Human Skeletal System Terms



Skull Bones


Cranial bones (8)


Frontal bone (1): Forehead bone; forms anterior cranium & roof of orbits; contains frontal sinuses.

Markings:

Supraorbital foramen - allows passage of supraorbital arteries and nerves

Supraorbital margins - superior margins of orbits that form the eyebrow ridges


Parietal bones (2): Superolateral skull bones; form roof and sides of the cranium


Temporal bones (2): Inferolateral cranial bones; contain mastoid sinuses and ear cavities

Markings:

Zygomatic process - bridgelike projection that forms the posterior zygomatic arch

Mastoid process - attachment site for neck muscles

Styloid process - needlelike projection; attachment site for tongue and neck muscles and ligaments

External acoustic meatus - canal leading to the eardrum and middle ear

Mandibular fossa - articulates with mandibular condyle of mandible


Occipital bone (1): Posterior cranial bone

Markings:

Foramen magnum - allows the spinal cord to attach to the brain stem

Occipital condyles - articulate with the atlas (first vertebra)


Sphenoid bone (1): Keystone bone of the cranium; deep, bat-shaped bone; forms part of the orbits; contains sphenoidal sinuses.

Markings:

Sella turcica - contains hypophyseal fossa that houses the pituitary gland

Optic canals - allow passage of the optic nerve (cranial nerve II) and the ophthalmic arteries


Ethmoid bone (1): Deep, irregularly shaped cranial bone, between sphenoid and nasal bones; forms the roof of the nasal cavity and parts of the nasal septum and orbits; contains the ethmoidal sinuses (air cells).

Markings:

Crista galli - attachment point for the falx cerebri (part of the dura mater that surrounds the brain)

Cribriform plate - contains olfactory foramina for passage of olfactory nerves to the roof of the nasal cavity.

Perpendicular plate - forms superior part of the nasal septum

Superior and middle nasal conchae - form part of lateral walls of nasal cavity; increase turbulence of airflow


Coronal suture: Line of junction of the frontal with the two parietal bones.


Lambdoid suture: Line of junction of the occipital with the two parietal bones.


Sagittal suture: Line of junction of the two parietal bones.


Squamous suture: Line of junction of the parietal with the temporal bone.


Occipitomastoid suture: Line of junction of the occipital with the temporal bone.




Facial Bones (14)


Mandible (1): Lower jawbone; the largest and strongest bone of the face.

Markings:

Mandibular body - the horizontal U-shaped portion that forms the chin

Mandibular ramus - the upturned, armlike bars on either side of the body that articulate with the skull

Mandibular condyle - articulates with mandibular fossa of temporal bone; only freely movable joint in the skull; also called condylar process

Mental foramen - canal on the body of the mandible that allows passage of the mental artery and nerve

Coronoid process - insertion points for the temporalis muscle

Alveolar margins - projecting ridge that contains the teeth sockets (alveoli)


Maxilla (2): Upper jawbone; keystone bone of the face; forms part of hard palate, orbits, and nasal cavity; contains maxillary sinuses

Markings:

Palatine processes - form the anterior hard palate (roof of mouth)

Alveolar margins - projecting ridge that contains the teeth sockets (alveoli)


Zygomatic bones (2): Cheekbones; form the cheek and part of the orbits.

Marking:

Temporal process - bridgelike projection that forms the anterior zygomatic arch


Inferior nasal conchae bones (2): Form part of the lateral walls of the nasal cavity.


Nasal bones (2): Form bridge of the nose.


Vomer bone (1): Forms floor of nasal cavity, and inferior nasal septum.


Lacrimal bones (2): Form part of the medial orbit wall; contains lacrimal fossa that houses the lacrimal sac, and contains grooves that allow tears to flow into the nasal cavity.


Palatine bones (2): Form posterior hard palate (roof of mouth), and part of nasal cavity and orbits.




Anterior Neck (1)


Hyoid Bone: U-shaped bone in the anterior neck, the only bone of the body that does not articulate directly with another bone; suspended by ligament and muscle from the skull; provides attachment for tongue, neck and pharyngeal muscles.




Vertebrae (26)


Vertebral column: The 26 vertebrae of an adult and 33 vertebrae of an infant; provides support, forms a flexible bony case for the spinal cord, and serves as a point of attachment for the ribs and back muscles. Also called the backbone, spine, or spinal column.

Markings:

Vertebral body - anterior, thick disc-shaped, weight-bearing portion of vertebra; not present in the atlas (C1)

Vertebral arch - posterior projection from the body of a vertebra that encloses the vertebral foramen; consists of paired pedicles and laminae; the spinous, transverse, and articular processes arise from the arch

Pedicles - paired, short, thick processes that project posteriorly from the body to the lamina to form the lateral vertebral arch.

Laminae - paired, broad, flattened plates that extend from the pedicles and fuse at the midline to form the posterior vertebral arch

Vertebral notches - two cavities above (superior) and below (inferior) the pedicle of a vertebra; the notches of two adjacent vertebrae form the intervertebral foramen

Intervertebral foramen - opening formed by the inferior and superior notches on the pedicles of adjacent vertebrae; allows passage of spinal nerves and vessels

Vertebral foramen - large aperture in vertebra formed by body and arch; allows passage of the spinal cord

Vertebral canal - cavity within the articulated vertebral column; formed by the vertebral foramina of successive vertebrae; contains the spinal cord (also called the spinal canal)

Spinous process - posterior projection from junction of the two laminae; attachment site for muscles; not present in the atlas (C1)

Transverse processes - lateral projections from junctions of lamina and pedicle; attachment sites for muscles

Articular processes - paired protrusions above (superior) and below (inferior) the junction of the pedicles and laminae; form the synovial joints between vertebrae

Costal facets - articular surfaces above (superior) and below (inferior) the body of a thoracic vertebra for articulation with heads of the ribs

Transverse costal facet - articular surface on transverse process of a thoracic vertebra for articulation with the tubercle of a rib




Thoracic Cage


Sternum: Breastbone; flat narrow bone formed by fusion of the manubrium, body, and xiphoid process; forms middle part of anterior wall of thorax; articulates with clavicle and cartilages of first seven ribs.

Parts and Markings:

Manubrium - flat, handle-like, upper portion of the sternum

Body - middle and largest portion of the sternum

Xiphoid process - sword-shaped hyaline cartilage at lower end of the sternum; ossifies in adulthood

Clavicular notches - articulates with the clavicles at upper surfaces of the manubrium

Sternal angle - junction of the manubrium and body of the sternum at the level of the second costal cartilage


Ribs: 12 pairs of elongated curved bones that form the main portion of the thoracic cage.

Parts and Markings:

Tubercle - knob on posterior surface at junction of neck and shaft; articulates with the transverse process of the corresponding vertebra

Head - rounded medial extremity with facets that articulate with the costal facets on the bodies of the corresponding vertebrae

True ribs - Vertebrosternal ribs 1-7 that articulate directly with the sternum

False ribs - Ribs 8-12; includes the vertebrochondral ribs 8-10 that connect indirectly with sternum through the costal cartilage of rib 7, and the vertebral ribs 11-12 (floating ribs) that are not attached anteriorly.

Costal cartilage - Hyaline cartilage that forms the anterior continuation of a rib; articulates with the sternum.

Intercostal Spaces - Interval between the ribs, occupied by intercostal muscles, veins, arteries, and nerves.




Pectoral Girdle and Upper Limb Bones


Clavicle: Collarbone; extends horizontally across the superior anterior thorax.

Markings:

Acromial end - lateral flattened end; articulates with acromion of the scapula to form part of the shoulder joint

Sternal end - medial conical end; articulates with the clavicular notches of the manubrium

Conoid tubercle - attachment site for the conoid ligament, on the lateral posteroinferior surface, that connects to the coracoid process of the scapula


Scapula: Shoulder blade; lies over the ribs at the posterior thorax; forms part of the shoulder joint.

Markings:

Glenoid cavity - articulates with head of the humerus to form the ball-and-socket shoulder joint

Acromion - articulates with acromial end of the clavicle to form part of the shoulder joint

Coracoid process - attachment site for the biceps brachii muscle of the arm, and the conoid ligament that connects to the clavicle

Spine - prominant ridge; runs diagonally across the posterior surface of the body of the scapula


Humerus: Arm bone.

Markings:

Head - proximal hemispheric extremity; articulates with glenoid cavity of the scapula to form shoulder joint

Tubercles (Greater and Lesser) - attachment sites for scapular muscles

Deltoid tuberosity - attachment site for deltoid muscle of the shoulder

Radial fossa - receives head of the radius when the forearm is flexed

Capitulum - distal lateral ball-like condyle; articulates with head of the radius

Olecranon fossa - posterior distal depression; receives olecranon processes of ulna when forearm is extended

Coronoid fossa - anterior distal depression; receives coronoid processes of ulna when forearm is flexed

Trochlea - distal medial pulley-like condyle; articulates with trochlear notch of the ulna


Ulna: Medial forearm bone; forms elbow joint.

Markings:

Olecranon process - posterior elbow projection; grips trochlea of the humerus, forming the elbow joint

Coronoid process - anterior elbow projection; receives trochlea of the humerus when the forearm is flexed

Radial notch - concavity on lateral coronoid process; articulates with head of the radius

Trochlear notch - large semicircular notch between the olecranon and coronoid processes; articulates with the trochlea of humerus to form part of the elbow joint

Styloid process - distal medial pointed projection; attachment site for wrist ligament

Head - distal knob-like extremity; articulates with ulnar notch of the radius and the articular disk


Radius: Lateral forearm bone (thumb side); forms most of the wrist joints.

Markings:

Head - proximal disc-shaped extremity; superior surface articulates with capitulum of the humerus; medial surface articulates with radial notch of the ulna

Radial tuberosity - attachment site for the biceps brachii muscle

Styloid process - distal lateral pointed projection; attachment site for wrist ligaments

Ulnar notch - distal medial concave surface; articulates with head of the ulna


Carpus: Wrist bones; arranged in two rows of four bones each


Metacarpus: Palm bones; five bones between the wrist and fingers


Phalanges: Finger bones; two in digit 1 (thumb); three in digits 2-5




Pelvic Girdle and Lower Limb Bones


Coxal bones: Hip bones; the two coxal bone articulate with the sacrum to form the bony pelvis.

Parts and Markings:

Ilium - superior coxal bone

Ischium - inferior posterior coxal bone

Pubic bone - inferior anterior coxal bone

Pubic symphysis - fibrocartilage that forms anterior junction of the two coxal bones

Sacroiliac joint - articulation of auricular surface of ilium with the sacrum

Iliac crest - the hip; thickened superior margin of the ilium

Ischial tuberosity - weight-bearing point in the sitting position; attachment site for hamstring muscles

Acetabulum - lateral cup-shaped socket; articulates with head of femur to form the ball-and-socket hip joint

Pubic arch - inverted V-shaped arch inferior to pubic symphysis, over 90° in females, and about 60° in males

Pelvic brim - upper opening of true pelvis; wide oval-shape in females, and narrow heart-shape in males


Femur: Thigh bone; largest bone of the body.

Markings:

Head - proximal hemispheric extremity; articulates with acetabulum to form the ball-and-socket hip joint

Neck - constricted region distal to the head

Trochanters (Greater and Lesser) - attachment sites of thigh and buttock muscles

Gluteal tuberosity - attachment site of gluteus maximus muscle

Patellar surface - distal anterior groove; accommodates the patella

Condyles (Lateral and Medial) - articulate with corresponding condyles of the tibia


Patella: Kneecap; sesamoid bone lodged in the tendon of the quadriceps muscles; articulates with patellar surface of the femur; ligaments attach to the tibial tuberosity.


Tibia: Shinbone; medial leg bone; large weight-bearing bone.

Markings:

Condyles (Lateral and Medial) - articulate with corresponding condyles of the femur

Tibial tuberosity - proximal anterior elevation; attachment site of patellar ligament

Anterior border - the shin; sharp anterior ridge (also called anterior crest, or tibial crest)

Medial malleolus - forms the medial bulge of the ankle


Fibula: Lateral leg bone; stick-like bone that does not bear weight.

Markings:

Head - proximal end; articulates with undersurface of the lateral condyle of the tibia

Lateral malleolus - forms the lateral ankle bulge; articulates with the talus


Tarsus: Ankle bones; seven bones of the instep; the talus articulates with the tibia and fibula to form the ankle joint; the calcaneus forms the heel.


Metatarsus: Distal portion of the foot; five bones between the instep and toes.


Phalanges: Toe bones; two in digit 1 (great toe); three in digits 2-5.



References:

(1) Marieb, Elaine and Hoehn, K., 2013, Human Anatomy and Physiology, 9th Edition, Pearson.

(2) Tortora, Gerard and Derrickson, B., 2012, Principles of Anatomy and Physiology, 13th Edition, Wiley.

(3) Stedman’s Medical Dictionary, 28th Edition, 2007, Lippincott, Williams & Wilkins.

(4) Dorland's Illustrated Medical Dictionary, 31st Edition, 2009, Elsevier Inc.