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Published in Clare E. Milner, Functional Anatomy for Sport and Exercise, 2019
The only carpometacarpal joint with any significant movement is that of the thumb – the first metacarpal. The movements permitted at this saddle joint are flexion and extension in the plane of the palm of the hand, abduction and adduction in a plane perpendicular to the palm of the hand, and opposition. The opposable thumb gives the hand its grasping ability by enabling the tip of the thumb to come into contact with the palmar surfaces of the fingers when they are slightly flexed. The ellipsoidal metacarpophalangeal joints, easily recognizable as the knuckles of the hand, also allow significant movement of the digits. This joint is capable of flexion and extension, abduction and adduction, and circumduction. Finally, the interphalangeal hinge joints of the fingers and thumb are capable of a large amount of flexion, enabling the hand to make a fist, and a little extension.
Biomechanics of the Spine
Published in Manoj Ramachandran, Tom Nunn, Basic Orthopaedic Sciences, 2018
Amir Ali Narvani, Arun Ranganathan, Brian Hsu, Lester Wilson
The subaxial cervical vertebrae articulate with each other through the intervertebral discs in front and the facet joints posteriorly. The end plates of subjacent vertebrae are angled forwards and downwards favouring flexion–extension in this region of the cervical spine. The posterior ends of the vertebral bodies form an ellipsoid joint between the convexity of the vertebral body above and the concavity of the posterior end of the body below; this culminates in the uncinate processes bilaterally. The intervertebral joints constitute a saddle joint that permits flexion–extension in the sagittal plane, and facetal sliding facilitates side-to-side rocking motion in the transverse plane. Rotation is possible in a plane perpendicular to the axis of the facet joints and the cervical facets are normally oriented 45° to the transverse plane of the vertebral bodies. Any horizontal rotation leads to lateral flexion of the vertebral body towards the side of rotation. The structure of the intervertebral disc also varies in the cervical spine, in that it lacks a posterior annulus except for a few longitudinal fibres in the median plane. Transverse fissures are a normal feature in cervical discs, which also assist axial rotation.
Skeletal System
Published in David Sturgeon, Introduction to Anatomy and Physiology for Healthcare Students, 2018
Although synovial joints share the same characteristics, there are six different types of joint which are classified by their shape and range of movement. For example, there are ball and socket joints located at the shoulder and hip, hinge joints located at the elbow and knee, pivot joints located at the top of the neck (between the atlas and axis bones), saddle joints located between the base of the thumb and trapezium (carpal) bone of the wrist, gliding joints located between the carpal and tarsal bones and – finally – condyloid bones located between the distal radius and proximal carpal bones. Range of movement is summarised in Table 4.1.
Ciliated cell observation by SEM on the surface of human incudo-malleolar-joint articular cartilage: are they a new chondrocyte phenotype?
Published in Acta Oto-Laryngologica, 2019
Michela Relucenti, Selenia Miglietta, Edoardo Covelli, Pietro Familiari, Ezio Battaglione, Giuseppe Familiari, Maurizio Barbara
The middle ear cavity is a bony space in the petrous part of the temporal bone where the ossicular chain (malleus, incus, stapes) is also accommodated. It communicates with the nasopharynx via the Eustachian tube and with the mastoid air–cell complex via the antrum cell. In addition, the mucosa lining the tympanic cavity, consisting in a flattened squamous epithelium with a thin lamina propria, closely adherent to the underlying bone, is in continuation with those of the Eustachian tube and of the mastoid air cells. This mucosal lining envelops the ossicular chain, including the incus, the middle component of the ossicular chain which articulates with the malleus by means of a saddle joint containing an intra-articular disc. The human incudo-malleolar joint is a non-weight-bearing joint described in detail by Gussen [1] and Stockwell [2] using light microscopy.
A musculoskeletal model of the hand and wrist: model definition and evaluation
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2018
M. Mirakhorlo, N. Van Beek, M. Wesseling, H. Maas, H. E. J. Veeger, I. Jonkers
The MCP joints have two degrees of freedom, allowing for flexion–extension and abduction–adduction. The PIP and distal interphalangeal (DIP) joints have one degree of freedom (flexion–extension). The thumb carpal-metacarpal (CMC) joint is modeled as a saddle joint connecting metacarpal bones to the carpals with two degrees of freedom (flexion–extension and abduction–adduction). The carpal segment, linked to the ulna as a saddle joint, allows the flexion–extension and radial/ulnar deviation relative to the wrist. This simplified modeling of wrist, in contrast to more realistic modeling (Fischli et al. 2009; Majors and Wayne 2011) that accounts for complex kinematics of the human wrist, may affect the outcomes of the model, as elaborated in the limitation section of discussion. A joint with one degree of freedom connects the ulna and radius enabling forearm pronation/supination.