Anatomy and Physiology

biceps femoris

Biceps femoris is a long muscle of the posterior aspect of the thigh. Together with the semitendinosus and semimembranosus muscles, it makes the group of muscles commonly known as the hamstrings.Biceps femoris muscle runs from the ischial tuberosity, all the way to the proximal part of the fibula. In doing so the muscle crosses two joints; the hip joint and the knee joint. Acting simultaneously on these joints, biceps femoris has many important functions; flexion and external rotation at the knee joint, extension and external rotation in the hip joint, flexes leg and extends thigh.

Buccinator

Buccinator is a thin quadrilateral facial muscle that is the main component of the cheek. It belongs to the buccolabial group of facial muscles. Buccinator has a number of origin points which is the basis for subdividing the muscle fibers into superior, inferior and posterior parts. This muscle is the main muscle of the cheek, that provides it with structure and tightness. It compresses the cheek against the molar teeth, which is important to keep the food bolus central in the oral cavity, and to prevent the cheeks from being bitten during mastication.

quadriceps tendon

Connects the quadriceps femoris muscles to the superior aspects of the patella on the anterior of the thigh and controls knee flexion and extension

extensor digitorum

Extensor digitorum is a long muscle located in the posterior compartment of the forearm. Together with extensor carpi ulnaris and extensor digiti minimi, it comprises the group of superficial extensors of the forearm. These muscles can be easily palpated in the lateral aspect of the posterior forearm, especially during the extension of hand when they are contracted. Extensor digitorum runs from the lateral epicondyle of humerus to the medial four phalanges of the hand. In this way, it generates the pull for the extension of the four medial fingers in their metacarpophalangeal and both interphalangeal joints. Extensor digitorum also participates in the extension of the fingers and wrist.

external/internal oblique

External/internal abdominal oblique is a paired muscle located on the lateral sides of the abdominal wall. Along with internal abdominal oblique and transversus abdominis, it comprises the lateral abdominal muscles. In a broader picture, these muscles make up the anterolateral abdominal wall together with two anterior abdominal muscles; the rectus abdominis and pyramidalis. Flexes and rotates vertebral column

fibularis longus

Fibularis (peroneus) longus is a long muscle located superficially in the lateral compartment of the leg, together with the fibularis brevis muscle. The main function of this muscle is to produce the plantarflexion and eversion of the foot on the ankle joint.

Gastrocnemius

Gastrocnemius is a large muscle located in the posterior leg. Posteriorly, is the most superficial of the muscles of the leg, and forms the bulk of the calf. In conjunction with the soleus muscle, it is a component of a composite, three-headed group of muscles referred to as triceps surae. Together, they act in many basic activities, such as walking, running and leaping.

internal intercostals

Internal intercostals are part of the muscles of the thoracic wall located in the intercostal spaces between the ribs. they assist breathing (accessory respiratory musculature), as well as support the integrity of the thoracic cage. Depresses ribs.

levator scapulae

Levator scapulae is a long and slender muscle that anatomically belongs to the superficial layer of extrinsic muscles of the back. The levator scapulae muscle extends from the transverse processes of vertebrae C1-C4 to the medial border of scapula. As its name suggests, the main function of this muscle is to elevate and adduct the scapula.

Masseter

Masseter muscle is a paired, strong, thick and rectangular muscle that is originating from the zygomatic arch and extends down to the mandibular angle. It is one of the masticatory muscles, and its specific function is to close the jaw.

obicularis oculi

Orbicularis oculi is a paired facial muscle that surrounds each orbit and the adjacent periorbital region. Together with corrugator supercilii and levator palpebrae superioris, it belongs to the circumorbital and palpebral group of muscles that surround the eye. Orbicularis oculi is a paired facial muscle that surrounds each orbit and the adjacent periorbital region. Together with corrugator supercilii and levator palpebrae superioris, it belongs to the circumorbital and palpebral group of muscles that surround the eye, such as blinking or squinting.

orbicularis oris

Orbicularis oris is a complex circular muscle that surrounds the orifice of the mouth and forms the majority of the lips. It belongs to a large group of muscles of facial expression called the buccolabial group. Just like the other muscles of the buccolabial group, the function of orbicularis oris is to control the shape and movements of the lips. It closes, protrudes and compresses the lips. Performing these actions, orbicularis oris facilitates speech and helps in producing various facial expressions, such as anger, sadness and others.

palmaris longus

Palmaris longus is a long muscle of the anterior forearm. It extends from the distal humerus to the root of the hand. The specific actions of palmaris longus are wrist flexion and tensioning the palmar aponeurosis. This muscle plays an important function in the anatomy of the grip.

pronator teres

Pronator teres is a fusiform muscle found in the anterior forearm. It belongs to the group of superficial flexors of the forearm, together with flexor carpi radialis, palmaris longus, flexor digitorum superficialis and flexor carpi ulnaris muscles. Pronator teres is the most lateral muscle of this group. It is composed of two heads named after the bones from which they originate; Humeral head that arises from the distal aspect of humerus Ulnar head that arises from coronoid process of ulna The main action of pronator teres is the pronation of the forearm, while it also contributes to the flexion of the forearm at the elbow joint.

Major bones

Skull (Cranium), Humerus (upper arm), radius and ulna (forearm bones), vertebrae (backbone), pelvis (hip bone), femur (thigh bone), patella (knee bone), tibia and fibular (lower leg bones) and scapula (shoulder bones), hyoid.

spinous process

Spinous process is a bony projection off the posterior (back) of each vertebra. The spinous process protrudes where the laminae of the vertebral arch join and provides the point of attachment for muscles and ligaments of the spine.

teres minor action

Teres minor is a posterior muscle of the shoulder that extends between the scapula and the head of humerus. It is one of the four muscles of the rotator cuff, along with the supraspinatus, infraspinatus and subscapularis. Laterally rotates arm

anterior cruciate ligament

The anterior cruciate ligament (ACL) is one of the key ligaments that help stabilize your knee joint. The ACL connects your thighbone (femur) to your shinbone (tibia). It's most commonly torn during sports that involve sudden stops and changes in direction — such as basketball, soccer, tennis and volleyball.

biceps brachii

The biceps brachii muscle is one of the chief muscles of the arm. The origin at the scapula and the insertion into the radius of the biceps brachii means it can act on both the shoulder joint and the elbow joint, which is why this muscle participates in a few movements of the arm. Flexes elbow and supinates forearm.

Deltoid

The deltoid is a thick, triangular shoulder muscle. It gets its name because of its similar shape to the Greek letter 'delta' (Δ). The muscle has a wide origin spanning the clavicle, acromion and spine of scapula. It passes inferiorly surrounding the glenohumeral joint on all sides and inserts onto the humerus. Abducts arm.

external intercostals

The external intercostal muscles are the most superficial set of muscles that occupy the 11 intercostal spaces. Their name is derived from their spatial relationship with other intercostal muscles, since they are found superficially to the internal and innermost intercostals. The intercostal muscles, together with serratus posterior, levatores costarum, subcostal, and transversus thoracis muscles comprise the muscles of the thoracic wall. The external intercostal muscles elevate the ribs during forced inhalation and are functionally classified as the accessory respiratory musculature. Additionally, all three groups of intercostal muscles maintain the stability of the thoracic cage.

gluteus maximus

The gluteus maximus is the most superficial gluteal muscle that forms the prominence of the gluteal region. The main functions of the gluteus maximus muscle are the extension and external rotation of the thigh at the hip joint. Additionally, its superior part can produce thigh abduction, while the inferior part causes the thigh adduction.

lateral (fibular) collateral ligament (LCL)

The lateral collateral ligament is a thin band of tissue running along the outside of the knee. It connects the thighbone (femur) to the fibula, which is the small bone of the lower leg that runs down the side of the knee and connects to the ankle. Like the medial collateral ligament, the lateral collateral ligament's main function is to keep the knee stable.

latissimus dorsi

The latissimus dorsi muscle (AKA: 'the lats muscle' or 'the lats') is the widest muscle in the human body. It is relatively thin and covers almost all back muscles at the posterior trunk, except the trapezius. Along with the levator scapulae, trapezius and rhomboid muscles, the latissimus dorsi belongs to the superficial layer of the extrinsic back muscles. Extends, adducts, and medially rotates the arm; draws the shoulder downward and backward. Extends and adducts humerus.

Medial (tibial) collateral ligament (MCL)

The medial collateral ligament (MCL) is a flat band of connective tissue that runs from the medial epicondyle of the femur to the medial condyle of the tibia and is one of four major ligaments that supports the knee.

medial meniscus and lateral meniscus

The menisci — the medial meniscus and lateral meniscus - are crescent-shaped bands of thick, rubbery cartilage attached to the shinbone (tibia). They act as shock absorbers and stabilize the knee. The medial meniscus is on the inner side of the knee joint. The lateral meniscus is on the outside of the knee.

patellar ligament

The patellar ligament is an extension of the quadriceps tendon. It extends from the patella, better known as the kneecap. Connects patella to tibial tuberosity.

pectoralis major

The pectoralis major (from Latin pectus, meaning 'breast') is a thick, fan-shaped muscle, situated at the chest of the human body. It makes up the bulk of the chest muscles and lies under the breast. Adducts and flexes humerus.

posterior cruciate ligament

The posterior cruciate ligament, located in the back of the knee, is one of several ligaments that connect the femur (thighbone) to the tibia (shinbone). The posterior cruciate ligament keeps the shinbone from moving backwards too far. It is stronger than the anterior cruciate ligament and is injured less often.

rectus abdominis

The rectus abdominis muscle is located in the front of the body, beginning at the pubic bone and ending at the sternum. It is located inside the abdominal region. Better known as the "abs".

rectus femoris

The rectus femoris muscle is one of the four quadriceps muscles. It is located in the middle of the front of the thigh. It is responsible for knee extension and hip and thigh flexion. It is the main muscle that can flex the hip.

Sartorius

The sartorius muscle is the longest muscle in the human body. Together with the quadriceps femoris, it belongs to the anterior (extensor) muscles of the thigh. The sartorius muscle has an oblique course throughout the thigh; it arises from the anterior superior iliac spine, crosses to the medial side of the thigh, and finally inserts to the medial side of the proximal tibia. Flexes, abducts, and laterally rotates thigh at the hip; flexes knee.

serratus anterior

The serratus anterior muscle is a fan-shaped muscle at the lateral wall of the thorax. Its main part lies deep under the scapula and the pectoral muscles. Protracts scapula

Soleus

The soleus muscle is a wide flat leg muscle found on the posterior leg. It runs from just below the knee to the heel and lays immediately deep to the gastrocnemius. These two muscles, along with the plantaris muscle, belong to the group of superficial posterior compartment calf muscles. Soleus' contraction results in strong plantar flexion. It also allows us to maintain an upright posture due to its important role as an antigravity muscle.

Sternocleidomastoid

The sternocleidomastoid muscle is a two-headed neck muscle, which true to its name bears attachments to the manubrium of sternum (sterno-), the clavicle (-cleido-), and the mastoid process of the temporal bone (-mastoid). Flexes neck ; rotates head.

teres major

The teres major is a thick muscle of the shoulder joint. It spans from the inferior aspect of the scapula to the proximal part of the humeral shaft. Unlike the teres minor, the teres major muscle does not attach to the capsule of the glenohumeral joint. Thus it is not regarded as part of the rotator cuff muscles. Extends, adducts, and medially rotates arm. By contracting, it pulls the humerus posteriorly (extension) and rotates it medially towards the trunk (medial rotation). Additionally, it contributes to the stabilization of the shoulder joint.

Trapezius

The trapezius muscle is a large, triangular, paired muscle located on the posterior aspect of the neck and thorax. When viewed together, this pair forms a diamond or trapezoid shape, hence its name. The trapezius has many attachment points, extending from the skull and vertebral column to the shoulder girdle. Elevates, depresses, retracts, and rotates the scapula; rotates the arm

vastus lateralis

The vastus lateralis is located on the side of the thigh. This muscle is the largest of the quadriceps group. The specific function is to extend the leg at knee to allow the body to rise from a sitting or squatting position.

tibialis anterior

Tibialis anterior is a fusiform muscle found in the anterior part of the leg. Acts as the main dorsiflexion and inversion of the foot.

zygomatic major

Zygomaticus major is a thin paired facial muscle that extends diagonally from the zygomatic bone (hence the name) to the angle of the mouth. These muscles form the structure and carry out the functions of the cheeks and lips.The main action of zygomaticus major is to pull the angle of the mouth superolaterally. In coordination with other buccolabial muscles, it facilitates speech and creates facial expressions. Along with risorius, zygomaticus major contributes to laughing, which is why they are deemed the "laughing muscles".

Sternum

manubrium, body, xiphoid process