Principles of Human Anatomy: Bones and Muscles of the Upper Extremity PDF

Principles of Human Anatomy ANAT 3651 Lecture notes: Bones and Muscles of the Upper Extremity Objectives: 1.Understand the terminology of bone markings 2.Differentiate between bones of the axial and appendicular skeleton 3.Understand homologous relationship between upper and lower limbs...

Principles of Human Anatomy ANAT 3651 Lecture notes: Bones and Muscles of the Upper Extremity Objectives: 1.Understand the terminology of bone markings 2.Differentiate between bones of the axial and appendicular skeleton 3.Understand homologous relationship between upper and lower limbs 4.Identify bones that form the pectoral girdle and their features 5.Identify bones of the upper limb and their features 6.Describe how specific bones come together (articulate) to form specific joints 7.Identify muscles of the upper extremity with their origins, insertions, & movements ______________________________________________________________________ Bone Markings A bone’s shape is determined by various tissues that are attached to or pass near/through them. For example, protrusions on bone are formed by muscles that attached to the bone. Additionally, holes or grooves are formed as nerves and blood vessels pass near or through the bone. The following terminology is used to describe these features, or markings, of bones: A hole or opening in a bone: If round, it is a foramen If slit-like, it is a fissure If tube-like, it is a canal or meatus If a hollow space, it is a cavity or sinus A ridge on a bone: If extensive, it is a crest If it is thin, it is a line A projection on a bone: If it is large, it is a trochanter, tuberosity, or malleolus If it is small, it is a tubercle or process If it is pointed or spear-like, it is a spinous process or styloid process A depression in bone: If small, it is a fovea If larger and deeper, it is a fossa If half-moon shaped, it may be called a notch If it is long, it may be called a sulcus or groove Where one bone articulates with another capped with hyaline cartilage: Upper Extremity 1  If rounded, it is called a condyle or head There is other terminology for bone features. Please refer to the above descriptions or the table below (or in your textbook) as we discuss specific features of each bone. Axial vs. Appendicular Skeleton The skeleton can be divided into axial and appendicular portions. The axial skeleton forms the central axis of the body and the appendicular skeleton forms the bones of the pectoral and pelvic girdles and extremities. Upper Extremity 2 The axial skeleton includes: skull bones, auditory ossicles, teeth, hyoid, vertebrae, sacrum, coccyx, ribs, and sternum. The axial skeleton is shown in green in the image below. The appendicular skeleton includes: the clavicle, scapula, humerus, radius, ulna, carpals, metacarpals, phalanges, os coxae, femur, tibia, patella, fibula, tarsals, and, metatarsals. The appendicular skeleton is shown in the tan/brown color below. Relationship between upper and lower limbs Upper and lower limbs are considered serial homologues which means they are similar, repetitive structures (such as vertebrae or ribs). As you learn the bones and muscles of the upper and lower limbs, appreciate the similarities and differences between the limbs. Upper Extremity 3 During embryonic development, both upper and lower limbs start in a neutral position. After birth the upper limb rotates laterally 90 degrees and the lower limb rotates medially 90 degrees. This explains why the elbow and knee (homologous structures) bend in opposite directions (i.e., flexion at the elbow brings the forearm anteriorly whereas flexion at the knee brings the leg posteriorly). Bones of the Upper Extremity Below are the bones and bony features of the upper extremity that you should be familiar with. Pectoral girdle The pectoral girdle is formed by the clavicle and scapula and is the connection of the upper limb to the axial skeleton. Clavicle- strut between the sternum and acromial process of the scapula Scapula o Superior angle o Inferior angle o Spine of the scapula- ridge of bone on the posterior side o Acromial process- process at the end of the spine o Coracoid process- anterior projection from the superior scapula o Supraspinous fossa- depression above the spine o Infraspinous fossa- depression below the spine o Subscapular fossa- depression on the anterior side of the scapula o Glenoid fossa- depression on the lateral side of the scapula, articulates with the humerus to form the shoulder (glenohumeral) joint Upper Extremity 4 Upper limb bones Humerus- bone of the arm o Head- articulates with the scapula to form the shoulder joint o Greater tubercle- projection on the superior, lateral side of the humerus o Lesser tubercle- projection on the superior, anterior side of the humerus o Intertubercular groove- groove between the greater and lesser tubercles o Deltoid tuberosity- insertion site for the deltoid muscle o Trochlea- medial articular surface at the distal end of the humerus, articulates with the ulna o Capitulum- lateral articular surface at the distal end of the humerus, articulates with the radius o Medial epicondyle- projection of bone above the trochlea o Lateral epicondyle- projection of bone above the capitulum o Olecranon fossa- depression on the posterior, distal end of the humerus, the olecranon process of the ulna Radius- lateral bone of the forearm o Head- articulates with the capitulum of the humerus o Radial tuberosity- rough bump of bone at the proximal end o Styloid process- narrow projection of bone at the distal end Ulna- medial bone of the forearm o Olecranon process- projection of bone at the proximal end o Trochlear notch- articular surface that forms the elbow joint with the trochlea of the humerus o Coronoid process- anterior projection from the trochlear notch o Styloid process- narrow projection of bone at the distal end Interosseous membrane- dense connective tissue connecting the shafts of the radius and ulna The skeleton of the hand is formed by 3 sets of bones: carpals, metacarpals, and phalanges. The carpals form the wrist (or carpus) in the proximal hand. The metacarpals are the long bones within the palm of the hand. The phalanges are the long bones of the fingers. The metacarpals and digits are numbered I to V beginning with the thumb (or pollex) and ending with the small finger. Carpals o group of 8 short bones in the wrist, organized in two rows of four bones Proximal Row o Scaphoid o Lunate Upper Extremity 5  o Triquetral (aka triquetrum) o Pisiform (only seen from anterior/palmar view because it sits on the anterior side of the triquetral) Distal Row o Trapezium o Trapezoid o Capitate o Hamate Metacarpals o five long bones in the palm of the hand Phalanges o long bones in the fingers, each finger or digit has three phalanges (proximal, intermediate, and distal) except the thumb only has two (proximal and distal) Joints of the Upper Extremity Shoulder joint- also called glenohumeral joint o Between the glenoid fossa of the scapula and head of the humerus o Ball and socket joint, multiaxial, most mobile joint of the body o Surrounded by ligaments and rotator cuff muscles for support ▪ Glenohumeral ligaments ▪ Coracohumeral ligament o Movements at this joint: ▪ Medial rotation-lateral rotation ▪ Abduction-adduction ▪ Flexion-extension Elbow joint o Between the trochlea of the humerus and the trochlear notch of the ulna, and head of the radius and capitulum of the humerus o Hinge joint, uniaxial o Ligaments ▪ Ulnar (medial) collateral ligament ▪ Radial (lateral) collateral ligament o Movements at this joint: ▪ Flexion-extension Radioulnar joint o Between the radius and ulna, has two articulations (proximal and distal) o Annular ligament holds head of radius against the ulna o Pivot joint, uniaxial o Movements at this joint: Upper Extremity 6  ▪ Supination-pronation Wrist joint- also called the radiocarpal joint o Between distal radius and carpals o Condylar joint, biaxial o Movements at this joint: ▪ Flexion-extension ▪ Abduction (radial deviation)-adduction (ulnar deviation) Metacarpophalangeal joints o Between metacarpals and phalanges o Condylar joints, biaxial o Movements at these joints: ▪ Flexion-extension ▪ Abduction-adduction Interphalangeal joints o Between phalanges o Two joints in digits 2-5, only one in thumb o Hinge joints, uniaxial o Movements at these joints: ▪ Flexion-extension Muscles of the Upper Extremity Muscles that move the scapula The muscles that move the scapula are the trapezius, rhomboids, levator scapulae, pectoralis minor, and serratus anterior. Trapezius, rhomboids, and levator scapulae are superficial muscles of the back and neck. Pectoralis minor is a muscle of the chest located deep to pectoralis major. Serratus anterior has a unique path. It originates from the anterior side of the ribs and passes posteriorly between the scapula and rib cage to insert on the medial border of the scapula. Muscle Origin Insertion Action Trapezius Occipital bone, spinous Clavicle, acromion, and Elevate/depress processes of vertebrae spine of scapula /adduct scapula Rhomboids Spinous processes of vertebrae medial border of scapula Adduct scapula Levator scapulae Transverse processes of Superior angle of Elevate scapula cervical vertebrae scapula Pectoralis minor Ribs Coracoid process of Depress scapula scapula Upper Extremity 7 Serratus anterior Ribs medial border of scapula Abduct scapula Muscles that move the arm Pectoralis major and coracobrachialis are found on the anterior side of the body and both flex and adduct the arm at the shoulder. Latissimus dorsi and teres major are found on the posterior side of the body and both extend and adduct the arm at the shoulder. The deltoid muscle is the large muscle that covers over your shoulder joint. The rotator cuff muscles are supraspinatus, infraspinatus, teres minor, and subscapularis. Supraspinatus, infraspinatus, and teres minor originate from the posterior side of the scapula whereas subscapularis originates from the anterior side of the scapula. Together they form a supportive cuff around the shoulder. Muscle Origin Insertion Action Pectoralis major Sternum and clavicle Greater tubercle of Flex/adduct arm humerus Deltoid Clavicle and scapula Deltoid tuberosity of Flex/extend/abdu humerus ct arm Latissimus dorsi Spinous processes of Lesser tubercle of Extend/adduct vertebrae, iliac crest humerus arm Teres major Inferior angle of scapula Lesser tubercle of Extend/adduct humerus arm Coracobrachialis Coracoid process Proximal humerus Flex/adduct arm Supraspinatus Supraspinous fossa of scapula Greater tubercle of Abduct arm humerus Infraspinatus Infraspinous fossa of scapula Greater tubercle of Rotate arm humerus laterally Teres minor Lateral border of scapula Greater tubercle of Rotate arm humerus laterally Subscapularis Subscapular fossa of scapula Lesser tubercle of Rotate arm humerus medially Muscles that move the forearm The biceps brachii and brachialis muscles are found in the anterior compartment of the arm. The brachioradialis muscle, in addition to biceps brachii and brachialis, flexes the forearm at the elbow but is found primarily in the forearm. Triceps brachii is a three-headed muscle found in the posterior compartment of the arm. The pronator muscles and supinator are found in the forearm. Pronator muscles are in the anterior compartment of the forearm and supinator is in the posterior compartment of the forearm. Muscle Origin Insertion Action Upper Extremity 8 Biceps brachii Short head: coracoid process of Radial tuberosity Flex forearm at scapula elbow and Long head: above glenoid fossa supinate forearm of scapula Brachialis Distal humerus Proximal ulna Flex forearm Triceps brachii Lateral head: lateral surface of Olecranon process of Extends forearm humerus ulna at elbow Long head: below glenoid fossa Medial head: posterior surface of humerus Brachioradialis Distal, lateral humerus Styloid process of radius Flex forearm Pronator muscles Ulna Radius Pronates forearm Supinator Ulna Radius Supinates forearm Muscles that move the hand and fingers There are many muscles in the forearm and hand that move the hand at the wrist and the fingers at various joints. We will only be learning the muscles of the forearm based on compartments. The muscles in the anterior compartment of the forearm flex the wrist, fingers, and thumb. The muscles in the posterior compartment of the forearm extend the wrist, fingers and thumb (and also abduct the thumb). We will not be learning the muscles of the hand. Muscle Origin Insertion Action forearm flexors Medial epicondyle of humerus, Carpals, metacarpals, Flex wrist, (anterior comp.) radius, and ulna and phalanges fingers, and thumb forearm extensors Lateral epicondyle of humerus, Carpals, metacarpals, Extend wrist, (posterior comp.) radius, and ulna and phalanges fingers, and thumb; abduct thumb Upper Extremity 9