Anatomy, Bone Markings (2024)

Structure and Function

Common Bone Markings

Common bone markings are distinctive features onbone surfaces that serve various anatomical, functional, and developmental roles. These markings provide essential reference points for understanding skeletal structure, identifying specific bones, and comprehending their interactions within the body (see Image. Labeled Bone Markings). The following arecommon bone markings:

• Angles:Sharp bony angulationsthat may serve as bony or soft tissue attachments butare often used for precise anatomical description. Examples include the scapula's superior, inferior, and acromial angles and the occiput's superior, inferior, and lateral angles.

• Body:The bone's largest, most prominent segment.Examples include the diaphysis or shaft of long bones like the femur and humerus.

• Condyle:Refers to a large prominencethat provides structural support to the overlying hyaline cartilage.Condyles bear the brunt of the force exerted by a muscleabouta joint. Examples include the knee, a hinge jointunitingthe femoral lateral and medial condyleswith the tibial lateral and medial condyles. The occiput also has an occipital condylethat articulates with the atlas (1st cervical vertebra or C1) and accounts for approximately 25° of cervical flexion and extension.[4]

• Crest:A bone edge's raised or prominent part. Crestsprovidesites for muscle and connective tissue attachments.The iliac crest is found on the ilium.

• Diaphysis:Refers toa long bone'sshaft.Examples of longbones include the femur, humerus, and tibia.

• Epicondyle:A prominence superior toa condyle. The epicondyle providesmuscle and connective tissue attachment sites. Examples include the femoral and humeral medial and lateral epicondyles.

• Epiphysis:The bone's articulating segment, usually at the bone's proximal and distal poles.The epiphysistypically has a larger diameter than the diaphysis. This segment is criticalto bone growth, as it sits adjacent to the physeal line (growth plate).

• Facet:A facet is a smooth, flat surface that forms a gliding joint with another flat bone or facet. Examplesmay be seen in the vertebrae's facet joints,which allow forspinal flexion and extension.

• Fissure:An open slit in a bone that usually houses nerves and blood vessels. Examples includethe skull's superior and inferior orbital fissures.[5]

• Foramen:A hole through which nerves and blood vessels pass. Examples includethe supraorbital, infraorbital, and mental foraminain the cranium.[6]

• Fossa:A shallow depression on the bone surface,which may receive an articulating bone or act to support soft tissue structures. Examples include the trochlear and the posterior, middle, and anterior cranial fossae.

• Groove:A furrow on the bone surface that houses long bloodvesselor nerve segments for protection againstcompression by adjacent structures (see Image. Anterior Surface of Clavicle). Examples includethe radial and transverse sinus grooves.

• Head:A rounded, prominent, bony extension that forms part of a joint.The head is separated from the bone shaftby the neck. The head is usually covered in hyaline cartilageanda synovial capsule.This partcomprisesa bone's main articulating surfaceinball-and-socket joints. An example is the femoral head in the hip joint.

• Margin:A flat bone's edge.Marginsmay be used to define a bone's borders accurately. For example, the partof the temporal bone articulating with the occipital bone is called the "occipital margin" of the temporal bone." Similarly, thepart of the occipital bone articulating with the temporal bone is called the occipital bone's "temporal margin."

• Meatus:A tube-like channel that extends within the bone, which may provide passage and protection to nervesand vessels.Theexternal and internal acoustic meatus accommodate sound transmission (see Image. External Ear, HorizontalSection).

• Neck:The segment betweena bone's head and shaft.This part is often demarcated from the head by the physeal line in pediatric patients and physeal scar (or physeal line remnant) in adults.The neck is often separated into surgical and anatomical necks. The anatomical neck, representingthe old epiphyseal plate, is often demarcated by its attachment to capsular ligaments. The surgical neck is often more distalthan the anatomical neck and is acommonly fractured location. For example, the humeral anatomical neck runs obliquely from the greater tuberosity to the humeral head's inferior aspect.The surgical neck runs horizontally and a few centimeters distal to the humeral tuberosities.

• Notch:Abony depressionthat often, but not always,stabilizes an adjacent articulating bone. The articulating bone slides into and out of the notch, which guides the joint's range of motion. Examples include the ulna's trochlearandradial notches and the suprasternal and mandibular notches.

• Ramus:The curved part of a bone that gives structural support to the rest of the bone. Examples include the superiorand inferior pubicand mandibular rami.

• Sinus:A hollow cavityhousing air, fluid, or blood. Examples include paranasal and dural venous sinuses.

• Spinous process:A raised, sharpbonyelevation where muscles and connective tissues attach.Spinous processes aremore pronounced than other bonyprocesses (see Image. Lumbar Vertebral Anatomy).

• Trochanter:A large prominence on one side ofabone. Some of the largest muscle groups and most dense connective tissues attach to the trochanter. The most notable examples are thefemur's greater and lesser trochanters.

• Tuberosity:A moderate prominence where muscles and connective tissues attach.Tuberosities function similarly to trochanters. Examples include the tibial, deltoid, and ischial tuberosities.

• Tubercle:A small, rounded prominence where connective tissues attach.Examples include the greater and lesserhumeral tubercles.

Bone Markings in theUpper Limb

The upper limb is involved ina wide range ofmovements essential for daily activities and physical function.Thus, the upper limb'sbone markings are particularly relevant for clinical and anatomical study.

Scapula

The scapula serves as the upper limb's mobile platform. One can think ofthis boneas a massive construction crane with jacks that anchor the cab to the ground, like how muscles and connective tissues attach the scapula to the body. The crane also has a long, mobilearm,resemblingthe upper limb.The scapula has medial, lateral, and superior borders. The inferior pole is the junction of the medial and lateral borders.

The dorsal scapular surfacecontains the bone's prominent spine. The trapezius inserts on the scapular spine. The deltoid muscle arises from the scapular spine's lateral aspect, the acromion, and the lateral clavicle.[7]The supraspinous fossa above the scapular spineis thesupraspinatus muscle's origin.This muscle inserts on the greater humeral tubercle's“S” facet (see below). The infraspinous fossa below the scapular spine is where the infraspinatus muscle originates.This muscle inserts on the “I” (middle) facet of the greater humeral tubercle.

The acromion (acromial process) lies at the scapular spine's lateral end. The acromial process is one of the deltoid muscle's proximal insertion sites.Thedeltoid is a triangular musclenamedafter the capital Greek letter delta. The scapula's medial borderis aninsertion site for the rhomboid minor and major muscles. The teres minor originates from the scapula's lateral border, while the teres major arises from the inferior scapular angle.

The scapula's anterior surface containsthe prominent coracoid process, which resembles a crow’s beak. This process acts as a pectoralis minor attachment point. The coracoid process is also where the biceps brachii's short head and coracobrachialis muscles arise.The subscapular fossa houses the subscapularis' proximal insertion point.The subscapularisdistally inserts on the lesser humeral tubercle.

The glenoid fossa receives the humeral head at the scapulohumeral articulation or shoulder joint (see Image. Scapula, Lateral View).[8]

Humerus

The humerus is the arm bone (see Image. Upper Arm Anatomy). The greater and lesser tubercles lie on the superior aspect of this bone.The greater tubercle is located laterally and has3prominent facetstermed the “S,”“I,”and “T” facets.The superior or "S" facet serves as the distal insertion site for thesupraspinatus muscle, which initiates arm abduction.The muscle acts as the primary arm abductor for the first 15° to 20° of abduction.The deltoid becomes the primary abductor beyond this angle.The middle or "I" facethouses theinfraspinatus insertion site. This muscle isa lateral arm rotator. The lower or "T" facet contains the teres minor insertion point. Theteres minoris another lateral arm rotator.[9]

The lesserhumeral tuberclecontains the subscapularis muscle's distal insertion point.The subscapularis is a major arm adductor, preventing arm dislocation at the shoulder.[9]

The humeral midshaft's lateral surface exhibits the deltoid tuberosity, the deltoid insertion site. This muscle abducts the arm beyond the first15° to 20°. The deltoid's anterior fibers rotate the arm medially, while the posterior fibers laterally rotate the arm.[10]

The humeral midshaft's posterior aspect demonstrates the radial spiral groove, which ordinarily lies between the triceps brachii's lateral and medial heads.This groove transmits the radial nerve and profunda brachii artery.

The arm bone's inferior aspectcontains the lateral and medial epicondyles. The lateral supracondylar ridge, which contains the proximal insertion point of the brachioradialis and extensor carpi radialis longus,flows into the lateral epicondyle. The lateral epicondyle is a bony prominencewherethe extensor carpi radialis brevis, extensordigitorum, extensordigitiminimi, and extensor carpi ulnaris originate.

The olecranon fossa lies on the arm bone's posterior aspect between the lateral and medial epicondyles.This regionreceives the ulna's olecranon process at the elbow joint. The distal humeral articulating surfaces include thelaterally located capitulum (Latin for "little head") and the trochlea (Greek for "pulley").[11]

Radius

The headcomprises the proximal radial end and articulates with the capitulum, allowing rotation for supination (palm up)and pronation (palm down). This mobility, while beneficial, makes the radius susceptible to dislocation, as in "nursemaid's elbow." The radial tuberosity serves as an insertion site for the biceps brachii.The radial shaft leads to the large styloid process at the distal end, where the brachioradialis muscle inserts.The radius articulates with thescaphoid and lunate at the radiocarpal joint.[12]

Ulna

The proximal ulnar endcontains the coronoid process, which articulates with the humeral trochlea. This articulation is strong, only permitting flexion and extension. Theulnar tuberosityis where thebrachialis muscle distally inserts. This muscle is a pure forearm flexor.[13] The distally located ulnar head articulates with the radius.

Wrist bones, metacarpals, and fingers

The8carpal bones are divided into proximal and distal rows.The proximal wrist bones articulate with the radius.The proximal row includes the scaphoid, which resembles the prow of a ship and articulates with the trapezium distally. The trapezium then connects to the1st metacarpal bonethat supportsthe thumb.Moving from lateral to medial, the proximal row continues with the lunate (resemblingthemoon), triquetrum(which has3corners), and the rounded pisiform. The pisiform can bepalpatedon the hand's anterioraspect.This bone moves withhandmotion, confirming its location within the wrist rather than the forearm.

Thedistal carpalrowstarts with the laterally located trapezium (which resembles a 4-sidedfigurewith2parallel sides), articulating with the thumb and index finger metacarpals.Medial to the trapezium isthe trapezoid, shapedsimilarly tothe trapezium, and capitate, the largest wrist bone. The hamate is medially located and features a prominent hook. The Guyon canal is the space between the pisiform and the hamate's hook that transmits the ulnar nerve.A hamate hook fracture can damage this nerve.

The 14 finger bones areknown asthe phalanges, a term derived fromthe military formation "phalanx." Each finger has3phalanges, except the thumb, which has 2. Finger movements include flexion (forward), extension (backward),abduction(finger separation),and adduction (fingers coming together). Metacarpal bones, 1 for each finger, connect the wrist bones to the fingers. The thumb's carpometacarpal articulation is rotated 90° compared to the other fingers, allowing flexion and extensionalongthe plane of the hand. Abduction leads the thumb away from thepalm, while adduction brings it towardthe palm.[14]

Bone Markings in the Lower Limb

The lower limbbonemarkingsserve asattachment sites for muscles, ligaments, and tendons, influencing joint stability and functionimportantfor weight-bearing and ambulation.Lower limb bone markings aid healthcare professionals in diagnosing injuries, planning surgical procedures, and guiding rehabilitation efforts.

Hip bone

The hip bone (innominate bone), consisting of the ilium (superior), ischium (posteroinferior), and pubis (anteroinferior), forms a sturdy basin that supports the trunk and provides attachment for lower limb muscles and ligaments.The iliac crest is located along the superior iliac border andacts as athoracoabdominopelvic, hip, and thigh muscle attachment site. The acetabulum is a deep socket formed by the fusion of the3hip bones thatreceives thefemoral head to form the hip joint. The greater sciatic notch on the ilium's posterior aspect allows for the sciatic nerve's passage. The inferoposteriorly locatedischial tuberosity is an important weight-bearing structure thatalsoacts asa hip and thigh muscle attachment site. The pubic symphysis is a fibrocartilaginousjoint(secondary cartilaginous joint) that unites the pubic bones and stabilizes the hip.[15]

Femur

As the body's longest and strongest bone, the femur (thigh bone) transmitsthe upper body's weightto the lower limbs when standing and ambulating.Theproximal femoral end features the femoral head, articulating with the hip's acetabulum to form the hip joint. The femoral neck unites the head to the shaft and is a common fracture site, particularly in older individuals. The greater and lesser trochantersact asattachment points forhipand thigh muscles. The intertrochanteric line and crest provide additional hip and thigh muscle attachment areas. The linea aspera is a ridge on the posterior surface of the femoral diaphysis that acts as an attachment site for various muscles, including the adductor magnus and vastus lateralis.[16]

Patella

The patella (kneecap) is a sesamoid bone embedded within the quadriceps tendon.This bone forms crucial articulations primarily with the femur and tibia,which arevital in knee stability and motion.The patella glides over the femoral condyles at the patellofemoral joint during flexion and extension.[17]

Tibia

The tibiais the stronger and larger of the2leg bones. This bone significantly contributes to weight-bearing andserves asanattachment site for thigh, leg, and extrinsic foot muscles.The tibia's proximal end features medial and lateral condyles, which unite with the femoral condyles to form the knee joint. The tibial tuberosity on the anterior diaphyseal surfaceprovides an attachment site for thepatellar ligament. The tibial shaft is relatively flat on its anterior surface, essential for protecting the underlying structures, includingthe anterior tibial vessels, deep fibular nerve, and leg extensor tendons. The medial malleolus at the distal end forms the prominence of the ankle's inner aspect and provides stability to the ankle joint.[18]

Fibula

The fibulais thinner and more slender than the tibia.This bone does not bear weight, though it provides stability to the ankle joint andisan attachment site forleg and extrinsicfoot muscles.The fibular head articulates with the tibia, contributing to the stability of the proximal tibiofibular joint. The lateral malleolus at the fibula's distal end forms the prominence of the ankle's outer aspect and provides additional ankle stability.[19]

Tarsals, metatarsals, and phalanges

The foot consists of multiple bones arranged in intricate arches to support body weight and facilitate movement. The tarsal bones, including the calcaneus, talus, navicular, cuboid, and cuneiforms, form the proximal part of the foot and provide stability and flexibility.The metatarsals, numbered1 through5 frommedial to lateral, articulate with the tarsal bones proximally and the phalanges distally. The phalanges, similar to those in the hand, consist of proximal, middle, and distal phalanges.The big toe (hallux) has only2phalanges. The metatarsophalangeal and interphalangeal joints allow for movement and flexibility during walking and running.[20]

Bone Markings in the Axial Skeleton

The axial skeleton forms the human body's central axisandis comprised ofthe skull, vertebral column, ribs, and sternum. Numerous bone markings in this regionserve diverse anatomical, biomechanical, and clinical functions.

Skull

The craniofacial bones exhibit various markings. The superior orbital fissure lies between the lesser and greater sphenoid wings.The inferior orbital fissure issituatedbetween the maxilla, zygomatic bone, and greater sphenoid wing.The cranial base exhibits various foramina, including the cribriform, anterior and posterior ethmoidal, and jugular foramina (see Image. Skull Base and Foramina).Paranasal sinuses, such as the maxillary sinus, are hollow cavities in craniofacial bones (see Image. Paranasal Sinuses).The transverse sinus groove on the occipital bone's inner surface runs horizontally near the tentorium cerebelli attachment.

The cranial fossae include the anterior, middle, and posterior cranial fossae, which are cranial base depressions supporting the brain, cranial nerves, and head and neck blood vessels. The occipital condyle articulates with the cervical atlas, contributing to the stability and mobility of the head and neck.The temporal bone's external and internal acoustic meatus accommodate sound transmission.

The mandibular bodyisthe bone's horizontal portion that forms the lower jawline. Rami are vertical mandibular extensions on each side, consisting of the ascending ramus and the condylar and coronoid processes.The condylar process connects with the temporal boneto form the temporomandibular joint (see Image. Pterygoids). The coronoid process provides an attachment site for the mastication muscles.

The angle of the mandible is where the mandible body meets the ramus, forming a distinct corner or angle. The mandibular notch (sigmoid notch) is a depression between the condylar and coronoid processes on the ramus' superior border. The mandibular foramen on the ramus' internal surface transmits the inferior alveolar vessels and nerves,supplying the lower teeth and the mandible. The mandibular symphysis is where the2halves of the mandible fuse anteriorly at the midline.[21]

Vertebral column

Each vertebra has a body, the main segment that provides structural support. Facet joints between adjacent vertebrae allow spinal flexion and extension. Intervertebral foraminaenablethoracicnerves and blood vessels to pass between adjacent vertebrae. The vertebral neck is the segment between the body and vertebral processes. Intervertebral notches on the superior and inferior aspects of adjacent vertebrae form the intervertebral foramina, where spinal nerves traverse from the cord to the body. Spinous processes are raised bony elevations where trunk muscles and connective tissues attach.[22]

Ribs

The rib has superior and inferior angles where the rib curves.These structures also serve as trunk muscle and ligament attachment sites.Ribs also have superior and inferior crests,which areraised edges for thoracic muscle and connective tissue attachment. The body is the rib's main segment. The costal groovesinside the ribs provide passage for intercostal vessels and nerves, supporting thoracic function.

Ribs have facets on their heads that articulate with the thoracic vertebrae, forming the costovertebral joints.The head of the rib is a rounded, prominent extension that articulates with the thoracic vertebrae. Costal margins define rib borders and serve as thoracic muscle attachment sites. The rib's neck is the segment between the head and the body. Costal notches articulate with the vertebrae or sternum. Ribs havearticular and nonarticular tubercles, the latter serving as trunk muscle attachment points.[23]

Sternum

The sternomanubrial angle (or sternal angle or angle of Louis) is the junction between the manubrium and sternal body (see Image. Sternum Anatomy). This angle is palpable as a slight elevation andserves asa landmark for locating the 2nd rib and the T4-T5 intervertebral disk.The sternal body(or gladiolus or gladiolus sterni) isthe sternum's largest andcentral segment. The sternal margins provide attachment points for the ribs' costal cartilages.The jugular notch(suprasternal notch) is a U-shaped depression at the sternum's superior aspect, serving as a palpable landmark for anatomical reference and facilitating the identification of cervical structures. Clavicular notches on the manubrium's superior border articulate with the clavicles.[24][25]

Blood Supply and Lymphatics

Blood vessels permeate bone tissue, except in cartilaginous regions like the growth plate. Arteries supply oxygenated blood to bones, while veins carry blood away, connected by capillary networks. Long bones such as the tibia and femur feature various artery types, including the principal nutrient artery, which splits into ascending and descending central arteries, supplying the medulla and cortical layers.[28]Additionally, periosteal and Haversian arteries traverse the bone's outer and cortical surfaces, respectively, with Volkmann arteriesacting as bridges between these vessels.[29]Veins exit bones via periosteal veins, and epiphyseal and metaphyseal arteries supply blood to bone ends. Flat bones like cranial bones are perfused primarily by periosteal arteries, while irregular bones like the mandible have complex vascular arrangements.

The bone capillary network fills the marrow cavity, predominantly comprising dense, fenestrated, and branched sinusoidal vessels. Linear columnar vessels predominate in the metaphysis and endosteum, interconnected by loops or arches. These vessels drain into a central vein in long bone diaphyses, with smaller veins branching off to periosteal veins. Type H vessels, expressing markers like endomucin and CD31, exhibit higher oxygen levels and blood velocity due to direct arteriolar connections, influencing tissue microenvironments. Various cell types surrounding blood vessels, like pericytes and stromal cells, show distinct characteristics depending on the vessel type and share similarities with mesenchymal progenitor cells, suggesting a role in tissue repair. These cells contribute to bone lineage during development and adulthood, supporting diverse cellular environments within bone tissue.

Transcortical vessels traverse cortical bone, providing direct arteriovenous connections in the endosteum. The distribution and heterogeneity of perivascular cells in bone contribute to tissue homeostasis and repair. Different cell types associated with specific vessel subtypes, such as Nestin-expressing cells around type H vessels and LepR-expressing cells near type L vessels, exhibit multilineage potential. These cells contribute to bone marrow stroma, hematopoiesis, and adipogenesis, playing crucial roles in bone health and repair. Additionally, recent studies highlight the role of new adipogenic lineage cells called "marrow adipogenic lineage precursors" in maintaining marrow vasculature and modulating bone formation.[30]

Clinical Significance

Uses of Bone Markings

Nearly all medical providers use bony landmarks to approximate injection sites, localize thetargeted tissue, orguide medical imaging. Spinous processes are palpated and used as anatomic guides during epidural steroid injections or lumbar punctures (spinal tap). Tibial and femoral condyles are palpated to approximate the meniscal sites during the McMurray test, which evaluates the menisci's structural integrity. Bony landmarks of the elbow are used to orient the operator and locate areas of interest for targeted medical imaging like ultrasound. These applications underscore the importance of these osteological features.

Nursemaid’s Elbow

Nursemaid's elbow, also known as radial head subluxation, typically occurs in young children when a sudden traction force on the extended arm causes the radius topartiallydislocate from the annular ligament. The patientholds the affected arm in a flexed and pronated position,demonstrating pain and reluctance to use the arm.The condition can impairarm supination.[35]

Greater Humeral Tubercular Fracture

Fracture of the greaterhumeral tubercle damages the insertions of the supraspinatus (“S” facet), infraspinatus (“I” facet), and teres minor (“T”) facet. Supraspinatus weaknessimpairs arm abduction. This conditionmay be tested by holding the patient’s arm and havingthem initiate abduction against resistance. The more powerful deltoid muscle can abduct the armpast the supraspinatus'range (15° to 20° degrees).Without testing against resistance, the patient may bump the arm enough to appear to be able to abductit completely. Having the patient abduct the arm against resistance reveals thedeficit. Lateral arm rotation weakness due to infraspinatus and teres minorimpairment may be observed.However, the stronger posterior fibers of the deltoid muscle can compensate. Another injury indicator is pain experienced upon palpation of the greater tubercle.[36][37].

Lesser Humeral Tubercular Fracture

Fracture of the lesser tubercle of the humerusmay damage the subscapularis insertion. Arm adduction and medial rotation subsequently weaken.Painoften worsensupon lesser tubercle palpation.[38][39][40]

Humeral Surgical Neck Fracture

Fracture of the humeral surgical neck damages the axillary nerve,weakeningthe deltoid and teres minor. The axillary nerve terminates as the arm's upper lateral cutaneous nerve.Injury to this nervemay causepain or anesthesia over the proximal lateral arm region.[41][42]

Lateral Epicondylar Fracture

This injury damages the radial nerve, which innervates the forearm and hand extensors. Radial nerve injuryproduces a wrist dropor the inability to extend the hand.Testing involves flexing the forearm in a pronated position, with the examiner holding the forearm and hand dorsum. The patient is theninstructedto extend the fingers against resistance.[43]

Medial Epicondylar Fracture

This condition damages the ulnar nerve,resultingin forearm flexion weakness and radial deviation of the wrist's medial side.A “claw hand” may also develop,with the 3rd and 4th fingers flexed due toimpairmentof the 3rd and 4th lumbricals and the interossei. Sensory loss over the hand's medial 1-1/2 side may also be observed.[44][45]

Hamate Hook Fracture

Fracture of the hook of the hamate causes swelling in the surrounding soft tissue that cancompress the ulnar nerve at the Guyon canal.Muscles that mayweaken include theabductor, flexor, and opponens digiti minimi, the 3rd and 4th lumbricals,interossei, and adductor pollicis brevis. Palpation of the pisiform and hook of the hamate bone produces pain. To test adductor pollicis weakness, the patient may be instructedto hold a piece of paper or the examiner's index finger tightly without letting it slip.Ulnar nerve injuryweakens this muscle,leading totheinabilityto maintain the grip and compensatory flexion of the thumb's distal phalanx, known as the Froment sign.[46][47][48]

Scaphoid Fracture

The scaphoid is located in the depths of the anatomical snuffbox, formed by the tendons of the abductor pollicis longus and extensor pollicis longus anteriorly and the tendon of the extensor pollicis longus posteriorly. A scaphoid injury produces pain, tenderness, and bruising over the anatomical snuffbox. Palpationover this area worsens thepain. The injury may not be detected on radiographyuntil a week postinjury.The wrist should be splinted to preventdisplacingthe fractured scaphoid. Allowing the fractured scaphoid segment to move freely may cause nonunion, which may become permanent due to the area's poor vascularity.[49][50][51]

Femoral Neck Fracture

Fractures of the femoral neck are common in older adults and can lead to significant morbidity and mortality. Other risk factors for femoral neck fractures include female sex, lower body mass index (<18.5), reduced bone mineral density, smoking, poor nutrition, medications, and sedentariness. Complications ofthese injuriesinclude avascular necrosis, nonunion, malunion, posttraumatic arthritis, and loss of mobility and function.[52][53]

Iliotibial Band Syndrome

The iliotibial band inserts onto the lateral tibial condyle.Repetitive friction over this bony prominence during activities likeswimming or cycling can lead to inflammation and lateral knee pain. This condition, known as iliotibial band syndrome, often presents as lateral knee pain aggravated by repetitive flexion and extension.[54]

Jumper's Knee

Patellar tendonitis or jumper's knee involves patellar tendon inflammation. Excessive stress on this attachment site at the tibial tuberosity,such as during repetitive jumping or running, can lead to pain, swelling, and tenderness over the tibial tuberosity.[55]

Medial Tibial Stress Syndrome

Shin splints involve tibial periosteal inflammation, particularly along the medial border where muscles attach.Medial stress syndrome arises from repetitive stress on the tibial attachment sites of leg muscles,eg, the tibialis posterior and soleus,presentingwithpain and tenderness along the tibia's medial aspect.[56]

Achilles Tendinopathy

The Achilles tendon insertion onto the calcaneus (heel bone) is vulnerable to inflammation and degeneration,a conditionknown as Achilles tendonitis. Thisdisorder commonlyaffects athletes involved in running or jumping sports and can manifest as pain, swelling, and stiffness at the back of the heel.[57]

Atlantoaxial Instability

Various ligaments and bony structures stabilize the atlantoaxial joint (C1-C2 joint), includingC2'sodontoid process (dens). Pathologies such as rheumatoid arthritis, trauma, or congenital abnormalities can lead to atlantoaxial instability, where excessive movement between C1 and C2 occurs. The condition can result inthe compression of the spinal cord or surrounding nervesand produceneurological deficits, neck pain, and potentially life-threatening complications.[58]

Temporal Bone Fracture

The temporal bone contains several notable landmarks, including the mastoid process and external auditory meatus. Temporal bone fractures typically result from significant head trauma, such as motor vehiclecrashes or falls from height. These injuries can disrupt the integrity of the middle and inner ear structures, potentially leading to hearing loss, vertigo, facial nerve paralysis (Bell palsy), or cerebrospinal fluid leakage.[59]

Cervical Rib

Acervical ribis an additional rib that arises from C7 and may extend to T1.[60] This anatomical variation can compress nearby nerves and blood vessels, leading to thoracic outlet syndrome. Symptoms include pain, numbness, upper extremity weakness, arm swelling, and discoloration.[61]

Spinous Process Fracture

Trauma or repetitive stress can lead to spinous process fractures.These injuriesmost frequently affect the vertebral column's thoracic and lumbar regions. Falls, motor vehicle collisions,and sports injuries are the usual causes. Symptoms include localized pain, tenderness, and restricted spinal mobility.[62]

Sternal Fracture

Sternal fractures commonlyarise from blunt chest trauma,eg, from motor vehicle accidents or direct blows to the chest. Fractures may involve the manubrium, body, or xiphoid process and may produce severe chest pain, difficulty breathing, and potential damage to underlying structures such as the heart or lungs.[63]

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