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The fasciae of the forearm and the hand




The antebrachial fascia

· The antebrachial fascia (fascia antebrachii /фасция предплечья) invests the forearm muscles and produces fibrous septa which projects between them.

· On the dorsal surface the antebrachial fascia forms a transverse thickening in the form of a ligament, which is called the extensor retinaculum (retinaculum musculorum extensorum /удерживатель мышц-разгибателей). Processes from the retinaculum fuse with the dorsal surface of the ulna and radius. Between the processes under ligament there are six dorsal carpal tendinous sheaths. These sheaths transmit the tendons of the finger and wrist extensors. If to count from the radial to the ulnar border:

- The first sheath transmits the tendons of the abductor pollicis longus and the extensor pollicis brevis.

- The second sheath transmits the tendons of the extensors carpi radials longus and brevis.

- The third sheath transmits the tendon of the extensor pollicis longus.

- The fourth sheath transmits the tendons of the extensor digitorum and extensor indicis.

- The fifth sheath transmits the tendons of the extensor digiti minimi.

- The sixth sheath transmits the tendons of the extensor carpi ulnaris.

The walls of the canals are lined with a synovial membrane, which, above and below the extensor retinaculum, folds over tendons and covers them. The sheaths protrude on the dorsal surface of the hand.

· On the palmar surface the antebrachial fascia forms a transverse thickening in the form of a ligament, which is called the flexor retinaculum (retinaculum musculorum flexorum /удерживатель мышц-сгибателей). The flexor retinaculum converts the carpal groove into the carpal canal or tunnel (canalis carpalis /канал запястья). In the carpal canal there are two separate palmar carpal tendinous sheaths:

- The common flexor sheath (vag. communis tendinum musculorum flexorum /общее влагалище сухожилий сгибателей) is a large medially located sac enclosing eight tendons of the deep and superficial flexors of the fingers. It protrudes 1-2 cm proximally of the flexor retinaculum superiorly, while inferiorly it reaches the middle of the palm. The sheath continues only on the tendons of the long flexors of the little finger and reaches the base of its distal phalanx.

- The tendinous sheath of flexor pollicis longus (vagina tendinis m. flexoris pollicis longi /влагалище сухожилия длинного сгибателя большого пальца кисти) is situated laterally. Superiorly this sheath protrudes 1-2 cm proximally of the flexor retinaculum, while inferiorly it extends on the tendon to the base of the distal phalanx of the thumb.

The remaining three fingers have separate sheaths, enclosing the tendons of the flexors of the corresponding finger. These sheaths extend from the line of the metacarpophalangeal joints to the base of the distal phalanges.

· The flexor retinaculum forms separating and running to the radial and ulnar sides, the radial carpal canal and the ulnar carpal canal respectively.

- The tendon of the flexor carpi radialis ensheathed in a synovial sheath lies in the radial carpal canal.

- The ulnar nerves and vessels pass in the ulnar carpal canal.

Palmar fascia

The palmar fascia covers the muscles of the hand.

· The thickened fascia in the middle of the palm forms a strong palmar aponeurosis (aponeurosis palmaris /ладонный апоневроз), which is a triangle extension of the tendon of the long palmar muscle. Its apex is directed to the flexor retinaculum, the base is directed to the fingers.

· The palmar aponeurosis forms on the palmar surface of the fingers osteofibrous canals called the fibrous sheaths of digits of hand (vaginae fibrosae digitorum manus /фиброзные влагалища пальцев кисти) that surrounds the tendons of flexors and their sheath. These sheaths has two types of fibres:

- The annular part of fibrous sheath (pars anularis vaginae fibrosae /кольцевая часть фиброзного влагалища) near the shaft of the phalanx.

- The cruciform part of fibrous sheath (pars cruciformis veginae fibrosae /крестообразная часть фиброзного влагалища) near the interphalangeal joints.

· The deep layer of the palmar fascia covers the middle muscles of the hand. Besides these muscles the deep layer fuses with the palmar aponeurosis.

Dorsal fascia of hand

The fascia has the superficial and the deep layers. The superficial layer covers the tendons of the extensors. The deep layer covers the dorsal interossei muscles.

 

The topography of the forearm and the hand

 

· In front of the elbow joint, in the bend of the arm, there is the cubital fossa (fossa cubitalis /локтевая ямка). It is bounded by the brachioradial muscle (laterally) and the pronator teres muscle (medially). The floor and the superior border of the fossa are formed by the brachial muscle.

· There are three grooves between the forearm muscles.

- The medial ulnar groove lies between flexor carpi ulnaris (medially) and the flexor digitorum superficialis (laterally). It transmits the ulnar nerve, artery and veins.

- The lateral radial groove lies between brachioradialis (laterally) and the flexor carpi radialis (medially). It transmits the radial nerve, artery and veins.

- The median groove lies between the flexor carpi radialis (laterally) and the flexor digitorum superficialis (medially). It transmits the median nerve.

 

THE MUSCLES OF LOWER LIMB

(musculi membri inferioris /мышцы верхней конечности)

 

The muscles of the hip region

 

The anterior group

 

Iliacus (m. iliacus /подвздошная мышца)

· Origin. From the concave inner surface of the ilium.

· Insertion. Passes under the inguinal ligament to the lesser trochanter, in company with psoas major.

· Action. Flexion of the thigh.

· Nerve supply. Femoral nerve.

Psoas major (m. psoas major /большая поясничная мышца)

· Origin. From the transverse processes and the sides of the bodies and intervertebral discs of the lumbar vertebrae.

· Insertion. Passes under the inguinal ligament to the lesser trochanter in company with iliacus. Joint muscle often called iliopsoas.

· Action. Flexion of the thigh.

· Nerve supply. Femoral nerve.

Psoas minor (m. psoas minor /малая поясничная мышца)

· Origin. From the twelfth thoracic and first lumbar vertebrae.

· Insertion. To the iliopubic eminence. It blends with the iliac fascia.

· Action. Tensesthe iliac fascia.

· Nerve supply. Femoral nerve.

 

The posterior group

Gluteus maximus (m. gluteus maximus /большая ягодичная мышца)

· Origin. From the posterior part of the gluteal surface of the ilium, the back of the sacrum and its associated ligaments.

· Insertion. To the gluteal tuberosity of the femur (25%) and the iliotibial tract (75%).

· Actions. Extension and lateral rotation of the thigh.

· Nerve supply. Inferior gluteal nerve.

Gluteus medius (m. gluteus medius /средняя ягодичная мышца)

· Origin. From the gluteal surface of the ilium.

· Insertion. To the greater trochanter.

· Actions. Abduction and medial rotation of the thigh.

· Nerve supply. Superior gluteal nerve.

Gluteus minimus (m. gluteus minimus /малая ягодичная мышца)

· Origin. From the gluteal. surface of the ilium below gluteus medius.

· Insertion. To the greater trochanter.

· Actions. Abduction and medial rotation of the thigh. The most import­ant action of medius and minimus is to prevent the pelvis tilting to the unsupported side when taking the weight on one leg, as in walking.

· Nerve supply. Superior gluteal nerve.

Tensor fasciae latae (m. tensor fasciae latae /напрягатель широкой фасции)

· Origin. From the anterior part of the crest of the ilium.

· Insertion. To the lateral condyle of the tibia via the iliotibial tract.

· Actions. Extension of the knee joint. Helps the gluteal muscles to pre­vent tilting of the pelvis.

· Nerve supply. Superior gluteal nerve.

Piriformis (m. piriformis /грушевидная мышца)

· Origin. From the front of the sacrum.

· Insertion. Into the greater trochanter via the greater sciatic notch.

· Action. Lateral rotation of the thigh.

· Nerve supply. From the sacral plexus.

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