscles. Origin: lateral supracondylar ridge of humerus Insertion: radial styloid process Innervation: radial nerve Action: flexes the forearm at the elbow – strongest when forearm is midway between pronation and supination. Learn more about the muscles of the forearm in this tutorial.

brachioradialis

Interspinales

Interspinales The structure indicated is the interspinales muscle. The interspinales muscles belong to the deep group of back muscles. The muscles of the back can be considered in terms of a superficial group, an intermediate group and a deep group of muscles. The deep group of back muscles consists of: Spinotransversales muscles Erector spinae muscles and transversospinales muscles Segmental muscles Suboccipital muscles The interspinales muscles belong to the segmental muscle group of the deep muscles. As the name suggests, the interspinales run between adjacent spinous processes. There is one interspinales muscle on either side, lateral to the interspinous ligament. The …

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interspinales

Splenius Capitis

Splenius Capitis The structure indicated is the splenius capitis muscle. The splenius capitis muscle is one of 8 muscles in the posterior triangle of the neck. The posterior triangle of the neck is bounded as follows: Anteriorly: posterior border of sternocleidomastoid Posteriorly: anterior border of trapezius Apex: Occipital bone between attachment sites of trapezius and sternocleidmastoid Base: middle third of clavicle Origin: Lower half of ligamentum nuchae and spinous processes of C7-T4 Insertion: Mastoid process, and part of skull inferior to lateral superior nuchal line. Action: Contraction together – extension of the neck. Contraction individually – Lateral flexion of neck …

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Splenius Capitis

Hyoglossus Muscle

Hyoglossus Muscle The structure indicated is the hyoglossus muscle of the tongue. The hyoglossus 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 Origin: Greater horn and body of hyoid bone Insertion: Lateral aspect of tongue Action: Depression and retraction of tongue Innervation:  Hypoglossal nerve (cranial nerve XII) Learn all …

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Hyoglossus

Adductor Magnus

Adductor Magnus The structure indicated is the adductor magnus muscle of the thigh. The adductor magnus muscle is one of six muscles in the medial compartment of the thigh. The medial compartments consists of the following muscles: Gracilis Pectineus Adductor longus Adductor brevis Adductor magnus Obturator externus The adductor magnus muscle is the largest muscle in the medial compartment. It lies deep to the adductor brevis and the adductor longus. It has two parts to it: Adductor part Hamstring part The adductor part originates on the ischiopubic ramus, and as the name suggests, contraction causes adduction, as well as medial …

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Adductor Magnus

Abductor Digiti Minimi

Abductor Digiti Minimi The structure indicated is the abductor digiti minimi muscle of the hand. The abductor digiti minimi muscle is one of the intrinsic muscles of the hand that belongs to the hypothenar group. The hypothenar group of intrinsic hand muscles consist of three muscles: Abductor digiti minimi Opponens digiti minimi Flexor digit minimi brevis 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 …

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Abductor Digiti Minimi

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