System: Musculoskeletal

Anterior Cranial Fossa

Anterior Cranial Fossa The anterior cranial fossa is shaded in yellow. The cranial cavity is divided into three fossae: 1)      Anterior 2)      Middle 3)      Posterior The anterior cranial cavity is formed from the following bones: Frontal bone (orbital plate) Ethmoid bone (cribriform plate) Sphenoid bone (body and lesser wings) The anterior cranial cavity contains the frontal lobes of the brain. Structures in the anterior cranial cavity include: Frontal crest – site of attachment for falx cerebri Foramen caecum – emissary veins from nasal cavity to superior sagittal sinus Crista Galli – site of attachment for falx cerebri Cribriform plate of …

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Anterior Cranial Fossa

Long Head of Triceps Brachii

Long Head of Triceps Brachii The structure indicated is the long 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. Origin: Long head – infraglenoid tubercle of scapula Medial head – posteriorly on the shaft of the humerus below the radial groove Lateral head – posteriorly on the humerus, above the radial groove Insertion: Olecranon of the ulna Action: Extension of the forearm …

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Triceps Brachii - Long Head

Lambdoid Suture

Lambdoid Suture The structure indicated is the lambdoid suture. Sutures are junctions between the bones of the skull – they are a type of fibrous joint, bound together by Sharpey’s fibres. Fibrous joints are fixed, immobile joints, with no joint cavity, and connected by fibrous connective tissue. There are three types of fibrous joint. 1)      Suture (joints between skull bones) 2)      Syndesmosis (joints between long bones of forearm and leg) 3)      Gomphosis (joints between roots of a tooth and socket in jaw) The lambdoid suture joins the parietal bones with the occipital bone, and is continuous with the occiptomastoid suture. …

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lambdoid suture

Sternocleidomastoid Muscle

Sternocleidomastoid Muscle The muscle shown in the image is the sternocleidomastoid muscle. Origin: manubrium and medial aspect of clavicle Insertion: mastoid process of the temporal bone, superior nuchal line Innervation: motor innervation via the accessory nerve (Cranial nerve 11), sensory innervation from the cervical plexus Blood Supply: Superior thyroid artery and occipital artery Action: If the muscle contracts on one side, then cervical rotation to the opposite side occurs whilst cervical lateral flexion occurs on the same side. With bilateral contraction, cervical flexion occurs and the manubrium is elevated – in this way it assists inspiration, and is one of the accessory muscles of …

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Masseter The muscle highlighted is the masseter. This muscle is one of the muscles of mastication. The muscles of mastication include: Masseter Temporalis Medial pterygoid Lateral pterygoid The masseter is rectangular in shape and consists of a superficial part and a deep part. Origin: zygomatic arch and maxillary process of the zygomatic bone Insertion: lateral surface of ramus of mandible Innervation: masseteric nerve – a branch of the mandibular nerve (V3) Blood supply: masseteric artery To learn more about the muscles of mastication, check out this tutorial!

Manubrium of Sternum

Manubrium of Sternum The highlighted structure is the manubrium of the sternum. The sternum consists of three parts Manubrium of the sternum Body of sternum Xiphoid process The manubrium of the sternum is the superior part of the sternum. The manubrium has the following features: Jugular notch (suprasternal notch) – you can palpate this notch yourself if you feel in the midline between the proximal ends of your clavicles. Articular site for clavicle Facet for attachment of first costal cartilage Demifacet for articulation with second costal cartilage Where the manubrium meets the body of the sternum, is a joint called …

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Learn all about the anatomy of the femur in this tutorial.

Biceps Brachii

Biceps Brachii The biceps brachii is a muscle in the anterior compartment of the arm. It has two heads, the long head and the short head. It is one of three muscles in the anterior compartment of the arm, the other two muscles being the brachialis and the coracobrachialis, which lie deep to it. The biceps muscle receives innervation via the musculocutaneous nerve and it functions mainly to supinate the forearm and flex the elbow. Despite being a relatively small muscle, the biceps brachii is one of the most highly trained muscles in the gym, along with the pectoral muscles …

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Biceps Brachii

Pectoralis Major

Pectoralis Major The pectoralis major is one of the muscles in the pectoral region of the thorax. The other muscles in this region include the pectoralis minor and the subclavius. The pectoralis minor lies underneath the pectoralis major, and is a much smaller muscle – hence the name. The subclavius, as the name suggests, is located under (“sub”) the clavicle (“clavius”), attaching at one end to the bottom of the clavicle. And at the other to the first rib. The pectoralis major muscle has a few actions at the shoulder joint: flexion adduction medial rotation There are two main parts …

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Pectoralis Major Muscle

Vastus Medialis

Vastus Medialis The vastus medialis is one of the muscles that makes up the quadriceps femoris, and is contained in the anterior compartment of the thigh. It is responsible for the tear-drop shape that is visible on the medial aspect of the thigh in trained athletes and footballers. The four muscles that make up the quadriceps femoris are the: –         Rectus femoris –         Vastus lateralis –         Vastus medialis –         Vastus intermedius   Learn more about the muscles of the anterior compartment in this tutorial. Click here to visualise and interact with these muscles.
Vastus Medialis