Chapter 6 Upper Limb Hand especially the thumb occupies almost the largest area of the motor cortex 6 1 Regions of the Upper Limb Figure 6 1A Some regions overlap with regions of trunk o Scapular region in back o Infraclavicular region anteriorly below the clavicle o Deltopectoral triangle o Axillary and deltoid regions 6 2 Bones of the Upper Limb 6 2 a Scapula Two surfaces anterior subscapular fossa and posterior surface o Posterior surface further divided into supraspinous and infraspinous fossae by spine of scapula Acromion process lateral expansion of spine of scapula articulates with clavicle Glenoid cavity Site of articulation with head of humerus lateral angle Coracoid process gives origin to or is an insertion site for 3 muscles o Short head of biceps brachii origin o Pectoralis minor insertion o Coracobrachialis muscle origin Suprascapular notch bridged at upper boundary by superior transverse scapular ligament o Suprascapular nerve and vessels run through 6 2 b Clavicle S shaped superior and inferior surface anterior and posterior border Two ends sternal end and acromial end covered by cartilage o Articulates with sternum sternoclavicular joint ball and socket type synovial joint o Acromioclavicular joint plant type joint permits sliding gliding movements Ossification Two ends have endochondral ossification o Appears in second decade of life Ossified centers fuse to each other 6 2 c Humerus Proximal End shoulder joint Body shaft of the Humerus Head of humerus covered with hyaline cartilage fits into glenoid cavity of scapula and forms Three surfaces anteromedial anterolateral posterior Three boders Distal End Medial epicondyle is bigger bears ulnar groove through which ulnar nerve passes through Capitulum articulates with the head of the radius and the trochlea articulates with the ulna at the trochlear notch 6 2 d Shoulder Joint Olecranon fossa olecranon process of ulna fits in when elbow is extended Ball and socket synovial joint between head of humerus ball and glenoid cavity socket o Extended by an articular lip glenoid lip or articular labrum at its border Rotator cuff muscles help strengthen the shoulder joint Ligaments o Coracohumeral ligament superiorly restricts movement o three weak glenohumeral ligaments superior middle interior Movements abduction adduction anteversion flexion retroversion extension lateral and medial rotation and circumduction 6 2 e Forearm Bones Radius and Ulna Radius Proximal End Head articular fovea facet Neck Radial tuberosity Body Triangular shaped Three surfaces anterior lateral posterior Three borders anterior posterior medial interosseous borders Ulnar notch articulates with head of ulna Carpal articular surface articulation with proximal row of carpal bones Distal End Ulna Medial bone Proximal End Trochlear notch hook shaped articulates with trochlea of humerus Radial notch articulation with circumference of head of radius Ulnar tuberosity site of attachment of the brachialis muscle Body Triangular shaped Three surfaces anterior lateral posterior Three borders anterior posterior medial interosseous borders Distal End Supinator crest seen inferior to radial notch Head articulates with ulnar notch of radius Ulna is not in direct contact with carpal bones radius connects o Wrist joint is called radiocarpal joint 6 2 f Elbow Joint Synovial Joint Compound joint capsule of three joints humeroulnar humeroradial proximal radioulnar joints Ligaments include two collateral ligaments medial ulnar and lateral radial restrict movement Movements flexion and extension supination and pronation of forearm assisted by middle and distal radioulnar joints o Proximal radioulnar articulation pivot joint o Head of radius is supported by annular ligament o Middle radioulnar joint between radius and ulna interosseous membrane continuous joint 6 2 g Carpal Joints Proximal Row Distal Row o Distal radioulnar joint synovial and pivot type joint Between radius and ulna o Pronation and supination are possible on these joints Arranged in two rows each with four bones Firmly articulated together to form carpal groove concave on palmar side Bridged by flexor retinaculum forms carpal tunnel median nerve Lateral to medial direction scaphoid lunate triquetrum and pisiform Scaphoid anterior tubercle boat shape hollow medially articulates with radius superiorly Lateral to medial trapezium trapezoid capitate largest hamate Trapezium anterior tubercle groove through which tendon of flexor carpi radialis muscle passes Flexor Retinaculum First continuous with antebrachial fascia considered as reinforcement Two different fibrous structures volar anterior aspect of wrist Deeper composed of strong lamina Points of insertion Carpal Tunnel Covered by flexor retinaculum and carpal groove Tendons of some flexor muscles and median nerve pass through 6 2 h Wrist Radiocarpal Joint o Four bony points tubercle of scaphoid pisiform tubercle of trapezium hook of hamate Ellipoid type synovial joint Proximally by radius and articular disc between the distal end of ulna and proximal row of carpal bones and distally by proximal row of carpal bones Movements abduction radial elevation adduction ulnar deviation flexion and dorsiflexion extension and circumduction Ligaments ulnar and radial collateral ligaments palmar and dorsal radiocarpal ligaments palmar ulnocarpal ligament o Joints between carpal bones S shaped o Little movement between bones of first row no movement between second row and between these joints and the metacarpal bones except for first carpometacarpal joint of thumb 6 2 i The Metacarpal Bones 5 in hand Each has a body a head and a base 6 2 j Carpometacarpal Joints First saddle joint movement abduction adduction opposition reposition and circumduction of thumb Other ones have very limited movement 6 2 k The Phalanges Bones of the digits 3 in each digit proximal middle and distal thumb only has 2 proximal and distal Each phalanx proximal base and distal head trochlea o Distal has distal flattened border with dentations 6 2 l Metacarpophalangeal Joints Synovial joints ball and socket shaped All freedom of movement is restricted due to collateral ligaments 6 2 m Interphalangeal Joints Hinge type synovial joints Movement flexion and extension of digits Supported by collateral and palmar ligaments 6 3 Innervations of Upper Limbs Brachial Plexus and the Axillary Region Axillary region bordered by pectoralis major muscle anteriorly the ribs and intercostal muscles medially and the