Posterior compartment of the forearm
The posterior compartment of the forearm contains twelve muscles which are chiefly responsible for extension of the wrist and digits, supination of the forearm. It is separated from the anterior compartment by the interosseous membrane between the radius and ulna. There are twelve muscles in the posterior compartment of the forearm, which can be further divided into a superficial and deep layer. Most of the muscles in the superficial and the intermediate layers share a common origin, the outer part of the elbow, the lateral epicondyle of humerus; the deep muscles arise from the distal part of the surrounding interosseous membrane. The brachioradialis, flexor of the elbow, is unusual in that it is located in the posterior compartment, but it is a muscle of flexor / anterior compartment of the forearm; the anconeus, assisting in extension of the elbow joint, is by some considered part of the posterior compartment of the arm. The majority of muscles found in the posterior compartment are extrinsic, meaning its origin has some distance from the part that it moves.
The brachioradialis and the anconeus are considered intrinsic muscles because they both arise within the forearm and they both move the forearm. Extensor tendons pass through the extensor retinaculum at wrist joint in 6 synovial sheaths referred to compartments; the supinator and the anconeus are the two muscles in the posterior compartment of the forearm that do not pass through wrist extensor compartments. The first compartment locating the most radial is occupied by the extensor pollicis brevis and the abductor pollicis longus to insert to the thumb; the second compartment is occupied by the two radial wrist extensors, the extensor carpi radialis longus and the extensor carpi radialis brevis. The third compartment accommodates the extensor pollicis longus, which hooks around Lister's tubercle of radius and inserts to the thumb; the fourth compartment is the largest of all. It is occupied by the extensors of the digits, the extensor digitorum communis and the extensor indicis proprius; the extensor indicis proprius runs and inserts onto the ulnar side of the extensor digitorum communis of the index finger.
The fifth compartment is occupied by the extensor of the little finger. The extensor carpi ulnaris passes through the sixth compartment to insert to the base of the fifth metacarpal bone; the muscles of the posterior compartment of the forearm are innervated by the radial nerve and its branches. The radial nerve arises from the posterior cord of the plexus; the somatomotor fibers of the radial nerve branch from the main radial nerve at the level of the radial groove of the humerus. In the early stage of development, the extensor precursor divides into 3 layers namely, superficial layer, radial layer and deep layer; the superficial group develops to become the extensor digitorum communis, the extensor carpi ulnaris and the extensor digiti minimi. The radial layer forms the extensor carpi radialis longus, the extensor carpi radialis brevis and the brachioradialis; the deep layer differentiates to become the abductor pollicis longus, the extensor pollicis longus and the extensor pollicis brevis. The deep layer of the precursor extensor mass is known to be phylogenetically unstable and is undergoing evolution as high variability is seen in non-human primates.
In humans, anomalous or additional muscles can be seen in small portion of population. Anomalous muscles in human extensor compartment are listed as follow: Extensor medii proprius Extensor indicis et medii communis Extensor pollicis et indicis communis Extensor carpi radialis tertius Extensor digitorum brevis manus Tennis elbow or lateral epicondylitis is a chronic or an acute inflammation of the tendons that arise from the outer part of the elbow; the affected tendons are the tendons of extensor muscles which originate from the lateral epicondyle of humerus. It is caused by the repetitive movements and overuse, it damages the tendons which results in tenderness on the outer part of the elbow. De Quervain's syndrome is a medical condition when the synovial sheath surrounding tendons in the first extensor tendon compartment becomes inflamed, so called tenosynovitis; the tendons of the abductor pollicis longus and the extensor pollicis brevis run narrower due to the thickening of the synovial sheath, which causes pain when extending and moving the thumb outward.
Carpal tunnel syndrome is a condition when the median nerve is compressed as it passes through the carpal tunnel, which causes pain and tingling. The presence of an additional tendon may result in a condition called fourth compartment syndrome. Supernumerary tendons are common in the fourth extensor tendon compartment. Supernumerary tendons can refer to the additional tendons of normal structures or tendons of rare anatomical variants such as the extensor medii proprius or the extensor digitorum brevis manus; the increased pressure in the synovial sheath is known to directly or indirectly compress the posterior interosseous nerve of radial nerve. The extra pressure causes synovitis which results in pain in the dorsal part of the wrist. Anatomical variants are encountered in the extensor compartment of the forearm. Clinical expressions of the extensor digitorum brevis manus are mistaken for ganglion, cyst or tumour. In the superfamily hominoidea or apes, configurations of the muscles of the posterior compartment of the forearm share similar characteristics.
However, the anconeus is not present in the hylobates. The extensor pollicis brevis is only present in the genus homo and the genus hylobates because the extensor pollicis brevis and the abductor pollicis longus exist as a single muscle in other genera. Anteri
In human anatomy, the thigh is the area between the hip and the knee. Anatomically, it is part of the lower limb; the single bone in the thigh is called the femur. This bone is thick and strong, forms a ball and socket joint at the hip, a modified hinge joint at the knee; the femur is the only bone in the thigh and serves for an attachment site for all muscles in the thigh. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with the tibia and kneecap forming the knee. By most measures the femur is the strongest bone in the body; the femur is the longest bone in the body. The femur is categorised as a long bone and comprises a diaphysis, the shaft and two epiphysis or extremities that articulate with adjacent bones in the hip and knee. In cross-section, the thigh is divided up into three separate compartments, divided by fascia, each containing muscles; these compartments use the femur as an axis, are separated by tough connective tissue membranes.
Each of these compartments has its own blood and nerve supply, contains a different group of muscles. Medial fascial compartment of thigh, adductor Posterior fascial compartment of thigh, hamstring Anterior fascial compartment of thigh, extensionAnterior compartment muscles of the thigh include sartorius, the four muscles that comprise the quadriceps muscles- rectus femoris, vastus medialis, vastus intermedius and vastus lateralis. Posterior compartment muscles of the thigh are the hamstring muscles, which include semimembranosus and biceps femoris. Medial compartment muscles are pectineus, adductor magnus, adductor longus and adductor brevis, gracilis; because the major muscles of the thigh are the largest muscles of the body, resistance exercises of them stimulate blood flow more than any other localized activity. The arterial supply is by the obturator artery; the lymphatic drainage follows the arterial supply and drains to the lumbar lymphatic trunks on the corresponding side, which in turn drains to the cisterna chyli.
The deep venous system of the thigh consists of the femoral vein, the proximal part of the popliteal vein, various smaller vessels. The venae perfortantes connect the deep and the superficial system, which consists of the saphenous veins. Thigh weakness can result in a positive Gowers' sign on physical examination; the thigh meat of some animals such as chicken and cow is consumed as a food in many parts of the world
Palmar interossei muscles
In human anatomy, the palmar or volar interossei are three small, unipennate muscles in the hand that lie between the metacarpal bones and are attached to the index and little fingers. They are smaller than the dorsal interossei of the hand. All palmar interossei originate along the shaft of the metacarpal bone of the digit on which they act, they are inserted into the base of the proximal phalanx and the extensor expansion of the extensor digitorum of the same digit. The first palmar interosseous is located at the thumb's medial side. Passing between the first dorsal interosseous and the oblique head of adductor pollicis, it is inserted on the base of the thumb's proximal phalanx together with adductor pollicis; this muscle, the so-called pollical palmar interosseous muscle, is present in more than 80% of individuals and was first described by Henle 1858. Its presence has been verified by numerous anatomists since, but others have either failed to mention it or considered it part of either adductor pollicis or flexor pollicis brevis.
However, the deep head of the flexor pollicis brevis originates on the thumb's ulnar sesamoid bone and the oblique portion of the adductor pollicis on several carpal bones as well as the bases of the second and third metacarpal bones and not on the first metacarpal. The other three palmar interossei originate on the side of the metacarpal facing the hand's midline; the tendons of these three muscles pass posterior to the deep transverse ligament before being inserted onto the extensor expansion. All of the interosseous muscles of the hand are innervated by the deep branch of the ulnar nerve; the palmar interossei are supplied by the palmar metacarpal artery of the deep palmar arch. The palmar interosseous muscles adduct the fingers towards the middle finger; this is in contrast to the dorsal interossei. In addition they flex the finger at the metacarpo-phalangeal joint and extend the finger at the interphalangeal joint and thus assist the lumbricals; the palmar interossei, together with the dorsal interossei and the lumbricals, are active components of the finger's extensor mechanism.
Fibers from some of the interossei contribute directly to the extensor hoods that wrap around the proximal phalanges while other fibers may contribute to the central tendon and lateral bands of the mechanism. All three intrinsic groups of muscles pass palmar to the axis of the metacarpophalangeal joints and therefore contribute to flexion there. Extension at the interphalangeal joints cannot be produced by the extensor digitorum alone, but active contraction of one of the three aforementioned intrinsic groups will because of their direct contribution to the extensor mechanism; the pollical palmar interosseous is absent in non-human primates and is an autapomorphic muscle unique to the human thumb which evolved from the oblique portion of adductor pollicis. In African apes, adductor pollicis is notably well-developed, with an origin on the carpus and its ligaments, an insertion that has migrated distally, in some cases as far as the distal phalanx; the insertion of the PPIM into the extensor mechanism is to have evolved with tool usage in early hominids.
As comparative anatomy studies of the human PPIM suggest that the muscle is evolutionarily derived from the adductor pollicis, it has been proposed that PPIM should be designated by the name musculus adductor pollicis accessorius, which indicates that the muscle is most a de novo structure derived from the adductor pollicis. Interosseous muscles of the hand Dorsal interossei of the hand Interosseous muscles of the foot Dorsal interossei of the foot Plantar interossei muscles
In vertebrate anatomy, hip refers to either an anatomical region or a joint. The hip region is located lateral and anterior to the gluteal region, inferior to the iliac crest, overlying the greater trochanter of the femur, or "thigh bone". In adults, three of the bones of the pelvis have fused into the hip bone or acetabulum which forms part of the hip region; the hip joint, scientifically referred to as the acetabulofemoral joint, is the joint between the femur and acetabulum of the pelvis and its primary function is to support the weight of the body in both static and dynamic postures. The hip joints have important roles in retaining balance, for maintaining the pelvic inclination angle. Pain of the hip may be the result of numerous causes, including nervous, infectious, trauma-related, genetic; the proximal femur is covered by muscles and, as a consequence, the greater trochanter is the only palpable bony structure in the hip region. The hip joint is a synovial joint formed by the articulation of the rounded head of the femur and the cup-like acetabulum of the pelvis.
It forms the primary connection between the bones of the lower limb and the axial skeleton of the trunk and pelvis. Both joint surfaces are covered with a strong but lubricated layer called articular hyaline cartilage; the cuplike acetabulum forms at the union of three pelvic bones — the ilium and ischium. The Y-shaped growth plate that separates them, the triradiate cartilage, is fused definitively at ages 14–16, it is a special type of spheroidal or ball and socket joint where the spherical femoral head is contained within the acetabulum and has an average radius of curvature of 2.5 cm. The acetabulum grasps half the femoral ball, a grip augmented by a ring-shaped fibrocartilaginous lip, the acetabular labrum, which extends the joint beyond the equator; the joint space between the femoral head and the superior acetabulum is between 2 and 7 mm. The head of the femur is attached to the shaft by a thin neck region, prone to fracture in the elderly, due to the degenerative effects of osteoporosis.
The acetabulum is oriented inferiorly and anteriorly, while the femoral neck is directed superiorly and anteriorly. The transverse angle of the acetabular inlet can be determined by measuring the angle between a line passing from the superior to the inferior acetabular rim and the horizontal plane; the sagittal angle of the acetabular inlet is an angle between a line passing from the anterior to the posterior acetabular rim and the sagittal plane. It measures 7° at birth and increases to 17° in adults. Wiberg's centre-edge angle is an angle between a vertical line and a line from the centre of the femoral head to the most lateral part of the acetabulum, as seen on an anteroposterior radiograph; the vertical-centre-anterior margin angle is an angle formed from a vertical line and a line from the centre of the femoral head and the anterior edge of the dense shadow of the subchondral bone posterior to the anterior edge of the acetabulum, with the radiograph being taken from the false angle, that is, a lateral view rotated 25 degrees towards becoming frontal.
The articular cartilage angle is an angle formed parallel to the weight bearing dome, that is, the acetabular sourcil or "roof", the horizontal plane, or a line connecting the corner of the triangular cartilage and the lateral acetabular rim. In normal hips in children aged between 11 and 24 months, it has been estimated to be on average 20°, ranging between 18° to 25°, it becomes progressively lower with age. Suggested cutoff values to classify the angle as abnormally increased include:30° up to 4 months of age. 25° up to 2 years of age. The angle between the longitudinal axes of the femoral neck and shaft, called the caput-collum-diaphyseal angle or CCD angle measures 150° in newborn and 126° in adults. An abnormally small angle is known as an abnormally large angle as coxa valga; because changes in shape of the femur affects the knee, coxa valga is combined with genu varum, while coxa vara leads to genu valgum. Changes in CCD angle is the result of changes in the stress patterns applied to the hip joint.
Such changes, caused for example by a dislocation, changes the trabecular patterns inside the bones. Two continuous trabecular systems emerging on auricular surface of the sacroiliac joint meander and criss-cross each other down through the hip bone, the femoral head and shaft. In the hip bone, one system arises on the upper part of auricular surface to converge onto the posterior surface of the greater sciatic notch, from where its trabeculae are reflected to the inferior part of the acetabulum; the other system emerges on the lower part of the auricular surface, converges at the level of the superior gluteal line, is reflected laterally onto the upper part of the acetabulum. In the femur, the first system lines up with a system arising from the lateral part of the femoral shaft to stretch to the inferior portion of the femoral neck and head; the other system lines up with a system in the femur stretching from the medial part of the femoral shaft to the superior part of the femoral head. On the lateral side of the hip joint the fascia lata is strengthened to
Teres major muscle
The teres major muscle is a muscle of the upper limb. It is one of the seven scapulohumeral muscles, it is a somewhat flattened muscle. The teres major muscle is positioned above the latissimus dorsi muscle and assists in the extension and medial rotation of the humerus; this muscle is confused as a rotator cuff muscle, but it is not because it does not attach to the capsule of the shoulder joint, unlike the teres minor muscle for example. The teres major muscle originates on the dorsal surface of the inferior angle and the lower part of the lateral border of the scapula; the fibers of teres major insert into the medial lip of the intertubercular sulcus of the humerus. It is supplied by the lower subscapular nerve and additionally by the thoracodorsal nerve; these are distal to the upper subscapular nerve. These three nerves branch off the posterior cord of the brachial plexus; the nerves that innervate teres major consist of fibers from spinal nerves C5-C8. The tendon, at its insertion, lies behind that of the latissimus dorsi, from which it is separated by a bursa, the two tendons being, united along their lower borders for a short distance.
The fibers of these two muscles run parallel to each other and both muscles insert at the crest of the lesser tubercle of the humerus. Together with teres minor muscle, teres major muscle forms the axillary space, through which several important arteries and veins pass; the teres major is a medial rotator and adductor of the humerus and assists the latissimus dorsi in drawing the raised humerus downwards and backwards. It helps stabilise the humeral head in the glenoid cavity. Isolated teres, they are exclusively encountered in professional and high-level recreational athletes— baseball pitchers in particular. These injuries can be debilitating, requiring lengthy rehabilitation periods and missed seasons of athletics. No clear indications for surgical treatment exist. Outcomes have been good after both nonoperative and operative treatment. Accessory muscles of the scapula This article incorporates text in the public domain from page 442 of the 20th edition of Gray's Anatomy Anatomy figure: 03:03-06 at Human Anatomy Online, SUNY Downstate Medical Center PTCentral
Anatomy is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science which deals with the structural organization of living things, it is an old science. Anatomy is inherently tied to developmental biology, comparative anatomy, evolutionary biology, phylogeny, as these are the processes by which anatomy is generated over immediate and long timescales. Anatomy and physiology, which study the structure and function of organisms and their parts, make a natural pair of related disciplines, they are studied together. Human anatomy is one of the essential basic sciences; the discipline of anatomy is divided into microscopic anatomy. Macroscopic anatomy, or gross anatomy, is the examination of an animal's body parts using unaided eyesight. Gross anatomy includes the branch of superficial anatomy. Microscopic anatomy involves the use of optical instruments in the study of the tissues of various structures, known as histology, in the study of cells.
The history of anatomy is characterized by a progressive understanding of the functions of the organs and structures of the human body. Methods have improved advancing from the examination of animals by dissection of carcasses and cadavers to 20th century medical imaging techniques including X-ray and magnetic resonance imaging. Derived from the Greek ἀνατομή anatomē "dissection", anatomy is the scientific study of the structure of organisms including their systems and tissues, it includes the appearance and position of the various parts, the materials from which they are composed, their locations and their relationships with other parts. Anatomy is quite distinct from physiology and biochemistry, which deal with the functions of those parts and the chemical processes involved. For example, an anatomist is concerned with the shape, position, blood supply and innervation of an organ such as the liver; the discipline of anatomy can be subdivided into a number of branches including gross or macroscopic anatomy and microscopic anatomy.
Gross anatomy is the study of structures large enough to be seen with the naked eye, includes superficial anatomy or surface anatomy, the study by sight of the external body features. Microscopic anatomy is the study of structures on a microscopic scale, along with histology, embryology. Anatomy can be studied using both invasive and non-invasive methods with the goal of obtaining information about the structure and organization of organs and systems. Methods used include dissection, in which a body is opened and its organs studied, endoscopy, in which a video camera-equipped instrument is inserted through a small incision in the body wall and used to explore the internal organs and other structures. Angiography using X-rays or magnetic resonance angiography are methods to visualize blood vessels; the term "anatomy" is taken to refer to human anatomy. However the same structures and tissues are found throughout the rest of the animal kingdom and the term includes the anatomy of other animals.
The term zootomy is sometimes used to refer to non-human animals. The structure and tissues of plants are of a dissimilar nature and they are studied in plant anatomy; the kingdom Animalia contains multicellular organisms that are motile. Most animals have bodies differentiated into separate tissues and these animals are known as eumetazoans, they have an internal digestive chamber, with two openings. Metazoans do not include the sponges. Unlike plant cells, animal cells have neither chloroplasts. Vacuoles, when present, are much smaller than those in the plant cell; the body tissues are composed of numerous types of cell, including those found in muscles and skin. Each has a cell membrane formed of phospholipids, cytoplasm and a nucleus. All of the different cells of an animal are derived from the embryonic germ layers; those simpler invertebrates which are formed from two germ layers of ectoderm and endoderm are called diploblastic and the more developed animals whose structures and organs are formed from three germ layers are called triploblastic.
All of a triploblastic animal's tissues and organs are derived from the three germ layers of the embryo, the ectoderm and endoderm. Animal tissues can be grouped into four basic types: connective, epithelial and nervous tissue. Connective tissues are fibrous and made up of cells scattered among inorganic material called the extracellular matrix. Connective tissue holds them in place; the main types are loose connective tissue, adipose tissue, fibrous connective tissue and bone. The extracellular matrix contains proteins, the chief and most abundant of, collagen. Collagen plays a major part in maintaining tissues; the matrix can be modified to form a skeleton to protect the body. An exoskeleton is a thickened, rigid cuticle, stiffened by mineralization, as in crustaceans or by the cross-linkin
The anconeus muscle is a small muscle on the posterior aspect of the elbow joint. Some consider anconeus to be a continuation of the triceps brachii muscle; some sources consider it to be part of the posterior compartment of the arm, while others consider it part of the posterior compartment of the forearm. The anconeus muscle can be palpated just lateral to the olecranon process of the ulna. Anconeus originates on the posterior surface of the lateral epicondyle of the humerus and inserts distally on the superior posterior surface of the ulna and the lateral aspect of the olecranon. Anconeus is innervated by a branch of the radial nerve from the posterior cord of the brachial plexus called the nerve to the anconeus; the somatomotor portion of radial nerve innervating anconeus bifurcates from the main branch in the radial groove of the humerus. This innervation pattern follows the rules of innervation of the musculature of the posterior forearm compartment by the radial nerve, its role in elbow extension is trivial in humans.
It assists in extension of the elbow, where the triceps brachii is the principal agonist, supports the elbow in full extension. It prevents the elbow joint capsule being pinched in the olecranon fossa during extension of the elbow. Anconeus abducts the ulna and stabilizes the elbow joint. Anconeus serves to make minute movements with the radius on the ulna. In making slight abduction of the ulna, it allows any finger to be used as an axis of rotation of the forearm. Anconeus is supplied by the middle collateral artery from the profunda brachii artery. Trauma to the nerve supply of the anconeus muscle can result from a shoulder dislocation or fractures of the upper part of the humerus or around the olecranon, or any injury that damages the radial nerve. Harm inflicted upon the radial nerve through these mechanisms can paralyze the anconeus muscle as well as other extensors of the elbow and wrist. There are no specific acquired injuries that affect the anconeus muscle. Heterotopic ossification can result from certain trauma as it is an abnormal growth of osseous tissue in non-osseous tissue.
The condition is found in the hips, although there have been documented cases of certain individuals with it occurring in the arms and legs. The cause for the process to initiate is not well understood, only that it results from surgery or trauma. Aconeus muscle is the anglicized form of the Latin expression musculus anconaeus, as can be found in the Nomina Anatomica as ratified in Basel in 1895 and in Jena in 1935; the anatomic Latin adjective aconaeus was written as aconeus in the subsequent edition of the Nomina Anatomica as authorized in 1955 in Paris, without any further explanation of this specific diphthong reduction. The following edition of 1961 specified its policy by stating that: All diphthongs should be eliminated. Although a selected number of monophthongizations was reverted, subsequent editions of the Nomina Anatomica and its most recent outing Terminologia Anatomica insisted on writing musculus anconeus. Despite the earlier preference of the Nomina Anatomica for anconaeus no ancient Greek form ἀγκωναῖος is attested.
In modern Greek the expression ἀγκωνιαίος μυς is used, with the from anconaeus deviating adjective ἀγκωνιαίος. Anconaeus is derived from the ancient Greek noun, ἀγκών.'Ακών can be translated as bend of the arm or elbow. The expression musculus aconaeus was translated into English as elbow muscle in 1907 in the English translation of the first edition of the Nomina Anatomica