The pectoral region. University of Babylon College of Medicine Dr.HaythemAli Alsayigh M.B.CH.B.-F.I.M.B.S. Surgical Clinical Anatomy

Transcription

1 The pectoral region University of Babylon College of Medicine Dr.HaythemAli Alsayigh M.B.CH.B.-F.I.M.B.S. Surgical Clinical Anatomy

2 Objective Study the Bones and Joints A. Clavicle (collarbone) B. Scapula (shoulder blade) C. Humerus D. Radius E. Ulna F. Carpal bones G. Metacarpals H. Phalanges

3 Upper Limb II. Joints and Ligaments A. Acromioclavicular joint B. Sternoclavicular joint C. Shoulder (glenohumeral) joint D. Elbow joint E. Proximal radioulnar joint F. Distal radioulnar joint G. Wrist (radiocarpal) joint H. Midcarpal joint I. Carpometacarpal joints J. Metacarpophalangeal joints K. Interphalangeal joints

4 Some clinical problems Fracture of the clavicle Calcification of the superior transverse scapular ligament Fracture of the greater tuberosity Fracture of the lesser tuberosity Fracture of the surgical neck Fracture of the shaft Supracondylar fracture Fracture of the medial epicondyle Colles' fracture of the wrist and a reverse Colles' fracture (Smith's fracture). Guyon's canal syndrome Guyon's canal (ulnar tunnel

5 The pectoral region Pectoralis major Rectus sternalis Morphology of body wall muscles Deltopectoral triangle Pectoralis minor Subclavius Clavipectoral fascia Serratus anterior

6 The pectoral region The pectoral region is located on the anterior aspect of the thorax It contains muscles that belong to the upper limb.

7 The pectoral muscles The pectoral muscles are 4 muscles; these are pectoralis major, pectoralis minor, subclavius, and serratus anterior.

8 Pectoralis major This is a large, powerful, fan-shaped (triangular) muscle. It is attached by means of two heads to the front of the chest

9 Pectoralis major Clavicular head arises from the medial half of the clavicle

10 Pectoralis major Sterno-costal head is attached to the anterior surface of the sternum and to the upper six costal cartilages

11 Pectoralis major Insertion The muscle fibers converge to be inserted into the lateral lip of the intertubercular groove of the humerus

12 Pectoralis major Trilaminar insertion The clavicular head is inserted by the anterior lamina of the tendon

13 Pectoralis major Trilaminar insertion the manubrial fibers are inserted into the intermediate lamina of insertion

14 Pectoralis major Trilaminar insertion the sterno-costal fibers arising below the sternal angle are inserted into the posterior lamina of the tendon

15 Pectoralis major insertion The fibers which arise lowest of all are inserted highest of all

16 Pectoralis major insertion this produces the rounded appearance of the anterior axillary fold

17 Pectoralis major Nerve supply

18 Pectoralis major Action The muscle is an adductor of the arm at the shoulder joint

19 Pectoralis major Action The muscle is a medial rotator of the arm at the shoulder joint

20 Pectoralis major Action The clavicular head alone flexes the humerus

21 Pectoralis major Action From a fixed insertion, the muscle acts as an accessory muscle of respiration and in climbing

22 Pectoralis major test To test the integrity of the muscle, the arm is abducted to 90 o or more and the patient pushes forwards against resistance

23 Absence of pectoralis major

24 Rectus sternalis One body in 20 (5%) shows the presence of vertical musculoaponeurotic fibers on the surface of pectoralis major alongside the sternum

25 Morphology of the body wall muscles The body wall of all vertebrates consists of three layers of muscles

26 Morphology of the body wall muscles embryologically, pectoral muscles are derived from upper limb myotomes

27 Morphology of the body wall muscles morphologically, pectoral muscles belong to the outer layer of the three primitive layers of the body wall, represented in the abdomen by the external oblique

28 Morphology of the body wall muscles Towards the midline, ventrally and dorsally, the three layers change direction to make muscles that run longitudinally.

29 Morphology of the body wall muscles Ventrally, the longitudinal muscle is formed by fusion together of all three layers

30 Morphology of the body wall muscles It begins behind the symphesis menti as the geniohyoid, thyrohyoid, sternohyoid, omohyoid, and sternothyroid.

31 Morphology of the body wall muscles Then the rectus abdominis begins and extends to the symphysis pubis

32 Morphology of the body wall muscles There is a gap where the sternum and costal cartilages intervene

33 Morphology of the body wall muscles Traces of the ventral rectus muscle appear in this gap in front of the sternal fibers of pectoralis major forming the rectus sternalis muscle

34 Delto-pectoral triangle 1/3 1/2 Since deltoid muscle is attached to the lateral third of the clavicle and pectoralis major to the medial half, there is a small part of the clavicle to which neither muscle is attached.

35 Delto-pectoral triangle This part forms the base of a triangular space (delto-pectoral triangle) between the two muscles, deltoid and pectoralis major

36 Delto-pectoral triangle The delto-pectoral triangle may be visible in thin people.

37 Delto-pectoral triangle Cephalic v. It contains lymph nodes called infraclavicular lymph nodes; it also contains the termination of the cephalic vein

38 Delto-pectoral triangle The floor of the triangle is formed by deep fascia called the clavi-pectoral fascia

39 Pectoralis minor This is a small triangular muscle that is largely covered by pectoralis major

40 Pectoralis minor It arises from the 3 rd, 4 th, and 5 th ribs (not costal cartilages); and is inserted into the coracoid process of the scapula

41 Pectoralis minor Lateral pectoral nerve Medial pectoral nerve Its nerve supply is the same as that of pectoralis major namely medial and lateral pectoral nerves. The medial pectoral nerve passes through pectoralis minor to reach the overlying pectoralis major Nerve supply

42 Action of pectoralis minor The muscle stabilizes the scapula and can pull it forwards against the thoracic wall (protraction). The muscle is elongated in full abduction of the arm; its subsequent contraction assists gravity in restoring the scapula to the rest position

43 Action of pectoralis minor The muscle is of no great functional importance; however, it is an important anatomical and surgical landmark being a landmark to the underlying axillary artery

44 Chest, cross section at T4

45 Chest: axial CT Pectoralis major Pectoralis minor Note pectoralis major pectoralis minor

46 Subclavius This is a small unimportant muscle that as its name indicates lies inferior to the clavicle

47 Subclavius It arises from the first costo-chondral junction and is inserted into the subclavian groove on the inferior surface of the clavicle the muscle thus lies almost horizontally

48 Action of subclavius The muscle acts to stabilize the clavicle during shoulder movement. Prime mover fixator

49 Action of subclavius It may prevent the jagged ends of a fractured clavicle from damaging the adjacent subclavian vein.

50 Nerve supply of subclavius nerve to subclavius A branch of the brachial plexus (roots of C5 &6)

51 Costo-coracoid ligament Clavipectoral fascia This is a sheet of deep fascia filling in the space between the clavicle and pectoralis minor (hence the name)

52 Clavipectoral fascia The fascia splits twice to enclose two muscles above to enclose subclavius below to enclose pectoralis minor

53 Clavipectoral fascia At the inferior border of pectoralis minor, the two layers of fascia rejoin and extend downwards as the suspensory ligament of the axilla

54 The suspensory ligament of the axilla Is attached to the deep fascia of the floor of the axilla. By its tension, it maintains the axillary hollow

55 Clavipectoral fascia The clavi-pectoral fascia is almost completely covered by pectoralis major and deltoid muscles; a small portion of it appears at the floor of the delto-pectoral triangle

56 Clavipectoral fascia Four structures two passing inwards and two passing outwards pierce the clavipectoral fascia

57 Clavipectoral fascia Passing inwards are lymphatic vessels from the infraclavicular ymph nodes to the apical group of axillary lymph nodes and the cephalic vein draining into the axillary vein

58 Clavipectoral fascia Passing outwards are the acromiothoracic axis (artery) which is a branch of the axillary artery and the lateral pectoral nerve Lateral pectoral nerve

59 Lateral pectoral nerve Medial pectoral nerve On the cadaver note that the medial pectoral nerve pierces pectoralis minor while the lateral pectoral nerve pierces the clavi-pectoral fascia at a position more medial to the lateral pectoral nerve. In other words, the relation of the pectoral nerves in the pectoral region is the reverse of their names

60 Axillary v. Medial cord medial pectoral n. Pectoralis minor Axillary a. laterall pectoral n. lateral cord The names of these nerves (medial and lateral) are derived from their origin from the cords of the brachial plexus (medial and lateral cords respectively) rather than their relation in the pectoral region posterior cord

61 Serratus anterior This muscle was given its name because of the sowtoothed appearance (L. Serratus = a sow) of its origin where the muscle arises by 8 digitations from the upper eight ribs lateral to their angles

62 Serratus anterior external oblique Since external oblique muscle arises from the lower eight ribs, then the lower 4 digitations of serratus anterior inter-digitate with the upper 4 digitations of external oblique

63 Serratus anterior The muscle forms a flat sheet that is attached to the anterior aspect of the medial border of the scapula

64 Serratus anterior The muscle is supplied by the long thoracic nerve, a branch of the brachial plexus

65 Serratus anterior action The muscle acting as a whole protracts the scapula (i.e. moves the scapula forwards) and is used by boxers to deliver a straight left

66 Serratus anterior action acts as a fixator of the scapula during movements of the humerus Prime mover fixator

67 Serratus anterior action The lower fibers are very strong, they pull forwards on the lower angle of the scapula and thus rotate the scapula so that the glenoid cavity faces upwards (as in raising the arm above the head)

68 Serratus anterior action this is similar to the coupled action of the upper and lower fibers trapezius

69 Serratus anterior action In quadrupeds, serratus anterior suspends the trunk between the forelimbs

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