These provide attachments for muscles of the arm. It is surrounded by muscles on both its anterior deep and posterior superficial sides, and it does not directly articulate with the ribs of the thoracic cage. Chapter Review The pectoral girdle, consisting of the clavicle and the scapula, attaches each upper limb to the axial skeleton. Zoom back in to the right wrist and identify the pisiform. The two axial muscles are the pectoralis major and the latissimus dorsi. .
Clavicle The clavicle is the only long bone that lies in a horizontal position in the body see. Which muscle extends the forearm? The scapula is a flat, triangular-shaped bone with a prominent ridge running across its posterior surface. These muscles and their associated blood vessels and nerves form the anterior compartment of the arm anterior flexor compartment of the arm and. If the fracture is complete, the shoulder and lateral clavicle fragment will drop due to the weight of the upper limb, causing the person to support the sagging limb with their other hand. This in turn holds the shoulder joint superiorly and laterally from the body trunk, allowing for maximal freedom of motion for the upper limb. Nine muscles cross the shoulder joint to move the humerus.
The pectoral girdle, or shoulder girdle, consists of the lateral ends of the clavicle and scapula, along with the proximal end of the humerus, and the muscles covering these three bones to stabilize the shoulder joint. Finally, the brachioradialis can flex the forearm quickly or help lift a load slowly. This connective tissue band anchors the coracoid process of the scapula to the inferior surface of the acromial end of the clavicle and thus provides important indirect support for the acromioclavicular joint. Finally, the intermediate muscles act on all the fingers and include the lumbrical, the palmar interossei, and the dorsal interossei. The posterior thoracic muscles are the trapezius, levator scapulae, rhomboid major, and rhomboid minor.
The clavicle also transmits forces acting on the upper limb to the sternum and axial skeleton. However, the primary support for the acromioclavicular joint comes from a very strong ligament called the coracoclavicular ligament see. Intrinsic Muscles of the Hand Table 9 Muscle Movement Target Target motion direction Prime mover Origin Insertion Thenar muscles Moves thumb toward body Thumb Abduction Abductor pollicis brevis Flexor retinaculum; and nearby carpals Lateral base of proximal phalanx of thumb Thenar muscles Moves thumb across palm to touch other fingers Thumb Opposition Opponens pollicis Flexor retinaculum; trapezium Anterior of first metacarpal Thenar muscles Flexes thumb Thumb Flexion Flexor pollicis brevis Flexor retinaculum; trapezium Lateral base of proximal phalanx of thumb Thenar muscles Moves thumb away from body Thumb Adduction Adductor pollicis Capitate bone; bases of metacarpals 2—4; front of metacarpal 3 Medial base of proximal phalanx of thumb Hypothenar muscles Moves little finger toward body Little finger Abduction Abductor digiti minimi Pisiform bone Medial side of proximal phalanx of little finger Hypothenar muscles Flexes little finger Little finger Flexion Flexor digiti minimi brevis Hamate bone; flexor retinaculum Medial side of proximal phalanx of little finger Hypothenar muscles Moves little finger across palm to touch thumb Little finger Opposition Opponens digiti minimi Hamate bone; flexor retinaculum Medial side of fifth metacarpal Intermediate muscles Flexes each finger at metacarpo-phalangeal joints; extends each finger at interphalangeal joints Fingers Flexion Lumbricals Palm lateral sides of tendons in flexor digitorum profundus Fingers 2—5 lateral edges of extensional expansions on first phalanges Intermediate muscles Adducts and flexes each finger at metacarpo-phalangeal joints; extends each finger at interphalangeal joints Fingers Adduction; flexion; extension Palmar interossei Side of each metacarpal that faces metacarpal 3 absent from metacarpal 3 Extensor expansion on first phalanx of each finger except finger 3 on side facing finger 3 Intermediate muscles Abducts and flexes the three middle fingers at metacarpo-phalangeal joints; extends the three middle fingers at interphalangeal joints Fingers Abduction; flexion; extension Dorsal interossei Sides of metacarpals Both sides of finger 3; for each other finger, extensor expansion over first phalanx on side opposite finger 3 Chapter Review The clavicle and scapula make up the pectoral girdle, which provides a stable origin for the muscles that move the humerus. This end is also anchored to the coracoid process of the scapula by the coracoclavicular ligament, which provides indirect support for the acromioclavicular joint. A hard fall may thus cause a fracture of the clavicle broken collarbone or may injure the ligaments of the acromioclavicular joint.
The clavicle also transmits forces acting on the upper limb to the sternum and axial skeleton. Because the clavicles transmit force from the upper limbs to the trunk, they are among the most frequently broken bones in the body. Term interosseous membranes Definition provides attachment points for deep muscles of forearm Term interosseous membrane Definition holds the radius and the ulna together Term radius Definition which styloid process of the ulna or radius is more distal? The hypothenar muscles, which are located on the medial part of the palm, are the abductor digiti minimi, flexor digiti minimi brevis, and opponens digiti minimi. This is certainly not the case with compression fractures of the bone caused, for instance, by automobile accidents when wearing a shoulder harness. Muscles That Move the Wrist, Hands, and Forearm The tendons of the forearm muscles attach to the wrist and extend into the hand.
These muscles form the thenar eminence, the rounded contour of the base of the thumb, and all act on the thumb. The deep anterior compartment produces flexion and bends fingers to make a fist. The thenar muscles include the abductor pollicis brevis, opponens pollicis, flexor pollicis brevis, and the adductor pollicis. In men, the clavicle is heavier and longer, and has a greater curvature and rougher surfaces where muscles attach, features that are more pronounced in manual workers. The coracoid process projects anteriorly, passing inferior to the lateral end of the clavicle. The medial end, known as the sternal end of the clavicle, has a triangular shape and articulates with the manubrium portion of the sternum.
Which muscles stabilize the pectoral girdle? The anatomical and ligamental structure of the shoulder joint and the arrangements of the muscles covering it, allows the arm to carry out different types of movements. In humans, the pectoral girdle, or shoulder girdle, is made up of the scapula, clavicle and various muscle groups. Term parallel Definition in anatomical position, is the radius and ulna criss crossing or are they parallel? Term annular ligament Definition what ligament holds the head of the radius to the radial notch of the ulna? Finally, it serves to protect the underlying nerves and blood vessels as they pass between the trunk of the body and the upper limb. Since the pectoral girdle is held in place by muscles only, it has a much wider range of motion than the pelvic girdle, but the pectoral girdle is much weaker as a result. The hypothenar muscles are on the medial aspect of the palm, and the intermediate muscles are midpalmar. The deep posterior compartment includes the abductor longus, extensor pollicis brevis, extensor pollicis longus, and the extensor indicis.
Fibrous bands called retinacula sheath the tendons at the wrist. The clavicle overlies many important blood vessels and nerves for the upper limb, but fortunately, due to the anterior displacement of a broken clavicle, these structures are rarely affected when the clavicle is fractured. The small bony bumps located immediately above and below the glenoid cavity are the supraglenoid tubercle and the infraglenoid tubercle, respectively. The biceps brachii, brachialis, and brachioradialis flex the forearm. The superficial anterior compartment of the forearm produces flexion. The clavicle has several important functions. Term capitulum Definition lateral condyle of the humerus distal Term head of the radius Definition where does the capitulum of the humerus articulate? Term Colle's fractures Definition what's it called when the styloid process of the radius lines up with the styloid process of the ulna? Muscles That Position the Pectoral Girdle Muscles that position the pectoral girdle are located either on the anterior thorax or on the posterior thorax and.
The flexor digitorum superficialis flexes the hand as well as the digits at the knuckles, which allows for rapid finger movements, as in typing or playing a musical instrument see and. The scapula is a flat, triangular-shaped bone with a prominent ridge running across its posterior surface. In men, the clavicle is heavier and longer, and has a greater curvature and rougher surfaces where muscles attach. Pectoral shoulder girdle bones, joints and ligaments The Joints of the Pectoral Girdle 1. The supinator is the only one that turns the forearm anteriorly.