Table 1.
Overview of cervical musculature.
Table 2.
Overview of frequency of muscle examination in the preparations.
Preparation 1: male, three years old, fresh and 70% ethanol. Preparation 2: female, one year old, perfused with 4% paraformaldehyde. Preparation 3: male, thirteen years old, fresh and 70% ethanol. Preparation 4: female, one year old, 70% ethanol. Preparation 5: male, two years old, 70% ethanol. “0” means not examined, “1” means examined.
Table 3.
Overview of identified muscles in T. f. pratincola with origin and insertion.
Fig 1.
A) Dorsolateral view of M. complexus sinister (c) held up with tweezers; fleshy insertion site on the cranium (cr) and originating muscle slips from cervical vertebrae C4-C6 are indicated by asterisks. The M. splenius capitis (sc) and M. rectus capitis lateralis (rcl) are indicated as a reference. The coordinate system indicates dorsal (D), caudal (Ca), ventral (V) and cranial (Cr). Scale bar represents one centimetre. B) Dorsal view on both M. complexus sinister and dexter (c) showing variation between the sides. The insertion of the M. complexus dexter was separated from the cranium (cr). Individual slips (attaching to C4-C6) are indicated by asterisks. The M. complexus sinister has an extra slip originating from C3. The coordinate system indicates lateral (L), caudal (Ca) and cranial (Cr). Scale bar represents one centimetre. C) Insertion site of M. complexus indicated with red line in three-dimensional model of a part of the skull from dorsal view. Foramen magnum (FM) and condylus occipitalis (CO) are indicated. Scale bar represents one millimetre (adapted from [5]). D-F) Origins of the M. complexus indicated with red circles in the three-dimensional models of the vertebrae of T. f. pratincola; vertebrae (C4-C6) from lateral left view, cranial is to the left. Scale bars in D-F represent one millimetre (adapted from [5]). G) Connection diagram from lateral view of M. complexus in T. f. pratincola; origin and insertion sites are connected with lines representing the muscle slips. H) Connection diagram from dorsal view of M. complexus in which the muscle attachment sites are indicated with red circles and are interconnected by a line representing the muscle.
Fig 2.
A) Dorsal view on both M. biventer cervicis sinister and dexter. The two sides are placed apart by needles, but in situ located dorsally from the M. longus colli dorsalis (lcd). M. biventer cervicis originates from the dorsocaudally located aponeurosis notarii (an), which is partly covered by thoracic muscles (tm). The cranial (cr) and caudal (ca) bellies are connected by the intersectio tendinea (it). M. biventer cervicis inserts at the cranium, ventral from the insertion of the M. complexus (c). Coordinate system indicates lateral (L), caudal (Ca) and cranial (Cr). Scale bar represents one centimetre. B) Insertion site of the M. biventer cervicis on the skull (red line) as seen from dorsal (D) view. Foramen magnum (FM) and condylus occipitalis (CO) are indicated in the skull. Scale bar represents one millimetre (adapted from [5]). C) Connection diagram from lateral view of M. biventer cervicis in T. f. pratincola; origin and insertion sites are connected with lines representing the muscle slips; broken line represents intersectio tendinea. The heavy line above C14 represents aponeurosis notarii. D) Connection diagram from dorsal view of M. biventer cervicis, in which the muscle attachment sites are indicated with red circles and are interconnected by a line representing the muscle and broken lines indicating intersectio tendinea. The heavy line above C14 represent the aponeurosis notarii.
Fig 3.
A) Dorsal view on M. splenius capitis of T. f. pratincola. The origin from C2 is indicated by an asterisk. The left cranial belly of the M. biventer cervicis was removed to expose the M. splenius capitis, whereas the right cranial belly of the M. biventer cervicis (bc) was left intact and flapped back cranially. From the M. splenius capitis a pars medialis (m) and a pars lateralis (l) could be distinguished and were separated by a thin fascial sheath, which is indicated by a broken line in the M. splenius capitis sinister. The M. splenius capitis inserts ventrally to the M. biventer cervicis (bc) and medially to the M. rectus capitis lateralis (rcl). Coordinate system indicates cranial (Cr), lateral (L) and caudal (Ca). Scale bar represents one centimetre. B) Dorsal view on the skull with indicated insertion sites of the M. splenius capitis, pars medialis (m) and pars lateralis (l). Foramen magnum (FM) and condylus occipitalis (CO) are indicated. Scale bar represents one millimetre (adapted from [5]). C-D) Originating muscle attachment sites of the M. splenius capitis (coloured areas) in the three-dimensional models of the vertebrae of T. f. pratincola. In D the red area represents the origin of the pars medialis and the white area the origin of the pars lateralis. View on the vertebrae (C1-C2) from lateral left; cranial is left. Scale bars in C-D represent one millimetre (adapted from: [5]). E) Connection diagram from lateral view of M. splenius capitis in T. f. pratincola; origin and insertion sites are connected with lines representing the muscle slips. F) Connection diagram from dorsal view of M. splenius capitis in which the muscle attachment sites are indicated with red circles and are interconnected by a line representing the muscle slips.
Fig 4.
A) Dorsolateral view on the M. rectus capitis lateralis (rcl). The muscle originates ventrally from C3-C5 (indicated by asterisks), wraps around the neck and inserts on the cranium. The M. rectus capitis lateralis is located superficially from the M. splenius capitis (sc) and M. rectus capitis dorsalis (rcd). Coordinate system indicates ventral (V), cranial (Cr), dorsal (D) and caudal (Ca). Scale bar represents one centimetre. B) Connection diagram from lateral view of M. rectus capitis lateralis in T. f. pratincola; origin and insertion sites are connected with lines representing the muscle slips, broken lines indicate tendinous parts. C) Connection diagram from dorsal view of M. rectus capitis lateralis in which the muscle attachment sites are indicated with red circles and are interconnected by a line representing the muscle slips. The blue lines represent ventrally located slips, which are thus actually behind the field of vision in a dorsal view. D) Dorsal view on the skull with indicated insertion sites of the M. rectus capitis lateralis. Foramen magnum (FM) and condylus occipitalis (CO) are indicated. Scale bar represents one millimetre (adapted from [5]). E-G) Origins of the M. rectus capitis lateralis indicated with red ellipses in the three-dimensional models of the vertebrae of T. f. pratincola from ventral view (cranial is on top) of vertebrae (C3-C5). Scale bars in E-G represent one millimetre (adapted from [5]).
Fig 5.
A) Craniocervical region from ventral view showing the M. rectus capitis ventralis from which the M. rectus capitis ventralis sinister, pars lateralis (l) and pars medialis (m) are bordered by a broken line. Coordinate system indicates lateral (L), caudal (Ca) and cranial (Cr). Scale bar represents one centimetre. B) Skull from caudal view with indicated foramen magnum (FM) and insertion site of M. rectus capitis ventralis on the os basioccipitale (red line). Scale bar represents one millimetre. C-G) Muscle attachment sites of the M. rectus capitis ventralis indicated with red ellipses in the three-dimensional models of the vertebrae of T. f. pratincola: ventral view (cranial is on top). Scale bars in C-G represent one millimetre (adapted from [5]). H) Connection diagram from lateral view of M. rectus capitis ventralis in T. f. pratincola; origin and insertion sites are connected with lines representing the muscle slips. I) Connection diagram from dorsal view of M. rectus capitis ventralis in which the muscle attachment sites are indicated with red circles and are interconnected by a line representing the muscle slips.
Fig 6.
A) Lateral view on M. rectus capitis dorsalis. The insertion points on the cranium are indicated by asterisks. Note the parallel orientation of the four muscles (indicated with arrowheads). The slips of the M. rectus capitis dorsalis are located deeply from the M. rectus capitis lateralis (rcl). Coordinate system indicates dorsal (D), caudal (Ca), ventral (V) and cranial (Cr). Scale bar represents one centimetre. B) Skull from caudal view with indicated foramen magnum (FM), and insertion sites of M. rectus capitis dorsalis indicated with red filled circles. C-F) Origin sites of M. rectus capitis dorsalis indicated with red circles in the three-dimensional models of the vertebrae of T. f. pratincola: lateral left view (cranial is left). Scale bars in C-F represent one millimetre (adapted from [5]). G) Connection diagram from lateral view of T. f. pratincola; origin and insertion sites are connected with lines representing the muscle slips.
Fig 7.
M. longus colli dorsalis overview.
Dorsal view on M. longus colli dorsalis: pars cranialis (bordered by solid line) is located cranially and connected to the more caudally located pars caudalis by the tendo axialis (ta). The pars profunda (surrounded by dotted rectangle) is located ventrally from the pars caudalis. All parts are located ventrally from the M. biventer cervicis (bc). Cranium (cr) and aponeurosis notarii (an) are indicated for clarity. Coordinate system indicates lateral (L), caudal (Ca) and cranial (Cr). Scale bar represents one centimetre.
Fig 8.
M. longus colli dorsalis, pars caudalis.
A) Lateral view. M. longus colli dorsalis, pars caudalis is located ventrally from the M. biventer cervicis (bc). The pars caudalis (ca) originates from the aponeurosis notarii (an) with one slip running cranially. It becomes tendinously (tendo axialis, ta) before insertion to C2 (indicated by an asterisk). The slips of the pars cranialis (cr) insert to the tendo axialis (ta). Coordinate system indicates dorsal (D), caudal (Ca), ventral (V) and cranial (Cr). Scale bar represents one centimetre. B-I) Muscle attachment sites of the M. longus colli dorsalis, pars caudalis indicated with red areas in the three-dimensional models of the vertebrae of T. f. pratincola: lateral view. Cranial is to the left. Scale bars in B-I represent one millimetre (adapted from: [5]). J) Connection diagram from lateral view of M. longus colli dorsalis, pars caudalis in T. f. pratincola; origin and insertion sites are connected with lines representing the muscle slips and broken line represents tendinous parts, heavy line represents aponeurosis notarii. K) Connection diagram from dorsal view of M. longus colli dorsalis, pars caudalis in which the muscle attachment sites are indicated with red circles and are interconnected by a line representing the muscle slips. The heavy lines represent the aponeurosis notarii.
Fig 9.
M. longus colli dorsalis, pars cranialis.
A) Dorsal view on M. longus colli dorsalis, pars cranialis. Vertebrae numbers are indicated (C2-C7). The slips from the pars cranialis insert to the tendo axialis (ta) from a pars caudalis (ca) slip. The lateral processus of C2, which serve as insertion point for the tendo axialis are indicated with broken lines. The M. interspinalis (is), M. splenius capitis (sc) and M. longus colli dorsalis, pars profunda (pr) are indicated for reference. Coordinate system indicates lateral (L), caudal (Ca) and cranial (Cr). Scale bar represents one centimetre. B-G) Muscle attachment sites of the M. longus colli dorsalis, pars cranialis indicated with red circles in the three-dimensional models of the vertebrae of T. f. pratincola from dorsal view (cranial is on top). Scale bars in B-G represent one millimetre (adapted from [5]). H) Connection diagram from lateral view of M. longus colli dorsalis, pars cranialis in T. f. pratincola; origin and insertion sites are connected with lines representing the muscle slips, broken lines represent the tendo axialis. The arrowhead indicates that this muscle slip (from the M. longus colli dorsalis, pars caudalis) runs further caudally. I) Connection diagram from dorsal view of M. rectus capitis ventralis in which the muscle attachment sites are indicated with red circles and are interconnected by a line representing the muscle slips. Broken lines indicate the tendo axialis. The arrowheads indicate that this muscle slip (from the M. longus colli dorsalis, pars caudalis) runs further caudally.
Fig 10.
M. longus colli dorsalis, pars profunda.
A) Dorsal view on M. longus colli dorsalis, pars profunda. Due to its deep location more dorsally located muscle slips were spread apart by needles. The numbers of the cervical vertebrae are indicated (C6-C12). Coordinate system indicates lateral (L), caudal (Ca) and cranial (Cr). Scale bar represents one centimetre. B-I) Attachment sites of the individual M. longus colli dorsalis, pars profunda slips. Vertebrae in B-E are shown in dorsal view in which cranial is on top, vertebrae in F-I are shown in lateral view in which left is cranial. The colours of the circles indicate to which slip the attachment site belongs and corresponds with the colours as used in the connection diagram (J). Scale bars in B-I represent one millimetre (adapted from: [5]). J) Connection diagram from lateral view of M. longus colli dorsalis, pars profunda in T. f. pratincola; origin and insertion sites are connected with lines representing the muscle slips. Colours are given for clarity and represent slips from the same muscle and correspond to the colours in B-I.
Fig 11.
A) Dorsal view on M. interspinalis (is) spanning the space between the processus spinosus of C2 (insertion) and C3 (origin) which are indicated by asterisks whereas the tori dorsales of C2 are indicated by circles with broken lines. The M. splenius capitis (sc), M. longus colli dorsalis, pars cranialis (cr) and a slip from the M. longus colli dorsalis, pars caudalis (ca) are indicated as a reference. Coordinate system indicates lateral (L), caudal (Ca) and cranial (Cr). Scale bar represents one centimetre. B-C) Muscle attachment sites of the M. interspinalis indicated with red circles in the three-dimensional models of the vertebrae of T. f. pratincola: lateral view (cranial is to the left). Scale bars represent one millimetre (adapted from [5]). D) Connection diagram from lateral view of the M. interspinalis origin and insertion sites are connected with a line representing the muscle. E) Connection diagram from dorsal view of M. interspinalis in which the muscle attachment sites are indicated with red circles and are interconnected by a line representing the muscle.
Fig 12.
A) Lateral view on M. longus colli ventralis. The muscle originates from T2 as indicated by an asterisk. Muscle starts fleshy and becomes aponeurotic and splits when it runs cranially. The aponeurotic parts can clearly be seen in the middle region. Coordinate system indicates dorsal (D), caudal (Ca), ventral (V) and cranial (Cr). Scale bar represents one centimetre. B-I) Muscle attachment sites of the M. longus colli ventralis indicated with red circles in the three-dimensional models of the vertebrae of T. f. pratincola: lateral left view (cranial is to the left). Scale bars represent one millimetre (adapted from [5]). J) Connection diagram from lateral view of M. longus colli ventralis in T. f. pratincola; origin and insertion sites are connected with lines representing the muscle slips, broken lines represent aponeurotic parts. K) Connection diagram from dorsal view of M. rectus capitis ventralis in which the muscle attachment sites are indicated with red circles and are interconnected by lines representing the muscle slips. The blue lines represent ventrally located slips, which are thus actually behind the field of vision in a dorsal view.
Fig 13.
Connection diagram of the cervical muscles as identified in T. f. pratincola from lateral view.
The head is represented as a rectangle and the fourteen cervical vertebrae and the first two thoracic vertebrae are represented as squares. The cervical vertebrae are numbered, and the consecutive numbers of the same region as defined by Krings et al. (2014) [5] are represented by the alternating use of bold and italic numbers. Osteological regions were defined as follows; region 1: C1, region 2: C2-C4, region 3: C5-C7, region 4: C8-C9, region 5: C10-C12 and region 6: C13-C14 [5]. The thoracic vertebrae were excluded from the regionalization [5]. Fleshy parts are indicated with solid lines; broken lines represent tendinous or aponeurotic parts. The heavy lines above C14, T1 and T2 represents the aponeurosis notarii. Colours are given for clarity and represent the individual muscles as listed below. Dorsally originating muscles: M. complexus (red), M. biventer cervicis (black), M. splenius capitis (purple), M. rectus capitis dorsalis (blue), M. longus colli dorsalis, pars caudalis (pink), M. longus colli dorsalis, pars cranialis (yellow), pars profunda (green), M. interspinalis (orange). Ventrally originating muscles: M. rectus capitis lateralis (yellow), M. rectus capitis ventralis (red), M. longus colli ventralis (black). Note that this figure represents an overview of the relative muscle positions. This figure does not represent precise attachment sites. These were already provided in Figs 1–12.
Fig 14.
Myology of T. f. pratincola indicated in a semi-diagrammatic reconstruction of the S-shaped neck.
Reconstruction of the back of the skull, the 14 cervical vertebrae and the first thoracic vertebra, the second thoracic vertebra is represented diagrammatically, because a three-dimensional model was lacking. The vertebrae are positioned in a natural S-shape which is based on X-ray images made from T. f. pratincola in rest [5]. The numbers in the cervical vertebrae represent the osteological regions as defined by Krings et al. (2014) [5]. Osteological regions were defined as follows; region 1: C1, region 2: C2-C4, region 3: C5-C7, region 4: C8-C9, region 5: C10-C12 and region 6: C13-C14 [5]. Fleshy parts are indicated with solid lines, broken lines represent tendinous or aponeurotic parts. The heavy lines above C14, T1 and T2 represent the aponeurosis notarii. Colours are given for clarity and represent the individual muscles as listed below. Dorsally originating muscles: M. complexus (red), M. biventer cervicis (black), M. splenius capitis (purple), M. rectus capitis dorsalis (blue), M. longus colli dorsalis, pars caudalis (pink), M. longus colli dorsalis, pars cranialis (yellow), pars profunda (green), M. interspinalis (orange). Ventrally originating muscles: M. rectus capitis lateralis (yellow), M. rectus capitis ventralis (red), M. longus colli ventralis (black). Note that this figure represents an overview of the relative muscle positions. This figure does not represent precise attachment sites. These were already provided in Figs 1–12.