Muscles

Superior Oblique Muscle

Superior Oblique Muscle The structure indicated is the superior oblique muscle. The superior oblique muscle is one of the extra-ocular muscles. The extra-ocular muscles include the medial, lateral, superior and inferior recti muscles, and the superior and inferior oblique muscles. Origin: Annulus of Zinn Insertion: Outer posterior quadrant of the eyeball Innervation: Trochlear nerve Action: Moves the eyeball down and out (depression, abduction, medial rotation). The superior oblique muscle inserts onto the eyeball via a long tendon which loops around a pulley (the trochlea of the superior oblique) on the medial aspect of the orbital roof, just lateral to the …

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Superior Oblique Muscle

Tibialis Anterior

Tibialis Anterior The muscle highlighted is the tibialis anterior muscle. The tibialis anterior is one of the four muscles of the anterior compartment of the leg. The muscles of the leg consist of three compartments: Anterior Posterior Lateral In the anterior compartment are the four following muscles: Tibialis anterior Extensor hallucis longus Extensor digitorum longus Fibularis tertius The muscles of the anterior compartment of the leg serve to dorsiflex the ankle joint, extend the toes and invert the foot, and they are supplied by the deep fibular (peroneal) nerve. Origin: Upper two-thirds and lateral condyle of the tibia Insertion: Medial …

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Tibialis Anterior

Quadratus Plantae Muscle

Quadratus Plantae Muscle The muscle highlighted is the quadratus plantae muscle of the foot. The intrinsic muscles on the plantar aspect of the foot are divided into four layers. The quadratus plantae muscle is found in the second layer of muscles. There are two muscles in the second layer: Quadratus plantae Lumbricals The muscles in the second layer are associated with the tendons of the flexor digitorum longus muscle. This tendon forms the site of insertion for the quadratus plantae muscle, and forms the site of origin for the four lumbricals. The quadratus plantae muscle has two heads – a …

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Quadratus Plantae

Internal Intercostal Muscle

Internal Intercostal Muscle The structure indicated is the internal intercostal muscle. The intercostal muscles are a set of three flat muscles which are located in each intercostal space. The three intercostal muscles, from superficial to deep are: External intercostal Internal intercostal Innermost intercostal Origin: Lateral edge of costal groove of rib directly above Insertion: Superiorly on rib directly below Innervation: Intercostal nerves (T1 – T11) Action: Forced expiration, movement of ribs inferiorly The muscle fibres of the internal intercostal muscles pass obliquely in the opposite direction to the external intercostal muscles, whose fibres pass anteroinferiorly (when the thoracic wall is viewed …

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Internal Intercostal

Styloglossus Muscle

Styloglossus Muscle The muscle indicated is the styloglossus muscle       . The styloglossus muscles is one of three styloid muscles. The three styloid muscles are: Styloglossus Stylohyoid Stylopharyngeus Origin: Styloid process of temporal bone Insertion: lateral aspect of tongue Innervation: Hypoglossal nerve (cranial nerve 12) Action: Elevation and retraction of the tongue The styloid muscle is one of several extrinsic muscles of the tongue. Learn all about the extrinsic muscle of the tongue in this anatomy tutorial.

Styloglossus

Longitudinal Muscle Layer of Stomach

Longitudinal Muscle Layer of Stomach The structure indicated is the outer longitudinal muscle layer of the stomach. The stomach walls consists of four parts: Mucosa Submucosa Muscularis externa Serosa The muscularis externa is the muscular layer of the gastrointestinal wall. In the stomach it consists of three layers: Inner oblique layer Middle circular layer Outer longitudinal layer Between the middle circular layer and outer longitudinal muscular layer lies Auerbach’s plexus (the myenteric plexus). Learn more about the digestive system in this tutorial

Longitudinal Muscle Layer of Stomach

External Abdominal Oblique Muscle

External Abdominal Oblique Muscle The muscle indicated is the external oblique muscle of the abdomen. The external oblique muscle is the most superficial lateral muscle of the anterior abdominal wall. The three muscles which make up the lateral part of the anterior wall of the abdomen from superficial to deep are the: External oblique Internal oblique Transversus abdominis Origin: ribs 5-12 Insertion: Iliac crest, pubic tubercle, linea alba Innervation: thoracoabdominal nerve and subcostal nerve Action: Flexion and rotation of the vertebral column – brings about contralateral rotation of the torso. Unilateral contraction causes lateral flexion of the vertebral column. Important …

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External Abdominal Oblique

Lateral Rectus Muscle

Lateral Rectus Muscle The structure indicated is the lateral rectus muscle. This muscle is one of six muscles that are involved in the movements of the eye. The muscles which move the eye are referred to as the extraocular muscles, these include: Superior rectus Inferior rectus Lateral rectus Medial rectus Superior oblique Inferior oblique Origin: Lateral part of annulus of Zinn Insertion: Lateral (temporal) aspect of eyeball Action: Abducts the eyeball – moves it away from the midline Innervation: Abducens nerve (Cranial nerve VI) If the abducens nerve is damaged (abducens nerves palsy/sixth nerve palsy), there is failure to abduct …

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Lateral Rectus Muscle

Semitendinosus

Semitendinosus The semitendinosus muscle is one of three muscles in the posterior compartment of the thigh. The other muscles are the semimembranosus, and the biceps femoris. 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. The semitendinosus gets its name from its structure which is comprised of a muscle belly which tapers into a long tendon that extends to insert onto the medial tibia. The semitendinosus sits on …

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Semitendinosus

Gracilis

Gracilis The muscle indicated is the gracilis. The gracilis is one of six muscles in the medial compartment of the thigh. The thigh consists of three muscular compartments: 1)      Anterior 2)      Medial 3)      Posterior The medial compartments consists of the following muscles: 1)      Gracilis 2)      Pectineus 3)      Adductor longus 4)      Adductor brevis 5)      Adductor magnus 6)      Obturator externus The gracilis is the most superficial muscle in the medial compartment. It is a thin muscle which descends vertically down the medial aspect of the thigh. Origin: inferior pubic ramus, ramus of ischium Insertion: proximal shaft of tibia medially (pes anserinus) Action: …

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Gracilis