Upper Limb Anatomy

• The appendicular skeleton has bones that make up the limbs and girdles that support them
• It can be divided into pectoral girdle, upper limb, pelvic girdle, and lower limb
• Characteristics of bones to be able to identify consist of left or right, anterior or posterior, superior or inferior, and distal or proximal ends

Pectoral Girdle

• Connects the upper limbs to the axial skeleton, and consists of 2 bones, the scapula and the clavicle

Scapula

• The scapula (shoulder blade) is a roughly triangular shaped bone with several features
• Borders consist of the superior, lateral, and medial border
• Angles consist of the superior angle (top corner), lateral angle (lateral corner), and inferior angle (bottom corner)
• The broad, flat surface of the scapula is called the scapular body.

Anterior Surface of the Scapula

• Subscapular fossa is a broad indentation in the anterior surface of the scapular body
• Glenoid Cavity is found on the lateral surface of the scapula
• Functions as a shallow depression that forms a joint with the humeral head (ball of the upper arm bone), called the glenohumeral joint
• Coracoid process is an anterior and inferior projection, shaped like a crow’s beak
• Acromion is a posterior and superior projection which forms a joint with the lateral portion of the clavicle, known as the acromioclavicular joint

Posterior Surface of the Scapula

• The scapular spine is a prominent ridge you can feel under the skin at the shoulder blade
• The supraspinous fossa is a depression located superior to the scapular spine
• The infraspinous fossa is a depression located inferior to the scapular spine
• You can identify the left or right scapula based on the location of the glenoid cavity, coracoid process, and acromion
• The anterior surface has the subscapular fossa, while the posterior surface has the scapular spine
• The glenoid cavity articulates with the humerus to form the glenohumeral joint
• The acromion articulates with the clavicle to form the acromioclavicular joint

Clavicle

• The pair of small S-shaped bones spans between the acromion of the scapula bone, with a lateral and posterior roundish & thinner acromial end
• Spans the manubrium of the sternum bone to its medial & anterior flat & thicker sternal end
• From a superior view, the clavicle is S-shaped, nearly straight from an anterior view
• Acts as a brace, holding the upper limb in place away from the body
• When fractured, the shoulder will be pulled anteriorly and medially

Upper Limb

• The upper limb consists of the arm, forearm, wrist, and hand
• The main bones include the humerus, radius, ulna, carpal bones, metacarpals, and phalanges

Humerous Bone

• At the proximal end, the humeral head fits into the glenoid cavity
• Has a greater tubercle and lesser tubercle separated by the intertubercular sulcus
• The deltoid tuberosity is where the deltoid muscle attaches
• The radial groove is where the radial nerve travels
• The distal end has medial and lateral epicondyles, medial trochlea and lateral capitulum
• Also has a radial fossa (lateral) and coronoid fossa (medial), and an olecranon fossa (posterior side)

Radius and Ulna

• At the proximal end of the ulna is the olecranon process (elbow bone), coronoid process, and trochlear notch (fits around humerus)
• The distal end of the ulna has ulnar head and medial styloid process along with the radial notch (proximal) and ulnar notch (distal)
• The proximal end of the radius has a radial head that articulates with the capitulum
• The distal end of the radius has a radial tuberosity and lateral styloid process
• The radius and ulna are connected by the interosseous membrane

Carpal Bones

• The proximal row from medial to lateral consists of the Triquetrum, Pisiform, lunate, and Scaphoid
• The distal row from medial to lateral consists of the Hamate, Capitate, trapezoid, and trapezium
• Metacarpals are the five bones of the hand, each articulating with phalanges
• Phalanges are 14 bones, with the thumb having 2 (proximal and distal), and other fingers having 3 (proximal, intermediate, and distal)

Pelvic Girdle

• Connects the lower limbs to the trunk and supports pelvic organs,consisting of the sacrum and two coxal (hip) bones
• The pelvic inlet is the opening into the pelvis
• The pelvic brim is a ridge around the pelvic inlet, separating the greater pelvis (above) and lesser pelvis (below)
• The pelvic outlet is the inferior edge of the lesser pelvis
• Coxal bones are made lip of the ilium, ischium, and pubis
• The ilium is the largest part, which includes the iliac crest, iliac fossa, anterior and posterior superior iliac spines
• The Ischium forms the posterior-inferior part of the pelvis, with ischial tuberosities
• The pubis forms the anterior portion of the pelvis, with the pubic symphysis connecting the two pubic bones (sit bones)
• The female pelvis has a wider, oval-shaped pelvic inlet, larger pubic arch, and more movable coccyx to allow for childbirth
• The male pelvis has a narrower, heart-shaped pelvic inlet, a smaller pubic arch, and a less movable coccyx

Lower Limb

• The components of the lower limb include the thigh, patella, leg, ankle, and foot

Femur (thigh)

• The proximal end of the femur has a femoral head that articulates with the acetabulum and fovea capitis, and the ligamentum teres attaches
• The femoral neck is the weakest part of the femur, and a common site of fractures such as broken hips
• The trochanters consist of the greater trochanter (anterolateral) and lesser trochanter (posteromedial)
• The diaphysis includes the gluteal tuberosity (for the gluteus maximus attachment) and linea aspera for muscle attachments
• The distal end has medial and lateral epicondyles, plus medial and lateral condyles that form the knee joint, and intercondylar fossa (posterior)

Tibia and Fibula

• The tibia is the larger, medial leg bone, and features a tibial plateau (articulates with femur) and tibial tuberosity to the patellar ligament attachment
• Also features the medial malleolus (medial ankle bone)
• The fibula is the smaller, lateral bone with the fibular head and the lateral malleolus (lateral ankle bone)
• The proximal and distal tibiofibular joints are connected by the interosseous membrane

Tarsal Bones

• Includes the calcaneus (heel bone), talus, navicular, cuneiforms, and cuboid
• The talus articulates with the tibia and fibula to form the ankle joint
• The navicular articulates distally with the talus
• Cuneiforms include medial, intermediate, and lateral
• The cuboid is the lateral tarsal bone

Metatarsals and Phalanges

• There are five long metatarsals bones of the foot
• The 14 phalanges include the big toe (hallux), which has two (proximal and distal), and other toes, which have three (proximal, intermediate, and distal)

Bone Markings

• An epicondyle is a knuckle-like projections above a condyle
• A tuberosity is a roughened projection
• A fossa is a shallow depression
• A process is any projection or bump
• A foramen Is an opening or hole

Skull

• The skull has 22 bones, divided into 8 cranial and 14 facial bones

Cranial Bones

• Encase and protect the brain
• The frontal bone forms the forehead, superior orbit, and anterior cranial fossa, and contains the frontal sinuses
• The parietal bones form the lateral walls of the cranium, meeting at the sagittal suture, coronal suture (front), lambdoid suture (back), and squamous suture (sides)
• The Temporal bones form lateral walls of the cranium
• Key regions of the temporal bone include the squamous (zygomatic process and mandibular fossa), tympanic (external auditory meatus, styloid process) and the mastoid (mastoid process)
• Contains petrous foramen lacerum, carotid canal, jugular foramen, and an internal acoustic meatus
• The occipital bone contains the foramen magnum (spinal cord) and occipital condyles (atlanto-occipital joint)
• The butterfly shaped sphenoid bone is a keystone bone, articulating with 12 bones
• It features the optic canals for vision nerves and the sella turcica, which houses the pituitary gland
• Greater wings have foramina, including the rotundum, ovale, and spinosum
• The ethmoid bone is located between the sphenoid and nasal bones, forming part of the nasal cavity
• The ethmoid bone features a cribriform plate (olfactory nerves), and the crista galli (the attachment for brain meninges)
• The nasal conchae is for airflow in the nasal cavity

Facial Bones

• These bones form the facial structure
• The mandible is the lower jaw, contains mental foramen, mandibular rami, and coronoid and condylar processes
• The maxillae are the upper jaw, forming part of the orbit and nasal cavity,and feature the infraorbital foramen
• The maxillary sinuses and palatine processes form the hard palate
• The lacrimal bones are small bones in the medial orbit, and part of the tear drainage system
• Nasal bones form the bridge of the nose
• Vomer forms the lower part of the bony nasal septum
• Inferior nasal conchae form part of the nasal cavity walls
• Palatine bones are L-shaped, forming the posterior hard palate and nasal cavity walls
• Zygomatic bones form the cheekbones, forming part of the zygomatic arch
• Paranasal sinuses are air-filled cavities, helping filter, warm, and humidify air.
• Bones in the paranasal sinus include the frontal, maxillae, ethmoid, sphenoid, and temporal bones (mastoid sinuses)
• Orbit formation includes parts of 7 bones: frontal, sphenoid, ethmoid, lacrimal, zygomatic, maxillae, and palatine
• Nasal cavity formation includes parts of 6 bones: ethmoid, sphenoid, vomer, maxillae, palatine, and inferior nasal conchae
• Cranial bones form the calvaria (skull cap) and the cranial base, which contains indentations as the cranial fossae, supporting the brain
• Facial bones form the anterior side of the skull and face
• Some cranial and facial bones contain paranasal sinuses, which are air-filled cavities lined with mucous membranes, helping filter, warm, and humidify air entering the nasal cavity
• Paranasal sinuses are found in the frontal maxillae, ethmoid, sphenoid, and temporal (mastoid) bones
• Near the frontal bone is the Glabella, and contains the Supraorbital foramina
• The frontal bone contains frontal sinuses internally
• The junction with frontal, sphenoid and temporal bones (in front) is the pterion
• The junction with occipital and temporal bones (in back) is the asterion

Test your knowledge of the upper limb anatomy, including the humerus, glenoid cavity, carpal bones, radius, and ulna. This quiz covers anatomical structures and potential injuries affecting the arm and forearm.