Upper Limb Bones PDF

UPPER LIMB BONES Dr TARI AGBALALAH  SCAPULA Location: The scapula also known as the shoulder blade, is a flat, triangular bone. It is located on the posterior aspect of the thorax, extending from the second to the seventh rib.  Anterior (Costal) Surface:...

UPPER LIMB BONES Dr TARI AGBALALAH  SCAPULA Location: The scapula also known as the shoulder blade, is a flat, triangular bone. It is located on the posterior aspect of the thorax, extending from the second to the seventh rib.  Anterior (Costal) Surface: The scapula has anterior, lateral and a posterior surface Subscapular Fossa: A large concave depression for the attachment of the subscapularis muscle. Coracoid Process: A beak-like projection providing attachment for the pectoralis minor, short head of the biceps brachii, and coracobrachialis muscles. Posterior Surface of Scapula Spine of the Scapula: A prominent ridge dividing the posterior surface into the supraspinous (above the spine) and the infraspinous fossa (below the spine). Supraspinous Fossa: A shallow depression for supraspinatus muscle attachment. Infraspinous Fossa: A larger depression for infraspinatus muscle attachment Acromion: An extension of the spine that forms the highest point of the shoulder, providing attachment for the deltoid and trapezius muscles.  Lateral Surface Site of the glenohumeral joint, and various muscle attachments. Its important bony landmarks include: Glenoid fossa – a shallow socket that articulates with the head of the humerus to form the glenohumeral (shoulder) joint. Supraglenoid tubercle – a roughening immediately superior to the glenoid fossa. Attachment site for the long head of the biceps brachii muscle. Infraglenoid tubercle – a roughening immediately inferior to the glenoid fossa. Attachment site for the long head of the triceps brachii muscle.  Medial Border: Attachment Sites: Rhomboid major, rhomboid minor, and serratus anterior muscles.  Joints: Glenohumeral Joint: Articulation between the glenoid cavity and the head of the humerus. Acromioclavicular Joint: Articulation between the acromion of the scapula and the clavicle. Scapulothoracic Joint: Functional joint between the anterior surface of the scapula and the posterior thoracic wall. Neurovascular Supply of the scapula Arteries: Suprascapular artery, circumflex scapular artery, dorsal scapular artery. Nerves: Suprascapular nerve, dorsal scapular nerve, axillary nerve (to the deltoid and teres minor). Clinical Considerations: Scapular Fracture: Typically occurs from high-energy trauma. May involve the body, neck, or glenoid. Winged Scapula: Caused by injury to the long thoracic nerve, affecting the serratus anterior muscle.  CLAVICLE or collarbone Location: Is an S-shaped long bone located horizontally across the front of the thorax, above the first rib, and extending from the sternum to the scapula. It has a shaft, sternal and acromial end. It can be palpated along its length. It is visible under the skin in thin individuals. Main functions: Attaches the upper limb to the trunk Protects the underlying neurovascular structures supplying the upper limb. Transmits force from the upper limb to the axial skeleton. Sternal (medial) End Contains a large facet – for articulation with the manubrium of the sternum at the manubriosternal joint. The inferior surface of the sternal end has a rough oval depression for the costoclavicular ligament. Shaft Acts a point of origin and attachment for several muscles – deltoid, trapezius, subclavius, pectoralis major, sternocleidomastoid and sternohyoid  Acromial (lateral) End The acromial end houses a small facet for articulation with the acromion of the scapula at the acromioclavicular joint. It also serves as an attachment point for two ligaments: Conoid tubercle – attachment point of the conoid ligament, the medial part of the coracoclavicular ligament. Trapezoid line – attachment point of the trapezoid ligament, the lateral part of the coracoclavicular ligament, a very strong structure, effectively suspending the weight of the upper limb from the clavicle. Muscles Attached Pectoralis Major: Attaches to the medial half of the clavicle. Deltoid: Attaches to the lateral third of the clavicle. Trapezius: Attaches to the lateral third of the clavicle. Sternocleidomastoid: Attaches to the medial third of the clavicle. Subclavius: Attaches to the inferior surface of the middle third.  Joints: Sternoclavicular Joint: Articulation between the clavicle and the manubrium of the sternum. Acromioclavicular Joint: Articulation between the clavicle and the acromion of the scapula. Neurovascular Supply: Arteries: Clavicular branch of the thoracoacromial artery, suprascapular artery. Nerves: Supraclavicular nerves (supply the skin over the clavicle), nerve to subclavius.  Clinical Considerations: The clavicle is particularly susceptible to fracture. Clavicle Fracture: Results from a fall on the shoulder or outstretched hand. Acromioclavicular Joint Dislocation: Often due to a direct blow to the shoulder. 15% of fractures occur in the lateral third 80% occur in the middle third After a fracture, the lateral end of the clavicle is displaced inferiorly by the weight of the arm and displaced medially by the pectoralis major. Management of a clavicular fracture can be conservative (e.g. sling immobilisation) or operative (e.g. open reduction and internal fixation).  The surgical neck is a frequent site of fracture – usually by a direct blow to the area, or falling on an outstretched hand. The axillary nerve and posterior circumflex artery are at risk when this happens. Axillary nerve damage will result in paralysis to the deltoid and teres minor muscles. The patient will have difficulty performing abduction of the affected limb. The nerve also innervates the skin over the lower deltoid (regimental badge area), and therefore sensation in this region may be impaired.  Humerus Long bone of the upper arm, extends from the shoulder to the elbow. Proximal Landmarks A head, anatomical & surgical neck, greater and lesser tuberosity and intertubercular sulcus. The head faces medially, and is separated from the greater and lesser tuberosities by the anatomical neck. The greater tuberosity is located laterally, and has anterior and posterior surfaces. It is an attachment site supraspinatus, infraspinatus and teres minor. The lesser tuberosity faces medially. It only has an anterior surface. It provides attachment for the subscapularis muscle.  intertubercular sulcus separates the two tuberosities. The tendon of the long head of the biceps runs through this groove. The edges of the intertubercular sulcus are known as lips. Pectoralis major, teres major and latissimus dorsi insert here. This can be remembered with the mnemonic “a lady between two majors”, with latissimus dorsi attaching between teres major on the medial lip and pectoralis major laterally. The surgical neck extends just distal to the tuberosities to the shaft of the humerus. The axillary nerve and circumflex humeral vessels lie against the bone here. Shaft site of various muscles attachment. Cross section views reveal it to be circular proximally and flattened distally. On the lateral side of the humeral shaft is a roughened surface, the deltoid tuberosity where the deltoid muscle attaches. The radial (or spiral) groove is a shallow depression that runs diagonally down the posterior surface of the humerus, parallel to the deltoid tuberosity. The radial nerve and profunda brachii artery lie in this groove. The following muscles attach to the humerus along its shaft: Anteriorly – coracobrachialis, deltoid, brachialis, brachioradialis. Posteriorly – medial and lateral heads of the triceps (the spiral groove demarcates their respective origins). Distal end The lateral and medial borders form medial and lateral supraepicondylar ridges. The lateral supraepicondylar ridge is more roughened, providing the site of origin of the forearm extensor muscles. Immediately distal to the supraepicondylar ridges are the lateral and medial epicondyles. The medial is the larger of the two and extends more distally. The ulnar nerve passes in a groove on the posterior surface of the medial epicondyle. Distally, the trochlea is located medially. Lateral to the trochlea is the capitulum, which articulates with the radius. There are three depressions, the coronoid, radial and olecranon fossae. They accommodate the forearm bones during flexion or extension at the elbow. Muscles Attached: Rotator Cuff Muscles (Supraspinatus, Infraspinatus, Teres Minor, Subscapularis): Attach to the greater and lesser tubercles. Deltoid: Attaches to the deltoid tuberosity. Pectoralis Major: Attaches to the lateral lip of the bicipital groove. Latissimus Dorsi: Attaches to the floor of the bicipital groove. Teres Major: Attaches to the medial lip of the bicipital groove. Biceps Brachii (short head): Attaches to the coracoid process. Triceps Brachii (long head): Attaches to the infraglenoid tubercle. Brachialis: Attaches to the distal half of the anterior surface. Coracobrachialis: Attaches to the middle third of the medial surface.  Joints: Glenohumeral Joint: Articulation between the head of the humerus and the glenoid cavity of the scapula. Elbow Joint: Articulation between the distal humerus and the radius and ulna (comprising the humeroradial and humeroulnar joints). Neurovascular Supply: Arteries: Brachial artery (main artery), profunda brachii artery (deep brachial artery). Nerves: Axillary nerve, radial nerve, musculocutaneous nerve, ulnar nerve, median nerve (all major nerves that course around or through the humerus). Clinical Considerations: Humeral Fracture: Can occur at the proximal end (near the shoulder), the shaft, or the distal end (near the elbow). Mid-shaft fractures may injure the radial nerve. Shoulder Dislocation: Displacement of the humeral head from the glenoid cavity, often anteriorly. Impingement Syndrome: Compression of the rotator cuff tendons or the subacromial bursa, often involving the supraspinatus tendon.